[GPU] Add explicit byte order and PM vs. UPM 8888 configs
Review URL: http://codereview.appspot.com/5347042/
git-svn-id: http://skia.googlecode.com/svn/trunk@2618 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/gpu/GrGpu.h b/src/gpu/GrGpu.h
index b0aaa18..11edfe3 100644
--- a/src/gpu/GrGpu.h
+++ b/src/gpu/GrGpu.h
@@ -184,7 +184,34 @@
void forceRenderTargetFlush();
/**
- * Reads a rectangle of pixels from a render target.
+ * OpenGL's readPixels returns the result bottom-to-top while the skia
+ * API is top-to-bottom. Thus we have to do a y-axis flip. The obvious
+ * solution is to have the subclass do the flip using either the CPU or GPU.
+ * However, the caller (GrContext) may have transformations to apply and can
+ * simply fold in the y-flip for free. On the other hand, the subclass may
+ * be able to do it for free itself. For example, the subclass may have to
+ * do memcpys to handle rowBytes that aren't tight. It could do the y-flip
+ * concurrently.
+ *
+ * This function returns true if a y-flip is required to put the pixels in
+ * top-to-bottom order and the subclass cannot do it for free.
+ *
+ * See read pixels for the params
+ * @return true if calling readPixels with the same set of params will
+ * produce bottom-to-top data
+ */
+ virtual bool readPixelsWillPayForYFlip(GrRenderTarget* renderTarget,
+ int left, int top,
+ int width, int height,
+ GrPixelConfig config,
+ size_t rowBytes) = 0;
+
+ /**
+ * Reads a rectangle of pixels from a render target. Fails if read requires
+ * conversion between premultiplied and unpremultiplied configs. The caller
+ * should do the conversion by rendering to a target with the desire config
+ * first.
+ *
* @param renderTarget the render target to read from. NULL means the
* current render target.
* @param left left edge of the rectangle to read (inclusive)
@@ -195,6 +222,8 @@
* @param buffer memory to read the rectangle into.
* @param rowBytes the number of bytes between consecutive rows. Zero
* means rows are tightly packed.
+ * @param invertY buffer should be populated bottom-to-top as opposed
+ * to top-to-bottom (skia's usual order)
*
* @return true if the read succeeded, false if not. The read can fail
* because of a unsupported pixel config or because no render
@@ -202,7 +231,8 @@
*/
bool readPixels(GrRenderTarget* renderTarget,
int left, int top, int width, int height,
- GrPixelConfig config, void* buffer, size_t rowBytes);
+ GrPixelConfig config, void* buffer, size_t rowBytes,
+ bool invertY);
const GrGpuStats& getStats() const;
void resetStats();
@@ -356,7 +386,10 @@
// overridden by API-specific derived class to perform the read pixels.
virtual bool onReadPixels(GrRenderTarget* target,
int left, int top, int width, int height,
- GrPixelConfig, void* buffer, size_t rowBytes) = 0;
+ GrPixelConfig,
+ void* buffer,
+ size_t rowBytes,
+ bool invertY) = 0;
// called to program the vertex data, indexCount will be 0 if drawing non-
// indexed geometry. The subclass may adjust the startVertex and/or