/*******************************************************************************
 * Copyright (c) 2000, 2026 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.swt.graphics;

import java.util.*;

import org.eclipse.swt.*;
import org.eclipse.swt.internal.*;
import org.eclipse.swt.internal.cairo.*;
import org.eclipse.swt.internal.gtk.*;

/**
 * <code>TextLayout</code> is a graphic object that represents
 * styled text.
 * <p>
 * Instances of this class provide support for drawing, cursor
 * navigation, hit testing, text wrapping, alignment, tab expansion
 * line breaking, etc.  These are aspects required for rendering internationalized text.
 * </p><p>
 * Application code must explicitly invoke the <code>TextLayout#dispose()</code>
 * method to release the operating system resources managed by each instance
 * when those instances are no longer required.
 * </p>
 *
 * @see <a href="https://eclipse.dev/eclipse/swt/snippets/#textlayout">TextLayout, TextStyle snippets</a>
 * @see <a href="https://eclipse.dev/eclipse/swt/examples.html">SWT Example: CustomControlExample, StyledText tab</a>
 * @see <a href="https://eclipse.dev/eclipse/swt/">Sample code and further information</a>
 *
 * @since 3.0
 */
public final class TextLayout extends Resource {

	static class StyleItem {
		TextStyle style;
		int start;

		@Override
		public String toString () {
			return "StyleItem {" + start + ", " + style + "}";
		}
	}

	Font font;
	String text;
	int ascentInPoints, descentInPoints;
	int indent, wrapIndent, wrapWidth;
	int[] segments;
	char[] segmentsChars;
	int[] tabs;
	StyleItem[] styles;
	int stylesCount;
	long layout, context, attrList, selAttrList;
	int[] invalidOffsets;
	int verticalIndentInPoints;
	MetricsAdapter metricsAdapter = new MetricsAdapter();
	static final char LTR_MARK = '\u200E', RTL_MARK = '\u200F', ZWS = '\u200B', ZWNBS = '\uFEFF';

/**
 * Adapts necessary Pango APIs to enforce fixed line metrics (when set)
 */
private static class MetricsAdapter {
	private FontMetrics lineMetricsInPixels;

	/**
	 * Calculates Y offset from line metrics configured in
	 * {@link #lineMetricsInPixels} to real text position for painting.
	 */
	private int wantToRealInPango(PangoRectangle realMetrics) {
		int wantHeightInPixels = lineMetricsInPixels.getHeight();
		int realHeightInPixels = OS.PANGO_PIXELS(realMetrics.height);
		if (realHeightInPixels == wantHeightInPixels) {
			return 0;
		}

		// The idea is to preserve baseline location, this looks best.
		// This is the behavior documented in `TextLayout#setFixedLineMetrics()`.
		int wantAboveInPango = OS.PANGO_SCALE * lineMetricsInPixels.getAscent();
		int realAboveInPango = -realMetrics.y;
		return wantAboveInPango - realAboveInPango;
	}

	private int wantToRealInPango(long line) {
		PangoRectangle rect = new PangoRectangle();
		// Pango caches result, so the API is very cheap to call multiple times
		OS.pango_layout_line_get_extents(line, null, rect);
		return wantToRealInPango(rect);
	}

	public boolean isFixedMetrics() {
		return (lineMetricsInPixels != null);
	}

	public FontMetrics getFixedLineMetrics(Device device) {
		if (lineMetricsInPixels == null) {
			return null;
		}

		FontMetrics result = new FontMetrics();
		result.ascentInPoints = lineMetricsInPixels.ascentInPoints;
		result.descentInPoints = lineMetricsInPixels.descentInPoints;
		result.averageCharWidthInPoints =lineMetricsInPixels.averageCharWidthInPoints;

		return result;
	}

	public void setFixedLineMetrics(Device device, FontMetrics metrics) {
		if (metrics == null) {
			lineMetricsInPixels = null;
			return;
		}

		FontMetrics result = new FontMetrics();
		result.ascentInPoints = metrics.ascentInPoints;
		result.descentInPoints = metrics.descentInPoints;
		result.averageCharWidthInPoints = metrics.averageCharWidthInPoints;

		lineMetricsInPixels = result;
	}

	private void validateLayout (long layout) {
		// Pango caches result, so the API is very cheap to call multiple times
		if (OS.pango_layout_get_line_count(layout) > 1) {
			// Multi-line layouts (including word wrapping) are not yet supported.
			// Note that `StyledText` uses separate `TextLayout` for every line.
			SWT.error (SWT.ERROR_INVALID_ARGUMENT);
		}
	}

	public long gdk_pango_layout_get_clip_region (long layout, int x_origin, int y_origin, int[] index_ranges, int n_ranges) {
		// In order to get proper text clip, adjust Y in the same way
		// as in pango_cairo_show_layout()
		int yAdjustInPixels = 0;
		if (isFixedMetrics()) {
			validateLayout(layout);
			long line0 = OS.pango_layout_get_line(layout, 0);
			yAdjustInPixels = OS.PANGO_PIXELS(wantToRealInPango(line0));
		}

		long rgn = GDK.gdk_pango_layout_get_clip_region(layout, x_origin, y_origin + yAdjustInPixels, index_ranges, n_ranges);

		// Adjust region via intersecting with desired region
		if (isFixedMetrics()) {
			cairo_rectangle_int_t wantRect = new cairo_rectangle_int_t();
			// Use real x,width with desired y,height
			Cairo.cairo_region_get_extents(rgn, wantRect);
			wantRect.y = y_origin;
			wantRect.height = lineMetricsInPixels.getHeight();

			long limitRgn = Cairo.cairo_region_create_rectangle(wantRect);
			Cairo.cairo_region_intersect(rgn, limitRgn);
			Cairo.cairo_region_destroy(limitRgn);
		}

		return rgn;
	}

	public void pango_cairo_show_layout (long cairo, long layout, double x, double y) {
		int yAdjustInPixels = 0;
		if (isFixedMetrics()) {
			validateLayout(layout);
			long line0 = OS.pango_layout_get_line(layout, 0);
			yAdjustInPixels = OS.PANGO_PIXELS(wantToRealInPango(line0));
		}

		Cairo.cairo_move_to(cairo, x, y + yAdjustInPixels);
		OS.pango_cairo_show_layout (cairo, layout);
	}

	public void pango_layout_get_size (long layout, int[] width, int[] height) {
		OS.pango_layout_get_size(layout, width, height);

		if (isFixedMetrics()) {
			validateLayout(layout);
			height[0] = lineMetricsInPixels.getHeight();
		}
	}

	public void pango_layout_iter_get_line_extents (long iter, PangoRectangle ink_rect, PangoRectangle logical_rect) {
		OS.pango_layout_iter_get_line_extents(iter, ink_rect, logical_rect);

		if (isFixedMetrics()) {
			if (ink_rect != null) {
				// SWT doesn't use that, so I didn't implement
				SWT.error(SWT.ERROR_INVALID_ARGUMENT);
			}

			if (logical_rect != null) {
				logical_rect.height = OS.PANGO_SCALE * lineMetricsInPixels.getHeight();
			}
		}
	}

	public void pango_layout_line_get_extents (long line, PangoRectangle ink_rect, PangoRectangle logical_rect) {
		OS.pango_layout_line_get_extents(line, ink_rect, logical_rect);

		if (isFixedMetrics()) {
			if (ink_rect != null) {
				// SWT doesn't use that, so I didn't implement
				SWT.error(SWT.ERROR_INVALID_ARGUMENT);
			}

			if (logical_rect != null) {
				logical_rect.height = OS.PANGO_SCALE * lineMetricsInPixels.getHeight();
			}
		}
	}
}

/**
 * Constructs a new instance of this class on the given device.
 * <p>
 * You must dispose the text layout when it is no longer required.
 * </p>
 *
 * @param device the device on which to allocate the text layout
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if device is null and there is no current device</li>
 * </ul>
 *
 * @see #dispose()
 */
public TextLayout (Device device) {
	super(device);
	device = this.device;
	if (GTK.GTK4) {
		long fontMap = OS.pango_cairo_font_map_get_default ();
		context = OS.pango_font_map_create_context (fontMap);
	} else {
		context = GDK.gdk_pango_context_get();
	}
	if (context == 0) SWT.error(SWT.ERROR_NO_HANDLES);
	OS.pango_context_set_language(context, GTK.gtk_get_default_language());
	OS.pango_context_set_base_dir(context, OS.PANGO_DIRECTION_LTR);
	layout = OS.pango_layout_new(context);
	if (layout == 0) SWT.error(SWT.ERROR_NO_HANDLES);
	OS.pango_layout_set_font_description(layout, device.systemFont.handle);
	OS.pango_layout_set_wrap(layout, OS.PANGO_WRAP_WORD_CHAR);
	OS.pango_layout_set_tabs(layout, device.emptyTab);
	OS.pango_layout_set_auto_dir(layout, false);
	text = "";
	wrapWidth = ascentInPoints = descentInPoints = -1;
	styles = new StyleItem[2];
	styles[0] = new StyleItem();
	styles[1] = new StyleItem();
	stylesCount = 2;
	init();
}

void checkLayout() {
	if (isDisposed()) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
}

void computeRuns () {
	if (attrList != 0) return;
	String segmentsText = getSegmentsText();
	byte[] buffer = Converter.wcsToMbcs(segmentsText, false);
	OS.pango_layout_set_text (layout, buffer, buffer.length);
	attrList = OS.pango_attr_list_new();
	selAttrList = OS.pango_attr_list_new();
	// pango_attr_insert_hyphens_new function is available only on Pango 1.44.0+
	// pango_version (used for version check) encodes the version in an integer via
	// the following formula:
	// MAJOR*10000+MINOR*100+MICRO
	if ((1 * 10000 + 44 * 100 + 0) <= OS.pango_version()) {
		long hyphenAttr = OS.pango_attr_insert_hyphens_new(false);
		OS.pango_attr_list_insert(attrList, hyphenAttr);
		OS.pango_attr_list_insert(selAttrList, OS.pango_attribute_copy(hyphenAttr));
	}
	if (stylesCount == 2 && styles[0].style == null && ascentInPoints == -1 && descentInPoints == -1 && segments == null) {
		OS.pango_layout_set_attributes(layout, attrList);
		return;
	}
	long ptr = OS.pango_layout_get_text(layout);
	PangoAttribute attribute = new PangoAttribute();
	char[] chars = null;
	int segementsLength = segmentsText.length();
	int nSegments = segementsLength - text.length();
	int offsetCount = nSegments;
	int[] lineOffsets = null;

