SkPDF: properly dedup bitmaps in shaders

BUG=skia:5161
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1848383002

Review URL: https://codereview.chromium.org/1848383002

3 files changed, 41 insertions, 6 deletions

diff --git a/gm/subsetshader.cpp b/gm/subsetshader.cpp
new file mode 100644
index 0000000000..c4ef5f7a77
--- /dev/null
+++ b/gm/subsetshader.cpp
@@ -0,0 +1,35 @@
+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "Resources.h"
+#include "SkBitmap.h"
+#include "gm.h"
+
+DEF_SIMPLE_GM(bitmap_subset_shader, canvas, 256, 256) {
+    canvas->clear(SK_ColorWHITE);
+
+    SkBitmap source;
+    if (!GetResourceAsBitmap("color_wheel.png", &source)) {
+        return;
+    }
+    SkIRect left = SkIRect::MakeWH(source.width()/2, source.height());
+    SkIRect right = SkIRect::MakeXYWH(source.width()/2, 0,
+                                      source.width()/2, source.height());
+    SkBitmap leftBitmap, rightBitmap;
+    source.extractSubset(&leftBitmap, left);
+    source.extractSubset(&rightBitmap, right);
+
+    SkMatrix matrix;
+    matrix.setScale(0.75f, 0.75f);
+    matrix.preRotate(30.0f);
+    SkShader::TileMode tm = SkShader::kRepeat_TileMode;
+    SkPaint paint;
+    paint.setShader(SkShader::MakeBitmapShader(leftBitmap, tm, tm, &matrix));
+    canvas->drawRect(SkRect::MakeWH(256.0f, 128.0f), paint);
+    paint.setShader(SkShader::MakeBitmapShader(rightBitmap, tm, tm, &matrix));
+    canvas->drawRect(SkRect::MakeXYWH(0, 128.0f, 256.0f, 128.0f), paint);
+}
diff --git a/src/pdf/SkBitmapKey.h b/src/pdf/SkBitmapKey.h
index 4723debac2..53d4d64f32 100644
--- a/src/pdf/SkBitmapKey.h
+++ b/src/pdf/SkBitmapKey.h
@@ -25,6 +25,7 @@ public:
         return fID == rhs.fID && fSubset == rhs.fSubset;
     }
     bool operator!=(const SkBitmapKey& rhs) const { return !(*this == rhs); }
+    uint32_t id() const { return fID; }
 
 private:
     SkIRect fSubset;
diff --git a/src/pdf/SkPDFShader.cpp b/src/pdf/SkPDFShader.cpp
index abcae7be12..c30d8a4281 100644
--- a/src/pdf/SkPDFShader.cpp
+++ b/src/pdf/SkPDFShader.cpp
@@ -430,7 +430,7 @@ public:
     SkIRect fBBox;
 
     SkBitmap fImage;
-    uint32_t fPixelGeneration;
+    SkBitmapKey fBitmapKey;
     SkShader::TileMode fImageTileModes[2];
 
     State(SkShader* shader, const SkMatrix& canvasTransform,
@@ -1052,8 +1052,8 @@ bool SkPDFShader::State::operator==(const SkPDFShader::State& b) const {
     }
 
     if (fType == SkShader::kNone_GradientType) {
-        if (fPixelGeneration != b.fPixelGeneration ||
-                fPixelGeneration == 0 ||
+        if (fBitmapKey != b.fBitmapKey ||
+                fBitmapKey.id() == 0 ||
                 fImageTileModes[0] != b.fImageTileModes[0] ||
                 fImageTileModes[1] != b.fImageTileModes[1]) {
             return false;
@@ -1099,8 +1099,7 @@ bool SkPDFShader::State::operator==(const SkPDFShader::State& b) const {
 SkPDFShader::State::State(SkShader* shader, const SkMatrix& canvasTransform,
                           const SkIRect& bbox, SkScalar rasterScale)
         : fCanvasTransform(canvasTransform),
-          fBBox(bbox),
-          fPixelGeneration(0) {
+          fBBox(bbox) {
     fInfo.fColorCount = 0;
     fInfo.fColors = nullptr;
     fInfo.fColorOffsets = nullptr;
@@ -1154,7 +1153,7 @@ SkPDFShader::State::State(SkShader* shader, const SkMatrix& canvasTransform,
             fShaderTransform.setTranslate(shaderRect.x(), shaderRect.y());
             fShaderTransform.preScale(1 / scale.width(), 1 / scale.height());
         }
-        fPixelGeneration = fImage.getGenerationID();
+        fBitmapKey = SkBitmapKey(fImage);
     } else {
         AllocateGradientInfoStorage();
         shader->asAGradient(&fInfo);