More general version of image filtering; reworked to be robust and easier to SSE

gm/scalebitmap.cpp

Index: gm/scalebitmap.cpp
diff --git a/gm/scalebitmap.cpp b/gm/scalebitmap.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..5d08ba85de299bf499b611d07053eda3c8c06b3a
--- /dev/null
+++ b/gm/scalebitmap.cpp
@@ -0,0 +1,114 @@
+/*
+ * Copyright 2013 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "gm.h"
+
+#include "SkImageDecoder.h"
+#include "SkStream.h"
+
+class ScaleBitmapGM : public skiagm::GM {
+    
+public:
+    
+    ScaleBitmapGM(const char filename[], float scale)
+        : fFilename(filename), fScale(scale)
+    {
+        this->setBGColor(0xFFDDDDDD);
+        fName.printf("scalebitmap_%s_%f", filename, scale);
+        
+        SkString path(skiagm::GM::gResourcePath);
+        path.append("/");
+        path.append(fFilename);
+
+        SkImageDecoder *codec = NULL;
+        SkFILEStream stream(path.c_str());
+        if (stream.isValid()) {
+            codec = SkImageDecoder::Factory(&stream);
+        }
+        if (codec) {
+            stream.rewind();
+            codec->decode(&stream, &fBM, SkBitmap::kARGB_8888_Config,
+                SkImageDecoder::kDecodePixels_Mode);
+            SkDELETE(codec);
+        } else {
+            fBM.setConfig(SkBitmap::kARGB_8888_Config, 1, 1);
+            fBM.allocPixels();
+            *(fBM.getAddr32(0,0)) = 0xFF0000FF; // red == bad
+        }
+        fSize = fBM.height();
+    }
+
+protected:
+    
+    
+    SkBitmap    fBM;
+    SkString    fName;
+    SkString    fFilename;
+    int         fSize;
+    float       fScale;
+    
+    
+    virtual SkString onShortName() SK_OVERRIDE {
+        return fName;
+    }
+
+    virtual SkISize onISize() SK_OVERRIDE {
+        return SkISize::Make(fBM.width() * fScale, fBM.height() * fScale);
+    }
+
+    virtual void onDraw(SkCanvas* canvas) SK_OVERRIDE {
+        SkBitmap dst;
+        dst.setConfig(SkBitmap::kARGB_8888_Config, fBM.width() * fScale, fBM.height() * fScale);
+        dst.allocPixels();
+        fBM.scale(&dst);
+        
+        canvas->drawBitmap(dst, 0, 0);
+    }
+
+private:
+    typedef skiagm::GM INHERITED;
+};
+
+class ScaleBitmapMipmapGM: public ScaleBitmapGM {
+    SkMatrix fMatrix;
+    
+public:
+    ScaleBitmapMipmapGM(const char filename[], float scale)
+        : INHERITED(filename, scale)
+    {
+        fName.printf("scalebitmap_mipmap_%s_%f", filename, scale);
+        fBM.buildMipMap();
+        fMatrix.setScale(scale, scale);
+    }
+protected:
+    virtual void onDraw(SkCanvas *canvas) SK_OVERRIDE {
+        SkPaint paint;
+        
+        paint.setFilterBitmap(true);
+        canvas->drawBitmapMatrix(fBM, fMatrix, &paint);
+    }
+private:
+     typedef ScaleBitmapGM INHERITED;  
+};
+
+//////////////////////////////////////////////////////////////////////////////
+
+DEF_GM( return new ScaleBitmapGM("mandrill_128.png", 2); )
+DEF_GM( return new ScaleBitmapGM("mandrill_64.png", 4); )
+DEF_GM( return new ScaleBitmapGM("mandrill_32.png", 8); )
+DEF_GM( return new ScaleBitmapGM("mandrill_16.png", 16); )
+
+DEF_GM( return new ScaleBitmapGM("nature.jpg", 0.5f); )
+DEF_GM( return new ScaleBitmapGM("nature.jpg", 0.25f); )
+DEF_GM( return new ScaleBitmapGM("nature.jpg", 0.125f); )
+DEF_GM( return new ScaleBitmapGM("nature.jpg", 0.0625f); )
+
+DEF_GM( return new ScaleBitmapMipmapGM("nature.jpg", 0.5f); )
+DEF_GM( return new ScaleBitmapMipmapGM("nature.jpg", 0.25f); )
+DEF_GM( return new ScaleBitmapMipmapGM("nature.jpg", 0.125f); )
+DEF_GM( return new ScaleBitmapMipmapGM("nature.jpg", 0.0625f); )
+