Bug 1049251 - Partially disable SkiaGL on Low total system memory r=jrmuizel

dom/canvas/CanvasRenderingContext2D.cpp

@@ -897,10 +897,13 @@ CanvasRenderingContext2D::CheckSizeForSkiaGL(IntSize size) {
   // Cache the number of pixels on the primary screen
   static int32_t gScreenPixels = -1;
   if (gScreenPixels < 0) {
-    // Default to historical mobile screen size of 980x480.  In addition,
-    // allow skia use up to this size even if the screen is smaller.  A lot
-    // content expects this size to work well.
-    gScreenPixels = 980 * 480;
+    // Default to historical mobile screen size of 980x480, like FishIEtank.
+    // In addition, allow skia use up to this size even if the screen is smaller.
+    // A lot content expects this size to work well.
+    // See Bug 999841
+    if (gfxPlatform::GetPlatform()->HasEnoughTotalSystemMemoryForSkiaGL()) {
+      gScreenPixels = 980 * 480;
+    }
 
     nsCOMPtr<nsIScreenManager> screenManager =
       do_GetService("@mozilla.org/gfx/screenmanager;1");
@@ -916,22 +919,8 @@ CanvasRenderingContext2D::CheckSizeForSkiaGL(IntSize size) {
     }
   }
 
-  // On high DPI devices the screen pixels may be scaled up.  Make
-  // sure to apply that scaling here as well if we are hooked up
-  // to a widget.
-  static double gDefaultScale = 0.0;
-  if (gDefaultScale < 1.0) {
-    nsIPresShell* ps = GetPresShell();
-    if (ps) {
-      nsIFrame* frame = ps->GetRootFrame();
-      if (frame) {
-        nsIWidget* widget = frame->GetNearestWidget();
-        if (widget) {
-          gDefaultScale = widget->GetDefaultScale().scale;
-        }
-      }
-    }
-  }
+  // Just always use a scale of 1.0. It can be changed if a lot of contents need it.
+  static double gDefaultScale = 1.0;
 
   double scale = gDefaultScale > 0 ? gDefaultScale : 1.0;
   int32_t threshold = ceil(scale * scale * gScreenPixels);

gfx/thebes/gfxPlatform.cpp

@@ -278,6 +278,7 @@ gfxPlatform::gfxPlatform()
     uint32_t contentMask = BackendTypeBit(BackendType::CAIRO);
     InitBackendPrefs(canvasMask, BackendType::CAIRO,
                      contentMask, BackendType::CAIRO);
+    mTotalSystemMemory = mozilla::hal::GetTotalSystemMemory();
 }
 
 gfxPlatform*
@@ -852,14 +853,12 @@ gfxPlatform::InitializeSkiaCacheLimits()
     cacheSizeLimit *= 1024*1024;
 
     if (usingDynamicCache) {
-      uint32_t totalMemory = mozilla::hal::GetTotalSystemMemory();
-
-      if (totalMemory < 512*1024*1024) {
+      if (mTotalSystemMemory < 512*1024*1024) {
         // We need a very minimal cache on anything smaller than 512mb.
         // Note the large jump as we cross 512mb (from 2mb to 32mb).
         cacheSizeLimit = 2*1024*1024;
-      } else if (totalMemory > 0) {
-        cacheSizeLimit = totalMemory / 16;
+      } else if (mTotalSystemMemory > 0) {
+        cacheSizeLimit = mTotalSystemMemory / 16;
       }
     }
 
@@ -912,6 +911,17 @@ gfxPlatform::PurgeSkiaCache()
 #endif
 }
 
+bool
+gfxPlatform::HasEnoughTotalSystemMemoryForSkiaGL()
+{
+#ifdef MOZ_WIDGET_GONK
+  if (mTotalSystemMemory < 250*1024*1024) {
+    return false;
+  }
+#endif
+  return true;
+}
+
 TemporaryRef<DrawTarget>
 gfxPlatform::CreateDrawTargetForBackend(BackendType aBackend, const IntSize& aSize, SurfaceFormat aFormat)
 {

gfx/thebes/gfxPlatform.h

@@ -547,6 +547,7 @@ public:
 
     static bool UsesOffMainThreadCompositing();
 
+    bool HasEnoughTotalSystemMemoryForSkiaGL();
 protected:
     gfxPlatform();
     virtual ~gfxPlatform();
@@ -616,6 +617,8 @@ protected:
     // max number of entries in word cache
     int32_t mWordCacheMaxEntries;
 
+    uint32_t mTotalSystemMemory;
+
 private:
     /**
      * Start up Thebes.