Reland "Optimize SkColorSpaceXformCanvas for GPU-acceleration"

This is a reland of 1d3df3848ff297e353a2d0f0fae6ec4a55ab7ba6
Original change's description:
> Optimize SkColorSpaceXformCanvas for GPU-acceleration
> 
> This change ensures that SkImages are uploaded to the GPU before
> applying the xform when the destination canvas is on the GPU. This
> makes it possible to get hits in the texture cache and it ensures
> that transforms get computed on the GPU.
> 
> This fixes a severe performance regression in Chrome that happened
> when color correction was enabled.
> 
> Associated chromium patch for layout test rebaselines:
> https://chromium-review.googlesource.com/c/chromium/src/+/655483
> 
> Merge dependency: Merging this change to the M-62 and M-61
> branches also requires merging the following change, otherwise
> there will be rendering errors:
> https://skia-review.googlesource.com/c/skia/+/43562
> 
> BUG=chromium:760738
> 
> Change-Id: I49fd5ef7968272d311249c3824fe15bee4648b73
> Reviewed-on: https://skia-review.googlesource.com/43183
> Commit-Queue: Justin Novosad <junov@chromium.org>
> Reviewed-by: Brian Osman <brianosman@google.com>

Bug: chromium:760738
Change-Id: I94a3482713dc4ff824ae21ea640c04d06bb7e29d
Reviewed-on: https://skia-review.googlesource.com/44760
Reviewed-by: Justin Novosad <junov@chromium.org>
Commit-Queue: Justin Novosad <junov@chromium.org>

1 files changed, 21 insertions, 5 deletions

diff --git a/src/core/SkColorSpaceXformCanvas.cpp b/src/core/SkColorSpaceXformCanvas.cpp
index 6d6d27b399..dc36d36716 100644
--- a/src/core/SkColorSpaceXformCanvas.cpp
+++ b/src/core/SkColorSpaceXformCanvas.cpp
@@ -139,25 +139,25 @@ public:
     void onDrawImage(const SkImage* img,
                      SkScalar l, SkScalar t,
                      const SkPaint* paint) override {
-        fTarget->drawImage(fXformer->apply(img).get(), l, t, MaybePaint(paint, fXformer.get()));
+        fTarget->drawImage(prepareImage(img).get(), l, t, MaybePaint(paint, fXformer.get()));
     }
     void onDrawImageRect(const SkImage* img,
                          const SkRect* src, const SkRect& dst,
                          const SkPaint* paint, SrcRectConstraint constraint) override {
-        fTarget->drawImageRect(fXformer->apply(img).get(),
+        fTarget->drawImageRect(prepareImage(img).get(),
                                src ? *src : SkRect::MakeIWH(img->width(), img->height()), dst,
                                MaybePaint(paint, fXformer.get()), constraint);
     }
     void onDrawImageNine(const SkImage* img,
                          const SkIRect& center, const SkRect& dst,
                          const SkPaint* paint) override {
-        fTarget->drawImageNine(fXformer->apply(img).get(), center, dst,
+        fTarget->drawImageNine(prepareImage(img).get(), center, dst,
                                MaybePaint(paint, fXformer.get()));
     }
     void onDrawImageLattice(const SkImage* img,
                             const Lattice& lattice, const SkRect& dst,
                             const SkPaint* paint) override {
-        fTarget->drawImageLattice(fXformer->apply(img).get(), lattice, dst,
+        fTarget->drawImageLattice(prepareImage(img).get(), lattice, dst,
                                   MaybePaint(paint, fXformer.get()));
     }
     void onDrawAtlas(const SkImage* atlas, const SkRSXform* xforms, const SkRect* tex,
@@ -169,7 +169,7 @@ public:
             fXformer->apply(xformed.begin(), colors, count);
             colors = xformed.begin();
         }
-        fTarget->drawAtlas(fXformer->apply(atlas).get(), xforms, tex, colors, count, mode, cull,
+        fTarget->drawAtlas(prepareImage(atlas).get(), xforms, tex, colors, count, mode, cull,
                            MaybePaint(paint, fXformer.get()));
     }
 
@@ -308,6 +308,22 @@ public:
     void onFlush() override { return fTarget->flush(); }
 
 private:
+    sk_sp<SkImage> prepareImage(const SkImage* image) {
+        GrContext* gr = fTarget->getGrContext();
+        if (gr) {
+            // If fTarget is GPU-accelerated, we want to upload to a texture
+            // before applying the transform. This way, we can get cache hits
+            // in the texture cache and the transform gets applied on the GPU.
+            sk_sp<SkImage> textureImage = image->makeTextureImage(gr, nullptr);
+            if (textureImage)
+                return fXformer->apply(textureImage.get());
+        }
+        // TODO: Extract a sub image corresponding to the src rect in order
+        // to xform only the useful part of the image. Sub image could be reduced
+        // even further by taking into account dst_rect+ctm+clip
+        return fXformer->apply(image);
+    }
+
     bool skipXform(const SkBitmap& bitmap) {
         return (!bitmap.colorSpace() && fTargetCS->isSRGB()) ||
                (SkColorSpace::Equals(bitmap.colorSpace(), fTargetCS.get())) ||