Add back overdraw visualization for Skia BenchmarkingCanvas

skia/ext/benchmarking_canvas.cc

Index: skia/ext/benchmarking_canvas.cc
diff --git a/skia/ext/benchmarking_canvas.cc b/skia/ext/benchmarking_canvas.cc
index 2af0d1a956ae58292ffe33461c97c39cdde30afd..b2c17288282de130441dd1b17b21e326d08aa681 100644
--- a/skia/ext/benchmarking_canvas.cc
+++ b/skia/ext/benchmarking_canvas.cc
@@ -6,10 +6,13 @@
 #include "base/strings/stringprintf.h"
 #include "base/time/time.h"
 #include "skia/ext/benchmarking_canvas.h"
+#include "skia/ext/refptr.h"
 #include "third_party/skia/include/core/SkColorFilter.h"
+#include "third_party/skia/include/core/SkDrawFilter.h"
 #include "third_party/skia/include/core/SkImageFilter.h"
 #include "third_party/skia/include/core/SkPicture.h"
 #include "third_party/skia/include/core/SkRegion.h"
+#include "third_party/skia/include/core/SkString.h"
 #include "third_party/skia/include/core/SkTextBlob.h"
 #include "third_party/skia/include/core/SkXfermode.h"
 
@@ -406,6 +409,54 @@ scoped_ptr<base::Value> AsListValue(const T array[], size_t count) {
   return val.Pass();
 }
 
+class OverdrawXfermode : public SkXfermode {
+public:
+  SkPMColor xferColor(SkPMColor src, SkPMColor dst) const override {
+    // This table encodes the color progression of the overdraw visualization
+    static const SkPMColor gTable[] = {
+      SkPackARGB32(0x00, 0x00, 0x00, 0x00),
+      SkPackARGB32(0xFF, 128, 158, 255),
+      SkPackARGB32(0xFF, 170, 185, 212),
+      SkPackARGB32(0xFF, 213, 195, 170),
+      SkPackARGB32(0xFF, 255, 192, 127),
+      SkPackARGB32(0xFF, 255, 185, 85),
+      SkPackARGB32(0xFF, 255, 165, 42),
+      SkPackARGB32(0xFF, 255, 135, 0),
+      SkPackARGB32(0xFF, 255,  95, 0),
+      SkPackARGB32(0xFF, 255,  50, 0),
+      SkPackARGB32(0xFF, 255,  0, 0)
+    };
+

[robertphillips, 2015/03/10 17:23:41]

// TODO: seems like there should be a far faster way to do this  

if (dst.blue / 42 > 0) {
    i = 7 - dst.blue/42;
} else if (dst.green / 45 >0) {
    i = 10 - dst.green / 42;
} else if (dst.red > 128) {
    i = 10;
} else {
    i = 0;
}
SkASSERT(gTable[i] == dst);

?

[f(malita), 2015/03/10 22:28:32]

Refactored to use interpolation instead of table lookup.

+    for (size_t i = 0; i < SK_ARRAY_COUNT(gTable) - 1; ++i) {
+      if (gTable[i] == dst) {
+        return gTable[i + 1];
+      }
+    }
+
+    return gTable[SK_ARRAY_COUNT(gTable) - 1];
+  }
+
+  Factory getFactory() const override { return NULL; }
+#ifndef SK_IGNORE_TO_STRING
+  void toString(SkString* str) const override { str->set("OverdrawXfermode"); }
+#endif

[robertphillips, 2015/03/10 17:23:41]

private:
    typedef SkXfermode INHERITED;

?

[f(malita), 2015/03/10 22:28:32]

Done.

+};
+
+class OverdrawFilter : public SkDrawFilter {
+public:
+  OverdrawFilter() { fXferMode = skia::AdoptRef(new OverdrawXfermode); }
+
+  bool filter(SkPaint* p, Type) override {
+    p->setXfermode(fXferMode.get());
+    return true;
+  }
+
+private:
+  typedef SkDrawFilter INHERITED;
+
+  skia::RefPtr<SkXfermode> fXferMode;
+};
+
 } // namespace
 
 namespace skia {
@@ -456,6 +507,11 @@ BenchmarkingCanvas::BenchmarkingCanvas(SkCanvas* canvas, unsigned flags)
                 canvas->imageInfo().height())
     , flags_(flags) {
   addCanvas(canvas);
+
+  if (flags & kOverdrawVisualization_Flag) {
+    skia::RefPtr<SkDrawFilter> draw_filter = skia::AdoptRef(new OverdrawFilter);
+    this->setDrawFilter(draw_filter.get());
+  }
 }
 
 BenchmarkingCanvas::~BenchmarkingCanvas() {