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Resetting a canvas [message #445707]

Tue, 09 November 2004 20:30

Eclipse User

Originally posted by: wayneg.ananzi.co.za

Hi all,

Could anyone tell me how to reset a canvas to its original state after
drawing on it with GC (pictures or simple lines). If it makes any
difference all the drawings are done in paintListeners.

Regards
Wayne

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Re: Resetting a canvas [message #445733 is a reply to message #445707]

Wed, 10 November 2004 07:14

Ryan

Messages: 34
Registered: July 2009

Member

Hi Wayne,

The only way I know of doing this is to create a new GC, set its
background colour to the background colour of the canvas, and then draw a
big fill-rectangle to cover the whole canvas. i.e.:

GC gc = new GC(canvas);
gc.setBackground(canvas.getBackground());
gc.fillRectangle(0, 0, canvas.getSize().x, canvas.getSize().y);
gc.dispose();

Ryan

Wayne Gemmell wrote:

> Hi all,

> Could anyone tell me how to reset a canvas to its original state after
> drawing on it with GC (pictures or simple lines). If it makes any
> difference all the drawings are done in paintListeners.

> Regards
> Wayne

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Re: Resetting a canvas [message #445746 is a reply to message #445707]

Wed, 10 November 2004 14:47

Steve Northover

Messages: 1636
Registered: July 2009

Senior Member

You could use Control.redraw() and Control.update(). The redraw() method
will cause the operating system to invalidate the canvas and queue a paint
event. If you update() right away, then the paint will get delivered after
the operating system has filled the canvas with the background. Then you
can draw. It's a bit of a hack but should work.

"Wayne Gemmell" <wayneg@ananzi.co.za> wrote in message
news:cmr9dg$15e$1@eclipse.org...
> Hi all,
>
> Could anyone tell me how to reset a canvas to its original state after
> drawing on it with GC (pictures or simple lines). If it makes any
> difference all the drawings are done in paintListeners.
>
> Regards
> Wayne
>

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