Switch AlphaThresholdFilter over to new onFilterImage interface

gm/imagealphathreshold.cpp

Index: gm/imagealphathreshold.cpp
diff --git a/gm/imagealphathreshold.cpp b/gm/imagealphathreshold.cpp
index fdd93bd2105cc1ffa5a02e2fc455be26e4e90ed5..2b65202c1067856228984d1507203aca5f97c344 100644
--- a/gm/imagealphathreshold.cpp
+++ b/gm/imagealphathreshold.cpp
@@ -27,7 +27,7 @@ void draw_rects(SkCanvas* canvas) {
     canvas->drawRect(SkRect::MakeXYWH(WIDTH / 2, HEIGHT / 2, WIDTH / 2, HEIGHT / 2), rectPaint);
 }
 
-SkPaint create_filter_paint() {
+SkPaint create_filter_paint(SkImageFilter::CropRect* cropRect = nullptr) {
     SkIRect rects[2];
     rects[0] = SkIRect::MakeXYWH(0, 150, WIDTH, HEIGHT - 300);
     rects[1] = SkIRect::MakeXYWH(150, 0, WIDTH - 300, HEIGHT);
@@ -35,7 +35,7 @@ SkPaint create_filter_paint() {
     region.setRects(rects, 2);
 
     SkPaint paint;
-    paint.setImageFilter(SkAlphaThresholdFilter::Make(region, 0.2f, 0.7f, nullptr));
+    paint.setImageFilter(SkAlphaThresholdFilter::Make(region, 0.2f, 0.7f, nullptr, cropRect));
     return paint;
 }
 
@@ -45,13 +45,17 @@ namespace skiagm {
 
 class ImageAlphaThresholdGM : public GM {
 public:
-    ImageAlphaThresholdGM() {
+    ImageAlphaThresholdGM(bool useCropRect) : fUseCropRect(true) { 
         this->setBGColor(0xFFFFFFFF);
     }
 
 protected:
 
     SkString onShortName() override {
+        if (fUseCropRect) {
+            return SkString("imagealphathreshold_crop");
+        }
+
         return SkString("imagealphathreshold");
     }
 
@@ -67,7 +71,10 @@ protected:
 
         canvas->concat(matrix);
 
-        SkPaint paint = create_filter_paint();
+        SkRect r = SkRect::MakeLTRB(100, 100, WIDTH - 100, HEIGHT - 100);
+        SkImageFilter::CropRect cropRect(r);
+
+        SkPaint paint = create_filter_paint(fUseCropRect ? &cropRect : nullptr);
         canvas->saveLayer(nullptr, &paint);
         draw_rects(canvas);
 
@@ -75,9 +82,12 @@ protected:
     }
 
 private:
+    bool fUseCropRect;
+
     typedef GM INHERITED;
 };
 
+
 class ImageAlphaThresholdSurfaceGM : public GM {
 public:
     ImageAlphaThresholdSurfaceGM() {
@@ -113,7 +123,8 @@ private:
 
 //////////////////////////////////////////////////////////////////////////////
 
-DEF_GM(return new ImageAlphaThresholdGM();)
+DEF_GM(return new ImageAlphaThresholdGM(true);)
+DEF_GM(return new ImageAlphaThresholdGM(false);)
 DEF_GM(return new ImageAlphaThresholdSurfaceGM();)
 
 }