am 996d3974: am ed35f5c7: Merge "Fast loadInverse() implementation for the common case"

* commit '996d39743a73cc37fb888779d52323743f50c666':
  Fast loadInverse() implementation for the common case

libs/hwui/Matrix.cpp

@@ -203,6 +203,34 @@ void Matrix4::copyTo(SkMatrix& v) const {
 }
 
 void Matrix4::loadInverse(const Matrix4& v) {
+    // Fast case for common translation matrices
+    if (v.isPureTranslate()) {
+        // Reset the matrix
+        // Unnamed fields are never written to except by
+        // loadIdentity(), they don't need to be reset
+        data[kScaleX]       = 1.0f;
+        data[kSkewX]        = 0.0f;
+
+        data[kScaleY]       = 1.0f;
+        data[kSkewY]        = 0.0f;
+
+        data[kScaleZ]       = 1.0f;
+
+        data[kPerspective0] = 0.0f;
+        data[kPerspective1] = 0.0f;
+        data[kPerspective2] = 1.0f;
+
+        // No need to deal with kTranslateZ because isPureTranslate()
+        // only returns true when the kTranslateZ component is 0
+        data[kTranslateX]   = -v.data[kTranslateX];
+        data[kTranslateY]   = -v.data[kTranslateY];
+        data[kTranslateZ]   = 0.0f;
+
+        // A "pure translate" matrix can be identity or translation
+        mType = v.getType();
+        return;
+    }
+
     double scale = 1.0 /
             (v.data[kScaleX] * ((double) v.data[kScaleY]  * v.data[kPerspective2] -
                     (double) v.data[kTranslateY] * v.data[kPerspective1]) +