Implement a resize image filter. This is needed for the "filterRes" feature in SVG filter effects, …

gm/resizeimagefilter.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 "SkColor.h"
+#include "SkResizeImageFilter.h"
+
+namespace skiagm {
+
+// Don't use SkBitmapSource here, since it will resize automatically by the CTM.
+// We want the resize image filter to take care of that, so this one simply returns the bitmap.
+
+class SimpleBitmapSource : public SkImageFilter {
+public:
+    SimpleBitmapSource(const SkBitmap& bitmap)
+      : INHERITED(0, 0),
+        fBitmap(bitmap) {
+    }
+
+    SimpleBitmapSource(SkFlattenableReadBuffer& buffer)
+      : INHERITED(0, buffer) {
+        fBitmap.unflatten(buffer);
+    }
+
+    virtual void flatten(SkFlattenableWriteBuffer& buffer) const SK_OVERRIDE {
+        this->INHERITED::flatten(buffer);
+        fBitmap.flatten(buffer);
+    }
+
+    virtual bool onFilterImage(Proxy* proxy, const SkBitmap&, const SkMatrix& matrix,
+                               SkBitmap* result, SkIPoint* offset) SK_OVERRIDE {
+        *result = fBitmap;
+        offset->fX = offset->fY = 0;
+        return true;
+    }
+
+    SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SimpleBitmapSource)
+
+private:
+    SkBitmap fBitmap;
+    typedef SkImageFilter INHERITED;
+};
+
+class ResizeGM : public GM {
+public:
+    ResizeGM() : fInitialized(false) {
+        this->setBGColor(0x00000000);
+    }
+
+protected:
+    virtual SkString onShortName() {
+        return SkString("resizeimagefilter");
+    }
+
+    void make_checkerboard(int width, int height) {
+        SkASSERT(width % 2 == 0);
+        SkASSERT(height % 2 == 0);
+        fCheckerboard.setConfig(SkBitmap::kARGB_8888_Config, width, height);
+        fCheckerboard.allocPixels();
+        SkAutoLockPixels lock(fCheckerboard);
+        for (int y = 0; y < height; y += 2) {
+            SkPMColor* s = fCheckerboard.getAddr32(0, y);
+            for (int x = 0; x < width; x += 2) {
+                *s++ = 0xFFFFFFFF;
+                *s++ = 0xFF000000;
+            }
+            s = fCheckerboard.getAddr32(0, y + 1);
+            for (int x = 0; x < width; x += 2) {
+                *s++ = 0xFF000000;
+                *s++ = 0xFFFFFFFF;
+            }
+        }
+    }
+
+    virtual SkISize onISize() {
+        return make_isize(400, 300);
+    }
+
+    virtual void onDraw(SkCanvas* canvas) {
+        if (!fInitialized) {
+            make_checkerboard(4, 4);
+            fInitialized = true;
+        }
+        canvas->clear(0x00000000);
+        SkPaint paint;
+        SkSize scale = SkSize::Make(SkIntToScalar(32), SkIntToScalar(32));
+        SkAutoTUnref<SkImageFilter> source(new SimpleBitmapSource(fCheckerboard));
+        SkAutoTUnref<SkImageFilter> noneResize(new SkResizeImageFilter(scale, SkPaint::kNone_FilterLevel, source.get()));
+        SkAutoTUnref<SkImageFilter> lowResize(new SkResizeImageFilter(scale, SkPaint::kLow_FilterLevel, source.get()));
+        SkAutoTUnref<SkImageFilter> mediumResize(new SkResizeImageFilter(scale, SkPaint::kMedium_FilterLevel, source.get()));
+        SkAutoTUnref<SkImageFilter> highResize(new SkResizeImageFilter(scale, SkPaint::kHigh_FilterLevel, source.get()));
+        paint.setFilterLevel(SkPaint::kNone_FilterLevel); // Outer paint does no filtering; leave it all for the filter
+
+        SkRect srcRect;
+        fCheckerboard.getBounds(&srcRect);
+
+        paint.setImageFilter(noneResize);
+        canvas->drawRect(srcRect, paint);
+
+        paint.setImageFilter(lowResize);
+        canvas->translate(SkIntToScalar(140), 0);
+        canvas->drawRect(srcRect, paint);
+
+        paint.setImageFilter(mediumResize);
+        canvas->translate(SkIntToScalar(140), 0);
+        canvas->drawRect(srcRect, paint);
+
+        paint.setImageFilter(highResize);
+        canvas->translate(SkIntToScalar(140), 0);
+        canvas->drawRect(srcRect, paint);
+    }
+
+private:
+    typedef GM INHERITED;
+    SkBitmap fCheckerboard;
+    bool fInitialized;
+};
+
+//////////////////////////////////////////////////////////////////////////////
+
+static GM* MyFactory(void*) { return new ResizeGM; }
+static GMRegistry reg(MyFactory);
+
+}