From 6dfcecad33c949e775a3fd0a58637721ab5e295e Mon Sep 17 00:00:00 2001
From: Mike Klein <mtklein@chromium.org>
Date: Tue, 9 May 2017 11:52:35 -0400
Subject: [PATCH] Make SkColorFilter::appendStages() not fail.

This makes SkColorFilter::appendStages() first try onAppendStages(),
and if it's unimplemented or fails, fall back to filterSpan4f().

This also makes onAppendStages() private to try to ensure that
appendStages() is now its only caller, ensuring everyone goes
through this fallback path.

The fallback uses the color filter transformed into the dst colorspace
using our new SkColorSpaceXformer... that seem ok Matt?

Change-Id: I4751a6859596fa4f7e844e69ef0d986f005b52c7
Reviewed-on: https://skia-review.googlesource.com/16031
Reviewed-by: Mike Reed <reed@google.com>
Reviewed-by: Matt Sarett <msarett@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>
---
 include/core/SkColorFilter.h         | 10 ++++-----
 src/core/SkColorFilter.cpp           | 31 ++++++++++++++++++++++------
 src/core/SkRasterPipelineBlitter.cpp |  4 +---
 src/effects/SkColorMatrixFilter.cpp  |  3 ++-
 4 files changed, 33 insertions(+), 15 deletions(-)

diff --git a/include/core/SkColorFilter.h b/include/core/SkColorFilter.h
index 5845573c42..16375499e5 100644
--- a/include/core/SkColorFilter.h
+++ b/include/core/SkColorFilter.h
@@ -74,8 +74,7 @@ public:
 
     virtual void filterSpan4f(const SkPM4f src[], int count, SkPM4f result[]) const = 0;
 
-    bool appendStages(SkRasterPipeline*, SkColorSpace*, SkArenaAlloc*,
-                      bool shaderIsOpaque) const;
+    void appendStages(SkRasterPipeline*, SkColorSpace*, SkArenaAlloc*, bool shaderIsOpaque) const;
 
     enum Flags {
         /** If set the filter methods will not change the alpha channel of the colors.
@@ -161,9 +160,6 @@ public:
 protected:
     SkColorFilter() {}
 
-    virtual bool onAppendStages(SkRasterPipeline*, SkColorSpace*, SkArenaAlloc*,
-                                bool shaderIsOpaque) const;
-
     sk_sp<SkColorFilter> makeColorSpace(SkColorSpaceXformer* xformer) const {
         return this->onMakeColorSpace(xformer);
     }
@@ -189,6 +185,10 @@ private:
         return false;
     }
 
+    virtual bool onAppendStages(SkRasterPipeline*, SkColorSpace*, SkArenaAlloc*,
+                                bool shaderIsOpaque) const;
+
+
     friend class SkColorSpaceXformer;
     friend class SkComposeColorFilter;
 
diff --git a/src/core/SkColorFilter.cpp b/src/core/SkColorFilter.cpp
index 6dcee068ea..07e97919f5 100644
--- a/src/core/SkColorFilter.cpp
+++ b/src/core/SkColorFilter.cpp
@@ -10,12 +10,14 @@
 #include "SkColorSpaceXformer.h"
 #include "SkNx.h"
 #include "SkPM4f.h"
+#include "SkRasterPipeline.h"
 #include "SkReadBuffer.h"
 #include "SkRefCnt.h"
 #include "SkString.h"
 #include "SkTDArray.h"
 #include "SkUnPreMultiply.h"
 #include "SkWriteBuffer.h"
+#include "../jumper/SkJumper.h"
 
 #if SK_SUPPORT_GPU
 #include "GrFragmentProcessor.h"
@@ -39,11 +41,27 @@ sk_sp<GrFragmentProcessor> SkColorFilter::asFragmentProcessor(GrContext*, SkColo
 }
 #endif
 
-bool SkColorFilter::appendStages(SkRasterPipeline* pipeline,
-                                 SkColorSpace* dst,
-                                 SkArenaAlloc* scratch,
+void SkColorFilter::appendStages(SkRasterPipeline* p,
+                                 SkColorSpace* dstCS,
+                                 SkArenaAlloc* alloc,
                                  bool shaderIsOpaque) const {
-    return this->onAppendStages(pipeline, dst, scratch, shaderIsOpaque);
+    SkRasterPipeline subclass;
+    if (this->onAppendStages(&subclass, dstCS, alloc, shaderIsOpaque)) {
+        p->extend(subclass);
+        return;
+    }
+
+    struct Ctx : SkJumper_CallbackCtx {
+        sk_sp<SkColorFilter> cf;
+    };
+    auto ctx = alloc->make<Ctx>();
+    ctx->cf = SkColorSpaceXformer::Make(sk_ref_sp(dstCS))->apply(this);
+    ctx->fn = [](SkJumper_CallbackCtx* arg, int active_pixels) {
+        auto ctx = (Ctx*)arg;
+        auto buf = (SkPM4f*)ctx->rgba;
+        ctx->cf->filterSpan4f(buf, active_pixels, buf);
+    };
+    p->append(SkRasterPipeline::callback, ctx);
 }
 
 bool SkColorFilter::onAppendStages(SkRasterPipeline*, SkColorSpace*, SkArenaAlloc*, bool) const {
@@ -108,8 +126,9 @@ public:
         if (!(fInner->getFlags() & kAlphaUnchanged_Flag)) {
             innerIsOpaque = false;
         }
-        return fInner->appendStages(p, dst, scratch, shaderIsOpaque) &&
-               fOuter->appendStages(p, dst, scratch, innerIsOpaque);
+        fInner->appendStages(p, dst, scratch, shaderIsOpaque);
+        fOuter->appendStages(p, dst, scratch, innerIsOpaque);
+        return true;
     }
 
 #if SK_SUPPORT_GPU
diff --git a/src/core/SkRasterPipelineBlitter.cpp b/src/core/SkRasterPipelineBlitter.cpp
index 9b882c2ca1..badd83d73c 100644
--- a/src/core/SkRasterPipelineBlitter.cpp
+++ b/src/core/SkRasterPipelineBlitter.cpp
@@ -125,9 +125,7 @@ SkBlitter* SkRasterPipelineBlitter::Create(const SkPixmap& dst,
     }
 
     if (colorFilter) {
-        if (!colorFilter->appendStages(pipeline, dst.colorSpace(), alloc, is_opaque)) {
-            return nullptr;
-        }
+        colorFilter->appendStages(pipeline, dst.colorSpace(), alloc, is_opaque);
         is_opaque = is_opaque && (colorFilter->getFlags() & SkColorFilter::kAlphaUnchanged_Flag);
     }
 
diff --git a/src/effects/SkColorMatrixFilter.cpp b/src/effects/SkColorMatrixFilter.cpp
index 52bf71eb70..ebd806e3c0 100644
--- a/src/effects/SkColorMatrixFilter.cpp
+++ b/src/effects/SkColorMatrixFilter.cpp
@@ -58,7 +58,8 @@ public:
     }
     bool onAppendStages(SkRasterPipeline* p, SkColorSpace* cs, SkArenaAlloc* alloc,
                         bool shaderIsOpaque) const override {
-        return fMatrixFilter->appendStages(p, cs, alloc, shaderIsOpaque);
+        fMatrixFilter->appendStages(p, cs, alloc, shaderIsOpaque);
+        return true;
     }
 
     // TODO: might want to remember we're a lighting color filter through serialization?