Alternate version of SkLocalMatrixImageFilter using an input.

gm/localmatriximagefilter.cpp

+/*
+ * Copyright 2015 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 "SkBlurImageFilter.h"
+#include "SkColorFilterImageFilter.h"
+#include "SkModeColorFilter.h"
+#include "SkMorphologyImageFilter.h"
+#include "SkOffsetImageFilter.h"
+#include "SkSurface.h"
+
+static SkImage* make_image(SkCanvas* rootCanvas) {
+    SkImageInfo info = SkImageInfo::MakeN32Premul(100, 100);
+    SkAutoTUnref<SkSurface> surface(rootCanvas->newSurface(info));
+    if (!surface) {
+        surface.reset(SkSurface::NewRaster(info));
+    }
+
+    SkPaint paint;
+    paint.setAntiAlias(true);
+    paint.setColor(SK_ColorRED);
+    surface->getCanvas()->drawCircle(50, 50, 50, paint);
+    return surface->newImageSnapshot();
+}
+
+typedef SkImageFilter* (*ImageFilterFactory)();
+
+// +[]{...} did not work on windows (VS)
+// (ImageFilterFactory)[]{...} did not work on linux (gcc)
+// hence this cast function
+template <typename T> ImageFilterFactory IFCCast(T arg) { return arg; }
+
+// Show the effect of localmatriximagefilter with various matrices, on various filters
+class LocalMatrixImageFilterGM : public skiagm::GM {
+public:
+    LocalMatrixImageFilterGM() {}
+
+protected:
+    SkString onShortName() override {
+        return SkString("localmatriximagefilter");
+    }
+
+    SkISize onISize() override {
+        return SkISize::Make(640, 640);
+    }
+
+    static void show_image(SkCanvas* canvas, SkImage* image, SkImageFilter* filter) {
+        SkPaint paint;
+        paint.setStyle(SkPaint::kStroke_Style);
+        SkRect r = SkRect::MakeIWH(image->width(), image->height()).makeOutset(SK_ScalarHalf,
+                                                                               SK_ScalarHalf);
+        canvas->drawRect(r, paint);
+
+        paint.setStyle(SkPaint::kFill_Style);
+        paint.setImageFilter(filter);
+        canvas->drawImage(image, 0, 0, &paint);
+    }
+
+    void onDraw(SkCanvas* canvas) override {
+        SkAutoTUnref<SkImage> image0(make_image(canvas));
+
+        const ImageFilterFactory factories[] = {
+            IFCCast([]{ return SkBlurImageFilter::Create(8, 8); }),
+            IFCCast([]{ return SkDilateImageFilter::Create(8, 8); }),
+            IFCCast([]{ return SkErodeImageFilter::Create(8, 8); }),
+            IFCCast([]{ return SkOffsetImageFilter::Create(8, 8); }),
+        };
+
+        const SkMatrix matrices[] = {
+            SkMatrix::MakeScale(SK_ScalarHalf, SK_ScalarHalf),
+            SkMatrix::MakeScale(2, 2),
+            SkMatrix::MakeTrans(10, 10)
+        };
+
+        const SkScalar spacer = image0->width() * 3.0f / 2;
+
+        canvas->translate(40, 40);
+        for (auto&& factory : factories) {
+            SkAutoTUnref<SkImageFilter> filter(factory());
+
+            canvas->save();
+            show_image(canvas, image0, filter);
+            for (const auto& matrix : matrices) {
+                SkAutoTUnref<SkImageFilter> localFilter(
+                    SkImageFilter::CreateLocalMatrixFilter(matrix, filter));
+                canvas->translate(spacer, 0);
+                show_image(canvas, image0, localFilter);
+            }
+            canvas->restore();
+            canvas->translate(0, spacer);
+        }
+    }
+
+private:
+    typedef GM INHERITED;
+};
+DEF_GM( return new LocalMatrixImageFilterGM; )
+