Create abstract base class for OpenGLRenderer

This will eventually serve as a base class to allow
DisplayListRenderer to split off from OpenGLRenderer, and could
eventually support other rendering approaches, such as an
SkCanvas/SkPicture.

This will also be the main source of (implementation-independent)
documentation of the canvas/renderer methods.

Change-Id: I52047f338f5cf86a3b0b3002af7154bff5c3c227
diff --git a/libs/hwui/Renderer.h b/libs/hwui/Renderer.h
new file mode 100644
index 0000000..ac216fe
--- /dev/null
+++ b/libs/hwui/Renderer.h
@@ -0,0 +1,267 @@
+/*
+ * Copyright (C) 2013 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_RENDERER_H
+#define ANDROID_HWUI_RENDERER_H
+
+#include "AssetAtlas.h"
+#include "SkPaint.h"
+
+namespace android {
+namespace uirenderer {
+
+class DisplayList;
+class Layer;
+class Matrix4;
+class SkiaColorFilter;
+class SkiaShader;
+class Patch;
+
+enum DrawOpMode {
+    kDrawOpMode_Immediate,
+    kDrawOpMode_Defer,
+    kDrawOpMode_Flush
+};
+
+/**
+ * Hwui's abstract version of Canvas.
+ *
+ * Provides methods for frame state operations, as well as the SkCanvas style transform/clip state,
+ * and varied drawing operations.
+ *
+ * Should at some point interact with native SkCanvas.
+ */
+class ANDROID_API Renderer {
+public:
+    virtual ~Renderer() {}
+
+    /**
+     * Sets the name of this renderer. The name is optional and empty by default, for debugging
+     * purposes only. If the pointer is null the name is set to the empty string.
+     */
+    void setName(const char * name) {
+        if (name) {
+            mName.setTo(name);
+        } else {
+            mName.clear();
+        }
+    }
+
+    /**
+     * Returns the name of this renderer as UTF8 string.
+     * The returned pointer is never null.
+     */
+    const char* getName() const {
+        return mName.string();
+    }
+
+    /**
+     * Indicates whether this renderer is recording drawing commands for later playback.
+     * If this method returns true, the drawing commands are deferred.
+     */
+    virtual bool isRecording() const {
+        return false;
+    }
+
+    /**
+     * Safely retrieves the mode from the specified xfermode. If the specified
+     * xfermode is null, the mode is assumed to be SkXfermode::kSrcOver_Mode.
+     */
+    static inline SkXfermode::Mode getXfermode(SkXfermode* mode) {
+        SkXfermode::Mode resultMode;
+        if (!SkXfermode::AsMode(mode, &resultMode)) {
+            resultMode = SkXfermode::kSrcOver_Mode;
+        }
+        return resultMode;
+    }
+
+// ----------------------------------------------------------------------------
+// Frame state operations
+// ----------------------------------------------------------------------------
+    /**
+     * Sets the dimension of the underlying drawing surface. This method must
+     * be called at least once every time the drawing surface changes size.
+     *
+     * @param width The width in pixels of the underlysing surface
+     * @param height The height in pixels of the underlysing surface
+     */
+    virtual void setViewport(int width, int height) = 0;
+
+    /**
+     * Prepares the renderer to draw a frame. This method must be invoked
+     * at the beginning of each frame. When this method is invoked, the
+     * entire drawing surface is assumed to be redrawn.
+     *
+     * @param opaque If true, the target surface is considered opaque
+     *               and will not be cleared. If false, the target surface
+     *               will be cleared
+     */
+    virtual status_t prepare(bool opaque) = 0;
+
+    /**
+     * Prepares the renderer to draw a frame. This method must be invoked
+     * at the beginning of each frame. Only the specified rectangle of the
+     * frame is assumed to be dirty. A clip will automatically be set to
+     * the specified rectangle.
+     *
+     * @param left The left coordinate of the dirty rectangle
+     * @param top The top coordinate of the dirty rectangle
+     * @param right The right coordinate of the dirty rectangle
+     * @param bottom The bottom coordinate of the dirty rectangle
+     * @param opaque If true, the target surface is considered opaque
+     *               and will not be cleared. If false, the target surface
+     *               will be cleared in the specified dirty rectangle
+     */
+    virtual status_t prepareDirty(float left, float top, float right, float bottom,
+            bool opaque) = 0;
+
+    /**
+     * Indicates the end of a frame. This method must be invoked whenever
+     * the caller is done rendering a frame.
+     */
+    virtual void finish() = 0;
+
+    /**
+     * This method must be invoked before handing control over to a draw functor.
+     * See callDrawGLFunction() for instance.
+     *
+     * This command must not be recorded inside display lists.
+     */
+    virtual void interrupt() = 0;
+
+    /**
+     * This method must be invoked after getting control back from a draw functor.
+     *
+     * This command must not be recorded inside display lists.
+     */
+    virtual void resume() = 0;
+
+// ----------------------------------------------------------------------------
+// Canvas state operations
+// ----------------------------------------------------------------------------
+    // getters
+    virtual int getSaveCount() const = 0;
+    virtual void getMatrix(SkMatrix* outMatrix) const = 0;
