styledtext.java

源码为Eclipse开源开发平台桌面开发工具SWT的源代码,

	 */
	class ContentWidthCache implements LineCache {
		StyledText parent;				// parent widget, used to create a GC for line measuring
		int[] lineWidth;				// width in pixel of each line in the document, -1 for unknown width
		StyledTextContent content;		// content to use for line width calculation
		int lineCount;					// number of lines in lineWidth array
		int maxWidth;					// maximum line width of all measured lines
		int maxWidthLineIndex;			// index of the widest line
				
	/** 
	 * Creates a new <code>ContentWidthCache</code> and allocates space 
	 * for the given number of lines.
	 * <p>
	 *
	 * @param parent the StyledText widget used to create a GC for 
	 * 	line measuring
	 * @param lineCount initial number of lines to allocate space for
	 */
	public ContentWidthCache(StyledText parent, StyledTextContent content) {
		this.parent = parent;
		this.content = content;
		this.lineCount = content.getLineCount();
		lineWidth = new int[lineCount];
		reset(0, lineCount, false);
	}
	/**
	 * Calculates the width of each line in the given range if it has
	 * not been calculated yet.
	 * If any line in the given range is wider than the currently widest
	 * line, the maximum line width is updated,
	 * <p>
	 * 
	 * @param startLine first line to calculate the line width of
	 * @param lineCount number of lines to calculate the line width for
	 */
	public void calculate(int startLine, int lineCount) {
		int caretWidth = 0;
		int endLine = startLine + lineCount;
			
		if (startLine < 0 || endLine > lineWidth.length) {
			return;
		}
		caretWidth = getCaretWidth();
		for (int i = startLine; i < endLine; i++) {
			if (lineWidth[i] == -1) {
				String line = content.getLine(i);
				int lineOffset = content.getOffsetAtLine(i);
				lineWidth[i] = contentWidth(line, lineOffset) + caretWidth;
			}
			if (lineWidth[i] > maxWidth) {
				maxWidth = lineWidth[i];
				maxWidthLineIndex = i;
			}
		}
	}
	/** 
	 * Calculates the width of the visible lines in the specified 
	 * range.
	 * <p>
	 *
	 * @param startLine	the first changed line
	 * @param newLineCount the number of inserted lines
	 */  
	void calculateVisible(int startLine, int newLineCount) {
		int topIndex = parent.getTopIndex();
		int bottomLine = Math.min(getPartialBottomIndex(), startLine + newLineCount);
		
		startLine = Math.max(startLine, topIndex);
		calculate(startLine, bottomLine - startLine + 1);
	}
	/**
	 * Measures the width of the given line.
	 * <p>
	 * 
	 * @param line the line to measure
	 * @param lineOffset start offset of the line to measure, relative 
	 * 	to the start of the document
	 * @param gc the GC to use for measuring the line
	 * @param currentFont the font currently set in gc. Cached for better 
	 * 	performance. Null when running in a bidi locale.
	 * @return the width of the given line
	 */
	int contentWidth(String line, int lineOffset) {
		TextLayout layout = renderer.getTextLayout(line, lineOffset);
		Rectangle rect = layout.getLineBounds(0);
		renderer.disposeTextLayout(layout);
		return rect.x + rect.width + leftMargin + rightMargin;
	}
	/**
	 * Grows the <code>lineWidth</code> array to accomodate new line width
	 * information.
	 * <p>
	 *
	 * @param numLines the number of elements to increase the array by
	 */
	void expandLines(int numLines) {
		int size = lineWidth.length;
		if (size - lineCount >= numLines) {
			return;
		}
		int[] newLines = new int[Math.max(size * 2, size + numLines)];
		System.arraycopy(lineWidth, 0, newLines, 0, size);
		lineWidth = newLines;
		reset(size, lineWidth.length - size, false);
	}
	/**
	 * Returns the width of the longest measured line.
	 * <p>
	 *
	 * @return the width of the longest measured line.
	 */
	public int getWidth() {
		return maxWidth;
	}
	/**
	 * Updates the line width array to reflect inserted or deleted lines.
	 * <p>
	 *
	 * @param start	the starting line of the change that took place
	 * @param delta	the number of lines in the change, > 0 indicates lines inserted,
	 * 	< 0 indicates lines deleted
	 */
	void linesChanged(int startLine, int delta) {
		boolean inserting = delta > 0;
		
