Bug 59849 – Avoid allocating a new image buffer in ~CanvasRenderingContext2D()

• Component: Canvas
• Status: RESOLVED FIXED

[Simon Fraser (smfr)]

The code I added to ~CanvasRenderingContext2D() to unwind the graphics stack can end up allocating a new image buffer, which is bad.

[Simon Fraser (smfr)]

<rdar://problem/9362156>

[Simon Fraser (smfr)]

Created attachment 92273 [details]
Patch

[Darin Adler]

Comment on attachment 92273 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=92273&action=review

> Source/WebCore/html/HTMLCanvasElement.h:103
> -    GraphicsContext* drawingContext() const;
> +    enum ImageBufferCreation { AllowImageBufferCreation, DisallowImageBufferCreation };
> +    GraphicsContext* drawingContext(ImageBufferCreation allowBufferCreation = AllowImageBufferCreation) const;

Can we just add a second function with this behavior? Or maybe just a function that returns a boolean to tell us if we already have a buffer? I think that adding this argument is unnecessary given how simple the function is.

[Darin Adler]

Comment on attachment 92273 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=92273&action=review

>> Source/WebCore/html/HTMLCanvasElement.h:103
>> +    GraphicsContext* drawingContext(ImageBufferCreation allowBufferCreation = AllowImageBufferCreation) const;
> 
> Can we just add a second function with this behavior? Or maybe just a function that returns a boolean to tell us if we already have a buffer? I think that adding this argument is unnecessary given how simple the function is.

One possible name for a new function would be existingDrawingContext. But I think that the hasImageBuffer solution would be fine.

[Simon Fraser (smfr)]

Comment on attachment 92273 [details]
Patch

Yeah, sounds good.

[Simon Fraser (smfr)]

Created attachment 92278 [details]
Patch

[Simon Fraser (smfr)]

http://trac.webkit.org/changeset/85760