Image filters: implement offsets in GPU path.

gm/xfermodeimagefilter.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 "SkArithmeticMode.h"
+#include "SkOffsetImageFilter.h"
 #include "SkXfermodeImageFilter.h"
 #include "SkBitmapSource.h"
 
 #define WIDTH 600
 #define HEIGHT 600
 #define MARGIN 12
 
 namespace skiagm {
 
 class XfermodeImageFilterGM : public GM {
@@ skipping 41 matching lines @@
             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) {
+    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();
@@ skipping 36 matching lines @@
             { 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)));
+            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));
+        x += fBitmap.width() + MARGIN;
+        if (x + fBitmap.width() > WIDTH) {
+            x = 0;
+            y += fBitmap.height() + MARGIN;
+        }
+        // Test offsets on SrcMode (uses fixed-function blend)
+        SkAutoTUnref<SkImageFilter> foreground(SkNEW_ARGS(SkBitmapSource, (fBitmap)));
+        SkAutoTUnref<SkImageFilter> offsetForeground(SkNEW_ARGS(SkOffsetImageFilter,
+            (SkIntToScalar(4), SkIntToScalar(-4), foreground)));
+        SkAutoTUnref<SkImageFilter> offsetBackground(SkNEW_ARGS(SkOffsetImageFilter,
+            (SkIntToScalar(4), SkIntToScalar(4), background)));
+        mode.reset(SkXfermode::Create(SkXfermode::kSrcOver_Mode));
+        filter.reset(SkNEW_ARGS(SkXfermodeImageFilter,
+            (mode, offsetBackground, offsetForeground)));
+        paint.setImageFilter(filter);
+        canvas->save();
+        canvas->clipRect(SkRect::MakeXYWH(x, y,
+            SkIntToScalar(fBitmap.width() + 4), SkIntToScalar(fBitmap.height() + 4)));
+        canvas->drawPaint(paint);
+        canvas->restore();
+        x += fBitmap.width() + MARGIN;
+        if (x + fBitmap.width() > WIDTH) {
+            x = 0;
+            y += fBitmap.height() + MARGIN;
+        }
+        // Test offsets on Darken (uses shader blend)
+        mode.reset(SkXfermode::Create(SkXfermode::kDarken_Mode));
+        filter.reset(SkNEW_ARGS(SkXfermodeImageFilter, (mode, offsetBackground, offsetForeground)));
+        paint.setImageFilter(filter);
+        canvas->save();
+        canvas->clipRect(SkRect::MakeXYWH(x, y,
+            SkIntToScalar(fBitmap.width() + 4), SkIntToScalar(fBitmap.height() + 4)));
+        canvas->drawPaint(paint);
+        canvas->restore();
     }
 private:
     typedef GM INHERITED;
     SkBitmap fBitmap, fCheckerboard;
     bool fInitialized;
 };
 
 //////////////////////////////////////////////////////////////////////////////
 
 static GM* MyFactory(void*) { return new XfermodeImageFilterGM; }
 static GMRegistry reg(MyFactory);
 
 }