Implement SkLocalMatrixImageFilter.

At draw time, this filter simply concatenates the given matrix to the
CTM, and recurses on its input. The matrix is thus applied to any
upstream filter parameters and crop rects.

BUG=skia:

Review URL: https://codereview.chromium.org/1392833005

1 files changed, 103 insertions, 0 deletions

diff --git a/gm/localmatriximagefilter.cpp b/gm/localmatriximagefilter.cpp
new file mode 100644
index 0000000000..1bdc940d92
--- /dev/null
+++ b/gm/localmatriximagefilter.cpp
@@ -0,0 +1,103 @@
+/*
+ * 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; )
+