Actually identify required saveLayers in SkGpuDevice::EXPERIMENTAL_drawPicture

src/gpu/GrPictureUtils.h

+/*
+ * Copyright 2014 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef GrPictureUtils_DEFINED
+#define GrPictureUtils_DEFINED
+
+#include "SkPicture.h"
+#include "SkTDArray.h"
+
+// This class encapsulates the GPU-backend-specific acceleration data
+// for a single SkPicture
+class GPUAccelData : public SkPicture::AccelData {
+public:
+    // Information about a given saveLayer in an SkPicture
+    struct SaveLayerInfo {
+        // The size of the saveLayer
+        SkISize fSize;
+        // The ID of this saveLayer in the picture. 0 is an invalid ID.
+        size_t  fSaveLayerOpID;
+        // The ID of the matching restore in the picture. 0 is an invalid ID.
+        size_t  fRestoreOpID;
+        // True if this saveLayer has at least one other saveLayer nested within it.
+        // False otherwise.
+        bool    fHasNestedLayers;
+    };
+
+    GPUAccelData(Key key) : INHERITED(key) { }
+
+    void addSaveLayerInfo(const SaveLayerInfo& info) {
+        SkASSERT(info.fSaveLayerOpID < info.fRestoreOpID);
+        *fSaveLayerInfo.push() = info;
+    }
+
+    int numSaveLayers() const { return fSaveLayerInfo.count(); }
+
+    const SaveLayerInfo& saveLayerInfo(int index) const {
+        SkASSERT(index < fSaveLayerInfo.count());
+
+        return fSaveLayerInfo[index];
+    }
+
+protected:
+    SkTDArray<SaveLayerInfo> fSaveLayerInfo;
+
+private:
+    typedef SkPicture::AccelData INHERITED;
+};
+
+void GatherGPUInfo(SkPicture* pict, GPUAccelData* accelData);
+
+#endif // GrPictureUtils_DEFINED