[whatwg] "canvas" tag and animations ?

[Andrew Fedoniouk]

----- Original Message ----- 
From: "Ian Hickson" <ian at hixie.ch>
Subject: Re: [whatwg] "canvas" tag and animations ?


> On Tue, 16 May 2006, Andrew Fedoniouk wrote:
>> |
>> | Canvases are automatically double-buffered.
>>
>> Why? Is this a requirement?
>
> Not in theory, but in practice it is. Early Opera implementations didn't
> do this and the performance was too slow for practical use.
>

This does not mean that acceptable implementation without double-buffering
is not possible or does not make sense.

For simple cases like custom bullet for the list it makes sense to have one 
of
these (or combination of these):
1) non-buffered draw, small area to draw and simple image. If
    buffered draw needed - use Image;
2) or to have getGraphics defined as
    getGraphics("what",x,y,width, height, backgroundColor = transparent) or
3) or to be able to say for example
    element.style.listStyleImage = new Image();
4) or in <style> to define
    li {  list-style-image: url("script: nameOfVariableHoldingImage;");  }

(assumption was made that getGraphics/Canvas will be available
for any element)

Andrew Fedoniouk
http://terrainformatica.com