	// Set minimum line ascent/descent. Feature in Pango: glyphs affected
	// by `pango_attr_shape_new()` become invisible. Workaround: insert
	// additional control characters and shape these instead.
	boolean useMinAscentDescent = !metricsAdapter.isFixedMetrics() && (ascentInPoints != -1 || descentInPoints != -1);
	if (useMinAscentDescent && segementsLength > 0) {
		PangoRectangle rect = new PangoRectangle();
		if (ascentInPoints != -1) rect.y =  -(ascentInPoints * OS.PANGO_SCALE);
		rect.height = (Math.max(0, ascentInPoints) + Math.max(0, descentInPoints)) * OS.PANGO_SCALE;
		int lineCount = OS.pango_layout_get_line_count(layout);
		chars = new char[segementsLength + lineCount * 2];
		lineOffsets = new int [lineCount];
		int oldPos = 0, lineIndex = 0;
		PangoLayoutLine line = new PangoLayoutLine();
		while (lineIndex < lineCount) {
			long linePtr = OS.pango_layout_get_line(layout, lineIndex);
			OS.memmove(line, linePtr, PangoLayoutLine.sizeof);
			int bytePos = line.start_index;
			/* Note: The length in bytes of ZWS and ZWNBS are both equals to 3 */
			int offset = lineIndex * 6;
			long attr = OS.pango_attr_shape_new (rect, rect);
			OS.memmove (attribute, attr, PangoAttribute.sizeof);
			attribute.start_index = bytePos + offset;
			attribute.end_index = bytePos + offset + 3;
			OS.memmove (attr, attribute, PangoAttribute.sizeof);
			OS.pango_attr_list_insert(attrList, attr);
			OS.pango_attr_list_insert(selAttrList, OS.pango_attribute_copy(attr));
			attr = OS.pango_attr_shape_new (rect, rect);
			OS.memmove (attribute, attr, PangoAttribute.sizeof);
			attribute.start_index = bytePos + offset + 3;
			attribute.end_index = bytePos + offset + 6;
			OS.memmove (attr, attribute, PangoAttribute.sizeof);
			OS.pango_attr_list_insert(attrList, attr);
			OS.pango_attr_list_insert(selAttrList, OS.pango_attribute_copy(attr));
			int pos = (int)OS.g_utf16_pointer_to_offset(ptr, ptr + bytePos);
			chars[pos + lineIndex * 2] = ZWS;
			chars[pos + lineIndex * 2 + 1] = ZWNBS;
			segmentsText.getChars(oldPos, pos, chars,  oldPos + lineIndex * 2);
			lineOffsets[lineIndex] = pos + lineIndex * 2;
			oldPos = pos;
			lineIndex++;
		}
		segmentsText.getChars(oldPos, segementsLength, chars,  oldPos + lineIndex * 2);
		buffer = Converter.wcsToMbcs(chars, false);
		OS.pango_layout_set_text (layout, buffer, buffer.length);
		ptr = OS.pango_layout_get_text(layout);
		offsetCount += 2 * lineCount;
	} else {
		chars = new char[segementsLength];
		segmentsText.getChars(0, segementsLength, chars, 0);
	}
	invalidOffsets = new int[offsetCount];
	if (offsetCount > 0) {
		offsetCount = 0;
		int lineIndex = 0;
		int segmentCount = 0;
		for (int i = 0; i < chars.length; i++) {
			char c = chars[i];
			if (c == ZWS && lineOffsets != null && lineIndex < lineOffsets.length && i == lineOffsets[lineIndex]) {
				invalidOffsets[offsetCount++] = i;		//ZWS
				invalidOffsets[offsetCount++] = ++i;	//ZWNBS
				lineIndex++;
			} else if (segmentCount < nSegments && i - offsetCount == segments[segmentCount]) {
				invalidOffsets[offsetCount++] = i;
				segmentCount++;
			}
		}
	}
	int strlen = C.strlen(ptr);
	Font defaultFont = font != null ? font : device.systemFont;
	for (int i = 0; i < stylesCount - 1; i++) {
		StyleItem styleItem = styles[i];
		TextStyle style = styleItem.style;
		if (style == null) continue;
		int start = translateOffset(styleItem.start);
		int end = translateOffset(styles[i+1].start - 1);
		int byteStart = (int)(OS.g_utf16_offset_to_pointer(ptr, start) - ptr);
		int byteEnd = (int)(OS.g_utf16_offset_to_pointer(ptr, end + 1) - ptr);
		byteStart = Math.min(byteStart, strlen);
		byteEnd = Math.min(byteEnd, strlen);
		Font font = style.font;
		if (font != null && !font.isDisposed() && !defaultFont.equals(font)) {
			long attr = OS.pango_attr_font_desc_new (font.handle);
			OS.memmove (attribute, attr, PangoAttribute.sizeof);
			attribute.start_index = byteStart;
			attribute.end_index = byteEnd;
			OS.memmove (attr, attribute, PangoAttribute.sizeof);
			OS.pango_attr_list_insert(attrList, attr);
			OS.pango_attr_list_insert(selAttrList, OS.pango_attribute_copy(attr));
		}
		if (style.underline) {
			int underlineStyle = OS.PANGO_UNDERLINE_NONE;
			switch (style.underlineStyle) {
				case SWT.UNDERLINE_SINGLE:
					underlineStyle = OS.PANGO_UNDERLINE_SINGLE;
					break;
				case SWT.UNDERLINE_DOUBLE:
					underlineStyle = OS.PANGO_UNDERLINE_DOUBLE;
					break;
				case SWT.UNDERLINE_SQUIGGLE:
				case SWT.UNDERLINE_ERROR:
					underlineStyle = OS.PANGO_UNDERLINE_ERROR;
					break;
				case SWT.UNDERLINE_LINK: {
					if (style.foreground == null) {
						// Bug 497071: use COLOR_LINK_FOREGROUND for StyledText links
						long attr;
						GdkRGBA linkRGBA = device.getSystemColor(SWT.COLOR_LINK_FOREGROUND).handle;
						// Manual conversion since PangoAttrColor is a special case.
						// It uses GdkColor style colors but is supported on GTK3.
						attr = OS.pango_attr_foreground_new((short)(linkRGBA.red * 0xFFFF),
								(short)(linkRGBA.green * 0xFFFF), (short)(linkRGBA.blue * 0xFFFF));
						OS.memmove (attribute, attr, PangoAttribute.sizeof);
						attribute.start_index = byteStart;
						attribute.end_index = byteEnd;
						OS.memmove (attr, attribute, PangoAttribute.sizeof);
						OS.pango_attr_list_insert(attrList, attr);
					}
					underlineStyle = OS.PANGO_UNDERLINE_SINGLE;
					break;
				}
			}
			long attr = OS.pango_attr_underline_new(underlineStyle);
			OS.memmove(attribute, attr, PangoAttribute.sizeof);
			attribute.start_index = byteStart;
			attribute.end_index = byteEnd;
			OS.memmove(attr, attribute, PangoAttribute.sizeof);
			OS.pango_attr_list_insert(attrList, attr);
			OS.pango_attr_list_insert(selAttrList, OS.pango_attribute_copy(attr));
			if (style.underlineColor != null) {
				GdkRGBA rgba = style.underlineColor.handle;
				attr = OS.pango_attr_underline_color_new((short)(rgba.red * 0xFFFF),
						(short)(rgba.green * 0xFFFF), (short)(rgba.blue * 0xFFFF));
				if (attr != 0) {
					OS.memmove(attribute, attr, PangoAttribute.sizeof);
					attribute.start_index = byteStart;
					attribute.end_index = byteEnd;
					OS.memmove(attr, attribute, PangoAttribute.sizeof);
					OS.pango_attr_list_insert(attrList, attr);
					OS.pango_attr_list_insert(selAttrList, OS.pango_attribute_copy(attr));
				}
			}
		}
		if (style.strikeout) {
			long attr = OS.pango_attr_strikethrough_new(true);
			OS.memmove(attribute, attr, PangoAttribute.sizeof);
			attribute.start_index = byteStart;
			attribute.end_index = byteEnd;
			OS.memmove(attr, attribute, PangoAttribute.sizeof);
			OS.pango_attr_list_insert(attrList, attr);
			OS.pango_attr_list_insert(selAttrList, OS.pango_attribute_copy(attr));
			if (style.strikeoutColor != null) {
				GdkRGBA rgba = style.strikeoutColor.handle;
				attr = OS.pango_attr_strikethrough_color_new((short)(rgba.red * 0xFFFF),
						(short)(rgba.green * 0xFFFF), (short)(rgba.blue * 0xFFFF));
				if (attr != 0) {
					OS.memmove(attribute, attr, PangoAttribute.sizeof);
					attribute.start_index = byteStart;
					attribute.end_index = byteEnd;
					OS.memmove(attr, attribute, PangoAttribute.sizeof);
					OS.pango_attr_list_insert(attrList, attr);
					OS.pango_attr_list_insert(selAttrList, OS.pango_attribute_copy(attr));
				}
			}
		}
		Color foreground = style.foreground;
		if (foreground != null && !foreground.isDisposed()) {
			long attr;
			GdkRGBA rgba = foreground.handle;
			attr = OS.pango_attr_foreground_new((short)(rgba.red * 0xFFFF),
					(short)(rgba.green * 0xFFFF), (short)(rgba.blue * 0xFFFF));
			OS.memmove (attribute, attr, PangoAttribute.sizeof);
			attribute.start_index = byteStart;
			attribute.end_index = byteEnd;
			OS.memmove (attr, attribute, PangoAttribute.sizeof);
			OS.pango_attr_list_insert(attrList, attr);
		}
		Color background = style.background;
		if (background != null && !background.isDisposed()) {
			long attr;
			GdkRGBA rgba = background.handle;
			attr = OS.pango_attr_background_new((short)(rgba.red * 0xFFFF),
					(short)(rgba.green * 0xFFFF), (short)(rgba.blue * 0xFFFF));
			OS.memmove (attribute, attr, PangoAttribute.sizeof);
			attribute.start_index = byteStart;
			attribute.end_index = byteEnd;
			OS.memmove (attr, attribute, PangoAttribute.sizeof);
			OS.pango_attr_list_insert(attrList, attr);
		}
		GlyphMetrics metrics = style.metrics;
		if (metrics != null) {
			PangoRectangle rect = new PangoRectangle();
			rect.y =  -(metrics.ascent * OS.PANGO_SCALE);
			rect.height = (metrics.ascent + metrics.descent) * OS.PANGO_SCALE;
			rect.width = metrics.width * OS.PANGO_SCALE;
			long attr = OS.pango_attr_shape_new (rect, rect);
			OS.memmove (attribute, attr, PangoAttribute.sizeof);
			attribute.start_index = byteStart;
			attribute.end_index = byteEnd;
			OS.memmove (attr, attribute, PangoAttribute.sizeof);
			OS.pango_attr_list_insert(attrList, attr);
			OS.pango_attr_list_insert(selAttrList, OS.pango_attribute_copy(attr));
		}
		int rise = style.rise;
		if (rise != 0) {
			long attr = OS.pango_attr_rise_new (rise * OS.PANGO_SCALE);
			OS.memmove (attribute, attr, PangoAttribute.sizeof);
			attribute.start_index = byteStart;
			attribute.end_index = byteEnd;
			OS.memmove (attr, attribute, PangoAttribute.sizeof);
			OS.pango_attr_list_insert(attrList, attr);
			OS.pango_attr_list_insert(selAttrList, OS.pango_attribute_copy(attr));
		}
	}
	OS.pango_layout_set_attributes(layout, attrList);
}

int[] computePolyline(int left, int top, int right, int bottom) {
	int height = bottom - top; // can be any number
	int width = 2 * height; // must be even
	int peaks = Compatibility.ceil(right - left, width);
	if (peaks == 0 && right - left > 2) {
		peaks = 1;
	}
	int length = ((2 * peaks) + 1) * 2;
	if (length < 0) return new int[0];

	int[] coordinates = new int[length];
	for (int i = 0; i < peaks; i++) {
		int index = 4 * i;
		coordinates[index] = left + (width * i);
		coordinates[index+1] = bottom;
		coordinates[index+2] = coordinates[index] + width / 2;
		coordinates[index+3] = top;
	}
	coordinates[length-2] = left + (width * peaks);
	coordinates[length-1] = bottom;
	return coordinates;
}

