Fix SkAlphaThresholdFilter bounds handling.

gm/imagealphathreshold.cpp

Index: gm/imagealphathreshold.cpp
diff --git a/gm/imagealphathreshold.cpp b/gm/imagealphathreshold.cpp
index 13a0ffa90b404fcf2a1c8c098940107ff5b1b2e5..ea7185be1dbb8747d8cadcd9109f8ef3a602ed38 100644
--- a/gm/imagealphathreshold.cpp
+++ b/gm/imagealphathreshold.cpp
@@ -8,10 +8,39 @@
 #include "gm.h"
 #include "SkAlphaThresholdFilter.h"
 #include "SkRandom.h"
+#include "SkSurface.h"
 
 #define WIDTH 500
 #define HEIGHT 500
 
+namespace {
+
+void draw_rects(SkCanvas* canvas) {
+    SkPaint rectPaint;
+    rectPaint.setColor(0xFF0000FF);
+    canvas->drawRect(SkRect::MakeXYWH(0, 0, WIDTH / 2, HEIGHT / 2), rectPaint);
+    rectPaint.setColor(0xBFFF0000);
+    canvas->drawRect(SkRect::MakeXYWH(WIDTH / 2, 0, WIDTH / 2, HEIGHT / 2), rectPaint);
+    rectPaint.setColor(0x3F00FF00);
+    canvas->drawRect(SkRect::MakeXYWH(0, HEIGHT / 2, WIDTH / 2, HEIGHT / 2), rectPaint);
+    rectPaint.setColor(0x00000000);
+    canvas->drawRect(SkRect::MakeXYWH(WIDTH / 2, HEIGHT / 2, WIDTH / 2, HEIGHT / 2), rectPaint);
+}
+
+SkPaint create_filter_paint() {
+    SkIRect rects[2];
+    rects[0] = SkIRect::MakeXYWH(0, 150, WIDTH, HEIGHT - 300);
+    rects[1] = SkIRect::MakeXYWH(150, 0, WIDTH - 300, HEIGHT);
+    SkRegion region;
+    region.setRects(rects, 2);
+
+    SkPaint paint;
+    paint.setImageFilter(SkAlphaThresholdFilter::Create(region, 0.2f, 0.7f))->unref();
+    return paint;
+}
+
+};
+
 namespace skiagm {
 
 class ImageAlphaThresholdGM : public GM {
@@ -31,12 +60,6 @@ protected:
     }
 
     void onDraw(SkCanvas* canvas) override {
-        SkIRect rects[2];
-        rects[0] = SkIRect::MakeXYWH(0, 150, WIDTH, HEIGHT - 300);
-        rects[1] = SkIRect::MakeXYWH(150, 0, WIDTH - 300, HEIGHT);
-        SkRegion region;
-        region.setRects(rects, 2);
-
         SkMatrix matrix;
         matrix.reset();
         matrix.setTranslate(WIDTH * .1f, HEIGHT * .1f);
@@ -44,25 +67,9 @@ protected:
 
         canvas->concat(matrix);
 
-        SkPaint paint;
-        paint.setImageFilter(
-            SkAlphaThresholdFilter::Create(region, 0.2f, 0.7f))->unref();
+        SkPaint paint = create_filter_paint();
         canvas->saveLayer(nullptr, &paint);
-        paint.setAntiAlias(true);
-
-        SkPaint rect_paint;
-        rect_paint.setColor(0xFF0000FF);
-        canvas->drawRect(SkRect::MakeXYWH(0, 0, WIDTH / 2, HEIGHT / 2),
-                         rect_paint);
-        rect_paint.setColor(0xBFFF0000);
-        canvas->drawRect(SkRect::MakeXYWH(WIDTH / 2, 0, WIDTH / 2, HEIGHT / 2),
-                         rect_paint);
-        rect_paint.setColor(0x3F00FF00);
-        canvas->drawRect(SkRect::MakeXYWH(0, HEIGHT / 2, WIDTH / 2, HEIGHT / 2),
-                         rect_paint);
-        rect_paint.setColor(0x00000000);
-        canvas->drawRect(SkRect::MakeXYWH(WIDTH / 2, HEIGHT / 2, WIDTH / 2, HEIGHT / 2),
-                         rect_paint);
+        draw_rects(canvas);
 
         canvas->restore();
     }
@@ -71,9 +78,43 @@ private:
     typedef GM INHERITED;
 };
 
+class ImageAlphaThresholdSurfaceGM : public GM {
+public:
+    ImageAlphaThresholdSurfaceGM() {
+        this->setBGColor(0xFFFFFFFF);
+    }
+
+protected:
+    SkString onShortName() override {
+        return SkString("imagealphathreshold_surface");
+    }
+
+    SkISize onISize() override {
+        return SkISize::Make(WIDTH, HEIGHT);
+    }
+
+    void onDraw(SkCanvas* canvas) override {
+        SkImageInfo info = SkImageInfo::MakeN32(WIDTH, HEIGHT, kOpaque_SkAlphaType);
+        SkAutoTUnref<SkSurface> surface(canvas->newSurface(info));
+        if (nullptr == surface) {
+            surface.reset(SkSurface::NewRaster(info));
+        }
+        surface->getCanvas()->clear(SK_ColorWHITE);
+        draw_rects(surface->getCanvas());
+
+        SkAutoTUnref<SkImage> image(surface->newImageSnapshot());
+        SkPaint paint = create_filter_paint();
+        canvas->clipRect(SkRect::MakeLTRB(100, 100, WIDTH - 100, HEIGHT - 100));
+        canvas->drawImage(image, 0, 0, &paint);
+    }
+
+private:
+    typedef GM INHERITED;
+};
+
 //////////////////////////////////////////////////////////////////////////////
 
-static GM* MyFactory(void*) { return new ImageAlphaThresholdGM; }
-static GMRegistry reg(MyFactory);
+DEF_GM(return new ImageAlphaThresholdGM();)
+DEF_GM(return new ImageAlphaThresholdSurfaceGM();)
 
 }