Revert "Revert "Add more support for transformed clip rects and paths""

This reverts commit a8557d2169e14997637f57bc897640c8882d4a46.

Change-Id: I36d4883d548fc47ba6c0b4a42012107d0d2f85a6
diff --git a/libs/hwui/Stencil.h b/libs/hwui/Stencil.h
new file mode 100644
index 0000000..67ccc78
--- /dev/null
+++ b/libs/hwui/Stencil.h
@@ -0,0 +1,89 @@
+/*
+ * Copyright (C) 2012 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ANDROID_HWUI_STENCIL_H
+#define ANDROID_HWUI_STENCIL_H
+
+#ifndef LOG_TAG
+    #define LOG_TAG "OpenGLRenderer"
+#endif
+
+#include <cutils/compiler.h>
+
+namespace android {
+namespace uirenderer {
+
+///////////////////////////////////////////////////////////////////////////////
+// Stencil buffer management
+///////////////////////////////////////////////////////////////////////////////
+
+class ANDROID_API Stencil {
+public:
+    Stencil();
+
+    /**
+     * Returns the desired size for the stencil buffer. If the returned value
+     * is 0, then no stencil buffer is required.
+     */
+    ANDROID_API static uint32_t getStencilSize();
+
+    /**
+     * Clears the stencil buffer.
+     */
+    void clear();
+
+    /**
+     * Enables stencil test. When the stencil test is enabled the stencil
+     * buffer is not written into.
+     */
+    void enableTest();
+
+    /**
+     * Enables stencil write. When stencil write is enabled, the stencil
+     * test always succeeds and the value 0x1 is written in the stencil
+     * buffer for each fragment.
+     */
+    void enableWrite();
+
+    /**
+     * Disables stencil test and write.
+     */
+    void disable();
+
+    /**
+     * Indicates whether either test or write is enabled.
+     */
+    bool isEnabled() {
+        return mState != kDisabled;
+    }
+
+private:
+    void enable();
+
+    enum StencilState {
+        kDisabled,
+        kTest,
+        kWrite
+    };
+
+    StencilState mState;
+
+}; // class Stencil
+
+}; // namespace uirenderer
+}; // namespace android
+
+#endif // ANDROID_HWUI_STENCIL_H