@Override
void destroy() {
	font = null;
	text = null;
	styles = null;
	freeRuns();
	segments = null;
	segmentsChars = null;
	if (layout != 0) OS.g_object_unref(layout);
	layout = 0;
	if (context != 0) OS.g_object_unref(context);
	context = 0;
}

/**
 * Draws the receiver's text using the specified GC at the specified
 * point.
 *
 * @param gc the GC to draw
 * @param x the x coordinate of the top left corner of the rectangular area where the text is to be drawn
 * @param y the y coordinate of the top left corner of the rectangular area where the text is to be drawn
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the gc is null</li>
 * </ul>
 */
public void draw(GC gc, int x, int y) {
	drawInPixels(gc, x, y, -1, -1, null, null, 0);
}

/**
 * Draws the receiver's text using the specified GC at the specified
 * point.
 *
 * @param gc the GC to draw
 * @param x the x coordinate of the top left corner of the rectangular area where the text is to be drawn
 * @param y the y coordinate of the top left corner of the rectangular area where the text is to be drawn
 * @param selectionStart the offset where the selections starts, or -1 indicating no selection
 * @param selectionEnd the offset where the selections ends, or -1 indicating no selection
 * @param selectionForeground selection foreground, or NULL to use the system default color
 * @param selectionBackground selection background, or NULL to use the system default color
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the gc is null</li>
 * </ul>
 */
public void draw(GC gc, int x, int y, int selectionStart, int selectionEnd, Color selectionForeground, Color selectionBackground) {
	checkLayout ();
	drawInPixels(gc, x, y, selectionStart, selectionEnd, selectionForeground, selectionBackground, 0);
}

/**
 * Draws the receiver's text using the specified GC at the specified
 * point.
 * <p>
 * The parameter <code>flags</code> can include one of <code>SWT.DELIMITER_SELECTION</code>
 * or <code>SWT.FULL_SELECTION</code> to specify the selection behavior on all lines except
 * for the last line, and can also include <code>SWT.LAST_LINE_SELECTION</code> to extend
 * the specified selection behavior to the last line.
 * </p>
 * @param gc the GC to draw
 * @param x the x coordinate of the top left corner of the rectangular area where the text is to be drawn
 * @param y the y coordinate of the top left corner of the rectangular area where the text is to be drawn
 * @param selectionStart the offset where the selections starts, or -1 indicating no selection
 * @param selectionEnd the offset where the selections ends, or -1 indicating no selection
 * @param selectionForeground selection foreground, or NULL to use the system default color
 * @param selectionBackground selection background, or NULL to use the system default color
 * @param flags drawing options
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the gc is null</li>
 * </ul>
 *
 * @since 3.3
 */
public void draw(GC gc, int x, int y, int selectionStart, int selectionEnd, Color selectionForeground, Color selectionBackground, int flags) {
	checkLayout ();
	drawInPixels(gc, x, y, selectionStart, selectionEnd, selectionForeground, selectionBackground, flags);
}
void drawInPixels(GC gc, int x, int y, int selectionStart, int selectionEnd, Color selectionForeground, Color selectionBackground, int flags) {
	checkLayout ();
	computeRuns();
	if (gc == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
	if (gc.isDisposed()) SWT.error(SWT.ERROR_INVALID_ARGUMENT);
	if (selectionForeground != null && selectionForeground.isDisposed()) SWT.error(SWT.ERROR_INVALID_ARGUMENT);
	if (selectionBackground != null && selectionBackground.isDisposed()) SWT.error(SWT.ERROR_INVALID_ARGUMENT);
	gc.checkGC(GC.FOREGROUND);
	int length = text.length();
	x += Math.min (indent, wrapIndent);
	y += getScaledVerticalIndent();
	boolean hasSelection = selectionStart <= selectionEnd && selectionStart != -1 && selectionEnd != -1;
	GCData data = gc.data;
	long cairo = data.cairo;
	boolean extent = false;
	if ((flags & (SWT.FULL_SELECTION | SWT.DELIMITER_SELECTION)) != 0 && (hasSelection || (flags & SWT.LAST_LINE_SELECTION) != 0)) {
		long [] attrs = new long [1];
		int[] nAttrs = new int[1];
		PangoLogAttr logAttr = new PangoLogAttr();
		PangoRectangle rect = new PangoRectangle();
		int lineCount = OS.pango_layout_get_line_count(layout);
		long ptr = OS.pango_layout_get_text(layout);
		long iter = OS.pango_layout_get_iter(layout);
		if (selectionBackground == null) selectionBackground = device.getSystemColor(SWT.COLOR_LIST_SELECTION);
		Cairo.cairo_save(cairo);
		GdkRGBA rgba = selectionBackground.handle;
		Cairo.cairo_set_source_rgba(cairo, rgba.red, rgba.green, rgba.blue, rgba.alpha);
		int lineIndex = 0;
		do {
			int lineEnd;
			metricsAdapter.pango_layout_iter_get_line_extents(iter, null, rect);
			if (OS.pango_layout_iter_next_line(iter)) {
				int bytePos = OS.pango_layout_iter_get_index(iter);
				lineEnd = (int)OS.g_utf16_pointer_to_offset(ptr, ptr + bytePos);
			} else {
				lineEnd = (int)OS.g_utf16_strlen(ptr, -1);
			}
			if (lineIndex == lineCount - 1 && (flags & SWT.LAST_LINE_SELECTION) != 0) {
				extent = true;
			} else {
				if (attrs[0] == 0) OS.pango_layout_get_log_attrs(layout, attrs, nAttrs);
				OS.memmove(logAttr, attrs[0] + lineEnd * PangoLogAttr.sizeof, PangoLogAttr.sizeof);
				if (!logAttr.is_line_break) {
					if (selectionStart <= lineEnd && lineEnd <= selectionEnd) extent = true;
				} else {
					if (selectionStart <= lineEnd && lineEnd < selectionEnd && (flags & SWT.FULL_SELECTION) != 0) {
						extent = true;
					}
				}
			}
			if (extent) {
				int lineX = x + OS.PANGO_PIXELS(rect.x) + OS.PANGO_PIXELS(rect.width);
				int lineY = y + OS.PANGO_PIXELS(rect.y);
				int height = OS.PANGO_PIXELS(rect.height);
				if (ascentInPoints != -1 && descentInPoints != -1) {
					height = Math.max (height, ascentInPoints + descentInPoints);
				}
				height += OS.PANGO_PIXELS(OS.pango_layout_get_spacing(layout));
				int width = (flags & SWT.FULL_SELECTION) != 0 ? 0x7fff : height / 3;
				Cairo.cairo_rectangle(cairo, lineX, lineY, width, height);
				Cairo.cairo_fill(cairo);
			}
			lineIndex++;
		} while (lineIndex < lineCount);
		OS.pango_layout_iter_free(iter);
		if (attrs[0] != 0) OS.g_free(attrs[0]);
		Cairo.cairo_restore(cairo);
	}
	if (length == 0) return;
	if (!hasSelection) {
		if ((data.style & SWT.MIRRORED) != 0) {
			Cairo.cairo_save(cairo);
			Cairo.cairo_scale(cairo, -1,  1);
			Cairo.cairo_translate(cairo, -2 * x - width(), 0);
		}
		metricsAdapter.pango_cairo_show_layout(cairo, layout, x, y);
		drawBorder(gc, x, y, null);
		if ((data.style & SWT.MIRRORED) != 0) {
			Cairo.cairo_restore(cairo);
		}
	} else {
		selectionStart = Math.min(Math.max(0, selectionStart), length - 1);
		selectionEnd = Math.min(Math.max(0, selectionEnd), length - 1);
		length = (int)OS.g_utf16_strlen(OS.pango_layout_get_text(layout), -1);
		selectionStart = translateOffset(selectionStart);
		selectionEnd = translateOffset(selectionEnd);
		if (selectionForeground == null) selectionForeground = device.getSystemColor(SWT.COLOR_LIST_SELECTION_TEXT);
		if (selectionBackground == null) selectionBackground = device.getSystemColor(SWT.COLOR_LIST_SELECTION);
		int yExtent = extent ? OS.PANGO_PIXELS(OS.pango_layout_get_spacing(layout)) : 0;
		boolean fullSelection = selectionStart == 0 && selectionEnd == length - 1;
		if (fullSelection) {
			long ptr = OS.pango_layout_get_text(layout);
			if ((data.style & SWT.MIRRORED) != 0) {
				Cairo.cairo_save(cairo);
				Cairo.cairo_scale(cairo, -1,  1);
				Cairo.cairo_translate(cairo, -2 * x - width(), 0);
			}
			drawWithCairo(gc, x, y, 0, C.strlen(ptr), yExtent, fullSelection, selectionForeground.handle,
					selectionBackground.handle);
			if ((data.style & SWT.MIRRORED) != 0) {
				Cairo.cairo_restore(cairo);
			}
		} else {
			long ptr = OS.pango_layout_get_text(layout);
			int byteSelStart = (int)(OS.g_utf16_offset_to_pointer(ptr, selectionStart) - ptr);
			int byteSelEnd = (int)(OS.g_utf16_offset_to_pointer(ptr, selectionEnd + 1) - ptr);
			int strlen = C.strlen(ptr);
			byteSelStart = Math.min(byteSelStart, strlen);
			byteSelEnd = Math.min(byteSelEnd, strlen);
			if ((data.style & SWT.MIRRORED) != 0) {
				Cairo.cairo_save(cairo);
				Cairo.cairo_scale(cairo, -1,  1);
				Cairo.cairo_translate(cairo, -2 * x - width(), 0);
			}
			drawWithCairo(gc, x, y, byteSelStart, byteSelEnd, yExtent, fullSelection, selectionForeground.handle,
					selectionBackground.handle);
			if ((data.style & SWT.MIRRORED) != 0) {
				Cairo.cairo_restore(cairo);
			}
		}
	}
	Cairo.cairo_new_path(cairo);
}

