1309917 - Stop defaulting to system wide default fonts if no IDWriteFont exists

Status: RESOLVED FIXED

(Core :: Graphics, defect)

Description

[Mason Chang [Inactive] [:mchang]]

+++ This bug was initially created as a clone of Bug #842894 +++

See https://bugzilla.mozilla.org/show_bug.cgi?id=842894#c21

Comment 1

[Mason Chang [Inactive] [:mchang]]

Attachment: font.patch

(In reply to Jonathan Kew (:jfkthame) from comment #21)
> Comment on attachment 8704768 [details] [diff] [review]
> Support dwrite fonts in skia
> It's expected that a gfxDWriteFontEntry may not hold an IDWriteFont
> reference; in the case of an @font-face resource, it will *instead* have an
> IDWriteFontFile. See
> https://dxr.mozilla.org/mozilla-central/rev/
> 7ae377917236b7e6111146aa9fb4c073c0efc7f4/gfx/thebes/gfxDWriteFontList.h#190-
> 195.
> 
> But if it's a font entry for a downloaded resource (and therefore
> fe->GetFont() returns null), it doesn't make sense to just substitute some
> default font instead. I don't know what this IDWriteFont ends up getting
> used for in the Skia backend -- maybe nothing, if we're lucky?! -- but if
> we're supposed to be using the downloaded font, we can't just start using
> the default font instead for any meaningful purpose.

You're right, luckily it wasn't using the IDWriteFontFamily for anything but debug purposes. The IDwriteFont was being used to calculate some style data [1]. To actually render the glyph, Skia was using only the font face, which we always seem to have.

This patch stops using IDWriteFont and instead creates a ScaledDWriteFont with style data from gfxFontStyle information. It also stops defaulting to a system wide default font if it can't find an IDwriteFont. Thanks for finding the bug!

Try looks good - https://treeherder.mozilla.org/#/jobs?repo=try&revision=85063d2d16cc

[1] http://searchfox.org/mozilla-central/source/gfx/skia/skia/src/ports/SkTypeface_win_dw.h#27

Comment 2

[Jonathan Kew [:jfkthame]]

Comment on attachment 8800732 [details] [diff] [review]
font.patch

Review of attachment 8800732 [details] [diff] [review]:
-----------------------------------------------------------------

Thanks for dealing with this; looks reasonable to me.

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/5b7c66cd059c
Stop defaulting to system wide default fonts if no IDWriteFont exists. r=jfkthame

Comment 4

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/5b7c66cd059c