Mark layers that can use LCD text based on layer transform and opacity.

cc/layer.h

Index: cc/layer.h
diff --git a/cc/layer.h b/cc/layer.h
index 91a7cdbcd94c76b89476ea9473909f1bd46f4f60..f0dd307f8efa3cc4fd928a1c80cdea811b4a0c84 100644
--- a/cc/layer.h
+++ b/cc/layer.h
@@ -140,6 +140,7 @@ public:
     bool drawOpacityIsAnimating() const { return m_drawProperties.opacity_is_animating; }
     bool drawTransformIsAnimating() const { return m_drawProperties.target_space_transform_is_animating; }
     bool screenSpaceTransformIsAnimating() const { return m_drawProperties.screen_space_transform_is_animating; }
+    bool screenSpaceOpacityIsAnimating() const { return m_drawProperties.screen_space_opacity_is_animating; }
     bool isClipped() const { return m_drawProperties.is_clipped; }
     const gfx::Rect& clipRect() const { return m_drawProperties.clip_rect; }
     const gfx::Rect& drawableContentRect() const { return m_drawProperties.drawable_content_rect; }
@@ -193,8 +194,8 @@ public:
     void setUseParentBackfaceVisibility(bool useParentBackfaceVisibility) { m_useParentBackfaceVisibility = useParentBackfaceVisibility; }
     bool useParentBackfaceVisibility() const { return m_useParentBackfaceVisibility; }
 
-    void setUseLCDText(bool);
-    bool useLCDText() const { return m_useLCDText; }
+    void setCanUseLCDText(bool);
+    bool canUseLCDText() const { return m_canUseLCDText; }
 
     virtual void setLayerTreeHost(LayerTreeHost*);
 
@@ -298,6 +299,12 @@ protected:
     void setNeedsCommit();
     void setNeedsFullTreeSync();
 
+    // Called when LCD text setting is about to potentially change.
+    // If this function returns true, the setting is allowed to change.
+    // If it returns false, the setting is not changed.
+    virtual bool canUseLCDTextWillChange();

[enne (OOO), 2012/12/11 02:47:15]

Can you do this without adding more virtuals to Layer? I'm sorry to be picky,
but I feel like it's easy to dump things into the already overflowing base
class.

I'd really prefer a solution that encapsulated all of this inside of TiledLayer,
such as using some internal bool m_usingLCDText in TiledLayer (initialized to
true).  When updating a layer, you could check if canUseLCDText() is ever false
while m_usingLCDText is true, and then set it to false and invalidate.

[alokp, 2012/12/11 05:07:21]

I do not understand your solution but the reason I want to make the decision at
the ContentLayer level and not TiledLayer because other layer types (image,
video, etc) should not be invalidated because of a change in LCD text settings.
I will talk to you offline.

On 2012/12/11 02:47:15, enne wrote:

[alokp, 2012/12/12 17:42:24]

Done.

+    virtual void canUseLCDTextDidChange() { }
+
     // This flag is set when layer need repainting/updating.
     bool m_needsDisplay;
 
@@ -368,7 +375,7 @@ private:
     bool m_masksToBounds;
     bool m_contentsOpaque;
     bool m_doubleSided;
-    bool m_useLCDText;
+    bool m_canUseLCDText;

[enne (OOO), 2012/12/11 02:47:15]

Can you move this to DrawProperties? I think it belongs there.

[alokp, 2012/12/11 05:07:21]

I considered doing that but I could think of a good way to invalidate layers
when this property changes. May be it will become clearer once I understand your
solution described above.

On 2012/12/11 02:47:15, enne wrote:

[alokp, 2012/12/12 17:42:24]

Done.

     bool m_preserves3D;
     bool m_useParentBackfaceVisibility;
     bool m_drawCheckerboardForMissingTiles;