SkPDF: properly dedup bitmaps in shaders

gm/subsetshader.cpp

Index: gm/subsetshader.cpp
diff --git a/gm/subsetshader.cpp b/gm/subsetshader.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..c4ef5f7a774f7b1a5476ec9d23c1d00e83987d19
--- /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);
+}