Implement SkXfermode image filter

gm/xfermodeimagefilter.cpp

Index: gm/xfermodeimagefilter.cpp
diff --git a/gm/xfermodeimagefilter.cpp b/gm/xfermodeimagefilter.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..a6d395e658a3044c8d8cf3e2ed5037a165705892
--- /dev/null
+++ b/gm/xfermodeimagefilter.cpp
@@ -0,0 +1,163 @@
+/*
+ * 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 "SkArithmeticMode.h"
+#include "SkXfermodeImageFilter.h"
+#include "SkBitmapSource.h"
+
+#define WIDTH 600
+#define HEIGHT 600
+#define MARGIN 12
+
+namespace skiagm {
+
+class XfermodeImageFilterGM : public GM {
+public:
+    XfermodeImageFilterGM() : fInitialized(false) {
+        this->setBGColor(0xFF000000);
+    }
+
+protected:
+    virtual SkString onShortName() {
+        return SkString("xfermodeimagefilter");
+    }
+
+    void make_bitmap() {
+        fBitmap.setConfig(SkBitmap::kARGB_8888_Config, 80, 80);
+        fBitmap.allocPixels();
+        SkDevice device(fBitmap);
+        SkCanvas canvas(&device);
+        canvas.clear(0x00000000);
+        SkPaint paint;
+        paint.setAntiAlias(true);
+        paint.setColor(0xD000D000);
+        paint.setTextSize(SkIntToScalar(96));
+        const char* str = "e";
+        canvas.drawText(str, strlen(str), SkIntToScalar(15), SkIntToScalar(65), paint);
+    }
+
+    void make_checkerboard() {
+        fCheckerboard.setConfig(SkBitmap::kARGB_8888_Config, 80, 80);
+        fCheckerboard.allocPixels();
+        SkDevice device(fCheckerboard);
+        SkCanvas canvas(&device);
+        canvas.clear(0x00000000);
+        SkPaint darkPaint;
+        darkPaint.setColor(0xFF404040);
+        SkPaint lightPaint;
+        lightPaint.setColor(0xFFA0A0A0);
+        for (int y = 0; y < 80; y += 16) {
+          for (int x = 0; x < 80; x += 16) {
+            canvas.save();
+            canvas.translate(SkIntToScalar(x), SkIntToScalar(y));
+            canvas.drawRect(SkRect::MakeXYWH(0, 0, 8, 8), darkPaint);
+            canvas.drawRect(SkRect::MakeXYWH(8, 0, 8, 8), lightPaint);
+            canvas.drawRect(SkRect::MakeXYWH(0, 8, 8, 8), lightPaint);
+            canvas.drawRect(SkRect::MakeXYWH(8, 8, 8, 8), darkPaint);
+            canvas.restore();
+          }
+        }
+    }
+
+    virtual SkISize onISize() {
+        return make_isize(WIDTH, HEIGHT);
+    }
+
+    void drawClippedBitmap(SkCanvas* canvas, const SkBitmap& bitmap, const SkPaint& paint, SkScalar x, SkScalar y) {
+        canvas->save();
+        canvas->clipRect(SkRect::MakeXYWH(x, y,
+            SkIntToScalar(bitmap.width()), SkIntToScalar(bitmap.height())));
+        canvas->drawBitmap(bitmap, x, y, &paint);
+        canvas->restore();
+    }
+
+    virtual void onDraw(SkCanvas* canvas) {
+        if (!fInitialized) {
+            make_bitmap();
+            make_checkerboard();
+            fInitialized = true;
+        }
+        canvas->clear(0x00000000);
+        SkPaint paint;
+
+        const struct {
+            SkXfermode::Mode  fMode;
+            const char*         fLabel;
+        } gModes[] = {
+            { SkXfermode::kClear_Mode,    "Clear"     },
+            { SkXfermode::kSrc_Mode,      "Src"       },
+            { SkXfermode::kDst_Mode,      "Dst"       },
+            { SkXfermode::kSrcOver_Mode,  "SrcOver"   },
+            { SkXfermode::kDstOver_Mode,  "DstOver"   },
