Add GrDrawTarget::copySurface.

src/gpu/GrDrawTarget.h

 
 /*
  * Copyright 2010 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #ifndef GrDrawTarget_DEFINED
@@ skipping 121 matching lines @@
      *    GrVertexLayout. The data in the array is consumed at the time that
      *    set*SourceToArray is called and subsequent edits to the array will not
      *    be reflected in draws.
      *
      * 2. Reserve. This is most useful when the caller has data it must
      *    transform before drawing and is not long-lived. The caller requests
      *    that the draw target make room for some amount of vertex and/or index
      *    data. The target provides ptrs to hold the vertex and/or index data.
      *
      *    The data is writable up until the next drawIndexed, drawNonIndexed,
-     *    drawIndexedInstances, or pushGeometrySource. At this point the data is
-     *    frozen and the ptrs are no longer valid.
+     *    drawIndexedInstances, drawRect, copySurface, or pushGeometrySource. At
+     *    this point the data is frozen and the ptrs are no longer valid.
      *
      *    Where the space is allocated and how it is uploaded to the GPU is
      *    subclass-dependent.
      *
      * 3. Vertex and Index Buffers. This is most useful for geometry that will
      *    is long-lived. When the data in the buffer is consumed depends on the
      *    GrDrawTarget subclass. For deferred subclasses the caller has to
      *    guarantee that the data is still available in the buffers at playback.
      *    (TODO: Make this more automatic as we have done for read/write pixels)
      *
      * The size of each vertex is determined by querying the current GrDrawState.
      */
 
     /**
      * Reserves space for vertices and/or indices. Zero can be specifed as
      * either the vertex or index count if the caller desires to only reserve
      * space for only indices or only vertices. If zero is specifed for
      * vertexCount then the vertex source will be unmodified and likewise for
      * indexCount.
      *
      * If the function returns true then the reserve suceeded and the vertices
      * and indices pointers will point to the space created.
      *
      * If the target cannot make space for the request then this function will
      * return false. If vertexCount was non-zero then upon failure the vertex
      * source is reset and likewise for indexCount.
      *
      * The pointers to the space allocated for vertices and indices remain valid
-     * until a drawIndexed, drawNonIndexed, drawIndexedInstances, or push/
-     * popGeomtrySource is called. At that point logically a snapshot of the
-     * data is made and the pointers are invalid.
+     * until a drawIndexed, drawNonIndexed, drawIndexedInstances, drawRect,
+     * copySurface, or push/popGeomtrySource is called. At that point logically a
+     * snapshot of the data is made and the pointers are invalid.
      *
      * @param vertexCount  the number of vertices to reserve space for. Can be
      *                     0. Vertex size is queried from the current GrDrawState.
      * @param indexCount   the number of indices to reserve space for. Can be 0.
      * @param vertices     will point to reserved vertex space if vertexCount is
      *                     non-zero. Illegal to pass NULL if vertexCount > 0.
      * @param indices      will point to reserved index space if indexCount is
      *                     non-zero. Illegal to pass NULL if indexCount > 0.
      */
      bool reserveVertexAndIndexSpace(int vertexCount,
@@ skipping 214 matching lines @@
                               const SkRect* devBounds = NULL);
 
     /**
      * Clear the current render target if one isn't passed in. Ignores the
      * clip and all other draw state (blend mode, stages, etc). Clears the
      * whole thing if rect is NULL, otherwise just the rect.
      */
     virtual void clear(const GrIRect* rect,
                        GrColor color,
                        GrRenderTarget* renderTarget = NULL) = 0;
+    
+    /**
+     * Copies a pixel rectangle from one surface to another. This call may finalize
+     * reserved vertex/index data (as though a draw call was made). The src pixels
+     * copied are specified by srcRect. They are copied to a rect of the same
+     * size in dst with top left at dstPoint. If the src rect is clipped by the
+     * src bounds then  pixel values in the dst rect corresponding to area clipped
+     * by the src rect are not overwritten. This method can fail and return false
+     * depending on the type of surface, configs, etc, and the backend-specific
+     * limitations. If rect is clipped out entirely by the src or dst bounds then
+     * true is returned since there is no actual copy necessary to succeed.
+     */

[robertphillips, 2013/04/03 12:21:27]

can src be "const GrSurface& src"?

[bsalomon, 2013/04/03 12:51:53]

As for const, you can't do much with const GrResources. You can't draw from a
const GrTexture, for example.

As for ref, I think it should be a ptr because it is ref counted and we will
internally take refs to the texture.

[robertphillips, 2013/04/03 13:01:29]

That's what I thought but I figured it wouldn't hurt to ask.

+    bool copySurface(GrSurface* dst,
+                     GrSurface* src,
+                     const SkIRect& srcRect,
+                     const SkIPoint& dstPoint);
 
     /**
      * Release any resources that are cached but not currently in use. This
      * is intended to give an application some recourse when resources are low.
      */
     virtual void purgeResources() {};
 
     /**
      * For subclass internal use to invoke a call to onDraw(). See DrawInfo below.
      */
@@ skipping 190 matching lines @@
             case kArray_GeometrySrcType:
                 return src.fIndexCount;
             case kBuffer_GeometrySrcType:
                 return src.fIndexBuffer->sizeInBytes() / sizeof(uint16_t);
             default:
                 GrCrash("Unexpected Index Source.");
                 return 0;
         }
     }
 
+    // This method is called by copySurface  The srcRect is guaranteed to be entirely within the
+    // src bounds. Likewise, the dst rect implied by dstPoint and srcRect's width and height falls
+    // entirely within the dst. The default implementation will draw a rect from the src to the
+    // dst if the src is a texture and the dst is a render target and fail otherwise.
+    virtual bool onCopySurface(GrSurface* dst,
+                               GrSurface* src,
+                               const SkIRect& srcRect,
+                               const SkIPoint& dstPoint);
+
+    // Called to determine whether an onCopySurface call would succeed or not. This is useful for
+    // proxy subclasses to test whether the copy would succeed without executing it yet. Derived
+    // classes must keep this consistent with their implementation of onCopySurface(). The inputs
+    // are the same as onCopySurface(), i.e. srcRect and dstPoint are clipped to be inside the src
+    // and dst bounds.
+    virtual bool canCopySurface(GrSurface* dst,
+                                GrSurface* src,
+                                const SkIRect& srcRect,
+                                const SkIPoint& dstPoint);
+
     GrContext* getContext() { return fContext; }
     const GrContext* getContext() const { return fContext; }
 
     // A subclass may override this function if it wishes to be notified when the clip is changed.
     // The override should call INHERITED::clipWillBeSet().
     virtual void clipWillBeSet(const GrClipData* clipData);
 
     // subclasses must call this in their destructors to ensure all vertex
     // and index sources have been released (including those held by
     // pushGeometrySource())
@@ skipping 148 matching lines @@
     const GrClipData*                                               fClip;
     GrDrawState*                                                    fDrawState;
     GrDrawState                                                     fDefaultDrawState;
     // The context owns us, not vice-versa, so this ptr is not ref'ed by DrawTarget.
     GrContext*                                                      fContext;
 
     typedef GrRefCnt INHERITED;
 };
 
 #endif