void drawWithCairo(GC gc, int x, int y, int start, int end, int yExtent, boolean fullSelection, GdkRGBA fg, GdkRGBA bg) {
	GCData data = gc.data;
	long cairo = data.cairo;
	Cairo.cairo_save(cairo);
	if (!fullSelection) {
		metricsAdapter.pango_cairo_show_layout(cairo, layout, x, y);
		drawBorder(gc, x, y, null);
	}
	int[] ranges = new int[]{start, end};
	long rgn = metricsAdapter.gdk_pango_layout_get_clip_region(layout, x, y, ranges, ranges.length / 2);
	if (rgn != 0) {
		if (yExtent > 0) {
			cairo_rectangle_int_t rect = new cairo_rectangle_int_t();
			Cairo.cairo_region_get_extents(rgn, rect);
			rect.height += yExtent;
			long extendRgn = Cairo.cairo_region_create_rectangle(rect);
			Cairo.cairo_region_union(rgn, extendRgn);
			Cairo.cairo_region_destroy(extendRgn);
		}
		GDK.gdk_cairo_region(cairo, rgn);
		Cairo.cairo_clip(cairo);
		Cairo.cairo_set_source_rgba(cairo, bg.red, bg.green, bg.blue, bg.alpha);
		Cairo.cairo_paint(cairo);
		Cairo.cairo_region_destroy(rgn);
	}
	Cairo.cairo_set_source_rgba(cairo, fg.red, fg.green, fg.blue, fg.alpha);
	OS.pango_layout_set_attributes(layout, selAttrList);
	metricsAdapter.pango_cairo_show_layout(cairo, layout, x, y);
	OS.pango_layout_set_attributes(layout, attrList);
	drawBorder(gc, x, y, fg);
	Cairo.cairo_restore(cairo);
}

void drawBorder(GC gc, int x, int y, GdkRGBA selectionColor) {
	GCData data = gc.data;
	long cairo = data.cairo;
	long ptr = OS.pango_layout_get_text(layout);
	Cairo.cairo_save(cairo);
	for (int i = 0; i < stylesCount - 1; i++) {
		TextStyle style = styles[i].style;
		if (style == null) continue;

		boolean drawBorder = style.borderStyle != SWT.NONE;
		if (drawBorder && !style.isAdherentBorder(styles[i+1].style)) {
			int start = styles[i].start;
			for (int j = i; j > 0 && style.isAdherentBorder(styles[j-1].style); j--) {
				start = styles[j - 1].start;
			}
			start = translateOffset(start);
			int end = translateOffset(styles[i+1].start - 1);
			int byteStart = (int)(OS.g_utf16_offset_to_pointer(ptr, start) - ptr);
			int byteEnd = (int)(OS.g_utf16_offset_to_pointer(ptr, end + 1) - ptr);
			int[] ranges = new int[]{byteStart, byteEnd};
			long rgn = metricsAdapter.gdk_pango_layout_get_clip_region(layout, x, y, ranges, ranges.length / 2);
			if (rgn != 0) {
				int[] nRects = new int[1];
				long [] rects = new long [1];
				Region.cairo_region_get_rectangles(rgn, rects, nRects);
				cairo_rectangle_int_t rect = new cairo_rectangle_int_t();
				GdkRGBA colorRGBA = null;
				if (colorRGBA == null && style.borderColor != null) colorRGBA = style.borderColor.handle;
				if (colorRGBA == null && selectionColor != null) colorRGBA = selectionColor;
				if (colorRGBA == null && style.foreground != null) colorRGBA = style.foreground.handle;
				if (colorRGBA == null) colorRGBA = data.foregroundRGBA;
				int width = 1;
				float[] dashes = null;
				switch (style.borderStyle) {
					case SWT.BORDER_SOLID: break;
					case SWT.BORDER_DASH: dashes = width != 0 ? GC.LINE_DASH : GC.LINE_DASH_ZERO; break;
					case SWT.BORDER_DOT: dashes = width != 0 ? GC.LINE_DOT : GC.LINE_DOT_ZERO; break;
				}
				Cairo.cairo_set_source_rgba(cairo, colorRGBA.red, colorRGBA.green, colorRGBA.blue, colorRGBA.alpha);
				Cairo.cairo_set_line_width(cairo, width);
				if (dashes != null) {
					double[] cairoDashes = new double[dashes.length];
					for (int j = 0; j < cairoDashes.length; j++) {
						cairoDashes[j] = width == 0 || data.lineStyle == SWT.LINE_CUSTOM ? dashes[j] : dashes[j] * width;
					}
					Cairo.cairo_set_dash(cairo, cairoDashes, cairoDashes.length, 0);
				} else {
					Cairo.cairo_set_dash(cairo, null, 0, 0);
				}
				for (int j=0; j<nRects[0]; j++) {
					Cairo.memmove(rect, rects[0] + (j * cairo_rectangle_int_t.sizeof), cairo_rectangle_int_t.sizeof);
					Cairo.cairo_rectangle(cairo, rect.x + 0.5, rect.y + 0.5, rect.width - 1, rect.height - 1);
				}
				Cairo.cairo_stroke(cairo);
				if (rects[0] != 0) OS.g_free(rects[0]);
				Cairo.cairo_region_destroy(rgn);
			}
		}
	}
	Cairo.cairo_restore(cairo);
}

void freeRuns() {
	if (attrList == 0) return;
	OS.pango_layout_set_attributes(layout, 0);
	OS.pango_attr_list_unref(attrList);
	attrList = 0;
	if (selAttrList != 0) {
		OS.pango_attr_list_unref(selAttrList);
		selAttrList = 0;
	}
	invalidOffsets = null;
}

/**
 * Returns the receiver's horizontal text alignment, which will be one
 * of <code>SWT.LEFT</code>, <code>SWT.CENTER</code> or
 * <code>SWT.RIGHT</code>.
 *
 * @return the alignment used to positioned text horizontally
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public int getAlignment() {
	checkLayout();
	int align = OS.pango_layout_get_alignment(layout);
	boolean rtl = OS.pango_context_get_base_dir(context) == OS.PANGO_DIRECTION_RTL;
	switch (align) {
		case OS.PANGO_ALIGN_LEFT: return rtl ? SWT.RIGHT : SWT.LEFT;
		case OS.PANGO_ALIGN_RIGHT: return rtl ? SWT.LEFT : SWT.RIGHT;
	}
	return SWT.CENTER;
}

/**
 * Returns the ascent of the receiver.
 *
 * @return the ascent
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @see #getDescent()
 * @see #setDescent(int)
 * @see #setAscent(int)
 * @see #getLineMetrics(int)
 */
public int getAscent () {
	checkLayout();
	return ascentInPoints;
}

/**
 * Returns the bounds of the receiver. The width returned is either the
 * width of the longest line or the width set using {@link TextLayout#setWidth(int)}.
 * To obtain the text bounds of a line use {@link TextLayout#getLineBounds(int)}.
 *
 * @return the bounds of the receiver
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @see #setWidth(int)
 * @see #getLineBounds(int)
 */
public Rectangle getBounds() {
	int spacingInPixels = OS.PANGO_PIXELS(OS.pango_layout_get_spacing(layout));
	checkLayout();
	computeRuns();
	int[] w = new int[1], h = new int[1];
	metricsAdapter.pango_layout_get_size(layout, w, h);
	int wrapWidth = OS.pango_layout_get_width(layout);
	w[0] = wrapWidth != -1 ? wrapWidth : w[0] + OS.pango_layout_get_indent(layout);
	int width = OS.PANGO_PIXELS(w[0]);
	int height = OS.PANGO_PIXELS(h[0]);
	if (ascentInPoints != -1 && descentInPoints != -1) {
		height = Math.max (height, ascentInPoints + descentInPoints);
	}
	height += spacingInPixels;
	return new Rectangle(0, 0, width, height + getScaledVerticalIndent());
}

/**
 * Returns the bounds for the specified range of characters. The
 * bounds is the smallest rectangle that encompasses all characters
 * in the range. The start and end offsets are inclusive and will be
 * clamped if out of range.
 *
 * @param start the start offset
 * @param end the end offset
 * @return the bounds of the character range
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public Rectangle getBounds(int start, int end) {
	checkLayout();
	computeRuns();
	int length = text.length();
	if (length == 0) return new Rectangle(0, 0, 0, 0);
	if (start > end) return new Rectangle(0, 0, 0, 0);
	start = Math.min(Math.max(0, start), length - 1);
	end = Math.min(Math.max(0, end), length - 1);
	start = translateOffset(start);
	end = translateOffset(end);
	long ptr = OS.pango_layout_get_text(layout);
	int byteStart = (int)(OS.g_utf16_offset_to_pointer (ptr, start) - ptr);
	int byteEnd = (int)(OS.g_utf16_offset_to_pointer (ptr, end + 1) - ptr);
	int strlen = C.strlen(ptr);
	byteStart = Math.min(byteStart, strlen);
	byteEnd = Math.min(byteEnd, strlen);
	int[] ranges = new int[]{byteStart, byteEnd};
	long clipRegion = metricsAdapter.gdk_pango_layout_get_clip_region(layout, 0, 0, ranges, 1);
	if (clipRegion == 0) return new Rectangle(0, 0, 0, 0);
	cairo_rectangle_int_t rect = new cairo_rectangle_int_t();

	/*
	* Bug in Pango. The region returned by gdk_pango_layout_get_clip_region()
	* includes areas from lines outside of the requested range.  The fix
	* is to subtract these areas from the clip region.
	*/
	PangoRectangle pangoRect = new PangoRectangle();
	long iter = OS.pango_layout_get_iter(layout);
	if (iter == 0) SWT.error(SWT.ERROR_NO_HANDLES);
	long linesRegion = Cairo.cairo_region_create();
	if (linesRegion == 0) SWT.error(SWT.ERROR_NO_HANDLES);
	int lineEnd = 0;
	do {
		metricsAdapter.pango_layout_iter_get_line_extents(iter, null, pangoRect);
		if (OS.pango_layout_iter_next_line(iter)) {
			lineEnd = OS.pango_layout_iter_get_index(iter) - 1;
		} else {
			lineEnd = strlen;
		}
		if (byteStart > lineEnd) continue;
		rect.x = OS.PANGO_PIXELS(pangoRect.x);
		rect.y = OS.PANGO_PIXELS(pangoRect.y);
		rect.width = OS.PANGO_PIXELS(pangoRect.width);
		rect.height = OS.PANGO_PIXELS(pangoRect.height);
		Cairo.cairo_region_union_rectangle(linesRegion, rect);
	} while (lineEnd + 1 <= byteEnd);
	Cairo.cairo_region_intersect(clipRegion, linesRegion);
	Cairo.cairo_region_destroy(linesRegion);
	OS.pango_layout_iter_free(iter);

