Avoid extra bitmap copies in SkColorSpaceXformCanvas

Before:
ColorCanvasDrawBitmap_sRGB_to_sRGB     5.09us
ColorCanvasDrawBitmap_AdobeRGB_to_sRGB 50.7us

After:
ColorCanvasDrawBitmap_sRGB_to_sRGB     2.43us
ColorCanvasDrawBitmap_AdobeRGB_to_sRGB 37.1us

BUG=skia:6456
Change-Id: Ie382936c36fd347b59485882cf8f27f315a5d35f

Change-Id: Ie382936c36fd347b59485882cf8f27f315a5d35f
Reviewed-on: https://skia-review.googlesource.com/11040
Reviewed-by: Mike Klein <mtklein@chromium.org>
Commit-Queue: Matt Sarett <msarett@google.com>

1 files changed, 57 insertions, 0 deletions

diff --git a/bench/ColorCanvasDrawBitmapBench.cpp b/bench/ColorCanvasDrawBitmapBench.cpp
new file mode 100644
index 0000000000..de13ba2afc
--- /dev/null
+++ b/bench/ColorCanvasDrawBitmapBench.cpp
@@ -0,0 +1,57 @@
+/*
+* Copyright 2017 Google Inc.
+*
+* Use of this source code is governed by a BSD-style license that can be
+* found in the LICENSE file.
+*/
+
+#include "Benchmark.h"
+#include "SkCanvas.h"
+#include "SkColorSpaceXformCanvas.h"
+#include "SkString.h"
+
+class ColorCanvasDrawBitmap : public Benchmark {
+public:
+    ColorCanvasDrawBitmap(sk_sp<SkColorSpace> src, sk_sp<SkColorSpace> dst, const char* name)
+        : fDst(dst)
+        , fName(SkStringPrintf("ColorCanvasDrawBitmap_%s", name))
+    {
+        fBitmap.allocPixels(SkImageInfo::MakeN32(100, 100, kOpaque_SkAlphaType, src));
+        fBitmap.eraseColor(SK_ColorBLUE);
+    }
+
+    const char* onGetName() override {
+        return fName.c_str();
+    }
+
+    SkIPoint onGetSize() override {
+        return SkIPoint::Make(100, 100);
+    }
+
+    bool isSuitableFor(Backend backend) override {
+        return kRaster_Backend == backend || kGPU_Backend == backend;
+    }
+
+    void onDraw(int n, SkCanvas* canvas) override {
+        // This simulates an Android app that draws bitmaps to a software canvas.
+        // Chrome and the Android framework both use SkImages exclusively.
+        std::unique_ptr<SkCanvas> colorCanvas = SkCreateColorSpaceXformCanvas(canvas, fDst);
+        for (int i = 0; i < n; i++) {
+            colorCanvas->drawBitmap(fBitmap, 0, 0, nullptr);
+        }
+    }
+
+private:
+    sk_sp<SkColorSpace> fDst;
+    SkString            fName;
+    SkBitmap            fBitmap;
+
+    typedef Benchmark INHERITED;
+};
+
+DEF_BENCH(return new ColorCanvasDrawBitmap(nullptr, SkColorSpace::MakeSRGB(), "null_to_sRGB");)
+DEF_BENCH(return new ColorCanvasDrawBitmap(SkColorSpace::MakeSRGB(), SkColorSpace::MakeSRGB(),
+        "sRGB_to_sRGB");)
+DEF_BENCH(return new ColorCanvasDrawBitmap(
+        SkColorSpace::MakeRGB(SkColorSpace::kSRGB_RenderTargetGamma, SkColorSpace::kAdobeRGB_Gamut),
+        SkColorSpace::MakeSRGB(), "AdobeRGB_to_sRGB");)