Brainstorm/Snippets/src/snippets/swt/StyledTextAndControls.java

package snippets.swt;

import org.eclipse.swt.SWT;
import org.eclipse.swt.custom.PaintObjectEvent;
import org.eclipse.swt.custom.PaintObjectListener;
import org.eclipse.swt.custom.StyleRange;
import org.eclipse.swt.custom.StyledText;
import org.eclipse.swt.events.VerifyEvent;
import org.eclipse.swt.events.VerifyListener;
import org.eclipse.swt.graphics.Font;
import org.eclipse.swt.graphics.GlyphMetrics;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Combo;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;

public class StyledTextAndControls {
	static StyledText styledText;
	static String text = 
		"This snippet shows how to embed widgets in a StyledText.\n"+
		"Here is one: \uFFFC, and here is another: \uFFFC.";
	static int[] offsets;
	static Control[] controls;
	static int MARGIN = 5;

static void addControl(Control control, int offset) {
	StyleRange style = new StyleRange ();
	style.start = offset;
	style.length = 1;
	control.pack();
	Rectangle rect = control.getBounds();
	int ascent = 2*rect.height/3;
	int descent = rect.height - ascent;
	style.metrics = new GlyphMetrics(ascent + MARGIN, descent + MARGIN, rect.width + 2*MARGIN);
	styledText.setStyleRange(style);	
}

public static void main(String[] args) {
	final Display display = new Display();
	Font font = new Font(display, "Tahoma", 32, SWT.NORMAL);
	final Shell shell = new Shell(display);
	shell.setLayout(new GridLayout());
	styledText = new StyledText(shell, SWT.WRAP | SWT.BORDER);
	styledText.setFont(font);
	styledText.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
	styledText.setText(text);
	controls = new Control[2];
	Button button = new Button(styledText, SWT.PUSH);
	button.setText("Button 1");
	controls[0] = button;
	Combo combo = new Combo(styledText, SWT.NONE);
	combo.add("item 1");
	combo.add("another item");
	controls[1] = combo;
	offsets = new int[controls.length];
	int lastOffset = 0;
	for (int i = 0; i < controls.length; i++) {
		int offset = text.indexOf("\uFFFC", lastOffset);
		offsets[i] = offset;
		addControl(controls[i], offsets[i]);
		lastOffset = offset + 1;
	}
	
	// use a verify listener to keep the offsets up to date
	styledText.addVerifyListener(new VerifyListener()  {
		public void verifyText(VerifyEvent e) {
			int start = e.start;
			int replaceCharCount = e.end - e.start;
			int newCharCount = e.text.length();
			for (int i = 0; i < offsets.length; i++) {
				int offset = offsets[i];
				if (start <= offset && offset < start + replaceCharCount) {
					// this widget is being deleted from the text
					if (controls[i] != null && !controls[i].isDisposed()) {
						controls[i].dispose();
						controls[i] = null;
					}
					offset = -1;
				}
				if (offset != -1 && offset >= start) offset += newCharCount - replaceCharCount;
				offsets[i] = offset;
			}
		}
	});
	
	// reposition widgets on paint event
	styledText.addPaintObjectListener(new PaintObjectListener() {
		public void paintObject(PaintObjectEvent event) {
			StyleRange style = event.style;
			int start = style.start;
			for (int i = 0; i < offsets.length; i++) {
				int offset = offsets[i];
				if (start == offset) {
					Point pt = controls[i].getSize();
					int x = event.x + MARGIN;
					int y = event.y + event.ascent - 2*pt.y/3;
					controls[i].setLocation(x, y);
					break;
				}
			}
		}
	});
		
	shell.setSize(400, 400);
	shell.open();
	while (!shell.isDisposed()) {
		if (!display.readAndDispatch())
			display.sleep();
	}
	font.dispose();
	display.dispose();
}
}