	Cairo.cairo_region_get_extents(clipRegion, rect);
	Cairo.cairo_region_destroy(clipRegion);
	rect.x += Math.min (indent, wrapIndent);
	return new Rectangle(rect.x, rect.y, rect.width, rect.height + getScaledVerticalIndent());
}

/**
 * Returns the descent of the receiver.
 *
 * @return the descent
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @see #getAscent()
 * @see #setAscent(int)
 * @see #setDescent(int)
 * @see #getLineMetrics(int)
 */
public int getDescent () {
	checkLayout();
	return descentInPoints;
}

/**
 * Returns the default font currently being used by the receiver
 * to draw and measure text.
 *
 * @return the receiver's font
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public Font getFont () {
	checkLayout();
	return font;
}

/**
* Returns the receiver's indent.
*
* @return the receiver's indent
*
* @exception SWTException <ul>
*    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
* </ul>
*
* @since 3.2
*/
public int getIndent () {
	checkLayout();
	return indent;
}

/**
* Returns the receiver's justification.
*
* @return the receiver's justification
*
* @exception SWTException <ul>
*    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
* </ul>
*
* @since 3.2
*/
public boolean getJustify () {
	checkLayout();
	return OS.pango_layout_get_justify(layout);
}

/**
 * Returns the embedding level for the specified character offset. The
 * embedding level is usually used to determine the directionality of a
 * character in bidirectional text.
 *
 * @param offset the character offset
 * @return the embedding level
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_ARGUMENT - if the character offset is out of range</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li></ul>
 */
public int getLevel(int offset) {
	checkLayout();
	computeRuns();
	int length = text.length();
	if (!(0 <= offset && offset <= length)) SWT.error(SWT.ERROR_INVALID_RANGE);
	offset = translateOffset(offset);
	long iter = OS.pango_layout_get_iter(layout);
	if (iter == 0) SWT.error(SWT.ERROR_NO_HANDLES);
	int level = 0;
	PangoItem item = new PangoItem();
	PangoLayoutRun run = new PangoLayoutRun();
	long ptr = OS.pango_layout_get_text(layout);
	long byteOffset = OS.g_utf16_offset_to_pointer(ptr, offset) - ptr;
	int strlen = C.strlen(ptr);
	byteOffset = Math.min(byteOffset, strlen);
	do {
		long runPtr = OS.pango_layout_iter_get_run(iter);
		if (runPtr != 0) {
			OS.memmove(run, runPtr, PangoLayoutRun.sizeof);
			OS.memmove(item, run.item, PangoItem.sizeof);
			if (item.offset <= byteOffset && byteOffset < item.offset + item.length) {
				level = item.analysis_level;
				break;
			}
		}
	} while (OS.pango_layout_iter_next_run(iter));
	OS.pango_layout_iter_free(iter);
	return level;
}

/**
 * Returns the bounds of the line for the specified line index.
 *
 * @param lineIndex the line index
 * @return the line bounds
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_ARGUMENT - if the line index is out of range</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public Rectangle getLineBounds(int lineIndex) {
	checkLayout();
	computeRuns();
	int lineCount = OS.pango_layout_get_line_count(layout);
	if (!(0 <= lineIndex && lineIndex < lineCount)) SWT.error(SWT.ERROR_INVALID_RANGE);
	long iter = OS.pango_layout_get_iter(layout);
	for (int i = 0; i < lineIndex; i++) {
		OS.pango_layout_iter_next_line(iter);
	}
	Rectangle lineBoundsInPixels = getLineBoundsInPixels(lineIndex, iter);
	OS.pango_layout_iter_free(iter);
	return lineBoundsInPixels;
}

private Rectangle getLineBoundsInPixels(int lineIndex, long iter) {
	if (iter == 0) SWT.error(SWT.ERROR_NO_HANDLES);
	PangoRectangle rect = new PangoRectangle();
	metricsAdapter.pango_layout_iter_get_line_extents(iter, null, rect);
	int x = OS.PANGO_PIXELS(rect.x);
	int y = OS.PANGO_PIXELS(rect.y);
	int width = OS.PANGO_PIXELS(rect.width);
	int height = OS.PANGO_PIXELS(rect.height);
	if (ascentInPoints != -1 && descentInPoints != -1) {
		height = Math.max (height, ascentInPoints + descentInPoints);
	}
	x += Math.min (indent, wrapIndent);
	return new Rectangle(x, y, width, height);
}

/**
 * Returns the receiver's line count. This includes lines caused
 * by wrapping.
 *
 * @return the line count
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public int getLineCount() {
	checkLayout ();
	computeRuns();
	return OS.pango_layout_get_line_count(layout);
}

/**
 * Returns the index of the line that contains the specified
 * character offset.
 *
 * @param offset the character offset
 * @return the line index
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_ARGUMENT - if the character offset is out of range</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public int getLineIndex(int offset) {
	checkLayout ();
	computeRuns();
	int length = text.length();
	if (!(0 <= offset && offset <= length)) SWT.error(SWT.ERROR_INVALID_ARGUMENT);
	offset = translateOffset(offset);
	int line = 0;
	long ptr = OS.pango_layout_get_text(layout);
	long byteOffset = OS.g_utf16_offset_to_pointer(ptr,offset) - ptr;
	int strlen = C.strlen(ptr);
	byteOffset = Math.min(byteOffset, strlen);
	long iter = OS.pango_layout_get_iter(layout);
	if (iter == 0) SWT.error(SWT.ERROR_NO_HANDLES);
	while (OS.pango_layout_iter_next_line(iter)) {
		if (OS.pango_layout_iter_get_index(iter) > byteOffset) break;
		line++;
	}
	OS.pango_layout_iter_free(iter);
	return line;
}

/**
 * Returns the font metrics for the specified line index.
 *
 * @param lineIndex the line index
 * @return the font metrics
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_ARGUMENT - if the line index is out of range</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public FontMetrics getLineMetrics (int lineIndex) {
	if (metricsAdapter.isFixedMetrics()) {
		return metricsAdapter.getFixedLineMetrics(getDevice());
	}

	checkLayout ();
	computeRuns();
	int lineCount = OS.pango_layout_get_line_count(layout);
	if (!(0 <= lineIndex && lineIndex < lineCount)) SWT.error(SWT.ERROR_INVALID_RANGE);
	PangoLayoutLine line = new PangoLayoutLine();
	OS.memmove(line, OS.pango_layout_get_line(layout, lineIndex), PangoLayoutLine.sizeof);
	int heightInPoints;
	int ascentInPoints;
	if (line.runs == 0) {
		long font = this.font != null ? this.font.handle : device.systemFont.handle;
		long lang = OS.pango_context_get_language(context);
		long metrics = OS.pango_context_get_metrics(context, font, lang);
		int ascent = OS.pango_font_metrics_get_ascent(metrics);
		int descent = OS.pango_font_metrics_get_descent(metrics);
		ascentInPoints = OS.PANGO_PIXELS(ascent);
		heightInPoints = OS.PANGO_PIXELS(ascent + descent);
		OS.pango_font_metrics_unref(metrics);
	} else {
		PangoRectangle rect = new PangoRectangle();
		metricsAdapter.pango_layout_line_get_extents(OS.pango_layout_get_line(layout, lineIndex), null, rect);
		ascentInPoints = OS.PANGO_PIXELS(-rect.y);
		heightInPoints = OS.PANGO_PIXELS(rect.height);
	}
	heightInPoints = Math.max(this.ascentInPoints + this.descentInPoints, heightInPoints);
	ascentInPoints = Math.max(this.ascentInPoints, ascentInPoints);
	int descentInPoints = heightInPoints - ascentInPoints;
	FontMetrics fm = new FontMetrics();
	fm.ascentInPoints = ascentInPoints;
	fm.descentInPoints = descentInPoints;
	fm.averageCharWidthInPoints = 0;
	return fm;
}

/**
 * Returns the line offsets.  Each value in the array is the
 * offset for the first character in a line except for the last
 * value, which contains the length of the text.
 *
 * @return the line offsets
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public int[] getLineOffsets() {
	checkLayout();
	computeRuns();
	int lineCount = OS.pango_layout_get_line_count(layout);
	int[] offsets = new int [lineCount + 1];
	long ptr = OS.pango_layout_get_text(layout);
	PangoLayoutLine line = new PangoLayoutLine();
	for (int i = 0; i < lineCount; i++) {
		long linePtr = OS.pango_layout_get_line(layout, i);
		OS.memmove(line, linePtr, PangoLayoutLine.sizeof);
		int pos = (int)OS.g_utf16_pointer_to_offset(ptr, ptr + line.start_index);
		offsets[i] = untranslateOffset(pos);
	}
	offsets[lineCount] = text.length();
	return offsets;
}

/**
 * Returns the location for the specified character offset. The
 * <code>trailing</code> argument indicates whether the offset
 * corresponds to the leading or trailing edge of the cluster.
 *
 * @param offset the character offset
 * @param trailing the trailing flag
 * @return the location of the character offset
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @see #getOffset(Point, int[])
 * @see #getOffset(int, int, int[])
 */
public Point getLocation(int offset, boolean trailing) {
	checkLayout();
	computeRuns();
	int length = text.length();
	if (!(0 <= offset && offset <= length)) SWT.error(SWT.ERROR_INVALID_RANGE);
	offset = translateOffset(offset);
	long ptr = OS.pango_layout_get_text(layout);
	int byteOffset = (int)(OS.g_utf16_offset_to_pointer(ptr, offset) - ptr);
	int strlen = C.strlen(ptr);
	byteOffset = Math.min(byteOffset, strlen);
	PangoRectangle pos = new PangoRectangle();
	OS.pango_layout_index_to_pos(layout, byteOffset, pos);
	int x = trailing ? pos.x + pos.width : pos.x;
	int y = pos.y;
	x = OS.PANGO_PIXELS(x);
	if (OS.pango_context_get_base_dir(context) == OS.PANGO_DIRECTION_RTL) {
		x = width() - x;
	}
	x += Math.min (indent, wrapIndent);
	return new Point(x, OS.PANGO_PIXELS(y) + getScaledVerticalIndent());
}

