Add luminance mask transfer modes.

gm/lumamode.cpp

+/*
+ * 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 "SkCanvas.h"
+#include "SkLumaXfermode.h"
+
+static void show_scene(SkCanvas* canvas, SkXfermode* mode, const char* label) {
+    SkPaint paint;
+    paint.setAntiAlias(true);
+    SkRect r, c, bounds = { 10, 10, 110, 110 };
+
+    c = bounds;
+    c.fRight = bounds.centerX();
+    r = bounds;
+    r.fBottom = bounds.centerY();
+    canvas->drawRect(r, paint);
+
+    SkScalar tw = paint.measureText(label, strlen(label));
+    canvas->drawText(label, strlen(label), bounds.centerX() - tw / 2,
+                     bounds.bottom() + 15, paint);
+
+    canvas->saveLayer(&bounds, NULL);
+
+    r = bounds;
+    r.inset(20, 0);
+    paint.setColor(0x80FFFF00);
+    canvas->drawOval(r, paint);
+    canvas->save();
+    canvas->clipRect(c);
+    paint.setColor(0xFFFFFF00);
+    canvas->drawOval(r, paint);
+    canvas->restore();
+
+    SkPaint xferPaint;
+    xferPaint.setXfermode(mode);
+    canvas->saveLayer(&bounds, &xferPaint);
+
+    r = bounds;
+    r.inset(0, 20);
+    paint.setColor(0x8080FF00);
+    canvas->drawOval(r, paint);
+    canvas->save();
+    canvas->clipRect(c);
+    paint.setColor(0xFF80FF00);
+    canvas->drawOval(r, paint);
+    canvas->restore();
+
+    canvas->restore();
+    canvas->restore();
+}
+
+class LumaXfermodeGM : public skiagm::GM {
+public:
+    LumaXfermodeGM() {}
+
+protected:
+    virtual SkString onShortName() SK_OVERRIDE {
+        return SkString("lumamode");
+    }
+
+    virtual SkISize onISize() SK_OVERRIDE {
+        return SkISize::Make(450, 140);
+    }
+
+    virtual void onDraw(SkCanvas* canvas) SK_OVERRIDE {
+        show_scene(canvas, NULL, "SrcOver");
+        canvas->translate(150, 0);
+        SkAutoTUnref<SkXfermode> src_in(SkLumaMaskXfermode::Create(SkXfermode::kSrcIn_Mode));
+        show_scene(canvas, src_in.get(), "SrcInLuma");
+        canvas->translate(150, 0);
+        SkAutoTUnref<SkXfermode> dst_in(SkLumaMaskXfermode::Create(SkXfermode::kDstIn_Mode));
+        show_scene(canvas, dst_in.get(), "DstInLuma");
+    }
+
+private:
+    typedef skiagm::GM INHERITED;
+};
+
+//////////////////////////////////////////////////////////////////////////////
+
+DEF_GM( return SkNEW(LumaXfermodeGM); )