| Transform.rotate(45) [message #653377] |
Wed, 09 February 2011 15:15  |
Eclipse User |
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Originally posted by: m.swillus.qualitype.de
Hej,
I am noticing a strange effect when rotating a GC by 45 degrees (135,
225 and 315 as well), and afterwards drawing some elements on it.
Especially drawOval() is painted on another position than fillOval(),
given the same coordinates. While fillOval() seems to get painted right,
drawOval() and drawLine() seem not. A goofy behaviour can also be
observed within the close proximity of the axes angle bisectors (45,
135, 225, 315 degrees).
Please find a rudimental snippet attached, which continuously rotates an
oval and a fillOval. In the proximity of the described angles you will
observe some strange deviations of the drawOval() output.
I already searched bugzilla, with no success though. Please give me a
hint if this one is a real bug or I am misusing the API.
Thanks in advance and best regards from Dresden,
Mirko Swillus
// snippet
package test;
import org.eclipse.swt.SWT;
import org.eclipse.swt.events.PaintEvent;
import org.eclipse.swt.events.PaintListener;
import org.eclipse.swt.graphics.Transform;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;
public class TransformTest {
public static void main(String[] args) throws InterruptedException {
Display display = new Display();
final Shell shell = new Shell(display, SWT.DOUBLE_BUFFERED
| SWT.NO_BACKGROUND);
final Transform transform = new Transform(display);
shell.addPaintListener(new PaintListener() {
@Override
public void paintControl(PaintEvent e) {
e.gc.setBackground(e.gc.getDevice().getSystemColor(
SWT.COLOR_RED));
e.gc.setForeground(e.gc.getDevice().getSystemColor(
SWT.COLOR_RED));
e.gc.setTransform(transform);
e.gc.fillOval(50, 50, 10, 10);
e.gc.drawOval(46, 46, 18, 18);
}
});
shell.pack();
shell.open();
shell.setSize(200, 200);
while (!shell.isDisposed()) {
if (!display.readAndDispatch()) {
display.sleep();
}
Thread.sleep(5);
transform.translate(100, 100);
transform.rotate(1);
transform.translate(-100, -100);
shell.redraw();
}
display.dispose();
}
}
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| Re: Transform.rotate(45) [message #653615 is a reply to message #653600] |
Thu, 10 February 2011 12:28  |
| Eclipse User |
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Originally posted by: m.swillus.qualitype.de
Hej,
Am 10.02.2011 12:34, schrieb Lakshmi Shanmugam:
> Looks like you are seeing this bug -->
> https://bugs.eclipse.org/bugs/show_bug.cgi?id=253670
Thanks a lot! Obviously, my bugzilla search skills are a little
expandable.
> I just verified that the workaround specified in the
> https://bugs.eclipse.org/bugs/show_bug.cgi?id=253670#c2 of the bug seems
> to fix the problem for your snippet too.
> It requires you to set the GC data state mask after rotation but before
> drawing ---> e.gc.getGCData().state |= <GC#DRAW_OFFSET value for your
> platform>
I'm on XP, so I guess 1 << 14 is fine by me, which actually did the
trick. Best regards,
Mirko Swillus
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