Initial refactor of shaderbuilder

src/gpu/gl/builders/GrGLFragmentShaderBuilder.h

+/*
+ * Copyright 2014 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef GrGLFragmentShaderBuilder_DEFINED
+#define GrGLFragmentShaderBuilder_DEFINED
+#include "GrGLShaderBuilder.h"
+
+class GrGLProgramBuilder;
+
+class GrGLFragmentShaderBuilder : public GrGLShaderBuilder {
+public:
+    typedef uint8_t DstReadKey;
+    typedef uint8_t FragPosKey;
+
+    /**  Returns a key for adding code to read the copy-of-dst color in service of effects that
+        require reading the dst. It must not return 0 because 0 indicates that there is no dst
+        copy read at all (in which case this function should not be called). */
+    static DstReadKey KeyForDstRead(const GrTexture* dstCopy, const GrGLCaps&);
+
+    /** Returns a key for reading the fragment location. This should only be called if there is an
+       effect that will requires the fragment position. If the fragment position is not required,
+       the key is 0. */
+    static FragPosKey KeyForFragmentPosition(const GrRenderTarget* dst, const GrGLCaps&);
+
+    GrGLFragmentShaderBuilder(GrGLProgramBuilder* program, const GrGLProgramDesc& desc);
+
+    /** Returns the variable name that holds the color of the destination pixel. This may be NULL if
+        no effect advertised that it will read the destination. */
+    const char* dstColor();
+
+    /**
+     * Use of these features may require a GLSL extension to be enabled. Shaders may not compile
+     * if code is added that uses one of these features without calling enableFeature()
+     */
+    enum GLSLFeature {
+        kStandardDerivatives_GLSLFeature = 0,
+        kLastGLSLFeature = kStandardDerivatives_GLSLFeature
+    };
+
+    /**
+     * If the feature is supported then true is returned and any necessary #extension declarations
+     * are added to the shaders. If the feature is not supported then false will be returned.
+     */
+    bool enableFeature(GLSLFeature);
+
+    /**
+     * This returns a variable name to access the 2D, perspective correct version of the coords in
+     * the fragment shader. If the coordinates at index are 3-dimensional, it immediately emits a
+     * perspective divide into the fragment shader (xy / z) to convert them to 2D.
+     */
+    SkString ensureFSCoords2D(const TransformedCoordsArray& coords, int index);
+
+
+    /** Returns a variable name that represents the position of the fragment in the FS. The position
+        is in device space (e.g. 0,0 is the top left and pixel centers are at half-integers). */
+    const char* fragmentPosition();
+
+private:
+    /*
+     * An internal call for GrGLFullProgramBuilder to use to add varyings to the vertex shader
+     */
+    void addVarying(GrSLType type,
+                   const char* name,
+                   const char** fsInName);
+
+    /*
+     * Private functions used by GrGLProgramBuilder for compilation
+    */
+    void bindProgramLocations(GrGLuint programId);
+    bool compileAndAttachShaders(GrGLuint programId, SkTDArray<GrGLuint>* shaderIds) const;
+    void emitCodeBeforeEffects();
+    void emitCodeAfterEffects(const GrGLSLExpr4& inputColor, const GrGLSLExpr4& inputCoverage);
+
+    /** Enables using the secondary color output and returns the name of the var in which it is
+        to be stored */
+    const char* enableSecondaryOutput();
+
+    /** Gets the name of the primary color output. */
+    const char* getColorOutputName() const;
+
+    /**
+     * Features that should only be enabled by GrGLFragmentShaderBuilder itself.
+     */
+    enum GLSLPrivateFeature {
+        kFragCoordConventions_GLSLPrivateFeature = kLastGLSLFeature + 1,
+        kLastGLSLPrivateFeature = kFragCoordConventions_GLSLPrivateFeature
+    };
+
+    // Interpretation of DstReadKey when generating code
+    enum {
+        kNoDstRead_DstReadKey           = 0,
+        kYesDstRead_DstReadKeyBit       = 0x1, // Set if we do a dst-copy-read.
+        kUseAlphaConfig_DstReadKeyBit   = 0x2, // Set if dst-copy config is alpha only.
+        kTopLeftOrigin_DstReadKeyBit    = 0x4, // Set if dst-copy origin is top-left.
+    };
+
+    enum {
+        kNoFragPosRead_FragPosKey           = 0,  // The fragment positition will not be needed.
+        kTopLeftFragPosRead_FragPosKey      = 0x1,// Read frag pos relative to top-left.
+        kBottomLeftFragPosRead_FragPosKey   = 0x2,// Read frag pos relative to bottom-left.
+    };
+
+    bool fHasCustomColorOutput;
+    bool fHasSecondaryOutput;
+    bool fSetupFragPosition;
+    bool fTopLeftFragPosRead;
+
+    friend class GrGLProgramBuilder;
+    friend class GrGLFullProgramBuilder;
+
+    typedef GrGLShaderBuilder INHERITED;
+};
+
+#endif