new image from backend desc

src/image/SkImage_Gpu.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkImage_Gpu.h"
 #include "SkCanvas.h"
 #include "GrContext.h"
+#include "SkGpuDevice.h"
 
-SkImage_Gpu::SkImage_Gpu(const SkBitmap& bitmap, int sampleCountForNewSurfaces,
-                         SkSurface::Budgeted budgeted)
-    : INHERITED(bitmap.width(), bitmap.height(), NULL)
-    , fBitmap(bitmap)
+SkImage_Gpu::SkImage_Gpu(int w, int h, SkAlphaType at, GrTexture* tex,
+                         int sampleCountForNewSurfaces, SkSurface::Budgeted budgeted)
+    : INHERITED(w, h, NULL)
+    , fTexture(SkRef(tex))
     , fSampleCountForNewSurfaces(sampleCountForNewSurfaces)
+    , fAlphaType(at)
     , fBudgeted(budgeted)
-{
-    SkASSERT(fBitmap.getTexture());
+    {}
+
+SkSurface* SkImage_Gpu::onNewSurface(const SkImageInfo& info, const SkSurfaceProps& props) const {
+    GrTexture* tex = this->getTexture();
+    SkASSERT(tex);
+    GrContext* ctx = tex->getContext();
+    if (!ctx) {
+        // the texture may have been abandoned, so we have to check
+        return NULL;
+    }
+    // TODO: Change signature of onNewSurface to take a budgeted param.
+    const SkSurface::Budgeted budgeted = SkSurface::kNo_Budgeted;
+    return SkSurface::NewRenderTarget(ctx, budgeted, info, fSampleCountForNewSurfaces, &props);
 }
 
-SkShader* SkImage_Gpu::onNewShader(SkShader::TileMode tileX,
-                                   SkShader::TileMode tileY,
-                                   const SkMatrix* localMatrix) const
-{
-    return SkShader::CreateBitmapShader(fBitmap, tileX, tileY, localMatrix);
+extern void SkTextureImageApplyBudgetedDecision(SkImage* image) {
+    if (image->getTexture()) {
+        ((SkImage_Gpu*)image)->applyBudgetDecision();
+    }
 }
 
-SkSurface* SkImage_Gpu::onNewSurface(const SkImageInfo& info, const SkSurfaceProps& props) const {
-    GrContext* ctx = this->getTexture()->getContext();
-    // TODO: Change signature of onNewSurface to take a budgeted param.
-    static const SkSurface::Budgeted kBudgeted = SkSurface::kNo_Budgeted;
-    return SkSurface::NewRenderTarget(ctx, kBudgeted, info, fSampleCountForNewSurfaces, &props);
-}
-
-GrTexture* SkImage_Gpu::onGetTexture() const {
-    return fBitmap.getTexture();
+SkShader* SkImage_Gpu::onNewShader(SkShader::TileMode tileX, SkShader::TileMode tileY,
+                                   const SkMatrix* localMatrix) const {
+    SkBitmap bm;
+    GrWrapTextureInBitmap(fTexture, this->width(), this->height(), this->isOpaque(), &bm);
+    return SkShader::CreateBitmapShader(bm, tileX, tileY, localMatrix);
 }
 
 bool SkImage_Gpu::getROPixels(SkBitmap* dst) const {
-    return fBitmap.copyTo(dst, kN32_SkColorType);
+    SkAlphaType at = this->isOpaque() ? kOpaque_SkAlphaType : kPremul_SkAlphaType;
+    if (!dst->tryAllocPixels(SkImageInfo::MakeN32(this->width(), this->height(), at))) {
+        return false;
+    }
+    if (!fTexture->readPixels(0, 0, dst->width(), dst->height(), kSkia8888_GrPixelConfig,
+                              dst->getPixels(), dst->rowBytes())) {
+        return false;
+    }
+    return true;
 }
 
 bool SkImage_Gpu::isOpaque() const {
-    return fBitmap.isOpaque();
+    return GrPixelConfigIsOpaque(fTexture->config());
 }
 
-///////////////////////////////////////////////////////////////////////////////
+static void apply_premul(const SkImageInfo& info, void* pixels, size_t rowBytes) {
+    switch (info.colorType()) {
+        case kRGBA_8888_SkColorType:
+        case kBGRA_8888_SkColorType:
+            break;
+        default:
+            return; // nothing to do
+    }
 
