StyledText offers three methods for redrawing its contents.
void redraw(): redraws the entire contents of the StyledText.
To restrict what's redrawn, use one of the other two redrawing methods:
void redraw(int x, int y, int width, int height, boolean all)
void redrawRange(int start, int length, boolean clearBackground)
/*
Revised from The Definitive Guide to SWT and JFace
by Robert Harris and Rob Warner
Apress 2004
*/
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import org.eclipse.swt.SWT;
import org.eclipse.swt.custom.ExtendedModifyEvent;
import org.eclipse.swt.custom.ExtendedModifyListener;
import org.eclipse.swt.custom.LineStyleEvent;
import org.eclipse.swt.custom.LineStyleListener;
import org.eclipse.swt.custom.StyleRange;
import org.eclipse.swt.custom.StyledText;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;
public class CrossLineStyleListener {
public static void main(String[] args) {
final Display display = new Display();
final Shell shell = new Shell(display);
final StyledText styledText = new StyledText(shell, SWT.V_SCROLL | SWT.BORDER);
final MultiLineCommentListener lineStyleListener = new MultiLineCommentListener();
styledText.addLineStyleListener(lineStyleListener);
styledText.addExtendedModifyListener(new ExtendedModifyListener() {
public void modifyText(ExtendedModifyEvent event) {
// Recalculate the comments
lineStyleListener.refreshMultilineComments(styledText.getText());
// Redraw the text
styledText.redraw();
}
});
styledText.setBounds(10, 10, 500, 100);
shell.open();
while (!shell.isDisposed()) {
if (!display.readAndDispatch()) {
display.sleep();
}
}
display.dispose();
}
}
class MultiLineCommentListener implements LineStyleListener {
// Markers for multiline comments
private static final String COMMENT_START = "/*";
private static final String COMMENT_END = "*/";
// Color for comments
private static final Color COMMENT_COLOR = Display.getCurrent().getSystemColor(SWT.COLOR_BLUE);
List commentOffsets = new LinkedList();
public void refreshMultilineComments(String text) {
// Clear any stored offsets
commentOffsets.clear();
// Go through all the instances of COMMENT_START
for (int pos = text.indexOf(COMMENT_START); pos > -1; pos = text.indexOf(
COMMENT_START, pos)) {
// offsets[0] holds the COMMENT_START offset
// and COMMENT_END holds the ending offset
int[] offsets = new int[2];
offsets[0] = pos;
// Find the corresponding end comment.
pos = text.indexOf(COMMENT_END, pos);
// If no corresponding end comment, use the end of the text
offsets[1] = pos == -1 ? text.length() - 1 :
pos + COMMENT_END.length() - 1;
pos = offsets[1];
// Add the offsets to the collection
commentOffsets.add(offsets);
}
}
/**
* Called by StyledText to get the styles for a line
*
* @param event the event
*/
public void lineGetStyle(LineStyleEvent event) {
// Create a collection to hold the StyleRanges
List styles = new ArrayList();
// Store the length for convenience
int length = event.lineText.length();
for (int i = 0, n = commentOffsets.size(); i < n; i++) {
int[] offsets = (int[]) commentOffsets.get(i);
// If starting offset is past current line--quit
if (offsets[0] > event.lineOffset + length) break;
// Check if we're inside a multiline comment
if (offsets[0] <= event.lineOffset + length
&& offsets[1] >= event.lineOffset) {
// Calculate starting offset for StyleRange
int start = Math.max(offsets[0], event.lineOffset);
// Calculate length for style range
int len = Math.min(offsets[1], event.lineOffset + length) - start + 1;
// Add the style range
styles.add(new StyleRange(start, len, COMMENT_COLOR, null));
}
}
// Copy all the ranges into the event
event.styles = (StyleRange[]) styles.toArray(new StyleRange[0]);
}
}
