[Reland] Relocate shaders to own dir

Consolidate all shader impls under src/shaders/.

(reland of https://skia-review.googlesource.com/c/17927/)

Change-Id: I7918bdc1aafe842ed194412ba95b9ae53a2ec1d7
Reviewed-on: https://skia-review.googlesource.com/18146
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Florin Malita <fmalita@chromium.org>

1 files changed, 88 insertions, 0 deletions

diff --git a/src/shaders/SkComposeShader.h b/src/shaders/SkComposeShader.h
new file mode 100644
index 0000000000..c7bb4b9eb8
--- /dev/null
+++ b/src/shaders/SkComposeShader.h
@@ -0,0 +1,88 @@
+/*
+ * Copyright 2006 The Android Open Source Project
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkComposeShader_DEFINED
+#define SkComposeShader_DEFINED
+
+#include "SkShaderBase.h"
+#include "SkBlendMode.h"
+
+class SkColorSpacXformer;
+
+///////////////////////////////////////////////////////////////////////////////////////////
+
+/** \class SkComposeShader
+    This subclass of shader returns the composition of two other shaders, combined by
+    a xfermode.
+*/
+class SkComposeShader : public SkShaderBase {
+public:
+    /** Create a new compose shader, given shaders A, B, and a combining xfermode mode.
+        When the xfermode is called, it will be given the result from shader A as its
+        "dst", and the result from shader B as its "src".
+        mode->xfer32(sA_result, sB_result, ...)
+        @param shaderA  The colors from this shader are seen as the "dst" by the xfermode
+        @param shaderB  The colors from this shader are seen as the "src" by the xfermode
+        @param mode     The xfermode that combines the colors from the two shaders. If mode
+                        is null, then SRC_OVER is assumed.
+    */
+    SkComposeShader(sk_sp<SkShader> sA, sk_sp<SkShader> sB, SkBlendMode mode)
+        : fShaderA(std::move(sA))
+        , fShaderB(std::move(sB))
+        , fMode(mode)
+    {}
+
+#if SK_SUPPORT_GPU
+    sk_sp<GrFragmentProcessor> asFragmentProcessor(const AsFPArgs&) const override;
+#endif
+
+    class ComposeShaderContext : public Context {
+    public:
+        // When this object gets destroyed, it will call contextA and contextB's destructor
+        // but it will NOT free the memory.
+        ComposeShaderContext(const SkComposeShader&, const ContextRec&,
+                             SkShaderBase::Context* contextA, SkShaderBase::Context* contextB);
+
+        void shadeSpan(int x, int y, SkPMColor[], int count) override;
+        void shadeSpan4f(int x, int y, SkPM4f[], int count) override;
+
+    private:
+        SkShaderBase::Context* fShaderContextA;
+        SkShaderBase::Context* fShaderContextB;
+
+        typedef Context INHERITED;
+    };
+
+#ifdef SK_DEBUG
+    SkShader* getShaderA() { return fShaderA.get(); }
+    SkShader* getShaderB() { return fShaderB.get(); }
+#endif
+
+    bool asACompose(ComposeRec* rec) const override;
+
+    SK_TO_STRING_OVERRIDE()
+    SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkComposeShader)
+
+protected:
+    SkComposeShader(SkReadBuffer&);
+    void flatten(SkWriteBuffer&) const override;
+    Context* onMakeContext(const ContextRec&, SkArenaAlloc*) const override;
+    sk_sp<SkShader> onMakeColorSpace(SkColorSpaceXformer* xformer) const override;
+    bool onAppendStages(SkRasterPipeline*, SkColorSpace* dstCS, SkArenaAlloc*,
+                        const SkMatrix&, const SkPaint&, const SkMatrix* localM) const override;
+
+    bool isRasterPipelineOnly() const final;
+
+private:
+    sk_sp<SkShader>     fShaderA;
+    sk_sp<SkShader>     fShaderB;
+    SkBlendMode         fMode;
+
+    typedef SkShaderBase INHERITED;
+};
+
+#endif