Remove down-casting to BitmapImage in GraphicsContext::drawImage.

• Component: Images
• Status: RESOLVED FIXED

[Dongseong Hwang]

Add a BitmapImage draw method which takes RespectImageOrientationEnum enum as the last argument for CG. Then we can remove the conditional down-casting in GraphicsContext::drawImage.

This change is needed for parallel image decoders. Because parallel image decoders use a Bitmap image wrapper class which extends Image (not Bitmap), the down-casting above causes the loss of RespectImageOrientationEnum which must be passed to BitmapImage.

[Dongseong Hwang]

Created attachment 151211 [details]
Patch

[Kwang Yul Seo]

Simon, this is a simple refactoring patch which removes a CG-specific conditional down-casting in GraphicsContext::drawImage. 

Because GraphicsContext already has a draw method with RespectImageOrientationEnum, there is no reason not to put the corresponding Image::draw method with RespectImageOrientationEnum in Image.

[Kwang Yul Seo]

Comment on attachment 151211 [details]
Patch

Clearing flags on attachment: 151211

Committed r122598: <http://trac.webkit.org/changeset/122598>

[Kwang Yul Seo]

All reviewed patches have been landed.  Closing bug.

[Nico Weber]

How does this patch work? Before this patch, BitmapImage::draw would be called from GraphicsContext.cpp, which had an implementation that honored the image orientation in ImageCG.cpp (BitmapImage::draw()).

Now GraphicsContext calls Image::draw() on all platforms, which always throws away the orientation parameter. How does this patch not break image orientation on mac?

[Dongseong Hwang]

(In reply to comment #5)
> How does this patch work? Before this patch, BitmapImage::draw would be called from GraphicsContext.cpp, which had an implementation that honored the image orientation in ImageCG.cpp (BitmapImage::draw()).
> 
> Now GraphicsContext calls Image::draw() on all platforms, which always throws away the orientation parameter. How does this patch not break image orientation on mac?

That's good question.

BitmapImage of mac only overrides Image::draw(). BitmapImage of other ports does not overrides Image::draw().

#if USE(CG)
    virtual void draw(GraphicsContext*, const FloatRect& dstRect, const FloatRect& srcRect, ColorSpace styleColorSpace, CompositeOperator, RespectImageOrientationEnum);
#endif

It means in mac if you call draw() of BitmapImage, Image::draw() is not called and BitmapImage::draw() of mac is called, which does not throw away the orientation parameter.

Please let me know if you have questions anymore :)

[Nico Weber]

Thanks for explaining! I missed the inheritance relationship.