initial preroll api

src/core/SkPicturePreroll.cpp

Index: src/core/SkPicturePreroll.cpp
diff --git a/src/core/SkPicturePreroll.cpp b/src/core/SkPicturePreroll.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..b0a4b17f56c71441fa2bd3c462ac6423082cccc2
--- /dev/null
+++ b/src/core/SkPicturePreroll.cpp
@@ -0,0 +1,162 @@
+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkCanvas.h"
+#include "SkPicture.h"
+
+class SkPrerollCanvas : public SkCanvas {
+public:
+    SkPrerollCanvas(int width, int height, const SkSurfaceProps* props)
+        : SkCanvas(width, height, props)
+    {}
+
+protected:
+    void onDrawDRRect(const SkRRect&, const SkRRect&, const SkPaint& paint) SK_OVERRIDE {
+        this->handlePaint(paint);
+    }
+    
+    void onDrawText(const void*, size_t, SkScalar, SkScalar, const SkPaint& paint) SK_OVERRIDE {
+        this->handlePaint(paint);
+    }
+    
+    void onDrawPosText(const void*, size_t, const SkPoint[], const SkPaint& paint) SK_OVERRIDE {
+        this->handlePaint(paint);
+    }
+    
+    void onDrawPosTextH(const void*, size_t, const SkScalar[], SkScalar,
+                        const SkPaint& paint) SK_OVERRIDE {
+        this->handlePaint(paint);
+    }
+    
+    void onDrawTextOnPath(const void*, size_t, const SkPath&, const SkMatrix*,
+                          const SkPaint& paint) SK_OVERRIDE {
+        this->handlePaint(paint);
+    }
+    
+    void onDrawTextBlob(const SkTextBlob*, SkScalar, SkScalar, const SkPaint& paint) SK_OVERRIDE {
+        this->handlePaint(paint);
+    }
+    
+    void onDrawPatch(const SkPoint[12], const SkColor[4], const SkPoint[4], SkXfermode*,
+                     const SkPaint& paint) SK_OVERRIDE {
+        this->handlePaint(paint);
+    }
+    
+    void onDrawPaint(const SkPaint& paint) SK_OVERRIDE {
+        this->handlePaint(paint);
+    }
+
+    void onDrawRect(const SkRect&, const SkPaint& paint) SK_OVERRIDE {
+        this->handlePaint(paint);
+    }
+
+    void onDrawOval(const SkRect&, const SkPaint& paint) SK_OVERRIDE {
+        this->handlePaint(paint);
+    }
+
+    void onDrawRRect(const SkRRect&, const SkPaint& paint) SK_OVERRIDE {
+        this->handlePaint(paint);
+    }
+
+    void onDrawPoints(PointMode, size_t, const SkPoint[], const SkPaint& paint) {
+        this->handlePaint(paint);
+    }
+
+    void onDrawVertices(VertexMode, int, const SkPoint[], const SkPoint[], const SkColor[],
+                        SkXfermode*, const uint16_t[], int, const SkPaint& paint) SK_OVERRIDE {
+        this->handlePaint(paint);
+    }
+
+    void onDrawPath(const SkPath&, const SkPaint& paint) SK_OVERRIDE {
+        this->handlePaint(paint);
+    }
+
+    void onDrawImage(const SkImage* image, SkScalar, SkScalar, const SkPaint* paint) SK_OVERRIDE {
+        this->handleImage(image);
+        if (paint) {
+            this->handlePaint(*paint);
+        }
+    }
+
+    void onDrawImageRect(const SkImage* image, const SkRect*, const SkRect&,
+                         const SkPaint* paint) SK_OVERRIDE {
+        this->handleImage(image);
+        if (paint) {
+            this->handlePaint(*paint);
+        }
+    }
+
+    void onDrawBitmap(const SkBitmap& bm, SkScalar, SkScalar, const SkPaint* paint) SK_OVERRIDE {
+        this->handleBitmap(bm);
+        if (paint) {
+            this->handlePaint(*paint);
+        }
+    }
+
+    void onDrawBitmapRect(const SkBitmap& bm, const SkRect*, const SkRect&, const SkPaint* paint,
+                          DrawBitmapRectFlags) SK_OVERRIDE {
+        this->handleBitmap(bm);
+        if (paint) {
+            this->handlePaint(*paint);
+        }
+    }
+
+    void onDrawBitmapNine(const SkBitmap& bm, const SkIRect&, const SkRect&,
+                          const SkPaint* paint) SK_OVERRIDE {
+        this->handleBitmap(bm);
+        if (paint) {
+            this->handlePaint(*paint);
+        }
+    }
+
+    void onDrawSprite(const SkBitmap& bm, int, int, const SkPaint* paint) SK_OVERRIDE {
+        this->handleBitmap(bm);
+        if (paint) {
+            this->handlePaint(*paint);
+        }
+    }
+
+private:
+    void handlePaint(const SkPaint& paint) {
+        const SkShader* shader = paint.getShader();
+        if (shader) {
+            shader->preroll();
+        }
+    }
+
+    void handleImage(const SkImage* image) {
+        image->preroll();
+    }
+
+    void handleBitmap(const SkBitmap& bitmap) {
+        SkBitmap bm(bitmap);
+        bm.lockPixels();
+    }
+
+    typedef SkCanvas INHERITED;
+};
+
+///////////////////////////////////////////////////////////////////////////////////////////////////
+
+void SkPicture::preroll(const SkRect* srcBounds, const SkMatrix* initialMatrix,
+                        const SkSurfaceProps* props, void* gpuCacheAccessor) const {
+    SkRect bounds = this->cullRect();
+    if (srcBounds && !bounds.intersect(*srcBounds)) {
+        return;
+    }
+
+    const SkIRect ibounds = bounds.roundOut();
+    if (ibounds.isEmpty()) {
+        return;
+    }
+
+    SkPrerollCanvas canvas(ibounds.width(), ibounds.height(), props);
+
+    canvas.translate(-SkIntToScalar(ibounds.left()), -SkIntToScalar(ibounds.top()));
+    canvas.drawPicture(this, initialMatrix, NULL);
+}
+