2 files changed, 47 insertions, 25 deletions

diff --git a/gm/imagealphathreshold.cpp b/gm/imagealphathreshold.cpp
index 1e90f76bf0..302cdeea52 100644
--- a/gm/imagealphathreshold.cpp
+++ b/gm/imagealphathreshold.cpp
@@ -7,27 +7,25 @@
 
 #include "gm.h"
 #include "SkAlphaThresholdFilter.h"
-#include "SkRandom.h"
+#include "SkOffsetImageFilter.h"
 #include "SkSurface.h"
 
 #define WIDTH 500
 #define HEIGHT 500
 
-namespace {
-
-void draw_rects(SkCanvas* canvas) {
+static void draw_rects(SkCanvas* canvas) {
     SkPaint rectPaint;
-    rectPaint.setColor(0xFF0000FF);
+    rectPaint.setColor(SK_ColorBLUE);
     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);
+    rectPaint.setColor(SK_ColorTRANSPARENT);
     canvas->drawRect(SkRect::MakeXYWH(WIDTH / 2, HEIGHT / 2, WIDTH / 2, HEIGHT / 2), rectPaint);
 }
 
-SkPaint create_filter_paint(SkImageFilter::CropRect* cropRect = nullptr) {
+static 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);
@@ -35,18 +33,15 @@ SkPaint create_filter_paint(SkImageFilter::CropRect* cropRect = nullptr) {
     region.setRects(rects, 2);
 
     SkPaint paint;
-    paint.setImageFilter(SkAlphaThresholdFilter::Make(region, 0.2f, 0.7f, nullptr, cropRect));
+    sk_sp<SkImageFilter> offset(SkOffsetImageFilter::Make(25, 25, nullptr));
+    paint.setImageFilter(SkAlphaThresholdFilter::Make(region, 0.2f, 0.7f, std::move(offset), cropRect));
     return paint;
 }
 
-};
-
-namespace skiagm {
-
-class ImageAlphaThresholdGM : public GM {
+class ImageAlphaThresholdGM : public skiagm::GM {
 public:
     ImageAlphaThresholdGM(bool useCropRect) : fUseCropRect(useCropRect) {
-        this->setBGColor(0xFFFFFFFF);
+        this->setBGColor(SK_ColorWHITE);
     }
 
 protected:
@@ -87,8 +82,31 @@ private:
     typedef GM INHERITED;
 };
 
+// Create a 'width' x 'height' SkSurface that matches the colorType of 'canvas' as
+// best we can
+static sk_sp<SkSurface> make_color_matching_surface(SkCanvas* canvas, int width, int height,
+                                                    SkAlphaType alphaType) {
+
+    SkColorType ct = canvas->imageInfo().colorType();
+    sk_sp<SkColorSpace> cs(sk_ref_sp(canvas->imageInfo().colorSpace()));
+
+    if (kUnknown_SkColorType == ct) {
+        // For backends that aren't yet color-space aware we just fallback to N32.
+        ct = kN32_SkColorType;
+        cs = nullptr;
+    }
+
+    SkImageInfo info = SkImageInfo::Make(width, height, ct, alphaType, std::move(cs));
+
+    sk_sp<SkSurface> result = canvas->makeSurface(info);
+    if (!result) {
+        result = SkSurface::MakeRaster(info);
+    }
+
+    return result;
+}
 
-class ImageAlphaThresholdSurfaceGM : public GM {
+class ImageAlphaThresholdSurfaceGM : public skiagm::GM {
 public:
     ImageAlphaThresholdSurfaceGM() {
         this->setBGColor(0xFFFFFFFF);
@@ -104,12 +122,17 @@ protected:
     }
 
     void onDraw(SkCanvas* canvas) override {
-        SkImageInfo info = SkImageInfo::MakeS32(WIDTH, HEIGHT, kOpaque_SkAlphaType);
-        auto surface(canvas->makeSurface(info));
-        if (nullptr == surface) {
-            surface = SkSurface::MakeRaster(info);
-        }
-        surface->getCanvas()->clear(SK_ColorWHITE);
+        SkMatrix matrix;
+        matrix.reset();
+        matrix.setTranslate(WIDTH * .1f, HEIGHT * .1f);
+        matrix.postScale(.8f, .8f);
+
+        canvas->concat(matrix);
+
+        sk_sp<SkSurface> surface(make_color_matching_surface(canvas, WIDTH, HEIGHT,
+                                                             kPremul_SkAlphaType));
+
+        surface->getCanvas()->clear(SK_ColorTRANSPARENT);
         draw_rects(surface->getCanvas());
 
         SkPaint paint = create_filter_paint();
@@ -118,7 +141,7 @@ protected:
     }
 
 private:
-    typedef GM INHERITED;
+    typedef skiagm::GM INHERITED;
 };
 
 //////////////////////////////////////////////////////////////////////////////
@@ -126,5 +149,3 @@ private:
 DEF_GM(return new ImageAlphaThresholdGM(true);)
 DEF_GM(return new ImageAlphaThresholdGM(false);)
 DEF_GM(return new ImageAlphaThresholdSurfaceGM();)
-
-}
diff --git a/src/effects/SkAlphaThresholdFilter.cpp b/src/effects/SkAlphaThresholdFilter.cpp
index 6cf1ce61e4..81416e2817 100644
--- a/src/effects/SkAlphaThresholdFilter.cpp
+++ b/src/effects/SkAlphaThresholdFilter.cpp
@@ -225,8 +225,9 @@ sk_sp<SkSpecialImage> SkAlphaThresholdFilterImpl::onFilterImage(SkSpecialImage*
     U8CPU outerThreshold = (U8CPU)(fOuterThreshold * 0xFF);
     SkColor* dptr = dst.getAddr32(0, 0);
     int dstWidth = dst.width(), dstHeight = dst.height();
+    SkIPoint srcOffset = { bounds.fLeft - inputOffset.fX, bounds.fTop - inputOffset.fY };
     for (int y = 0; y < dstHeight; ++y) {
-        const SkColor* sptr = inputBM.getAddr32(bounds.fLeft, bounds.fTop+y);
+        const SkColor* sptr = inputBM.getAddr32(srcOffset.fX, srcOffset.fY+y);
 
         for (int x = 0; x < dstWidth; ++x) {
             const SkColor& source = sptr[x];