		if (delta == 0) {
			return;
		}
		if (inserting) {
			// shift the lines down to make room for new lines
			expandLines(delta);
			for (int i = lineCount - 1; i >= startLine; i--) {
				lineWidth[i + delta] = lineWidth[i];
			}
			// reset the new lines
			for (int i = startLine + 1; i <= startLine + delta && i < lineWidth.length; i++) {
				lineWidth[i] = -1;
			}
			// have new lines been inserted above the longest line?
			if (maxWidthLineIndex >= startLine) {
				maxWidthLineIndex += delta;
			}
		} 
		else {
			// shift up the lines
			for (int i = startLine - delta; i < lineCount; i++) {
				lineWidth[i+delta] = lineWidth[i];
			}
			// has the longest line been removed?
			if (maxWidthLineIndex > startLine && maxWidthLineIndex <= startLine - delta) {
				maxWidth = 0;
				maxWidthLineIndex = -1;
			}
			else
			if (maxWidthLineIndex >= startLine - delta) {
				maxWidthLineIndex += delta;
			}
		}
		lineCount += delta;
	}
	/**
	 * Resets the line width of the lines in the specified range.
	 * <p>
	 *
	 * @param startLine	the first line to reset
	 * @param lineCount the number of lines to reset
	 * @param calculateMaxWidth true=if the widest line is being 
	 * 	reset the maximum width of all remaining cached lines is 
	 * 	calculated. false=the maximum width is set to 0 if the 
	 * 	widest line is being reset.
	 */
	public void redrawReset(int startLine, int lineCount, boolean calculateMaxWidth) {
		reset(startLine, lineCount, calculateMaxWidth);
	}
	/**
	 * Resets the line width of the lines in the specified range.
	 * <p>
	 *
	 * @param startLine	the first line to reset
	 * @param lineCount the number of lines to reset
	 * @param calculateMaxWidth true=if the widest line is being 
	 * 	reset the maximum width of all remaining cached lines is 
	 * 	calculated. false=the maximum width is set to 0 if the 
	 * 	widest line is being reset.
	 */
	public void reset(int startLine, int lineCount, boolean calculateMaxWidth) {
		int endLine = startLine + lineCount;
		
		if (startLine < 0 || endLine > lineWidth.length) {
			return;
		}
		for (int i = startLine; i < endLine; i++) {
			lineWidth[i] = -1;
		}		
		// if the longest line is one of the reset lines, the maximum line 
		// width is no longer valid
		if (maxWidthLineIndex >= startLine && maxWidthLineIndex < endLine) {
			maxWidth = 0;
			maxWidthLineIndex = -1;
			if (calculateMaxWidth) {
				for (int i = 0; i < lineCount; i++) {
					if (lineWidth[i] > maxWidth) {
						maxWidth = lineWidth[i];
						maxWidthLineIndex = i;
					}
				}			
			}
		}
	}
	/** 
	 * Updates the line width array to reflect a text change.
	 * Lines affected by the text change will be reset.
	 * <p>
	 *
	 * @param startOffset	the start offset of the text change
	 * @param newLineCount the number of inserted lines
	 * @param replaceLineCount the number of deleted lines
	 * @param newCharCount the number of new characters
	 * @param replaceCharCount the number of deleted characters
	 */  
	public void textChanged(int startOffset, int newLineCount, int replaceLineCount, int newCharCount, int replaceCharCount) {
		int startLine = parent.getLineAtOffset(startOffset);
		boolean removedMaxLine = (maxWidthLineIndex > startLine && maxWidthLineIndex <= startLine + replaceLineCount);
		// entire text deleted?
		if (startLine == 0 && replaceLineCount == lineCount) {
			lineCount = newLineCount;
			lineWidth = new int[lineCount];
			reset(0, lineCount, false);
			maxWidth = 0;
		}
		else {
			linesChanged(startLine, -replaceLineCount);
			linesChanged(startLine, newLineCount);
			lineWidth[startLine] = -1;
		}
		// only calculate the visible lines. otherwise measurements of changed lines 
		// outside the visible area may subsequently change again without the 
		// lines ever being visible.
		calculateVisible(startLine, newLineCount);
		// maxWidthLineIndex will be -1 (i.e., unknown line width) if the widget has 
		// not been visible yet and the changed lines have therefore not been
		// calculated above.
		if (removedMaxLine || 
			(maxWidthLineIndex != -1 && lineWidth[maxWidthLineIndex] < maxWidth)) {
			// longest line has been removed or changed and is now shorter.
			// need to recalculate maximum content width for all lines
			maxWidth = 0;
			for (int i = 0; i < lineCount; i++) {
				if (lineWidth[i] > maxWidth) {
					maxWidth = lineWidth[i];
					maxWidthLineIndex = i;
				}
			}			
		}
	}
	}
	/**
	 * Updates the line wrapping of the content.
	 * The line wrapping must always be in a consistent state. 
	 * Therefore, when <code>reset</code> or <code>redrawReset</code>
	 * is called, the line wrapping is recalculated immediately 
	 * instead of in <code>calculate</code>.
	 */
	class WordWrapCache implements LineCache {
		StyledText parent;
		WrappedContent visualContent;
				
