Switch SkMagnifierImageFilter over to new onFilterImage interface

gm/imagemagnifier.cpp

Index: gm/imagemagnifier.cpp
diff --git a/gm/imagemagnifier.cpp b/gm/imagemagnifier.cpp
index 5697aa2480e06ced45393e79a63f3f52016d6dd3..a012a9e39693095a3ea6e1b6606cfbdb1d0e2a1c 100644
--- a/gm/imagemagnifier.cpp
+++ b/gm/imagemagnifier.cpp
@@ -6,8 +6,10 @@
  */
 
 #include "gm.h"
+#include "SkImageSource.h"
 #include "SkMagnifierImageFilter.h"
 #include "SkRandom.h"
+#include "SkSurface.h"
 
 #define WIDTH 500
 #define HEIGHT 500
@@ -36,3 +38,51 @@ DEF_SIMPLE_GM_BG(imagemagnifier, canvas, WIDTH, HEIGHT, SK_ColorBLACK) {
         }
         canvas->restore();
 }
+
+////////////////////////////////////////////////////////////////////////////////
+#define WIDTH_HEIGHT 256
+
+static sk_sp<SkImage> make_img() {
+    const SkImageInfo info = SkImageInfo::MakeN32Premul(WIDTH_HEIGHT, WIDTH_HEIGHT);
+
+    sk_sp<SkSurface> surf(SkSurface::MakeRaster(info));
+
+    SkCanvas* canvas = surf->getCanvas();
+
+    canvas->clear(0x0);
+
+    SkPaint paint;
+    paint.setColor(SK_ColorBLUE);
+
+    for (float pos = 0; pos < WIDTH_HEIGHT; pos += 16) {
+        canvas->drawLine(0, pos, SkIntToScalar(WIDTH_HEIGHT), pos, paint);
+        canvas->drawLine(pos, 0, pos, SkIntToScalar(WIDTH_HEIGHT), paint);
+    }
+
+    return surf->makeImageSnapshot();
+}
+
+DEF_SIMPLE_GM_BG(imagemagnifier_cropped, canvas, WIDTH_HEIGHT, WIDTH_HEIGHT, SK_ColorBLACK) {
+
+    sk_sp<SkImage> image(make_img());
+
+    sk_sp<SkImageFilter> imageSource(SkImageSource::Make(std::move(image)));
+
+    SkRect srcRect = SkRect::MakeWH(SkIntToScalar(WIDTH_HEIGHT-32),
+                                    SkIntToScalar(WIDTH_HEIGHT-32));
+    srcRect.inset(64.0f, 64.0f);
+
+    static const SkScalar kInset = 64.0f;
+
+    // Crop out a 16 pixel ring around the result
+    const SkRect rect = SkRect::MakeXYWH(16, 16, WIDTH_HEIGHT-32, WIDTH_HEIGHT-32);
+    SkImageFilter::CropRect cropRect(rect);
+
+    SkPaint filterPaint;
+    filterPaint.setImageFilter(SkMagnifierImageFilter::Make(srcRect, kInset,
+                                                            std::move(imageSource),
+                                                            &cropRect));
+
+    canvas->saveLayer(nullptr, &filterPaint);
+    canvas->restore();
+}