Possible To Predraw things on the 'Canvas'?

[Andrew_of_New_Zealand]

I'm creating a video game interface and want to see if i can use a canvas 'widget' as a video screen. Can anyone tell me how to draw pictures on the canvas?

[Eric Clayberg]

I'm creating a video game interface and want to see if i can use a canvas 'widget' as a video screen. Can anyone tell me how to draw pictures on the canvas?

The following page has an impressive collection of SWT canvas drawing examples...

http://www.java2s.com/ExampleCode/SWT-JFace-Eclipse/2D.htm

[Andrew_of_New_Zealand]

Right thanks. This'll give me something to go on.

[Andrew_of_New_Zealand]

Eric or anyone, do you know if you can clear a canvas, ready to print a new 'screen' (or canvas-painting, which ever you want to call it)? I've set a button to progress from Title Screen to Start Screen (My game is called "Jolly Joy Stick"), but am I able to use a SWT instruction to bare a canvas for the next screen? I've looked through the list of things you can do with a canvas, but couldn't find an instruction that does that.

Well thanks.

[Kelly]

I am no expert but you might have to use the GC class and use fillRectangle method to draw a solid color onto the image.

A good site that helps me is
http://dev.eclipse.org/viewcvs/index.cg ... e/dev.html

[Andrew_of_New_Zealand]

Thanks Kelly, yes they way you discribe reminds me of image drawing I used to do with the Java abstract window toolkit.
Over writing images I knew to be onscreen didn't seem like a very easy way of doing it, but I guess, if theres no other way, I'll make progress that way.

[Andrew_of_New_Zealand]

lol. there is the 'e.gc' (is it PaintEvent-Graphics Controller?), has a big stack of drawing functions with it, but even the dispose function won't clear the canvas. I've even tried the delete function. There is a Java delete function isn't there?

Well I guess might be some way to do what I want to do, if I keep tryying.
I can't find the right 'e.gc' function for deleting ovals and strings yet.

[Kelly]

The one way I used to erase the last object drawn on an image was to keep a copy of the image being drawn on and using the

GC gc = new GC(canvas);
gc.drawImage(savedimg, x, y, w, h, x, y, w, h);

This copies a rectangle from savedimg to the canvas.

If you want to undo more than one event then you need to save copies of the area being drawn on in memory or on disk.

This is from my limited adventures into writing drawning programs in java.

You might look at http://alistairdickie.com/ at the free java drawing program thier for ideas.

[Andrew_of_New_Zealand]

Thanks, I'll try some of this some time. Right now I'm deviating from my little game, to attmepted to do this Doctor-Office building computer project, that the school has set us.