Revert "Remove deadcode for sRGB image shading."

This reverts commit 51f6a0f89e55b2c0f102aa7963320a23c586e71d.

Reason for revert: crazy attempt to fix chrome roll

Original change's description:
> Remove deadcode for sRGB image shading.
> 
> Change-Id: I9d98da67d97b64ab55cf44b9ae447882dccda1ca
> Reviewed-on: https://skia-review.googlesource.com/20695
> Reviewed-by: Mike Klein <mtklein@chromium.org>
> Commit-Queue: Herb Derby <herb@google.com>

TBR=mtklein@chromium.org,mtklein@google.com,herb@google.com,reed@google.com

# Not skipping CQ checks because original CL landed > 1 day ago.

Change-Id: Icab02936d6c18e50b8de353aa1cd4c225e15e0bf
Reviewed-on: https://skia-review.googlesource.com/20800
Reviewed-by: Mike Reed <reed@google.com>

1 files changed, 89 insertions, 5 deletions

diff --git a/src/shaders/SkBitmapProcShader.cpp b/src/shaders/SkBitmapProcShader.cpp
index 1a87491bf4..91697e2f1b 100644
--- a/src/shaders/SkBitmapProcShader.cpp
+++ b/src/shaders/SkBitmapProcShader.cpp
@@ -100,6 +100,79 @@ private:
 };
 
 ///////////////////////////////////////////////////////////////////////////////////////////////////
+#include "SkLinearBitmapPipeline.h"
+#include "SkPM4f.h"
+
+class LinearPipelineContext : public BitmapProcInfoContext {
+public:
+    LinearPipelineContext(const SkShaderBase& shader, const SkShaderBase::ContextRec& rec,
+                          SkBitmapProcInfo* info, SkArenaAlloc* alloc)
+        : INHERITED(shader, rec, info), fAllocator{alloc}
+    {
+        // Save things off in case we need to build a blitter pipeline.
+        fSrcPixmap = info->fPixmap;
+        fAlpha = SkColorGetA(info->fPaintColor) / 255.0f;
+        fFilterQuality = info->fFilterQuality;
+        fMatrixTypeMask = info->fRealInvMatrix.getType();
+
+        fShaderPipeline = alloc->make<SkLinearBitmapPipeline>(
+            info->fRealInvMatrix, info->fFilterQuality,
+            info->fTileModeX, info->fTileModeY,
+            info->fPaintColor,
+            info->fPixmap,
+            fAllocator);
+    }
+
+    void shadeSpan4f(int x, int y, SkPM4f dstC[], int count) override {
+        fShaderPipeline->shadeSpan4f(x, y, dstC, count);
+    }
+
+    void shadeSpan(int x, int y, SkPMColor dstC[], int count) override {
+        const int N = 128;
+        SkPM4f  tmp[N];
+
+        while (count > 0) {
+            const int n = SkTMin(count, N);
+            fShaderPipeline->shadeSpan4f(x, y, tmp, n);
+            // now convert to SkPMColor
+            for (int i = 0; i < n; ++i) {
+                dstC[i] = Sk4f_toL32(tmp[i].to4f_pmorder());
+            }
+            dstC += n;
+            x += n;
+            count -= n;
+        }
+    }
+
+private:
+    // Store the allocator from the context creation incase we are asked to build a blitter.
+    SkArenaAlloc*           fAllocator;
+    SkLinearBitmapPipeline* fShaderPipeline;
+    SkPixmap                fSrcPixmap;
+    float                   fAlpha;
+    SkMatrix::TypeMask      fMatrixTypeMask;
+    SkFilterQuality         fFilterQuality;
+
+    typedef BitmapProcInfoContext INHERITED;
+};
+
+///////////////////////////////////////////////////////////////////////////////////////////////////
+
+static bool choose_linear_pipeline(const SkShaderBase::ContextRec& rec, const SkImageInfo& srcInfo) {
+    // If we get here, we can reasonably use either context, respect the caller's preference
+    //
+    bool needsPremul = srcInfo.alphaType() == kUnpremul_SkAlphaType;
+    bool needsSwizzle = srcInfo.bytesPerPixel() == 4 && srcInfo.colorType() != kN32_SkColorType;
+    return SkShaderBase::ContextRec::kPM4f_DstType == rec.fPreferredDstType
+           || needsPremul || needsSwizzle;
+}
+
+size_t SkBitmapProcLegacyShader::ContextSize(const ContextRec& rec, const SkImageInfo& srcInfo) {
+    size_t size0 = sizeof(BitmapProcShaderContext) + sizeof(SkBitmapProcState);
+    size_t size1 = sizeof(LinearPipelineContext) + sizeof(SkBitmapProcInfo);
+    size_t s = SkTMax(size0, size1);
+    return s;
+}
 
 SkShaderBase::Context* SkBitmapProcLegacyShader::MakeContext(
     const SkShaderBase& shader, TileMode tmx, TileMode tmy,
@@ -111,10 +184,21 @@ SkShaderBase::Context* SkBitmapProcLegacyShader::MakeContext(
         return nullptr;
     }
 
-    SkBitmapProcState* state = alloc->make<SkBitmapProcState>(provider, tmx, tmy);
-    if (!state->setup(totalInverse, *rec.fPaint)) {
-        return nullptr;
-    }
-    return alloc->make<BitmapProcShaderContext>(shader, rec, state);
+    // Decide if we can/want to use the new linear pipeline
+    bool useLinearPipeline = choose_linear_pipeline(rec, provider.info());
 
+    if (useLinearPipeline) {
+        SkBitmapProcInfo* info = alloc->make<SkBitmapProcInfo>(provider, tmx, tmy);
+        if (!info->init(totalInverse, *rec.fPaint)) {
+            return nullptr;
+        }
+
+        return alloc->make<LinearPipelineContext>(shader, rec, info, alloc);
+    } else {
+        SkBitmapProcState* state = alloc->make<SkBitmapProcState>(provider, tmx, tmy);
+        if (!state->setup(totalInverse, *rec.fPaint)) {
+            return nullptr;
+        }
+        return alloc->make<BitmapProcShaderContext>(shader, rec, state);
+    }
 }