From c89157b9ea0a9203b350f95501192e9c92d07e70 Mon Sep 17 00:00:00 2001
From: Mason Chang <mchang@mozilla.com>
Date: Tue, 8 Mar 2016 07:37:16 -0800
Subject: [PATCH] Bug 1249600. Lookup font and font family from font face when
 requesting SkTypeface. r=bas

---
 gfx/2d/ScaledFontDWrite.cpp | 32 +++++++++++++++++++++++++++++++-
 gfx/2d/ScaledFontDWrite.h   |  2 ++
 2 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/gfx/2d/ScaledFontDWrite.cpp b/gfx/2d/ScaledFontDWrite.cpp
index a9c9e8f80512..06cfb6da2d73 100644
--- a/gfx/2d/ScaledFontDWrite.cpp
+++ b/gfx/2d/ScaledFontDWrite.cpp
@@ -115,12 +115,42 @@ ScaledFontDWrite::GetPathForGlyphs(const GlyphBuffer &aBuffer, const DrawTarget
 
 
 #ifdef USE_SKIA
+// This can happen if we have mixed backends which create DWrite
+// fonts in a mixed environment. e.g. a cairo content backend
+// but Skia canvas backend.
+void
+ScaledFontDWrite::GetFontDataFromSystemFonts(IDWriteFactory* aFactory)
+{
+  MOZ_ASSERT(mFontFace);
+  RefPtr<IDWriteFontCollection> systemFonts;
+  HRESULT hr = aFactory->GetSystemFontCollection(getter_AddRefs(systemFonts));
+  if (FAILED(hr)) {
+    gfxWarning() << "Failed to get system font collection from file data. Code: " << hexa(hr);
+    return;
+  }
+
+  hr = systemFonts->GetFontFromFontFace(mFontFace, getter_AddRefs(mFont));
+  if (FAILED(hr)) {
+    gfxWarning() << "Failed to get system font from font face. Code: " << hexa(hr);
+    return;
+  }
+
+  hr = mFont->GetFontFamily(getter_AddRefs(mFontFamily));
+  if (FAILED(hr)) {
+    gfxWarning() << "Failed to get font family from font face. Code: " << hexa(hr);
+    return;
+  }
+}
+
 SkTypeface*
 ScaledFontDWrite::GetSkTypeface()
 {
-  MOZ_ASSERT(mFont);
   if (!mTypeface) {
     IDWriteFactory *factory = DrawTargetD2D1::GetDWriteFactory();
+    if (!mFont || !mFontFamily) {
+      GetFontDataFromSystemFonts(factory);
+    }
+
     mTypeface = SkCreateTypefaceFromDWriteFont(factory, mFontFace, mFont, mFontFamily);
   }
   return mTypeface;
diff --git a/gfx/2d/ScaledFontDWrite.h b/gfx/2d/ScaledFontDWrite.h
index 65f25d89ff70..9a4d16264e13 100644
--- a/gfx/2d/ScaledFontDWrite.h
+++ b/gfx/2d/ScaledFontDWrite.h
@@ -46,8 +46,10 @@ public:
 
 #ifdef USE_SKIA
   virtual SkTypeface* GetSkTypeface();
+  void GetFontDataFromSystemFonts(IDWriteFactory* aFactory);
 #endif
 
+  // The font and font family are only used with Skia
   RefPtr<IDWriteFont> mFont;
   RefPtr<IDWriteFontFamily> mFontFamily;
   RefPtr<IDWriteFontFace> mFontFace;