/**
 * Returns the next offset for the specified offset and movement
 * type.  The movement is one of <code>SWT.MOVEMENT_CHAR</code>,
 * <code>SWT.MOVEMENT_CLUSTER</code>, <code>SWT.MOVEMENT_WORD</code>,
 * <code>SWT.MOVEMENT_WORD_END</code> or <code>SWT.MOVEMENT_WORD_START</code>.
 *
 * @param offset the start offset
 * @param movement the movement type
 * @return the next offset
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_ARGUMENT - if the offset is out of range</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @see #getPreviousOffset(int, int)
 */
public int getNextOffset (int offset, int movement) {
	return _getOffset(offset, movement, true);
}

int _getOffset (int offset, int movement, boolean forward) {
	checkLayout();
	computeRuns();
	int length = text.length();
	if (!(0 <= offset && offset <= length)) SWT.error(SWT.ERROR_INVALID_RANGE);
	if (forward) {
		if (offset == length) return length;
	} else {
		if (offset == 0) return 0;
	}
	int step = forward ? 1 : -1;
	if ((movement & SWT.MOVEMENT_CHAR) != 0) return offset + step;
	long [] attrs = new long [1];
	int[] nAttrs = new int[1];
	OS.pango_layout_get_log_attrs(layout, attrs, nAttrs);
	if (attrs[0] == 0) return offset + step;

	long ptr = OS.pango_layout_get_text(layout);
	int utf8Offset = (int)OS.g_utf16_offset_to_utf8_offset (ptr, translateOffset(offset));
	int utf8Length = (int)OS.g_utf8_strlen(ptr, -1);
	utf8Offset += step;
	PangoLogAttr logAttr = new PangoLogAttr();
	while (0 <= utf8Offset && utf8Offset <= utf8Length) {
		OS.memmove(logAttr, attrs[0] + utf8Offset * PangoLogAttr.sizeof, PangoLogAttr.sizeof);
		boolean found = false, limit = false;
		if (((movement & SWT.MOVEMENT_CLUSTER) != 0) && logAttr.is_cursor_position) found = true;
		if ((movement & SWT.MOVEMENT_WORD) != 0) {
			if (forward) {
				if (logAttr.is_word_end) found = true;
			} else {
				if (logAttr.is_word_start) found = true;
			}
		}
		if ((movement & SWT.MOVEMENT_WORD_START) != 0) {
			if (logAttr.is_word_start) found = true;
			if (logAttr.is_sentence_end) found = true;
		}
		if ((movement & SWT.MOVEMENT_WORD_END) != 0) {
			if (logAttr.is_word_end) found = true;
			if (logAttr.is_sentence_start) found = true;
		}
		if (forward) {
			if (utf8Offset == utf8Length) limit = true;
		} else {
			if (utf8Offset == 0) limit = true;
		}
		if (found || limit) {
			int testOffset = (int)OS.g_utf8_offset_to_utf16_offset (ptr, utf8Offset);
			if (found && invalidOffsets != null) {
				for (int i = 0; i < invalidOffsets.length; i++) {
					if (testOffset == invalidOffsets[i]) {
						found = false;
						break;
					}
				}
			}
			if (found || limit) {
				offset = untranslateOffset(testOffset);
				break;
			}
		}
		utf8Offset += step;
	}
	OS.g_free(attrs[0]);
	return Math.min(Math.max(0, offset), length);
}

/**
 * Returns the character offset for the specified point.
 * For a typical character, the trailing argument will be filled in to
 * indicate whether the point is closer to the leading edge (0) or
 * the trailing edge (1).  When the point is over a cluster composed
 * of multiple characters, the trailing argument will be filled with the
 * position of the character in the cluster that is closest to
 * the point.
 *
 * @param point the point
 * @param trailing the trailing buffer
 * @return the character offset
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_ARGUMENT - if the trailing length is less than <code>1</code></li>
 *    <li>ERROR_NULL_ARGUMENT - if the point is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @see #getLocation(int, boolean)
 */
public int getOffset(Point point, int[] trailing) {
	return getOffset(point.x, point.y, trailing);
}

/**
 * Returns the character offset for the specified point.
 * For a typical character, the trailing argument will be filled in to
 * indicate whether the point is closer to the leading edge (0) or
 * the trailing edge (1).  When the point is over a cluster composed
 * of multiple characters, the trailing argument will be filled with the
 * position of the character in the cluster that is closest to
 * the point.
 *
 * @param x the x coordinate of the point
 * @param y the y coordinate of the point
 * @param trailing the trailing buffer
 * @return the character offset
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_ARGUMENT - if the trailing length is less than <code>1</code></li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @see #getLocation(int, boolean)
 */
public int getOffset(int x, int y, int[] trailing) {
	checkLayout();
	computeRuns();
	if (trailing != null && trailing.length < 1) SWT.error(SWT.ERROR_INVALID_ARGUMENT);
	x -= Math.min (indent, wrapIndent);
	if (OS.pango_context_get_base_dir(context) == OS.PANGO_DIRECTION_RTL) {
		x = width() - x;
	}

	/*
	* Feature in GTK.  pango_layout_xy_to_index() returns the
	* logical end/start offset of a line when the coordinates are outside
	* the line bounds. In SWT the correct behavior is to return the closest
	* visual offset. The fix is to clamp the coordinates inside the
	* line bounds.
	*/
	long iter = OS.pango_layout_get_iter(layout);
	if (iter == 0) SWT.error(SWT.ERROR_NO_HANDLES);
	PangoRectangle rect = new PangoRectangle();
	do {
		metricsAdapter.pango_layout_iter_get_line_extents(iter, null, rect);
		rect.y = OS.PANGO_PIXELS(rect.y);
		rect.height = OS.PANGO_PIXELS(rect.height);
		if (rect.y <= y && y < rect.y + rect.height) {
			rect.x = OS.PANGO_PIXELS(rect.x);
			rect.width = OS.PANGO_PIXELS(rect.width);
			if (x >= rect.x + rect.width) x = rect.x + rect.width - 1;
			if (x < rect.x) x = rect.x;
			break;
		}
	} while (OS.pango_layout_iter_next_line(iter));
	OS.pango_layout_iter_free(iter);

	int[] index = new int[1];
	int[] piTrailing = new int[1];
	OS.pango_layout_xy_to_index(layout, x * OS.PANGO_SCALE, y * OS.PANGO_SCALE, index, piTrailing);
	long ptr = OS.pango_layout_get_text(layout);
	int offset = (int)OS.g_utf16_pointer_to_offset(ptr, ptr + index[0]);
	if (trailing != null) {
		trailing[0] = piTrailing[0];
		if (piTrailing[0] != 0) {
			trailing[0] = (int)OS.g_utf8_offset_to_utf16_offset(ptr, OS.g_utf8_pointer_to_offset(ptr, ptr + index[0]) + piTrailing[0]) - offset;
		}
	}
	return untranslateOffset(offset);
}

/**
 * Returns the orientation of the receiver.
 *
 * @return the orientation style
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public int getOrientation() {
	checkLayout();
	int baseDir = OS.pango_context_get_base_dir(context);
	return baseDir == OS.PANGO_DIRECTION_RTL ? SWT.RIGHT_TO_LEFT : SWT.LEFT_TO_RIGHT;
}

/**
 * Returns the previous offset for the specified offset and movement
 * type.  The movement is one of <code>SWT.MOVEMENT_CHAR</code>,
 * <code>SWT.MOVEMENT_CLUSTER</code> or <code>SWT.MOVEMENT_WORD</code>,
 * <code>SWT.MOVEMENT_WORD_END</code> or <code>SWT.MOVEMENT_WORD_START</code>.
 *
 * @param offset the start offset
 * @param movement the movement type
 * @return the previous offset
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_ARGUMENT - if the offset is out of range</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @see #getNextOffset(int, int)
 */
public int getPreviousOffset (int offset, int movement) {
	return _getOffset(offset, movement, false);
}

/**
 * Gets the ranges of text that are associated with a <code>TextStyle</code>.
 *
 * @return the ranges, an array of offsets representing the start and end of each
 * text style.
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @see #getStyles()
 *
 * @since 3.2
 */
public int[] getRanges () {
	checkLayout();
	int[] result = new int[stylesCount * 2];
	int count = 0;
	for (int i=0; i<stylesCount - 1; i++) {
		if (styles[i].style != null) {
			result[count++] = styles[i].start;
			result[count++] = styles[i + 1].start - 1;
		}
	}
	if (count != result.length) {
		int[] newResult = new int[count];
		System.arraycopy(result, 0, newResult, 0, count);
		result = newResult;
	}
	return result;
}

/**
 * Returns the text segments offsets of the receiver.
 *
 * @return the text segments offsets
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public int[] getSegments() {
	checkLayout();
	return segments;
}

/**
 * Returns the segments characters of the receiver.
 *
 * @return the segments characters
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @since 3.6
 */
public char[] getSegmentsChars () {
	checkLayout();
	return segmentsChars;
}

String getSegmentsText() {
	int length = text.length();
	if (length == 0) return text;
	if (segments == null) return text;
	int nSegments = segments.length;
	if (nSegments == 0) return text;
	if (segmentsChars == null) {
		if (nSegments == 1) return text;
		if (nSegments == 2) {
			if (segments[0] == 0 && segments[1] == length) return text;
		}
	}
	char[] oldChars = new char[length];
	text.getChars(0, length, oldChars, 0);
	char[] newChars = new char[length + nSegments];
	int charCount = 0, segmentCount = 0;
	char defaultSeparator = getOrientation() == SWT.RIGHT_TO_LEFT ? RTL_MARK : LTR_MARK;
	while (charCount < length) {
		if (segmentCount < nSegments && charCount == segments[segmentCount]) {
			char separator = segmentsChars != null && segmentsChars.length > segmentCount ? segmentsChars[segmentCount] : defaultSeparator;
			newChars[charCount + segmentCount++] = separator;
		} else {
			newChars[charCount + segmentCount] = oldChars[charCount++];
		}
	}
	while (segmentCount < nSegments) {
		segments[segmentCount] = charCount;
		char separator = segmentsChars != null && segmentsChars.length > segmentCount ? segmentsChars[segmentCount] : defaultSeparator;
		newChars[charCount + segmentCount++] = separator;
	}
	return new String(newChars, 0, newChars.length);
}

/**
 * Returns the line spacing of the receiver.
 *
 * @return the line spacing
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public int getSpacing () {
	checkLayout();
	return OS.PANGO_PIXELS(OS.pango_layout_get_spacing(layout));
}

/**
 * Returns the vertical indent of the receiver.
 *
 * @return the vertical indent
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 * @since 3.109
 */
public int getVerticalIndent () {
	checkLayout();
	return verticalIndentInPoints;
}

/**
 * Returns the scaled vertical indent.
 *
 * @return the scaled vertical indent.
 * @since 3.109
 */
private int getScaledVerticalIndent() {
	if (verticalIndentInPoints == 0) {
		return verticalIndentInPoints;
	}
	return verticalIndentInPoints;
}

/**
 * Gets the style of the receiver at the specified character offset.
 *
 * @param offset the text offset
 * @return the style or <code>null</code> if not set
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_ARGUMENT - if the character offset is out of range</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public TextStyle getStyle (int offset) {
	checkLayout();
	int length = text.length();
	if (!(0 <= offset && offset < length)) SWT.error(SWT.ERROR_INVALID_RANGE);
	for (int i=1; i<stylesCount; i++) {
		StyleItem item = styles[i];
		if (item.start > offset) {
			return styles[i - 1].style;
		}
	}
	return null;
}

