From eae84c2e0e2126374cd488a1c8a3e18169145635 Mon Sep 17 00:00:00 2001
From: senorblanco <senorblanco@chromium.org>
Date: Tue, 26 Jan 2016 08:41:02 -0800
Subject: [PATCH] Image filters: fix srcOffset handling in
 asFragmentProcessor() path.

Filters such as SkMatrixConvolutionImageFilter which use the
asFragmentProcessor() path were not correctly handling srcOffset.
It is correctly applied to the bounds, but the srcRect and dstRect
were computed from the pre-offset bounds.

The fix is to move them to just above where they're used in drawing.

Note: this change adds a new test case to the imagefiltersgraph GM,
so it will have to be rebaselined post-landing.

BUG=skia:4855
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1637443003

Review URL: https://codereview.chromium.org/1637443003
---
 gm/imagefiltersgraph.cpp   | 37 ++++++++++++++++++++++++++++++++++++-
 src/core/SkImageFilter.cpp |  8 +++-----
 2 files changed, 39 insertions(+), 6 deletions(-)

diff --git a/gm/imagefiltersgraph.cpp b/gm/imagefiltersgraph.cpp
index 14752db..e783789 100644
--- a/gm/imagefiltersgraph.cpp
+++ b/gm/imagefiltersgraph.cpp
@@ -15,6 +15,7 @@
 #include "SkColorMatrixFilter.h"
 #include "SkImage.h"
 #include "SkImageSource.h"
+#include "SkMatrixConvolutionImageFilter.h"
 #include "SkReadBuffer.h"
 #include "SkWriteBuffer.h"
 #include "SkMergeImageFilter.h"
@@ -107,7 +108,7 @@ protected:
         return SkString("imagefiltersgraph");
     }
 
-    SkISize onISize() override { return SkISize::Make(500, 150); }
+    SkISize onISize() override { return SkISize::Make(600, 150); }
 
     void onOnceBeforeDraw() override {
         fImage.reset(SkImage::NewFromBitmap(
@@ -182,6 +183,40 @@ protected:
             canvas->translate(SkIntToScalar(100), 0);
         }
         {
+            // Dilate -> matrix convolution.
+            // This tests that a filter using asFragmentProcessor (matrix
+            // convolution) correctly handles a non-zero source offset
+            // (supplied by the dilate).
+            SkAutoTUnref<SkImageFilter> dilate(SkDilateImageFilter::Create(5, 5));
+
+            SkAutoTUnref<SkXfermode> mode(SkXfermode::Create(SkXfermode::kSrcIn_Mode));
+
+            SkScalar kernel[9] = {
+                SkIntToScalar(-1), SkIntToScalar( -1 ), SkIntToScalar(-1),
+                SkIntToScalar(-1), SkIntToScalar(  7 ), SkIntToScalar(-1),
+                SkIntToScalar(-1), SkIntToScalar( -1 ), SkIntToScalar(-1),
+            };
+            SkISize kernelSize = SkISize::Make(3, 3);
+            SkScalar gain = 1.0f, bias = SkIntToScalar(0);
+            SkIPoint kernelOffset = SkIPoint::Make(1, 1);
+            auto tileMode = SkMatrixConvolutionImageFilter::kClamp_TileMode;
+            bool convolveAlpha = false;
+            SkAutoTUnref<SkImageFilter> convolve(
+                SkMatrixConvolutionImageFilter::Create(kernelSize,
+                                                       kernel,
+                                                       gain,
+                                                       bias,
+                                                       kernelOffset,
+                                                       tileMode,
+                                                       convolveAlpha,
+                                                       dilate));
+
+            SkPaint paint;
+            paint.setImageFilter(convolve);
+            DrawClippedImage(canvas, fImage, paint);
+            canvas->translate(SkIntToScalar(100), 0);
+        }
+        {
             // Test that crop offsets are absolute, not relative to the parent's crop rect.
             SkAutoTUnref<SkColorFilter> cf1(SkColorFilter::CreateModeFilter(SK_ColorBLUE,
                                                                             SkXfermode::kSrcIn_Mode));
diff --git a/src/core/SkImageFilter.cpp b/src/core/SkImageFilter.cpp
index 141d2e0..821edc0 100644
--- a/src/core/SkImageFilter.cpp
+++ b/src/core/SkImageFilter.cpp
@@ -334,8 +334,6 @@ bool SkImageFilter::filterImageGPU(Proxy* proxy, const SkBitmap& src, const Cont
     if (!this->applyCropRect(ctx, proxy, input, &srcOffset, &bounds, &input)) {
         return false;
     }
-    SkRect srcRect = SkRect::Make(bounds);
-    SkRect dstRect = SkRect::MakeWH(srcRect.width(), srcRect.height());
     GrContext* context = srcTexture->getContext();
 
     GrSurfaceDesc desc;
@@ -349,9 +347,6 @@ bool SkImageFilter::filterImageGPU(Proxy* proxy, const SkBitmap& src, const Cont
         return false;
     }
 
-    // setup new clip
-    GrClip clip(dstRect);
-
     GrFragmentProcessor* fp;
     offset->fX = bounds.left();
     offset->fY = bounds.top();
@@ -366,6 +361,9 @@ bool SkImageFilter::filterImageGPU(Proxy* proxy, const SkBitmap& src, const Cont
 
         SkAutoTUnref<GrDrawContext> drawContext(context->drawContext(dst->asRenderTarget()));
         if (drawContext) {
+            SkRect srcRect = SkRect::Make(bounds);
+            SkRect dstRect = SkRect::MakeWH(srcRect.width(), srcRect.height());
+            GrClip clip(dstRect);
             drawContext->fillRectToRect(clip, paint, SkMatrix::I(), dstRect, srcRect);
 
             GrWrapTextureInBitmap(dst, bounds.width(), bounds.height(), false, result);
-- 
2.7.4