Bug 1559810 - disallow Cairo as content/canvas backend. r=jrmuizel

Differential Revision: https://phabricator.services.mozilla.com/D35691

--HG--
extra : moz-landing-system : lando

gfx/thebes/gfxPlatform.cpp

@@ -1875,14 +1875,16 @@ mozilla::layers::DiagnosticTypes gfxPlatform::GetLayerDiagnosticTypes() {
 BackendPrefsData gfxPlatform::GetBackendPrefs() const {
   BackendPrefsData data;
 
-  data.mCanvasBitmask = BackendTypeBit(BackendType::CAIRO);
-  data.mContentBitmask = BackendTypeBit(BackendType::CAIRO);
-#ifdef USE_SKIA
-  data.mCanvasBitmask |= BackendTypeBit(BackendType::SKIA);
-  data.mContentBitmask |= BackendTypeBit(BackendType::SKIA);
+  data.mCanvasBitmask = BackendTypeBit(BackendType::SKIA);
+  data.mContentBitmask = BackendTypeBit(BackendType::SKIA);
+
+#ifdef MOZ_WIDGET_GTK
+  data.mCanvasBitmask |= BackendTypeBit(BackendType::CAIRO);
+  data.mContentBitmask |= BackendTypeBit(BackendType::CAIRO);
 #endif
-  data.mCanvasDefault = BackendType::CAIRO;
-  data.mContentDefault = BackendType::CAIRO;
+
+  data.mCanvasDefault = BackendType::SKIA;
+  data.mContentDefault = BackendType::SKIA;
 
   return data;
 }
@@ -1915,8 +1917,10 @@ void gfxPlatform::InitBackendPrefs(BackendPrefsData&& aPrefsData) {
     mContentBackendBitmask |= BackendTypeBit(aPrefsData.mContentDefault);
   }
 
-  uint32_t swBackendBits =
-      BackendTypeBit(BackendType::SKIA) | BackendTypeBit(BackendType::CAIRO);
+  uint32_t swBackendBits = BackendTypeBit(BackendType::SKIA);
+#ifdef MOZ_WIDGET_GTK
+  swBackendBits |= BackendTypeBit(BackendType::CAIRO);
+#endif
   mSoftwareBackend = GetContentBackendPref(swBackendBits);
 
   if (XRE_IsParentProcess()) {

gfx/thebes/gfxWindowsPlatform.cpp

@@ -516,10 +516,8 @@ bool gfxWindowsPlatform::HandleDeviceReset() {
 BackendPrefsData gfxWindowsPlatform::GetBackendPrefs() const {
   BackendPrefsData data;
 
-  data.mCanvasBitmask =
-      BackendTypeBit(BackendType::CAIRO) | BackendTypeBit(BackendType::SKIA);
-  data.mContentBitmask =
-      BackendTypeBit(BackendType::CAIRO) | BackendTypeBit(BackendType::SKIA);
+  data.mCanvasBitmask = BackendTypeBit(BackendType::SKIA);
+  data.mContentBitmask = BackendTypeBit(BackendType::SKIA);
   data.mCanvasDefault = BackendType::SKIA;
   data.mContentDefault = BackendType::SKIA;
 

modules/libpref/init/all.js

@@ -765,9 +765,9 @@ pref("gfx.font_ahem_antialias_none", false);
 
 #ifdef XP_WIN
 // comma separated list of backends to use in order of preference
-// e.g., pref("gfx.canvas.azure.backends", "direct2d,skia,cairo");
-pref("gfx.canvas.azure.backends", "direct2d1.1,skia,cairo");
-pref("gfx.content.azure.backends", "direct2d1.1,skia,cairo");
+// e.g., pref("gfx.canvas.azure.backends", "direct2d,skia");
+pref("gfx.canvas.azure.backends", "direct2d1.1,skia");
+pref("gfx.content.azure.backends", "direct2d1.1,skia");
 pref("gfx.canvas.remote", false);
 #else
 #ifdef XP_MACOSX