/**
 * Gets all styles of the receiver.
 *
 * @return the styles
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @see #getRanges()
 *
 * @since 3.2
 */
public TextStyle[] getStyles () {
	checkLayout();
	TextStyle[] result = new TextStyle[stylesCount];
	int count = 0;
	for (int i=0; i<stylesCount; i++) {
		if (styles[i].style != null) {
			result[count++] = styles[i].style;
		}
	}
	if (count != result.length) {
		TextStyle[] newResult = new TextStyle[count];
		System.arraycopy(result, 0, newResult, 0, count);
		result = newResult;
	}
	return result;
}

/**
 * Returns the tab list of the receiver.
 *
 * @return the tab list
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public int[] getTabs() {
	checkLayout();
	return getTabsInPixels ();
}

int[] getTabsInPixels () {
	return tabs;
}

/**
 * Gets the receiver's text, which will be an empty
 * string if it has never been set.
 *
 * @return the receiver's text
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public String getText () {
	checkLayout ();
	return text;
}

/**
 * Returns the text direction of the receiver.
 *
 * @return the text direction value
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 * @since 3.103
 */
public int getTextDirection () {
	return getOrientation ();
}

/**
 * Returns the width of the receiver.
 *
 * @return the width
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public int getWidth () {
	checkLayout ();
	return wrapWidth;
}

/**
* Returns the receiver's wrap indent.
*
* @return the receiver's wrap indent
*
* @exception SWTException <ul>
*    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
* </ul>
*
* @since 3.6
*/
public int getWrapIndent () {
	checkLayout ();
	return wrapIndent;
}

/**
 * Returns <code>true</code> if the text layout has been disposed,
 * and <code>false</code> otherwise.
 * <p>
 * This method gets the dispose state for the text layout.
 * When a text layout has been disposed, it is an error to
 * invoke any other method (except {@link #dispose()}) using the text layout.
 * </p>
 *
 * @return <code>true</code> when the text layout is disposed and <code>false</code> otherwise
 */
@Override
public boolean isDisposed () {
	return layout == 0;
}

/**
 * Sets the text alignment for the receiver. The alignment controls
 * how a line of text is positioned horizontally. The argument should
 * be one of <code>SWT.LEFT</code>, <code>SWT.RIGHT</code> or <code>SWT.CENTER</code>.
 * <p>
 * The default alignment is <code>SWT.LEFT</code>.  Note that the receiver's
 * width must be set in order to use <code>SWT.RIGHT</code> or <code>SWT.CENTER</code>
 * alignment.
 * </p>
 *
 * @param alignment the new alignment
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @see #setWidth(int)
 */
public void setAlignment (int alignment) {
	checkLayout();
	int mask = SWT.LEFT | SWT.CENTER | SWT.RIGHT;
	alignment &= mask;
	if (alignment == 0) return;
	if ((alignment & SWT.LEFT) != 0) alignment = SWT.LEFT;
	if ((alignment & SWT.RIGHT) != 0) alignment = SWT.RIGHT;
	boolean rtl = OS.pango_context_get_base_dir(context) == OS.PANGO_DIRECTION_RTL;
	int align = OS.PANGO_ALIGN_CENTER;
	switch (alignment) {
		case SWT.LEFT:
			align = rtl ? OS.PANGO_ALIGN_RIGHT : OS.PANGO_ALIGN_LEFT;
			break;
		case SWT.RIGHT:
			align = rtl ? OS.PANGO_ALIGN_LEFT : OS.PANGO_ALIGN_RIGHT;
			break;
	}
	OS.pango_layout_set_alignment(layout, align);
}

/**
 * Sets the ascent of the receiver. The ascent is distance in points
 * from the baseline to the top of the line and it is applied to all
 * lines. The default value is <code>-1</code> which means that the
 * ascent is calculated from the line fonts.
 *
 * @param ascent the new ascent
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_ARGUMENT - if the ascent is less than <code>-1</code></li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @see #setDescent(int)
 * @see #getLineMetrics(int)
 */
public void setAscent (int ascent) {
	checkLayout();
	if (ascent < -1) SWT.error(SWT.ERROR_INVALID_ARGUMENT);
	if (this.ascentInPoints == ascent) return;
	freeRuns();
	this.ascentInPoints = ascent;
}

/**
 * Sets the descent of the receiver. The descent is distance in points
 * from the baseline to the bottom of the line and it is applied to all
 * lines. The default value is <code>-1</code> which means that the
 * descent is calculated from the line fonts.
 *
 * @param descent the new descent
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_ARGUMENT - if the descent is less than <code>-1</code></li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @see #setAscent(int)
 * @see #getLineMetrics(int)
 */
public void setDescent (int descent) {
	checkLayout();
	if (descent < -1) SWT.error(SWT.ERROR_INVALID_ARGUMENT);
	if (this.descentInPoints == descent) return;
	freeRuns();
	this.descentInPoints = descent;
}

/**
 * Forces line heights in receiver to obey provided value. This is
 * useful with texts that contain glyphs from different scripts,
 * such as mixing latin glyphs with hieroglyphs or emojis.
 * <p>
 * Text lines with different metrics will be forced to fit. This means
 * painting text in such a way that its baseline is where specified by
 * given 'metrics'. This can sometimes introduce small visual artifacs,
 * such as taller lines overpainting or being clipped by content above
 * and below.
 * </p>
 * The possible ways to set FontMetrics include:
 * <ul>
 * <li>Obtaining 'FontMetrics' via {@link GC#getFontMetrics}. Note that
 * this will only obtain metrics for currently selected font and will not
 * account for font fallbacks (for example, with a latin font selected,
 * painting hieroglyphs usually involves a fallback font).</li>
 * <li>Obtaining 'FontMetrics' via a temporary 'TextLayout'. This would
 * involve setting a desired text sample to 'TextLayout', then measuring
 * it with {@link TextLayout#getLineMetrics(int)}. This approach will also
 * take fallback fonts into account.</li>
 * </ul>
 *
 * NOTE: Does not currently support (as in, undefined behavior) multi-line
 * layouts, including those caused by word wrapping. StyledText uses one
 * TextLayout per line and is only affected by word wrap restriction.
 *
 * @since 3.125
 */
public void setFixedLineMetrics (FontMetrics metrics) {
	metricsAdapter.setFixedLineMetrics(getDevice(), metrics);
}

/**
 * Sets the default font which will be used by the receiver
 * to draw and measure text. If the
 * argument is null, then a default font appropriate
 * for the platform will be used instead. Note that a text
 * style can override the default font.
 *
 * @param font the new font for the receiver, or null to indicate a default font
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_ARGUMENT - if the font has been disposed</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public void setFont (Font font) {
	checkLayout ();
	if (font != null && font.isDisposed()) SWT.error(SWT.ERROR_INVALID_ARGUMENT);
	Font oldFont = this.font;
	if (oldFont == font) return;
	freeRuns();
	this.font = font;
	if (oldFont != null && oldFont.equals(font)) return;
	OS.pango_layout_set_font_description(layout, font != null ? font.handle : device.systemFont.handle);
}

/**
 * Sets the indent of the receiver. This indent is applied to the first line of
 * each paragraph.
 *
 * @param indent new indent
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @see #setWrapIndent(int)
 *
 * @since 3.2
 */
public void setIndent (int indent) {
	checkLayout ();
	if (indent < 0) return;
	if (this.indent == indent) return;
	this.indent = indent;
	OS.pango_layout_set_indent(layout, (indent - wrapIndent) * OS.PANGO_SCALE);
	if (wrapWidth != -1) setWidth();
}

/**
 * Sets the justification of the receiver. Note that the receiver's
 * width must be set in order to use justification.
 *
 * @param justify new justify
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @since 3.2
 */
public void setJustify (boolean justify) {
	checkLayout();
	OS.pango_layout_set_justify(layout, justify);
}

/**
 * Sets the orientation of the receiver, which must be one
 * of <code>SWT.LEFT_TO_RIGHT</code> or <code>SWT.RIGHT_TO_LEFT</code>.
 *
 * @param orientation new orientation style
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public void setOrientation(int orientation) {
	checkLayout();
	int mask = SWT.RIGHT_TO_LEFT | SWT.LEFT_TO_RIGHT;
	orientation &= mask;
	if (orientation == 0) return;
	if ((orientation & SWT.LEFT_TO_RIGHT) != 0) orientation = SWT.LEFT_TO_RIGHT;
	int baseDir = orientation == SWT.RIGHT_TO_LEFT ? OS.PANGO_DIRECTION_RTL : OS.PANGO_DIRECTION_LTR;
	if (OS.pango_context_get_base_dir(context) == baseDir) return;
	freeRuns();
	OS.pango_context_set_base_dir(context, baseDir);
	OS.pango_layout_context_changed(layout);
	int align = OS.pango_layout_get_alignment(layout);
	if (align != OS.PANGO_ALIGN_CENTER) {
		align = align == OS.PANGO_ALIGN_LEFT ? OS.PANGO_ALIGN_RIGHT : OS.PANGO_ALIGN_LEFT;
		OS.pango_layout_set_alignment(layout, align);
	}
}

/**
 * Sets the line spacing of the receiver.  The line spacing
 * is the space left between lines.
 *
 * @param spacing the new line spacing
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_ARGUMENT - if the spacing is negative</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public void setSpacing (int spacing) {
	checkLayout();
	if (spacing < 0) SWT.error(SWT.ERROR_INVALID_ARGUMENT);
	OS.pango_layout_set_spacing(layout, spacing * OS.PANGO_SCALE);
}

/**
 * Sets the vertical indent of the receiver.  The vertical indent
 * is the space left before the first line.
 *
 * @param verticalIndent the new vertical indent
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_ARGUMENT - if the vertical indent is negative</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 * @since 3.109
 */
public void setVerticalIndent (int verticalIndent) {
	checkLayout();
	if (verticalIndent < 0) SWT.error(SWT.ERROR_INVALID_ARGUMENT);
	if (this.verticalIndentInPoints == verticalIndent) return;
	this.verticalIndentInPoints = verticalIndent;
}

/**
 * Sets the offsets of the receiver's text segments. Text segments are used to
 * override the default behavior of the bidirectional algorithm.
 * Bidirectional reordering can happen within a text segment but not
 * between two adjacent segments.
 * <p>
 * Each text segment is determined by two consecutive offsets in the
 * <code>segments</code> arrays. The first element of the array should
 * always be zero and the last one should always be equals to length of
 * the text.
 * </p>
 * <p>
 * When segments characters are set, the segments are the offsets where
 * the characters are inserted in the text.
 * </p>
 *
 * @param segments the text segments offset
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @see #setSegmentsChars(char[])
 */
public void setSegments(int[] segments) {
	checkLayout();
	if (this.segments == null && segments == null) return;
	if (this.segments != null && segments !=null) {
		if (this.segments.length == segments.length) {
			int i;
			for (i = 0; i <segments.length; i++) {
				if (this.segments[i] != segments[i]) break;
			}
			if (i == segments.length) return;
		}
	}
	freeRuns();
	this.segments = segments;
}

