Implement SkXfermode image filter

gm/arithmode.cpp

 /*
  * Copyright 2011 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 "SkColorPriv.h"
 #include "SkShader.h"
 
 #include "SkArithmeticMode.h"
+#include "SkBitmapSource.h"
 #include "SkGradientShader.h"
+#include "SkXfermodeImageFilter.h"
 #define WW  100
 #define HH  32
 
 static SkBitmap make_bm() {
     SkBitmap bm;
     bm.setConfig(SkBitmap::kARGB_8888_Config, WW, HH);
     bm.allocPixels();
     bm.eraseColor(SK_ColorTRANSPARENT);
     return bm;
 }
@@ skipping 81 matching lines @@
             SkScalar x = 0;
             canvas->drawBitmap(src, x, y, NULL);
             x += gap;
             canvas->drawBitmap(dst, x, y, NULL);
             x += gap;
             SkRect rect = SkRect::MakeXYWH(x, y, SkIntToScalar(WW), SkIntToScalar(HH));
             canvas->saveLayer(&rect, NULL);
             canvas->drawBitmap(dst, x, y, NULL);
             SkXfermode* xfer = SkArithmeticMode::Create(k[0], k[1], k[2], k[3]);
             SkPaint paint;
-            paint.setXfermode(xfer)->unref();
+            if ((k - K) % 2 != 0) {
+                // Test out an arithmode filter created as an xfermode image filter
+                SkAutoTUnref<SkImageFilter> background(new SkBitmapSource(dst));
+                SkXfermode* xfer = SkArithmeticMode::Create(0, one, one, 0);

[reed1, 2013/05/30 20:42:44]

I think this xfer leaks, and it makes us leak the outer-xfer as well.

[Stephen White, 2013/05/30 20:50:26]

Good point. This whole whole section never gets exercised, actually, since k - K
modulus 2 is always zero. Doh! So much for being clever.

I'm going to add a new case to the xfermodeimagefilter GM instead, which has no
baselines yet so it won't turn the bots red.

+                SkAutoTUnref<SkImageFilter> filter(new SkXfermodeImageFilter(xfer, background));
+                paint.setImageFilter(filter);
+            } else {
+                paint.setXfermode(xfer)->unref();
+            }
             canvas->drawBitmap(src, x, y, &paint);
             canvas->restore();
             x += gap;
             show_k_text(canvas, x, y, k);
             k += 4;
             y += SkIntToScalar(src.height() + 12);
         }
     }
 
 private:
     typedef GM INHERITED;
 };
 
 ///////////////////////////////////////////////////////////////////////////////
 
 static skiagm::GM* MyFactory(void*) { return new ArithmodeGM; }
 static skiagm::GMRegistry reg(MyFactory);