Description Knut Radloff 2001-10-11 14:22:49 EDT

Run the test case below. It renders and measures character using a non True Type font (MS Sans Serif).
gc.stringExtent returns a width of 8 for the regular font which matches the rendered glyph width.
When I render the same character using the bold version of the font stringExtent returns a width of 9
but the rendered glyph is actually 10 pixels wide.
This only appears to happen with non True Type fonts and causes problems in the bidi StyledText.
Bidi StyledText doesn't use gc.stringExtent but instead GetCharacterPlacement. GetCharacterPlacement
also returns the wrong width.


import org.eclipse.swt.*;
import org.eclipse.swt.graphics.*;
import org.eclipse.swt.widgets.*;

public class PR_1GI7ALA {
	Shell shell;
	Canvas canvas;
	Font boldFont;
	Font normalFont;

public void create() {
	shell = new Shell();
	Display display = shell.getDisplay();
	normalFont = new Font(display, "MS Sans Serif", 10, SWT.NORMAL);
	boldFont = new Font(display, "MS Sans Serif", 10, SWT.BOLD);	

	shell.setFont(normalFont);
	shell.setBackground(new Color(display, 155, 0, 0));
	shell.addListener(SWT.Paint, new Listener() {
		public void handleEvent(Event event) {
			String text = "s";	
			event.gc.setBackground(new Color(shell.getDisplay(), 255, 255, 255));
			event.gc.drawLine(9, 0, 9, 40);						
			event.gc.drawString(text, 0, 0);
			System.out.println("regular font " + event.gc.stringExtent(text));
			event.gc.setFont(boldFont);			
			event.gc.drawString(text, 0, 20);			
			System.out.println("bold font " + event.gc.stringExtent(text));
		}
	});
	shell.open();
	shell.setSize(300, 200);
}
public static void main(String[] args) {
	PR_1GI7ALA test = new PR_1GI7ALA();

	test.create();	
	test.run();
}
public void run() {
	Display display = shell.getDisplay ();
	while (!shell.isDisposed ()) {
		if (!display.readAndDispatch ()) display.sleep ();
	}	
}
}

NOTES:

KR (8/9/01 1:15:47 PM)
	We'd like to know if this is an SWT bug or if the platform is just plain not doing the right thing. 
	If it's the latter we'd have to work around it in StyledText (which would require non-trivial changes). 
	An actual fix is not particularly urgent (i.e., the problem only causes cheese, not a crash).

KR (8/20/01 2:20:29 PM)
	A similar problem occurs with True Type fonts in certain sizes. For example Times New Roman 10 
	regular (non-bold) is measured correctly as being 11 pixels wide. 
	Times New Roman 12, regular is measured incorrectly as 13 pixels wide when it really is 14 pixels 
	wide.
	This is on Arabic NT and with an Arabic 's' instead of the Latin 's' in the test case above.

KR (8/20/01 3:38:08 PM)
	Wordpad has problems with Times New Roman in sizes > 10 as well. The cursor is not placed 
	correctly. It overlaps the last pixel of the (logical) first character like we do. However if I then add 
	a space it doesn't overlap that pixel. This only happens on Arabic. I haven't seen this on Hebrew. 
	Perhaps the Arabic TrueType fonts are just bad?