577200 - Allow gfxWindowsSurface to contain Alpha

Status: RESOLVED FIXED

(Core :: Graphics, defect)

Description

[Bas Schouten (:bas.schouten)]

Attachment: Allow HDC surfaces to contain alpha

When a gfxWindowsSurface is created around an HDC it currently always believes it's opaque. For the glass window surface this isn't true. It should be told properly if it's wrapping a transparent DC, this allows BasicLayers to later determine if it's dealing with a transparent surface so it knows if it needs to clear it when reusing it.

Comment 1

[Bas Schouten (:bas.schouten)]

Attachment: Create transparent win32 surface for transparent windows

Comment 2

[Jeff Muizelaar [:jrmuizel]]

Comment on attachment 456229 [details] [diff] [review]
Allow HDC surfaces to contain alpha

The new function needs documentation describing what it is there for and what it does. I think one problem, is that the function doesn't really make it clear that difference between cairo_win32_surface_create and cairo_win32_surface_create_transparent is not really in the surface that's created but in the way that we interpret the data associated with the HDC. A better name would help, though I'm not exactly sure what that name should be.

Comment 3

[Jeff Muizelaar [:jrmuizel]]

roc and I came up with cairo_win32_surface_create_with_alpha which I think is better.

Comment 4

[[not reading bugmail]]

With Both of the patches shown here I was seeing bug 552114 with OOPP on.

Comment 5

[Robert O'Callahan (:roc) (email my personal email if necessary)]

Attachment: Part 1 v2

Comment 6

[Jeff Muizelaar [:jrmuizel]]

Comment on attachment 456603 [details] [diff] [review]
Part 1 v2


>- * Creates a cairo surface that targets the given DC.  The DC will be
>- * queried for its initial clip extents, and this
>+ * Creates a cairo surface that targets the given DC.  The DC will be
>+ * queried for its initial clip extents, and this will be used as the
>+ * size of the cairo surface.  The resulting surface will always be of
>+ * format %CAIRO_FORMAT_ARGB32 (as supported for transparent windows with
>+ * Windows Vista and up.

Fix up the comment and a close paren.

Comment 7

[Robert O'Callahan (:roc) (email my personal email if necessary)]

http://hg.mozilla.org/mozilla-central/rev/c48562866467
http://hg.mozilla.org/mozilla-central/rev/8c3a6563be2d