[webkit-dev] Canvas rendering changes between Safari and Nightlies

Dimitri Bouniol dimitri008 at mac.com
Sat Mar 29 18:07:38 PDT 2008

Will do so - just wasn't sure if I had enough information pertaining  
to what might be causing it.
Bug posted at http://bugs.webkit.org/show_bug.cgi?id=6745
Test case will be posted there as well once I make one.

On Mar 29, 2008, at 3:58 PM, Oliver Hunt wrote:

> Without the full source, or a reduced test case it's we can't see  
> what the bug is, so merely looking at code won't help.
> Rather than using this list to report the bug though, I'd encourage  
> you to file a bug at http://bugs.webkit.org as that
> means the report won't be lost, and many people will be able to look  
> at it and work out what is happening.
> --Oliver
> On Mar 29, 2008, at 12:47 PM, Dimitri Bouniol wrote:
>> I am using a canvas to render images at a perspective on my site by  
>> rendering each line of pixels at a different scale.
>> The canvas object is all the icons that appear at the top of the  
>> page in the grey bar.
>> In Safari (3.1 and below), everything renders quickly and looks  
>> normal, but in recent Nightly builds, rendering time is  
>> significantly increased and rendering looks very bizarre.
>> I think it has something to do with drawing and scaling images  
>> using transforming methods, but I'm not sure, and was wondering If  
>> someone could take a look at it so I can locate the issue and  
>> either file a bug of fix my own code.
>> Site: http://appkainime.bouniol.homeip.net/
>> Javascript: http://appkainime.bouniol.homeip.net/js/master.js
>> Methods of interest:
>> - drawAppFlow()
>> Calls drawInContextWithPerspectiveAndArg several times at different  
>> positions with each image to be drawn at a perspective.
>> - drawInContextWithPerspectiveAndArg(drawFunction, ctx, x, y, z,  
>> width, height, arg)
>> Draws the drawFunction(ctx, arg) in the context ctx using the one- 
>> point perspective at (x, y, z), by calling drawFunction(ctx, arg)  
>> for every vertical pixel line, then clip, scale, and apply shading  
>> to the result accordingly so a perspective is acheived.
>> drawFunction is always drawImage(ctx, image)
>> arg is an Image object to be passed to drawImage
>> - drawImage(ctx, image)
>> Draws the image in the context ctx with a shadow, or if the image  
>> is not yet loaded, draws a grey box instead.
>> Hope someone could help me find the issue for this.

Dimitri Bouniol
dimitri008 at mac.com

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