1150182 - Make HTMLCanvasElement::GetSize/GetWidthHeight return CSSIntSize instead of unitless nsIntSize

Status: RESOLVED FIXED

(Core :: Graphics: Canvas2D, task)

Comment 1

[Mats Palmgren (inactive)]

Attachment: wip

Comment 2

[Mats Palmgren (inactive)]

I think HTMLCanvasElement::GetSize/GetWidthHeight are dealing in CSS pixels,
and by extension also nsHTMLCanvasFrame::GetCanvasSize() (which is the one
I'm primarily interested in fixing).  HTMLCanvasElement::GetSize just returns
GetWidthHeight():
http://mxr.mozilla.org/mozilla-central/source/dom/html/HTMLCanvasElement.cpp#850

GetWidthHeight just returns the value of @width/@height or default to 300
if not present (which usually means they are CSS pixels IME):
http://mxr.mozilla.org/mozilla-central/source/dom/html/HTMLCanvasElement.cpp#146

Now to the strange stuff.  In multiple places we pass along these CSS pixels
directly into GFX to size the surface.  I've marked those in the patch with
XXX comments.  Perhaps this is intentional to make the rendering "crisp"
when zoomed in (same as for images) as described in bug 1149222 comment 16?
On line 6703 here for example:
http://hg.mozilla.org/mozilla-central/annotate/e5b72a8edb82/layout/base/nsLayoutUtils.cpp#l6696

Does anyone know why we're doing this?  (so I can add better explanations
than my XXX comments)

Comment 3

[Mats Palmgren (inactive)]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=6bce7d947513

Comment 4

[Ting-Yu Lin [:TYLin] (PST, UTC-8)]

Attachment: Bug 1150182 - Use strong-typed CSSIntSize instead of nsIntSize for canvas sizes.

Canvas uses CSS pixels, so this patch encodes the information into the type
system. Some painting code still uses unknown sizes, so we need to use
CSSIntSize::FromUnknownSize and ToUnknownSize() to convert them.

This patch doesn't change behavior.

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/399b1edeca46
Use strong-typed CSSIntSize instead of nsIntSize for canvas sizes. r=gfx-reviewers,layout-reviewers,emilio,nical

Comment 6

[Norisz Fay [:noriszfay]]

https://hg.mozilla.org/mozilla-central/rev/399b1edeca46