Demonstrates multiline comments : Text « SWT JFace Eclipse « Java
Demonstrates multiline comments
//Send questions, comments, bug reports, etc. to the authors:
//Rob Warner (rwarner@interspatial.com)
//Robert Harris (rbrt_harris@yahoo.com)
import org.eclipse.swt.*;
import org.eclipse.swt.custom.*;
import org.eclipse.swt.layout.*;
import org.eclipse.swt.widgets.*;
import java.util.LinkedList;
import java.util.ArrayList;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.widgets.Display;
/**
* This program demonstrates multiline comments. It uses MultiLineCommentListener
* to do the syntax coloring
*/
public class MultiLineComment {
/**
* Runs the application
*/
public void run() {
Display display = new Display();
Shell shell = new Shell(display);
shell.setText("Multiline Comments");
createContents(shell);
shell.open();
while (!shell.isDisposed()) {
if (!display.readAndDispatch()) {
display.sleep();
}
}
display.dispose();
}
/**
* Creates the main window contents
*
* @param shell the main window
*/
private void createContents(Shell shell) {
shell.setLayout(new FillLayout());
final StyledText styledText = new StyledText(shell, SWT.BORDER | SWT.H_SCROLL
| SWT.V_SCROLL);
// Add the line style listener
final MultiLineCommentListener lineStyleListener = new MultiLineCommentListener();
styledText.addLineStyleListener(lineStyleListener);
// Add the modification listener
styledText.addExtendedModifyListener(new ExtendedModifyListener() {
public void modifyText(ExtendedModifyEvent event) {
// Recalculate the comments
lineStyleListener.refreshMultilineComments(styledText.getText());
// Redraw the text
styledText.redraw();
}
});
}
/**
* The application entry point
*
* @param args the command line arguments
*/
public static void main(String[] args) {
new MultiLineComment().run();
}
}
//Send questions, comments, bug reports, etc. to the authors:
//Rob Warner (rwarner@interspatial.com)
//Robert Harris (rbrt_harris@yahoo.com)
/**
* This class supports multiline comments. It turns comments green.
*/
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_DARK_GREEN);
// Offsets for all multiline comments
List commentOffsets;
/**
* MultilineCommentListener constructor
*/
public MultiLineCommentListener() {
commentOffsets = new LinkedList();
}
/**
* Refreshes the offsets for all multiline comments in the parent StyledText.
* The parent StyledText should call this whenever its text is modified. Note
* that this code doesn't ignore comment markers inside strings.
*
* @param text the text from the StyledText
*/
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]);
}
}