	/** 
	 * Creates a new <code>WordWrapCache</code> and calculates an initial
	 * line wrapping.
	 * <p>
	 *
	 * @param parent the StyledText widget to wrap content in.
	 * @param content the content provider that does the actual line wrapping.
	 */
	public WordWrapCache(StyledText parent, WrappedContent content) {
		this.parent = parent;
		visualContent = content;
		visualContent.wrapLines();
	}
	/**
	 * Do nothing. Lines are wrapped immediately after reset.
	 * <p>
	 * 
	 * @param startLine first line to calculate
	 * @param lineCount number of lines to calculate
	 */
	public void calculate(int startLine, int lineCount) {
	}
	/**
	 * Returns the client area width. Lines are wrapped so there
	 * is no horizontal scroll bar.
	 * <p>
	 *
	 * @return the line width
	 */
	public int getWidth() {
		return parent.getClientArea().width;
	}
	/**
	 * Wraps the lines in the specified range.
	 * This method is called in <code>StyledText.redraw()</code>.
	 * A redraw is therefore not necessary.
	 * <p>
	 *
	 * @param startLine the first line to reset
	 * @param lineCount the number of lines to reset
	 * @param calculateMaxWidth true=implementors should retain a 
	 * 	valid width even if it is affected by the reset operation.
	 * 	false=the width may be set to 0
	 */
	public void redrawReset(int startLine, int lineCount, boolean calculateMaxWidth) {
	    if (lineCount == visualContent.getLineCount()) {
			// do a full rewrap if all lines are reset
			visualContent.wrapLines();
	    }
	    else {
		    visualContent.reset(startLine, lineCount);
	    }
	}
	/**
	 * Rewraps the lines in the specified range and redraws
	 * the widget if the line wrapping has changed.
	 * <p>
	 *
	 * @param startLine the first line to reset
	 * @param lineCount the number of lines to reset
	 * @param calculateMaxWidth true=implementors should retain a 
	 * 	valid width even if it is affected by the reset operation.
	 * 	false=the width may be set to 0
	 */
	public void reset(int startLine, int lineCount, boolean calculateMaxWidth) {
		int itemCount = getPartialBottomIndex() - topIndex + 1;
	    int[] oldLineOffsets = new int[itemCount];
	    
	    for (int i = 0; i < itemCount; i++) {
	    	oldLineOffsets[i] = visualContent.getOffsetAtLine(i + topIndex);
	    }
	    redrawReset(startLine, lineCount, calculateMaxWidth);
		// check for cases which will require a full redraw
	    if (getPartialBottomIndex() - topIndex + 1 != itemCount) {
	    	// number of visible lines has changed
	    	parent.internalRedraw();
	    }
	    else {
		    for (int i = 0; i < itemCount; i++) {
		    	if (visualContent.getOffsetAtLine(i + topIndex) != oldLineOffsets[i]) {
		    		// wrapping of one of the visible lines has changed
		    		parent.internalRedraw();
		    		break;
		    	}
	    	}	    	
	    }
	}
	/** 
	 * Passes the text change notification to the line wrap content.
	 * <p>
	 *
	 * @param startOffset	the start offset of the text change
	 * @param newLineCount the number of inserted lines
	 * @param replaceLineCount the number of deleted lines
	 * @param newCharCount the number of new characters
	 * @param replaceCharCount the number of deleted characters
	 */  
	public void textChanged(int startOffset, int newLineCount, int replaceLineCount, int newCharCount, int replaceCharCount) {
		int startLine = visualContent.getLineAtOffset(startOffset);
		visualContent.textChanged(startOffset, newLineCount, replaceLineCount, newCharCount, replaceCharCount);

		// if we are wrapping then it is possible for a deletion on the last
		// line of text to shorten the total text length by a line.  If this
		// occurs then the startIndex must be adjusted such that a redraw will
		// be performed if a visible region is affected.  fixes bug 42947.
		if (wordWrap) {
			int lineCount = content.getLineCount();
			if (startLine >= lineCount) startLine = lineCount - 1;  
		}
		if (startLine <= getPartialBottomIndex()) {
			// only redraw if the text change affects text inside or above 
			// the visible lines. if it is below the visible lines it will
			// not affect the word wrapping. fixes bug 14047.
			parent.internalRedraw();
		}
	}
	}

/**
 * Constructs a new instance of this class given its parent
 * and a style value describing its behavior and appearance.
 * <p>
 * The style value is either one of the style constants defined in
 * class <code>SWT</code> which is applicable to instances of this