1231864 - De-weirdify GetCairo() and its uses

Status: RESOLVED FIXED

(Core :: Graphics, defect)

Description

[Nicholas Nethercote [inactive]]

GetCairo()'s an odd function, in that it gets the current DrawTarget's cairo_t if it uses a Cairo backend, and falls back to the refCairo (which has a 1x1 surface) otherwise. Some of the callsites rely on the non-fallback behaviour.

This bug is about clarifying and simplifying this a bit.

Comment 1

[Nicholas Nethercote [inactive]]

Attachment: (part 1) - Remove useless GetCairo() call in gfxWindowsNativeDrawing::BeginNativeDrawing()

GetCairo() never returns null so testing its result like this is pointless.

Comment 2

[Nicholas Nethercote [inactive]]

Attachment: (part 2) - Clean up gfxWindowsNativeDrawing::BeginNativeDrawing()

This patch inlines the CurrentSurface() and GetDCWithClip() calls in
BeginNativeDrawing(). This allows them to share a single |cairo_t*| and gets
rid of the GetCairo() call in GetDCWithClip(), which was one of those confusing
ones that only made sense if its a Cairo backend.

The patch also inverts the sense of mDeviceOffset, and changes its type from
gfxPoint to Point.

Comment 3

[Nicholas Nethercote [inactive]]

Attachment: (part 3) - Pass a cairo_t* to GetSVGGlyphExtents()

This is a cut down version of part 1 from bug 1231550. It avoids one GetCairo()
calls.

Comment 4

[Matt Woodrow (:mattwoodrow)]

Comment on attachment 8697461 [details] [diff] [review]
(part 2) - Clean up gfxWindowsNativeDrawing::BeginNativeDrawing()

Review of attachment 8697461 [details] [diff] [review]:
-----------------------------------------------------------------

It would be nice to do a follow up that removes gfxASurface usage from this too.

It looks like we check GetType, GetContentType, MarkDirty and GetAsImageSurface on surf/mWinSurface/mBackSurface/mWhiteSurface. Those should all be fairly easy inlined.

Comment 5

[Nicholas Nethercote [inactive]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/747868feec5183a7bdea401472dce1dcdc31d137
Bug 1231864 (part 1) - Remove useless GetCairo() call in gfxWindowsNativeDrawing::BeginNativeDrawing(). r=mattwoodrow.

https://hg.mozilla.org/integration/mozilla-inbound/rev/5d48e09f0d179ab78efec9cca157e6f2aee09c16
Bug 1231864 (part 2) - Clean up gfxWindowsNativeDrawing::BeginNativeDrawing(). r=mattwoodrow.

Comment 6

[Nicholas Nethercote [inactive]]

Still waiting for review on part 3.

Comment 7

[Nicholas Nethercote [inactive]]

Comment on attachment 8697463 [details] [diff] [review]
(part 3) - Pass a cairo_t* to GetSVGGlyphExtents()

I'll move this patch to another bug.

Comment 8

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/747868feec51
https://hg.mozilla.org/mozilla-central/rev/5d48e09f0d17