refactor parts of SkGr.cpp for use by SkImages

src/gpu/GrYUVProvider.cpp

Index: src/gpu/GrYUVProvider.cpp
diff --git a/src/gpu/GrYUVProvider.cpp b/src/gpu/GrYUVProvider.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..09949113d7406d4f8624ae27db2d4793217f8745
--- /dev/null
+++ b/src/gpu/GrYUVProvider.cpp
@@ -0,0 +1,143 @@
+/*
+ * 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 "GrContext.h"
+#include "GrDrawContext.h"
+#include "GrYUVProvider.h"
+#include "effects/GrYUVtoRGBEffect.h"
+
+#include "SkCachedData.h"
+#include "SkRefCnt.h"
+#include "SkResourceCache.h"
+#include "SkYUVPlanesCache.h"
+
+namespace {
+/**
+ *  Helper class to manage the resources used for storing the YUV planar data. Depending on the
+ *  useCache option, we may find (and lock) the data in our ResourceCache, or we may have allocated
+ *  it in scratch storage.
+ */
+class YUVScoper {
+public:
+    bool init(GrYUVProvider*, SkYUVPlanesCache::Info*, void* planes[3], bool useCache);
+
+private:
+    // we only use one or the other of these
+    SkAutoTUnref<SkCachedData>  fCachedData;
+    SkAutoMalloc                fStorage;
+};
+}
+
+bool YUVScoper::init(GrYUVProvider* provider, SkYUVPlanesCache::Info* yuvInfo, void* planes[3],
+                     bool useCache) {
+    if (useCache) {
+        fCachedData.reset(SkYUVPlanesCache::FindAndRef(provider->onGetID(), yuvInfo));
+    }
+
+    if (fCachedData.get()) {
+        planes[0] = (void*)fCachedData->data();
+        planes[1] = (uint8_t*)planes[0] + yuvInfo->fSizeInMemory[0];
+        planes[2] = (uint8_t*)planes[1] + yuvInfo->fSizeInMemory[1];
+    } else {
+        // Fetch yuv plane sizes for memory allocation. Here, width and height can be
+        // rounded up to JPEG block size and be larger than the image's width and height.
+        if (!provider->onGetYUVSizes(yuvInfo->fSize)) {
+            return false;
+        }
+
+        // Allocate the memory for YUV
+        size_t totalSize(0);
+        for (int i = 0; i < GrYUVProvider::kPlaneCount; ++i) {
+            yuvInfo->fRowBytes[i] = yuvInfo->fSize[i].fWidth; // we assume snug fit: rb == width
+            yuvInfo->fSizeInMemory[i] = yuvInfo->fRowBytes[i] * yuvInfo->fSize[i].fHeight;
+            totalSize += yuvInfo->fSizeInMemory[i];
+        }
+        if (useCache) {
+            fCachedData.reset(SkResourceCache::NewCachedData(totalSize));
+            planes[0] = fCachedData->writable_data();
+        } else {
+            fStorage.reset(totalSize);
+            planes[0] = fStorage.get();
+        }
+        planes[1] = (uint8_t*)planes[0] + yuvInfo->fSizeInMemory[0];
+        planes[2] = (uint8_t*)planes[1] + yuvInfo->fSizeInMemory[1];
+
+        // Get the YUV planes and update plane sizes to actual image size
+        if (!provider->onGetYUVPlanes(yuvInfo->fSize, planes, yuvInfo->fRowBytes,
+                                      &yuvInfo->fColorSpace)) {
+            return false;
+        }
+
+        if (useCache) {
+            // Decoding is done, cache the resulting YUV planes
+            SkYUVPlanesCache::Add(provider->onGetID(), fCachedData, yuvInfo);
+        }
+    }
+    return true;
+}
+
+GrTexture* GrYUVProvider::refAsTexture(GrContext* ctx, const GrSurfaceDesc& desc, bool useCache) {
+    SkYUVPlanesCache::Info yuvInfo;
+    void* planes[3];
+    YUVScoper scoper;
+    if (!scoper.init(this, &yuvInfo, planes, useCache)) {
+        return nullptr;
+    }
+
+    GrSurfaceDesc yuvDesc;
+    yuvDesc.fConfig = kAlpha_8_GrPixelConfig;
+    SkAutoTUnref<GrTexture> yuvTextures[3];
+    for (int i = 0; i < 3; ++i) {
+        yuvDesc.fWidth  = yuvInfo.fSize[i].fWidth;
+        yuvDesc.fHeight = yuvInfo.fSize[i].fHeight;
+        // TODO: why do we need this check?
+        bool needsExactTexture = (yuvDesc.fWidth  != yuvInfo.fSize[0].fWidth) ||
+                                 (yuvDesc.fHeight != yuvInfo.fSize[0].fHeight);
+        if (needsExactTexture) {
+            yuvTextures[i].reset(ctx->textureProvider()->createTexture(yuvDesc, true));
+        } else {
+            yuvTextures[i].reset(ctx->textureProvider()->createApproxTexture(yuvDesc));
+        }
+        if (!yuvTextures[i] ||
+            !yuvTextures[i]->writePixels(0, 0, yuvDesc.fWidth, yuvDesc.fHeight,
+                                         yuvDesc.fConfig, planes[i], yuvInfo.fRowBytes[i])) {
+                return nullptr;
+            }
+    }
+
+    GrSurfaceDesc rtDesc = desc;
+    rtDesc.fFlags = rtDesc.fFlags | kRenderTarget_GrSurfaceFlag;
+
+    SkAutoTUnref<GrTexture> result(ctx->textureProvider()->createTexture(rtDesc, true, nullptr, 0));
+    if (!result) {
+        return nullptr;
+    }
+
+    GrRenderTarget* renderTarget = result->asRenderTarget();
+    SkASSERT(renderTarget);
+
+    GrPaint paint;
+    SkAutoTUnref<GrFragmentProcessor> yuvToRgbProcessor(
+                                        GrYUVtoRGBEffect::Create(paint.getProcessorDataManager(),
+                                                                 yuvTextures[0],
+                                                                 yuvTextures[1],
+                                                                 yuvTextures[2],
+                                                                 yuvInfo.fSize,
+                                                                 yuvInfo.fColorSpace));
+    paint.addColorFragmentProcessor(yuvToRgbProcessor);
+    const SkRect r = SkRect::MakeIWH(yuvInfo.fSize[0].fWidth, yuvInfo.fSize[0].fHeight);
+
+    SkAutoTUnref<GrDrawContext> drawContext(ctx->drawContext());
+    if (!drawContext) {
+        return nullptr;
+    }
+
+    drawContext->drawRect(renderTarget, GrClip::WideOpen(), paint, SkMatrix::I(), r);
+
+    return result.detach();
+}
+