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 {
+
+class ResizeGM : public GM {
+public:
+    ResizeGM() {
+        this->setBGColor(0x00000000);
+    }
+
+protected:
+    virtual SkString onShortName() {
+        return SkString("resizeimagefilter");
+    }
+
+    void draw(SkCanvas* canvas,
+              const SkRect& rect,
+              const SkSize& deviceSize,
+              SkPaint::FilterLevel filterLevel) {
+        SkRect dstRect;
+        canvas->getTotalMatrix().mapRect(&dstRect, rect);
+        canvas->save();
+        SkScalar deviceScaleX = SkScalarDiv(deviceSize.width(), dstRect.width());
+        SkScalar deviceScaleY = SkScalarDiv(deviceSize.height(), dstRect.height());
+        canvas->translate(rect.x(), rect.y());
+        canvas->scale(deviceScaleX, deviceScaleY);
+        canvas->translate(-rect.x(), -rect.y());
+        SkAutoTUnref<SkImageFilter> imageFilter(
+            new SkResizeImageFilter(SkScalarInvert(deviceScaleX),
+                                    SkScalarInvert(deviceScaleY),
+                                    filterLevel));
+        SkPaint filteredPaint;
+        filteredPaint.setImageFilter(imageFilter.get());
+        canvas->saveLayer(&rect, &filteredPaint);
+        SkPaint paint;
+        paint.setColor(0xFF00FF00);
+        SkRect ovalRect = rect;
+        ovalRect.inset(SkIntToScalar(4), SkIntToScalar(4));
+        canvas->drawOval(ovalRect, paint);
+        canvas->restore(); // for saveLayer
+        canvas->restore();
+    }
+
+    virtual SkISize onISize() {
+        return make_isize(420, 100);
+    }
+
+    virtual void onDraw(SkCanvas* canvas) {
+        canvas->clear(0x00000000);
+
+        SkRect srcRect = SkRect::MakeWH(96, 96);
+
+        SkSize deviceSize = SkSize::Make(16, 16);
+        draw(canvas,
+             srcRect,
+             deviceSize,
+             SkPaint::kNone_FilterLevel);
+
+        canvas->translate(srcRect.width() + SkIntToScalar(10), 0);
+        draw(canvas,
+             srcRect,
+             deviceSize,
+             SkPaint::kLow_FilterLevel);
+
+        canvas->translate(srcRect.width() + SkIntToScalar(10), 0);
+        draw(canvas,
+             srcRect,
+             deviceSize,
+             SkPaint::kMedium_FilterLevel);
+
+        canvas->translate(srcRect.width() + SkIntToScalar(10), 0);
+        draw(canvas,
+             srcRect,
+             deviceSize,
+             SkPaint::kHigh_FilterLevel);
+    }
+
+private:
+    typedef GM INHERITED;
+};
+
+//////////////////////////////////////////////////////////////////////////////
+
+static GM* MyFactory(void*) { return new ResizeGM; }
+static GMRegistry reg(MyFactory);
+
+}