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[whatwg] proposed canvas 2d API additions

From: Arve Bersvendsen <arveb@opera.com>
Date: Mon, 24 Apr 2006 11:53:34 +0200
Message-ID: <op.s8ia3k1dbyn2jm@localhost.localdomain>
[ Ian Hickson ]
>> I don't understand how these are supposed to work when the underlying
>> bitmap's device pixel space does not map 1:1 to the coordinate space.

[ Vladimir Vukicevic ]
> I'm not sure what you mean -- the coordinates here are explicit canvas
> pixels, and they specifically ignore the current canvas transform.
> So, given
>  <canvas width="100" height="200"></canvas>
>
> the coordinates would be 0..99, 0..199.

Without expressing any other opinion at the moment, I'd just like to  
clarify how Opera's implementation of getPixel/setPixel currently follows  
the coordinate space, as Vlad is suggesting here, disregarding any  
translation and rotation. Given the following script snippet:

   gc =  
document.getElementsByTagName('canvas')[0].getContext('opera-2dgame');
   for ( var y = 50; y < 100; y++){
     for (var x = 50; x < 100; x++){
       gc.setPixel(x,y,"blue");
     }
   }

... with this CSS:

   canvas  {
     width: 200px;
     height: 200px;
     border: 1px solid black;
   }

and the following markup:

   <canvas width="100" height="100">

we fill the bottom-right quadrant of the canvas, with a rectangle that is  
comprised of 100x100 CSS pixels.

-- 
Arve Bersvendsen, Opera Software ASA
Received on Monday, 24 April 2006 02:53:34 UTC

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