Re: [platform-swt-dev] GC on native components and painting

[Minh Chiem <minhchiem@xxxxxxxxxxxx>]

yep that code is much cleaner. Thanks.

Carolyn MacLeod wrote:

> The following snippet is the best I can do.
> Hope it helps.
> Carolyn
>
> *import* org.eclipse.swt.*;
> *import* org.eclipse.swt.graphics.*;
> *import* org.eclipse.swt.layout.*;
> *import* org.eclipse.swt.widgets.*;
>
> /**
>  * Buttons on Windows don't like transparent images.
>  * So you have to simulate transparency by setting the image's
>  * transparent pixel to the button's background color.
>  */
> *public* *class* Main {
>        
> *public* *static* *void* main (String [] args) {
>         Display display = *new* Display();
>        
>         /* Create a shell with a button. */
>         Shell shell = *new* Shell (display);
>         shell.setLayout (*new* FillLayout ());
>         Button button = *new* Button (shell, SWT.PUSH | SWT.BORDER);
>
>         /* Create an image data with a 2-color palette (red, white). */
>         PaletteData palette = *new* PaletteData (*new* RGB[] {
>                 display.getSystemColor (SWT.COLOR_RED).getRGB (),   // 
> pixel 0 = red
>                 display.getSystemColor (SWT.COLOR_WHITE).getRGB (), // 
> pixel 1 = white
>         });
>         ImageData imageData = *new* ImageData (24, 24, 1, palette);
>         imageData.transparentPixel = 1; // set the transparent color 
> to white
>        
>         /* Create an image from the image data, and draw on it. */
>         Image image = *new* Image (display, imageData);
>         GC gc = *new* GC (image);
>         gc.setBackground (display.getSystemColor (SWT.COLOR_WHITE));
>         gc.fillRectangle (0, 0, 24, 24); // fill with white
>         gc.setBackground (display.getSystemColor (SWT.COLOR_RED));
>         gc.fillArc (2, 2, 20, 20, 0, 360); // draw a red circle in the 
> middle
>         gc.dispose ();
>        
>         /* Tell the image to use the button's background color for 
> transparent pixels. */
>         image.setBackground (button.getBackground ());
>         button.setImage (image);
>        
>         shell.pack ();
>         shell.open ();
>         *while* (!shell.isDisposed ()) {
>                 *if* (!display.readAndDispatch ()) display.sleep ();
>         }
>         image.dispose ();
>         display.dispose ();
> }
> }
>
>
>
>
>
> *Minh Chiem <minhchiem@xxxxxxxxxxxx>*
> Sent by: platform-swt-dev-admin@xxxxxxxxxxx
>
> 11/26/2003 03:13 AM
> Please respond to
> platform-swt-dev
>
>
> 	
> To
> 	platform-swt-dev@xxxxxxxxxxx
> cc
> 	
> Subject
> 	[platform-swt-dev] GC on native components and painting
>
>
>
> 	
>
>
>
>
>
> Hi.
>
> I've followed the guide on
> http://www.eclipse.org/articles/Article-SWT-images/graphics-resources.html#Transparency
> to find out how to do transparency.
>
> I've added a paintlistener on a button however, when you go to click on
> the button there seems to be no refresh so it appears as if a image as
> disappeared.
>
> It looks like there's another paint listener when the button is pressed
> so what I've done is made the button repaint everytime the mouse down
> and mouse up event occurs and that seems to be a nice work around.
> However, I've got lots of buttons/toolbar items that have images and
> adding mouse listeners to all the buttons makes code look really messy
> IMHO. Since I can't just extend the Button so that it encapsulates the
> extra repainting behaviour, is another way to approach this problem?
>
> BTW, I'm running this on the windows version of SWT.
>
> _______________________________________________
> platform-swt-dev mailing list
> platform-swt-dev@xxxxxxxxxxx
> http://dev.eclipse.org/mailman/listinfo/platform-swt-dev