/**
 * Sets the characters to be used in the segments boundaries. The segments
 * are set by calling <code>setSegments(int[])</code>. The application can
 * use this API to insert Unicode Control Characters in the text to control
 * the display of the text and bidi reordering. The characters are not
 * accessible by any other API in <code>TextLayout</code>.
 *
 * @param segmentsChars the segments characters
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @see #setSegments(int[])
 *
 * @since 3.6
 */
public void setSegmentsChars(char[] segmentsChars) {
	checkLayout();
	if (this.segmentsChars == null && segmentsChars == null) return;
	if (this.segmentsChars != null && segmentsChars != null) {
		if (this.segmentsChars.length == segmentsChars.length) {
			int i;
			for (i = 0; i <segmentsChars.length; i++) {
				if (this.segmentsChars[i] != segmentsChars[i]) break;
			}
			if (i == segmentsChars.length) return;
		}
	}
	freeRuns();
	this.segmentsChars = segmentsChars;
}

/**
 * Sets the style of the receiver for the specified range.  Styles previously
 * set for that range will be overwritten.  The start and end offsets are
 * inclusive and will be clamped if out of range.
 *
 * @param style the style
 * @param start the start offset
 * @param end the end offset
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public void setStyle (TextStyle style, int start, int end) {
	checkLayout();
	int length = text.length();
	if (length == 0) return;
	if (start > end) return;
	start = Math.min(Math.max(0, start), length - 1);
	end = Math.min(Math.max(0, end), length - 1);

	/*
	* Bug in Pango. Pango 1.2.2 will cause a segmentation fault if a style
	* is not applied for a whole ligature.  The fix is to applied the
	* style for the whole ligature.
	*
	* NOTE that fix only LamAlef ligatures.
	*/
	if (start > 0 && isAlef(text.charAt(start)) && isLam(text.charAt(start - 1))) {
		start--;
	}
	if (end < length - 1 && isLam(text.charAt(end)) && isAlef(text.charAt(end + 1))) {
		end++;
	}

	int low = -1;
	int high = stylesCount;
	while (high - low > 1) {
		int index = (high + low) / 2;
		if (styles[index + 1].start > start) {
			high = index;
		} else {
			low = index;
		}
	}
	if (0 <= high && high < stylesCount) {
		StyleItem item = styles[high];
		if (item.start == start && styles[high + 1].start - 1 == end) {
			if (style == null) {
				if (item.style == null) return;
			} else {
				if (style.equals(item.style)) return;
			}
		}
	}
	freeRuns();
	int modifyStart = high;
	int modifyEnd = modifyStart;
	while (modifyEnd < stylesCount) {
		if (styles[modifyEnd + 1].start > end) break;
		modifyEnd++;
	}
	if (modifyStart == modifyEnd) {
		int styleStart = styles[modifyStart].start;
		int styleEnd = styles[modifyEnd + 1].start - 1;
		if (styleStart == start && styleEnd == end) {
			styles[modifyStart].style = style;
			return;
		}
		if (styleStart != start && styleEnd != end) {
			int newLength = stylesCount + 2;
			if (newLength > styles.length) {
				int newSize = Math.min(newLength + 1024, Math.max(64, newLength * 2));
				StyleItem[] newStyles = new StyleItem[newSize];
				System.arraycopy(styles, 0, newStyles, 0, stylesCount);
				styles = newStyles;
			}
			System.arraycopy(styles, modifyEnd + 1, styles, modifyEnd + 3, stylesCount - modifyEnd - 1);
			StyleItem item = new StyleItem();
			item.start = start;
			item.style = style;
			styles[modifyStart + 1] = item;
			item = new StyleItem();
			item.start = end + 1;
			item.style = styles[modifyStart].style;
			styles[modifyStart + 2] = item;
			stylesCount = newLength;
			return;
		}
	}
	if (start == styles[modifyStart].start) modifyStart--;
	if (end == styles[modifyEnd + 1].start - 1) modifyEnd++;
	int newLength = stylesCount + 1 - (modifyEnd - modifyStart - 1);
	if (newLength > styles.length) {
		int newSize = Math.min(newLength + 1024, Math.max(64, newLength * 2));
		StyleItem[] newStyles = new StyleItem[newSize];
		System.arraycopy(styles, 0, newStyles, 0, stylesCount);
		styles = newStyles;
	}
	System.arraycopy(styles, modifyEnd, styles, modifyStart + 2, stylesCount - modifyEnd);
	StyleItem item = new StyleItem();
	item.start = start;
	item.style = style;
	styles[modifyStart + 1] = item;
	styles[modifyStart + 2].start = end + 1;
	stylesCount = newLength;
}

/**
 * Sets the receiver's tab list. Each value in the tab list specifies
 * the space in points from the origin of the text layout to the respective
 * tab stop.  The last tab stop width is repeated continuously.
 *
 * @param tabs the new tab list
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public void setTabs(int[] tabs) {
	checkLayout();
	if (this.tabs == null && tabs == null) return;
	if (Arrays.equals (this.tabs, tabs)) return;
	this.tabs = tabs;
	if (tabs == null) {
		OS.pango_layout_set_tabs(layout, device.emptyTab);
	} else {
		long tabArray = OS.pango_tab_array_new(tabs.length, true);
		if (tabArray != 0) {
			for (int i = 0; i < tabs.length; i++) {
				OS.pango_tab_array_set_tab(tabArray, i, OS.PANGO_TAB_LEFT, tabs[i]);
			}
			OS.pango_layout_set_tabs(layout, tabArray);
			OS.pango_tab_array_free(tabArray);
		}
	}
	/*
	* Bug in Pango. A change in the tab stop array is not automatically reflected in the
	* pango layout object because the call pango_layout_set_tabs() does not free the
	* lines cache. The fix to use pango_layout_context_changed() to free the lines cache.
	*/
	OS.pango_layout_context_changed(layout);
}

/**
 * Sets the receiver's text.
 *<p>
 * Note: Setting the text also clears all the styles. This method
 * returns without doing anything if the new text is the same as
 * the current text.
 * </p>
 *
 * @param text the new text
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the text is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public void setText (String text) {
	checkLayout ();
	if (text == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
	if (text.equals(this.text)) return;
	freeRuns();
	this.text = text;
	styles = new StyleItem[2];
	styles[0] = new StyleItem();
	styles[1] = new StyleItem();
	styles[1].start = text.length();
	stylesCount = 2;
}

/**
 * Sets the text direction of the receiver, which must be one
 * of <code>SWT.LEFT_TO_RIGHT</code>, <code>SWT.RIGHT_TO_LEFT</code>
 * or <code>SWT.AUTO_TEXT_DIRECTION</code>.
 *
 * <p>
 * <b>Warning</b>: This API is currently only implemented on Windows.
 * It doesn't set the base text direction on GTK and Cocoa.
 * </p>
 *
 * @param textDirection the new text direction
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 * @since 3.103
 */
public void setTextDirection (int textDirection) {
	checkLayout();
}

/**
 * Sets the line width of the receiver, which determines how
 * text should be wrapped and aligned. The default value is
 * <code>-1</code> which means wrapping is disabled.
 *
 * @param width the new width
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_ARGUMENT - if the width is <code>0</code> or less than <code>-1</code></li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @see #setAlignment(int)
 */
public void setWidth (int width) {
	checkLayout ();
	if (width < -1 || width == 0) SWT.error(SWT.ERROR_INVALID_ARGUMENT);
	if (wrapWidth == width) return;
	freeRuns();
	wrapWidth = width;
	setWidth();
}

void setWidth () {
	if (wrapWidth == -1) {
		OS.pango_layout_set_width(layout, -1);
		boolean rtl = OS.pango_context_get_base_dir(context) == OS.PANGO_DIRECTION_RTL;
		OS.pango_layout_set_alignment(layout, rtl ? OS.PANGO_ALIGN_RIGHT : OS.PANGO_ALIGN_LEFT);
	} else {
		int margin = Math.min (indent, wrapIndent);
		OS.pango_layout_set_width(layout, (wrapWidth - margin) * OS.PANGO_SCALE);
	}
}

/**
 * Sets the wrap indent of the receiver. This indent is applied to all lines
 * in the paragraph except the first line.
 *
 * @param wrapIndent new wrap indent
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @see #setIndent(int)
 *
 * @since 3.6
 */
public void setWrapIndent (int wrapIndent) {
	checkLayout();
	if (wrapIndent < 0) return;
	if (this.wrapIndent == wrapIndent) return;
	this.wrapIndent = wrapIndent;
	OS.pango_layout_set_indent(layout, (indent - wrapIndent) * OS.PANGO_SCALE);
	if (wrapWidth != -1) setWidth();
}

static final boolean isLam(int ch) {
	return ch == 0x0644;
}

static final boolean isAlef(int ch) {
	switch (ch) {
		case 0x0622:
		case 0x0623:
		case 0x0625:
		case 0x0627:
		case 0x0649:
		case 0x0670:
		case 0x0671:
		case 0x0672:
		case 0x0673:
		case 0x0675:
			return true;
	}
	return false;
}

/**
 * Returns a string containing a concise, human-readable
 * description of the receiver.
 *
 * @return a string representation of the receiver
 */
@Override
public String toString () {
	if (isDisposed()) return "TextLayout {*DISPOSED*}";
	return "TextLayout {" + layout + "}";
}

/*
 *  Translate a client offset to an internal offset
 */
int translateOffset(int offset) {
	int length = text.length();
	if (length == 0) return offset;
	if (invalidOffsets == null) return offset;
	for (int i = 0; i < invalidOffsets.length; i++) {
		if (offset < invalidOffsets[i]) break;
		offset++;
	}
	return offset;
}

/*
 *  Translate an internal offset to a client offset
 */
int untranslateOffset(int offset) {
	int length = text.length();
	if (length == 0) return offset;
	if (invalidOffsets == null) return offset;
	int i = 0;
	while (i < invalidOffsets.length && offset > invalidOffsets[i]) {
		i++;
	}
	return offset - i;
}

int width () {
	int wrapWidth = OS.pango_layout_get_width(layout);
	if (wrapWidth != -1) return OS.PANGO_PIXELS(wrapWidth);
	int[] w = new int[1], h = new int[1];
	OS.pango_layout_get_pixel_size(layout, w, h);
	return w[0];
}

/**
 * Sets Default Tab Width in terms if number of space characters.
 *
 * @param tabLength in number of characters
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_ARGUMENT - if the tabLength is less than <code>0</code></li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @noreference This method is not intended to be referenced by clients.
 *
 * DO NOT USE This might be removed in 4.8
 * @since 3.107
 */
public void setDefaultTabWidth(int tabLength) {
	//unused in GTK
}

}
