[WinCairo] Accelerated compositing does not respect device scale factor.

• Component: WebKit Misc.
• Status: RESOLVED FIXED

Painting in accelerated compositing mode on WinCairo needs to take the device scale factor into account.

Created attachment 259171 [details]
Patch

[Alex Christensen]

Comment on attachment 259171 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=259171&action=review

does this fix pages like acko.net ?

> Source/WebKit/win/WebCoreSupport/AcceleratedCompositingContext.cpp:166
> +    TransformationMatrix m;
> +    m.scale(deviceScaleFactor());
> +    double tx = (size.width() - size.width() / deviceScaleFactor()) / 2.0;
> +    double ty = (size.height() - size.height() / deviceScaleFactor()) / 2.0;
> +    m.translate(tx, ty);

Why scale then translate?  Where does the 2.0 come from?

[Brent Fulgham]

Comment on attachment 259171 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=259171&action=review

r=me, with a few minor corrections.

> Source/WebKit/win/WebCoreSupport/AcceleratedCompositingContext.cpp:165
> +    double ty = (size.height() - size.height() / deviceScaleFactor()) / 2.0;

Is this to center the view?

> Source/WebKit/win/WebCoreSupport/AcceleratedCompositingContext.h:55
> +    virtual void paintContents(const WebCore::GraphicsLayer*, WebCore::GraphicsContext&, WebCore::GraphicsLayerPaintingPhase, const WebCore::FloatRect& rectToPaint) override;

Please remove 'virtual' for any methods that are 'override'.

(In reply to comment #3)
> Comment on attachment 259171 [details]
> Patch
> 
> View in context:
> https://bugs.webkit.org/attachment.cgi?id=259171&action=review
> 
> r=me, with a few minor corrections.
> 

Thanks!

> > Source/WebKit/win/WebCoreSupport/AcceleratedCompositingContext.cpp:165
> > +    double ty = (size.height() - size.height() / deviceScaleFactor()) / 2.0;
> 
> Is this to center the view?
> 

Yes, I will add a comment before landing.

> > Source/WebKit/win/WebCoreSupport/AcceleratedCompositingContext.h:55
> > +    virtual void paintContents(const WebCore::GraphicsLayer*, WebCore::GraphicsContext&, WebCore::GraphicsLayerPaintingPhase, const WebCore::FloatRect& rectToPaint) override;
> 
> Please remove 'virtual' for any methods that are 'override'.

Ok, I will remove 'virtual' before landing :)

(In reply to comment #2)
> Comment on attachment 259171 [details]
> Patch
> 
> View in context:
> https://bugs.webkit.org/attachment.cgi?id=259171&action=review
> 

Thanks for reviewing :)

> does this fix pages like acko.net ?
> 

Yes, I believe so.

> > Source/WebKit/win/WebCoreSupport/AcceleratedCompositingContext.cpp:166
> > +    TransformationMatrix m;
> > +    m.scale(deviceScaleFactor());
> > +    double tx = (size.width() - size.width() / deviceScaleFactor()) / 2.0;
> > +    double ty = (size.height() - size.height() / deviceScaleFactor()) / 2.0;
> > +    m.translate(tx, ty);
> 
> Why scale then translate?  Where does the 2.0 come from?

The translate will center the view.

Committed r188537: <http://trac.webkit.org/changeset/188537>.

[Alex Christensen]

Looks great!  Thanks!

(In reply to comment #7)
> Looks great!  Thanks!

Glad to hear it :)