add inherit-from-root-transform flag

Change-Id: I9ffdb50bde0c53070611c7dc626c384eca0906ea

2 files changed, 33 insertions, 7 deletions

diff --git a/include/utils/SkLayer.h b/include/utils/SkLayer.h
index c8dea484dd..d346c2f915 100644
--- a/include/utils/SkLayer.h
+++ b/include/utils/SkLayer.h
@@ -34,6 +34,7 @@ public:
     SkLayer(const SkLayer&);
     virtual ~SkLayer();
 
+    bool isInheritFromRootTransform() const;
     SkScalar getOpacity() const { return m_opacity; }
     const SkSize& getSize() const { return m_size; }
     const SkPoint& getPosition() const { return m_position; }
@@ -44,6 +45,7 @@ public:
     SkScalar getWidth() const { return m_size.width(); }
     SkScalar getHeight() const { return m_size.height(); }
 
+    void setInheritFromRootTransform(bool);
     void setOpacity(SkScalar opacity) { m_opacity = opacity; }
     void setSize(SkScalar w, SkScalar h) { m_size.set(w, h); }
     void setPosition(SkScalar x, SkScalar y) { m_position.set(x, y); }
@@ -112,6 +114,10 @@ protected:
     virtual void onDraw(SkCanvas*, SkScalar opacity);
 
 private:
+    enum Flags {
+        kInheritFromRootTransform_Flag = 0x01
+    };
+
     SkLayer*    fParent;
     SkScalar    m_opacity;
     SkSize      m_size;
@@ -119,6 +125,7 @@ private:
     SkPoint     m_anchorPoint;
     SkMatrix    fMatrix;
     SkMatrix    fChildrenMatrix;
+    uint32_t    fFlags;
 
     SkTDArray<SkLayer*> m_children;
 };
diff --git a/src/utils/SkLayer.cpp b/src/utils/SkLayer.cpp
index 888afec99e..d1503de74d 100644
--- a/src/utils/SkLayer.cpp
+++ b/src/utils/SkLayer.cpp
@@ -19,6 +19,7 @@ SkLayer::SkLayer() {
 
     fMatrix.reset();
     fChildrenMatrix.reset();
+    fFlags = 0;
 
 #ifdef DEBUG_TRACK_NEW_DELETE
     gLayerAllocCount += 1;
@@ -35,6 +36,7 @@ SkLayer::SkLayer(const SkLayer& src) {
 
     fMatrix = src.fMatrix;
     fChildrenMatrix = src.fChildrenMatrix;
+    fFlags = src.fFlags;
 
 #ifdef DEBUG_TRACK_NEW_DELETE
     gLayerAllocCount += 1;
@@ -53,6 +55,18 @@ SkLayer::~SkLayer() {
 
 ///////////////////////////////////////////////////////////////////////////////
 
+bool SkLayer::isInheritFromRootTransform() const {
+    return (fFlags & kInheritFromRootTransform_Flag) != 0;
+}
+
+void SkLayer::setInheritFromRootTransform(bool doInherit) {
+    if (doInherit) {
+        fFlags |= kInheritFromRootTransform_Flag;
+    } else {
+        fFlags &= ~kInheritFromRootTransform_Flag;
+    }
+}
+
 void SkLayer::setMatrix(const SkMatrix& matrix) {
     fMatrix = matrix;
 }
@@ -126,6 +140,11 @@ void SkLayer::getLocalTransform(SkMatrix* matrix) const {
 void SkLayer::localToGlobal(SkMatrix* matrix) const {
     this->getLocalTransform(matrix);
 
+    if (this->isInheritFromRootTransform()) {
+        matrix->postConcat(this->getRootLayer()->getMatrix());
+        return;
+    }
+
     const SkLayer* layer = this;
     while (layer->fParent != NULL) {
         layer = layer->fParent;
@@ -165,13 +184,13 @@ void SkLayer::draw(SkCanvas* canvas, SkScalar opacity) {
 
     // apply our local transform
     {
-        canvas->translate(m_position.fX, m_position.fY);
-        
-        SkScalar tx = SkScalarMul(m_anchorPoint.fX, m_size.width());
-        SkScalar ty = SkScalarMul(m_anchorPoint.fY, m_size.height());
-        canvas->translate(tx, ty);
-        canvas->concat(this->getMatrix());
-        canvas->translate(-tx, -ty);
+        SkMatrix tmp;
+        this->getLocalTransform(&tmp);
+        if (this->isInheritFromRootTransform()) {
+            // should we also apply the root's childrenMatrix?
+            canvas->setMatrix(getRootLayer()->getMatrix());
+        }
+        canvas->concat(tmp);
     }
 
     this->onDraw(canvas, opacity);