+            { SkXfermode::kSrcIn_Mode,    "SrcIn"     },
+            { SkXfermode::kDstIn_Mode,    "DstIn"     },
+            { SkXfermode::kSrcOut_Mode,   "SrcOut"    },
+            { SkXfermode::kDstOut_Mode,   "DstOut"    },
+            { SkXfermode::kSrcATop_Mode,  "SrcATop"   },
+            { SkXfermode::kDstATop_Mode,  "DstATop"   },
+            { SkXfermode::kXor_Mode,      "Xor"       },
+
+            { SkXfermode::kPlus_Mode,         "Plus"          },
+            { SkXfermode::kModulate_Mode,     "Modulate"      },
+            { SkXfermode::kScreen_Mode,       "Screen"        },
+            { SkXfermode::kOverlay_Mode,      "Overlay"       },
+            { SkXfermode::kDarken_Mode,       "Darken"        },
+            { SkXfermode::kLighten_Mode,      "Lighten"       },
+            { SkXfermode::kColorDodge_Mode,   "ColorDodge"    },
+            { SkXfermode::kColorBurn_Mode,    "ColorBurn"     },
+            { SkXfermode::kHardLight_Mode,    "HardLight"     },
+            { SkXfermode::kSoftLight_Mode,    "SoftLight"     },
+            { SkXfermode::kDifference_Mode,   "Difference"    },
+            { SkXfermode::kExclusion_Mode,    "Exclusion"     },
+            { SkXfermode::kMultiply_Mode,     "Multiply"      },
+            { SkXfermode::kHue_Mode,          "Hue"           },
+            { SkXfermode::kSaturation_Mode,   "Saturation"    },
+            { SkXfermode::kColor_Mode,        "Color"         },
+            { SkXfermode::kLuminosity_Mode,   "Luminosity"    },
+        };
+
+        int x = 0, y = 0;
+        SkAutoTUnref<SkImageFilter> background(SkNEW_ARGS(SkBitmapSource, (fCheckerboard)));
+        for (size_t i = 0; i < SK_ARRAY_COUNT(gModes); i++) {
+            SkAutoTUnref<SkXfermode> mode(SkXfermode::Create(gModes[i].fMode));
+            SkAutoTUnref<SkImageFilter> filter(SkNEW_ARGS(SkXfermodeImageFilter, (mode, background)));
+            paint.setImageFilter(filter);
+            drawClippedBitmap(canvas, fBitmap, paint, SkIntToScalar(x), SkIntToScalar(y));
+            x += fBitmap.width() + MARGIN;
+            if (x + fBitmap.width() > WIDTH) {
+                x = 0;
+                y += fBitmap.height() + MARGIN;
+            }
+        }
+        // Test arithmetic mode as image filter
+        SkAutoTUnref<SkXfermode> mode(SkArithmeticMode::Create(0, SK_Scalar1, SK_Scalar1, 0));
+        SkAutoTUnref<SkImageFilter> filter(SkNEW_ARGS(SkXfermodeImageFilter, (mode, background)));
+        paint.setImageFilter(filter);
+        drawClippedBitmap(canvas, fBitmap, paint, SkIntToScalar(x), SkIntToScalar(y));
+        x += fBitmap.width() + MARGIN;
+        if (x + fBitmap.width() > WIDTH) {
+            x = 0;
+            y += fBitmap.height() + MARGIN;
+        }
+        // Test NULL mode
+        filter.reset(SkNEW_ARGS(SkXfermodeImageFilter, (NULL, background)));
+        paint.setImageFilter(filter);
+        drawClippedBitmap(canvas, fBitmap, paint, SkIntToScalar(x), SkIntToScalar(y));
+    }
+private:
+    typedef GM INHERITED;
+    SkBitmap fBitmap, fCheckerboard;
+    bool fInitialized;
+};
+
+//////////////////////////////////////////////////////////////////////////////
+
+static GM* MyFactory(void*) { return new XfermodeImageFilterGM; }
+static GMRegistry reg(MyFactory);
+
+}