Add support for skew()

Change-Id: Ia3a9a867f74fd78b61f75179e3788fdc2f0cacd0
diff --git a/libs/hwui/DisplayListRenderer.cpp b/libs/hwui/DisplayListRenderer.cpp
index e3593da..ade85e5 100644
--- a/libs/hwui/DisplayListRenderer.cpp
+++ b/libs/hwui/DisplayListRenderer.cpp
@@ -268,6 +268,10 @@
                 renderer.scale(getFloat(), getFloat());
             }
             break;
+            case Skew: {
+                renderer.skew(getFloat(), getFloat());
+            }
+            break;
             case SetMatrix: {
                 renderer.setMatrix(getMatrix());
             }
@@ -508,6 +512,12 @@
     OpenGLRenderer::scale(sx, sy);
 }
 
+void DisplayListRenderer::skew(float sx, float sy) {
+    addOp(DisplayList::Skew);
+    addPoint(sx, sy);
+    OpenGLRenderer::skew(sx, sy);
+}
+
 void DisplayListRenderer::setMatrix(SkMatrix* matrix) {
     addOp(DisplayList::SetMatrix);
     addMatrix(matrix);
diff --git a/libs/hwui/DisplayListRenderer.h b/libs/hwui/DisplayListRenderer.h
index 7152334..05864ec 100644
--- a/libs/hwui/DisplayListRenderer.h
+++ b/libs/hwui/DisplayListRenderer.h
@@ -98,6 +98,7 @@
         Translate,
         Rotate,
         Scale,
+        Skew,
         SetMatrix,
         ConcatMatrix,
         ClipRect,
@@ -250,6 +251,7 @@
     void translate(float dx, float dy);
     void rotate(float degrees);
     void scale(float sx, float sy);
+    void skew(float sx, float sy);
 
     void setMatrix(SkMatrix* matrix);
     void concatMatrix(SkMatrix* matrix);
diff --git a/libs/hwui/Matrix.cpp b/libs/hwui/Matrix.cpp
index fe7f883..e7c0fe3 100644
--- a/libs/hwui/Matrix.cpp
+++ b/libs/hwui/Matrix.cpp
@@ -178,6 +178,24 @@
     data[kScaleZ] = sz;
 }
 
+void Matrix4::loadSkew(float sx, float sy) {
+    loadIdentity();
+
+    data[kScaleX]       = 1.0f;
+    data[kSkewX]        = sx;
+    data[kTranslateX]   = 0.0f;
+
+    data[kSkewY]        = sy;
+    data[kScaleY]       = 1.0f;
+    data[kTranslateY]   = 0.0f;
+
+    data[kPerspective0] = 0.0f;
+    data[kPerspective1] = 0.0f;
+    data[kPerspective2] = 1.0f;
+
+    mSimpleMatrix = false;
+}
+
 void Matrix4::loadRotate(float angle, float x, float y, float z) {
     data[kPerspective0]  = 0.0f;
     data[kPerspective1]  = 0.0f;
diff --git a/libs/hwui/Matrix.h b/libs/hwui/Matrix.h
index 23fc6c3..08f5d77 100644
--- a/libs/hwui/Matrix.h
+++ b/libs/hwui/Matrix.h
@@ -72,6 +72,7 @@
 
     void loadTranslate(float x, float y, float z);
     void loadScale(float sx, float sy, float sz);
+    void loadSkew(float sx, float sy);
     void loadRotate(float angle, float x, float y, float z);
     void loadMultiply(const Matrix4& u, const Matrix4& v);
 
@@ -97,6 +98,12 @@
         multiply(u);
     }
 
+    void skew(float sx, float sy) {
+        Matrix4 u;
+        u.loadSkew(sx, sy);
+        multiply(u);
+    }
+
     void rotate(float angle, float x, float y, float z) {
         Matrix4 u;
         u.loadRotate(angle, x, y, z);
diff --git a/libs/hwui/OpenGLRenderer.cpp b/libs/hwui/OpenGLRenderer.cpp
index 16a1de7..2067acc1 100644
--- a/libs/hwui/OpenGLRenderer.cpp
+++ b/libs/hwui/OpenGLRenderer.cpp
@@ -766,6 +766,10 @@
     mSnapshot->transform->scale(sx, sy, 1.0f);
 }
 
+void OpenGLRenderer::skew(float sx, float sy) {
+    mSnapshot->transform->skew(sx, sy);
+}
+
 void OpenGLRenderer::setMatrix(SkMatrix* matrix) {
     mSnapshot->transform->load(*matrix);
 }
diff --git a/libs/hwui/OpenGLRenderer.h b/libs/hwui/OpenGLRenderer.h
index 7387b92..272c5c2 100644
--- a/libs/hwui/OpenGLRenderer.h
+++ b/libs/hwui/OpenGLRenderer.h
@@ -84,6 +84,7 @@
     virtual void translate(float dx, float dy);
     virtual void rotate(float degrees);
     virtual void scale(float sx, float sy);
+    virtual void skew(float sx, float sy);
 
     const float* getMatrix() const;
     void getMatrix(SkMatrix* matrix);