Bug 587395: Expose whether DWrite is enabled through nsIGfxInfo. r=joedrew

gfx/thebes/gfxWindowsPlatform.h

@@ -213,6 +213,9 @@ public:
 
 #ifdef CAIRO_HAS_DWRITE_FONT
     IDWriteFactory *GetDWriteFactory() { return mDWriteFactory; }
+    inline PRBool DWriteEnabled() { return !!mDWriteFactory; }
+#else
+    inline PRBool DWriteEnabled() { return PR_FALSE; }
 #endif
 #ifdef CAIRO_HAS_D2D_SURFACE
     cairo_device_t *GetD2DDevice() { return mD2DDevice; }

widget/public/nsIGfxInfo.idl

@@ -38,9 +38,12 @@
 
 #include "nsISupports.idl"
 
+/* NOTE: this interface is completely undesigned, not stable and likely to change */
+
 [scriptable, uuid(5C05E5B7-0FCC-4070-BF6B-58BC33ECA427)]
 interface nsIGfxInfo : nsISupports
 {
   readonly attribute boolean D2DEnabled;
+  readonly attribute boolean DWriteEnabled;
 };
 

widget/src/windows/GfxInfo.cpp

@@ -47,3 +47,9 @@ nsresult GfxInfo::GetD2DEnabled(PRBool *aEnabled)
   *aEnabled = gfxWindowsPlatform::GetPlatform()->GetRenderMode() == gfxWindowsPlatform::RENDER_DIRECT2D;
   return NS_OK;
 }
+
+nsresult GfxInfo::GetDWriteEnabled(PRBool *aEnabled)
+{
+  *aEnabled = gfxWindowsPlatform::GetPlatform()->DWriteEnabled();
+  return NS_OK;
+}