+    virtual const Rect& getClipBounds() const = 0;
+
+    // save (layer)
+    virtual int save(int flags) = 0;
+    virtual void restore() = 0;
+    virtual void restoreToCount(int saveCount) = 0;
+
+    int saveLayer(float left, float top, float right, float bottom,
+            const SkPaint* paint, int flags) {
+        SkXfermode::Mode mode = SkXfermode::kSrcOver_Mode;
+        int alpha = 255;
+        if (paint) {
+            mode = getXfermode(paint->getXfermode());
+            alpha = paint->getAlpha();
+        }
+        return saveLayer(left, top, right, bottom, alpha, mode, flags);
+    }
+    int saveLayerAlpha(float left, float top, float right, float bottom,
+            int alpha, int flags) {
+        return saveLayer(left, top, right, bottom, alpha, SkXfermode::kSrcOver_Mode, flags);
+    }
+    virtual int saveLayer(float left, float top, float right, float bottom,
+            int alpha, SkXfermode::Mode mode, int flags) = 0;
+
+    // Matrix
+    virtual void translate(float dx, float dy, float dz = 0.0f) = 0;
+    virtual void rotate(float degrees) = 0;
+    virtual void scale(float sx, float sy) = 0;
+    virtual void skew(float sx, float sy) = 0;
+
+    virtual void setMatrix(SkMatrix* matrix) = 0;
+    virtual void concatMatrix(SkMatrix* matrix) = 0;
+    virtual void concatMatrix(Matrix4& matrix) = 0;
+
+    // Clip
+    virtual bool clipRect(float left, float top, float right, float bottom, SkRegion::Op op) = 0;
+    virtual bool clipPath(SkPath* path, SkRegion::Op op) = 0;
+    virtual bool clipRegion(SkRegion* region, SkRegion::Op op) = 0;
+
+    // Misc - should be implemented with SkPaint inspection
+    virtual void resetShader() = 0;
+    virtual void setupShader(SkiaShader* shader) = 0;
+
+    virtual void resetColorFilter() = 0;
+    virtual void setupColorFilter(SkiaColorFilter* filter) = 0;
+
+    virtual void resetShadow() = 0;
+    virtual void setupShadow(float radius, float dx, float dy, int color) = 0;
+
+    virtual void resetPaintFilter() = 0;
+    virtual void setupPaintFilter(int clearBits, int setBits) = 0;
+
+// ----------------------------------------------------------------------------
+// Canvas draw operations
+// ----------------------------------------------------------------------------
+    virtual status_t drawColor(int color, SkXfermode::Mode mode) = 0;
+
+    // Bitmap-based
+    virtual status_t drawBitmap(SkBitmap* bitmap, float left, float top, SkPaint* paint) = 0;
+    virtual status_t drawBitmap(SkBitmap* bitmap, SkMatrix* matrix, SkPaint* paint) = 0;
+    virtual status_t drawBitmap(SkBitmap* bitmap, float srcLeft, float srcTop,
+            float srcRight, float srcBottom, float dstLeft, float dstTop,
+            float dstRight, float dstBottom, SkPaint* paint) = 0;
+    virtual status_t drawBitmapData(SkBitmap* bitmap, float left, float top, SkPaint* paint) = 0;
+    virtual status_t drawBitmapMesh(SkBitmap* bitmap, int meshWidth, int meshHeight,
+            float* vertices, int* colors, SkPaint* paint) = 0;
+    virtual status_t drawPatch(SkBitmap* bitmap, Res_png_9patch* patch,
+            float left, float top, float right, float bottom, SkPaint* paint) = 0;
+
+    // Shapes
+    virtual status_t drawRect(float left, float top, float right, float bottom, SkPaint* paint) = 0;
+    virtual status_t drawRects(const float* rects, int count, SkPaint* paint) = 0;
+    virtual status_t drawRoundRect(float left, float top, float right, float bottom,
+            float rx, float ry, SkPaint* paint) = 0;
+    virtual status_t drawCircle(float x, float y, float radius, SkPaint* paint) = 0;
+    virtual status_t drawOval(float left, float top, float right, float bottom, SkPaint* paint) = 0;
+    virtual status_t drawArc(float left, float top, float right, float bottom,
+            float startAngle, float sweepAngle, bool useCenter, SkPaint* paint) = 0;
+    virtual status_t drawPath(SkPath* path, SkPaint* paint) = 0;
+    virtual status_t drawLines(float* points, int count, SkPaint* paint) = 0;
+    virtual status_t drawPoints(float* points, int count, SkPaint* paint) = 0;
+
+    // Text
+    virtual status_t drawText(const char* text, int bytesCount, int count, float x, float y,
+            const float* positions, SkPaint* paint, float totalAdvance, const Rect& bounds,
+            DrawOpMode drawOpMode = kDrawOpMode_Immediate) = 0;
+    virtual status_t drawTextOnPath(const char* text, int bytesCount, int count, SkPath* path,
+            float hOffset, float vOffset, SkPaint* paint) = 0;
+    virtual status_t drawPosText(const char* text, int bytesCount, int count,
+            const float* positions, SkPaint* paint) = 0;
+
+// ----------------------------------------------------------------------------
+// Canvas draw operations - special
+// ----------------------------------------------------------------------------
+    virtual status_t drawLayer(Layer* layer, float x, float y) = 0;
+    virtual status_t drawDisplayList(DisplayList* displayList, Rect& dirty,
+            int32_t replayFlags) = 0;
+
+    // TODO: rename for consistency
+    virtual status_t callDrawGLFunction(Functor* functor, Rect& dirty) = 0;
+
+private:
+    // Optional name of the renderer
+    String8 mName;
+}; // class Renderer
+
+}; // namespace uirenderer
+}; // namespace android
+
+#endif // ANDROID_HWUI_RENDERER_H