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Topic: XOR drawing (Read 432 times) |
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SJL
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XOR drawing
« on: Jun 7th, 2004, 12:06pm » |
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Hi there gurus,
I am trying to draw something (lines, etc) using a XOR mode between the current strike color and the background.
So far, I could not find in the documentation any fuction/method to specify the drawing mode (xor, and, or, etc). Do I have to dig to the java's Graphics2D handle in the applet or is there some easier way that I don't know about?
Thanks!
SJL
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JohnG
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Re: XOR drawing
« Reply #1 on: Jun 7th, 2004, 2:36pm » |
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I don't think there's a default mode you can just switch on to do it.
If you're willing to work out the pixels coloured with line yourself, you could use this:
Code:
color MyColour=new color(128,255,63);
pixels[x+y*width]^=MyColour;
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Or you could draw your line to a new BGraphics image, then do bitwise XOR into the displayed one:
Code:
BGraphics temp=new BGraphics(width,height);
temp.background(0);
temp.stroke(255,128,0);
temp.line(0,0,30,30);
for(int y=0;y<height;y++)
{
for(int x=0;x<width;x++)
{
pixels[x+y*width]^=temp.pixels[x+y*width];
}
}
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Here's an example I just cobbled together using the BGraphics method:
http://www.hardcorepawn.com/XOR_stroke
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| « Last Edit: Jun 7th, 2004, 2:54pm by JohnG » |
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SJL
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Re: XOR drawing
« Reply #2 on: Jun 7th, 2004, 3:16pm » |
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Excellent example applet. It does exactly what I had in mind. In fact, I want to draw a one pixel size rectagular frame using the mouse, and then zoom the content to the whole applet area on mouseRelease(). So I thought of XOR-ing the content with the stroke color such as to be able to restore the old content of the canvas when the mouse move.
My problem was that not for a single second did I considered to directly access the pixels, well...
Thank you!
SJL.
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