Image filters: simplify filterInputGPU().

Remove a call to canFilterImageGPU() / filterImageGPU() from
filterInputGPU(). There's no reason to do this, since
the subsequent filterImage() call will do it for us anyway.
And this call actually defeats caching (as demonstrated by
the attached bench).

BUG=skia:

Review URL: https://codereview.chromium.org/1411013004

2 files changed, 43 insertions, 15 deletions

diff --git a/bench/ImageFilterDAGBench.cpp b/bench/ImageFilterDAGBench.cpp
index 74e23efb00..d66d287e18 100644
--- a/bench/ImageFilterDAGBench.cpp
+++ b/bench/ImageFilterDAGBench.cpp
@@ -7,6 +7,7 @@
 
 #include "Benchmark.h"
 #include "SkBlurImageFilter.h"
+#include "SkDisplacementMapEffect.h"
 #include "SkCanvas.h"
 #include "SkMergeImageFilter.h"
 
@@ -44,4 +45,35 @@ private:
     typedef Benchmark INHERITED;
 };
 
+// Exercise a blur filter connected to both inputs of an SkDisplacementMapEffect.
+
+class ImageFilterDisplacedBlur : public Benchmark {
+public:
+    ImageFilterDisplacedBlur() {}
+
+protected:
+    const char* onGetName() override {
+        return "image_filter_displaced_blur";
+    }
+
+    void onDraw(int loops, SkCanvas* canvas) override {
+        for (int j = 0; j < loops; j++) {
+            SkAutoTUnref<SkImageFilter> blur(SkBlurImageFilter::Create(4.0f, 4.0f));
+            SkDisplacementMapEffect::ChannelSelectorType xSelector = SkDisplacementMapEffect::kR_ChannelSelectorType;
+            SkDisplacementMapEffect::ChannelSelectorType ySelector = SkDisplacementMapEffect::kB_ChannelSelectorType;
+            SkScalar scale = 2;
+            SkAutoTUnref<SkImageFilter> displ(SkDisplacementMapEffect::Create(xSelector, ySelector, scale,
+                                                                              blur.get(), blur.get()));
+            SkPaint paint;
+            paint.setImageFilter(displ);
+            SkRect rect = SkRect::Make(SkIRect::MakeWH(400, 400));
+            canvas->drawRect(rect, paint);
+        }
+    }
+
+private:
+    typedef Benchmark INHERITED;
+};
+
 DEF_BENCH(return new ImageFilterDAGBench;)
+DEF_BENCH(return new ImageFilterDisplacedBlur;)
diff --git a/src/core/SkImageFilter.cpp b/src/core/SkImageFilter.cpp
index fef88fdf37..95793025e8 100644
--- a/src/core/SkImageFilter.cpp
+++ b/src/core/SkImageFilter.cpp
@@ -496,23 +496,19 @@ bool SkImageFilter::filterInputGPU(int index, SkImageFilter::Proxy* proxy,
     }
     Context ctx(origCtx.ctm(), origCtx.clipBounds(), origCtx.cache(), constraint);
 
-    if (input->canFilterImageGPU()) {
-        return input->filterImageGPU(proxy, src, ctx, result, offset);
-    } else {
-        if (input->filterImage(proxy, src, ctx, result, offset)) {
-            if (!result->getTexture()) {
-                const SkImageInfo info = result->info();
-                if (kUnknown_SkColorType == info.colorType()) {
-                    return false;
-                }
-                SkAutoTUnref<GrTexture> resultTex(
-                    GrRefCachedBitmapTexture(context, *result,GrTextureParams::ClampNoFilter()));
-                result->setPixelRef(new SkGrPixelRef(info, resultTex))->unref();
+    if (input->filterImage(proxy, src, ctx, result, offset)) {
+        if (!result->getTexture()) {
+            const SkImageInfo info = result->info();
+            if (kUnknown_SkColorType == info.colorType()) {
+                return false;
             }
-            return true;
-        } else {
-            return false;
+            SkAutoTUnref<GrTexture> resultTex(
+                GrRefCachedBitmapTexture(context, *result,GrTextureParams::ClampNoFilter()));
+            result->setPixelRef(new SkGrPixelRef(info, resultTex))->unref();
         }
+        return true;
+    } else {
+        return false;
     }
 }
 #endif