-SkImage* SkNewImageFromBitmapTexture(const SkBitmap& bitmap, int sampleCountForNewSurfaces,
-                                     SkSurface::Budgeted budgeted) {
-    if (0 == bitmap.width() || 0 == bitmap.height() || NULL == bitmap.getTexture()) {
+    // SkColor is not necesarily RGBA or BGRA, but it is one of them on little-endian,
+    // and in either case, the alpha-byte is always in the same place, so we can safely call
+    // SkPreMultiplyColor()
+    //
+    SkColor* row = (SkColor*)pixels;
+    for (int y = 0; y < info.height(); ++y) {
+        for (int x = 0; x < info.width(); ++x) {
+            row[x] = SkPreMultiplyColor(row[x]);
+        }
+    }
+}
+
+bool SkImage_Gpu::onReadPixels(const SkImageInfo& info, void* pixels, size_t rowBytes,
+                               int srcX, int srcY) const {
+    GrPixelConfig config = SkImageInfo2GrPixelConfig(info.colorType(), info.alphaType(),
+                                                     info.profileType());
+    uint32_t flags = 0;
+    if (kUnpremul_SkAlphaType == info.alphaType() && kPremul_SkAlphaType == fAlphaType) {
+        // let the GPU perform this transformation for us
+        flags = GrContext::kUnpremul_PixelOpsFlag;
+    }
+    if (!fTexture->readPixels(srcX, srcY, info.width(), info.height(), config,
+                              pixels, rowBytes, flags)) {
+        return false;
+    }
+    // do we have to manually fix-up the alpha channel?
+    //      src         dst
+    //      unpremul    premul      fix manually
+    //      premul      unpremul    done by kUnpremul_PixelOpsFlag
+    // all other combos need to change.
+    //
+    // Should this be handled by Ganesh? todo:?
+    //
+    if (kPremul_SkAlphaType == info.alphaType() && kUnpremul_SkAlphaType == fAlphaType) {
+        apply_premul(info, pixels, rowBytes);
+    }
+    return true;
+}
+
+///////////////////////////////////////////////////////////////////////////////////////////////////
+
+SkImage* SkImage::NewFromTexture(GrContext* ctx, const GrBackendTextureDesc& desc, SkAlphaType at) {
+    if (desc.fWidth <= 0 || desc.fHeight <= 0) {
         return NULL;
     }
-    return SkNEW_ARGS(SkImage_Gpu, (bitmap, sampleCountForNewSurfaces, budgeted));
+    SkAutoTUnref<GrTexture> tex(ctx->textureProvider()->wrapBackendTexture(desc));
+    if (!tex) {
+        return NULL;
+    }
+    const SkSurface::Budgeted budgeted = SkSurface::kNo_Budgeted;
+    return SkNEW_ARGS(SkImage_Gpu, (desc.fWidth, desc.fHeight, at, tex, 0, budgeted));
 }
 
-GrTexture* SkTextureImageGetTexture(SkImage* image) {
-    return ((SkImage_Gpu*)image)->getTexture();
+SkImage* SkImage::NewFromTextureCopy(GrContext* ctx, const GrBackendTextureDesc& srcDesc,
+                                     SkAlphaType at) {
+    const bool isBudgeted = true;
+    const SkSurface::Budgeted budgeted = SkSurface::kYes_Budgeted;
+
+    if (srcDesc.fWidth <= 0 || srcDesc.fHeight <= 0) {
+        return NULL;
+    }
+    SkAutoTUnref<GrTexture> src(ctx->textureProvider()->wrapBackendTexture(srcDesc));
+    if (!src) {
+        return NULL;
+    }
+
+    GrSurfaceDesc dstDesc;
+    // need to be a rendertarget for readpixels to work, instead of kNone_GrSurfaceFlags
+    dstDesc.fFlags = kRenderTarget_GrSurfaceFlag;
+    dstDesc.fOrigin = srcDesc.fOrigin;
+    dstDesc.fWidth = srcDesc.fWidth;
+    dstDesc.fHeight = srcDesc.fHeight;
+    dstDesc.fConfig = srcDesc.fConfig;
+    dstDesc.fSampleCnt = srcDesc.fSampleCnt;
+
+    SkAutoTUnref<GrTexture> dst(ctx->textureProvider()->createTexture(
+                                                                  dstDesc, isBudgeted, NULL, 0));
+    if (!dst) {
+        return NULL;
+    }
+
+    const SkIRect srcR = SkIRect::MakeWH(dstDesc.fWidth, dstDesc.fHeight);
+    const SkIPoint dstP = SkIPoint::Make(0, 0);
+    ctx->copySurface(dst, src, srcR, dstP, GrContext::kFlushWrites_PixelOp);
+
+    const int sampleCount = 0;  // todo: make this an explicit parameter to newSurface()?
+    return SkNEW_ARGS(SkImage_Gpu, (dstDesc.fWidth, dstDesc.fHeight, at, dst, sampleCount,
+                                    budgeted));
 }
-
-extern void SkTextureImageApplyBudgetedDecision(SkImage* image) {
-    ((SkImage_Gpu*)image)->applyBudgetDecision();
-}