/*
 * Copyright 2011 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#ifndef GrGLInterface_DEFINED
#define GrGLInterface_DEFINED

#include "GrGLFunctions.h"
#include "SkRefCnt.h"

////////////////////////////////////////////////////////////////////////////////

/**
 * Classifies GL contexts (currently as Desktop vs. ES2). This is a bitfield.
 * A GrGLInterface (defined below) may support multiple bindings.
 */
enum GrGLBinding {
    kNone_GrGLBinding = 0x0,

    kDesktop_GrGLBinding = 0x01,
    kES_GrGLBinding = 0x02,  // ES2+ only

    // for iteration of GrGLBindings
    kFirstGrGLBinding = kDesktop_GrGLBinding,
    kLastGrGLBinding = kES_GrGLBinding
};

// Temporary alias until Chromium can be updated.
static const GrGLBinding kES2_GrGLBinding = kES_GrGLBinding;

////////////////////////////////////////////////////////////////////////////////

/**
 * Rather than depend on platform-specific GL headers and libraries, we require
 * the client to provide a struct of GL function pointers. This struct can be
 * specified per-GrContext as a parameter to GrContext::Create. If NULL is
 * passed to Create then the "default" GL interface is used. If the default is
 * also NULL GrContext creation will fail.
 *
 * The default interface is returned by GrGLDefaultInterface. This function's
 * implementation is platform-specific. Several have been provided, along with
 * an implementation that simply returns NULL. It is implementation-specific
 * whether the same GrGLInterface is returned or whether a new one is created
 * at each call. Some platforms may not be able to use a single GrGLInterface
 * because extension function ptrs vary across contexts. Note that GrGLInterface
 * is ref-counted. So if the same object is returned by multiple calls to
 * GrGLDefaultInterface, each should bump the ref count.
 *
 * By defining GR_GL_PER_GL_CALL_IFACE_CALLBACK to 1 the client can specify a
 * callback function that will be called prior to each GL function call. See
 * comments in GrGLConfig.h
 */

struct GrGLInterface;

const GrGLInterface* GrGLDefaultInterface();

/**
 * Creates a GrGLInterface for a "native" GL context (e.g. WGL on windows,
 * GLX on linux, AGL on Mac). On platforms that have context-specific function
 * pointers for GL extensions (e.g. windows) the returned interface is only
 * valid for the context that was current at creation.
 */
const GrGLInterface* GrGLCreateNativeInterface();

#if SK_MESA
/**
 * Creates a GrGLInterface for an OSMesa context.
 */
const GrGLInterface* GrGLCreateMesaInterface();
#endif

#if SK_ANGLE
/**
 * Creates a GrGLInterface for an ANGLE context.
 */
const GrGLInterface* GrGLCreateANGLEInterface();
#endif

/**
 * Creates a null GrGLInterface that doesn't draw anything. Used for measuring
 * CPU overhead.
 */
const GrGLInterface* GrGLCreateNullInterface();

/**
 * Creates a debugging GrGLInterface that doesn't draw anything. Used for
 * finding memory leaks and invalid memory accesses.
 */
const GrGLInterface* GrGLCreateDebugInterface();

#if GR_GL_PER_GL_FUNC_CALLBACK
typedef void (*GrGLInterfaceCallbackProc)(const GrGLInterface*);
typedef intptr_t GrGLInterfaceCallbackData;
#endif

/*
 * GrContext uses the following interface to make all calls into OpenGL. When a
 * GrContext is created it is given a GrGLInterface. The interface's function
 * pointers must be valid for the OpenGL context associated with the GrContext.
 * On some platforms, such as Windows, function pointers for OpenGL extensions
 * may vary between OpenGL contexts. So the caller must be careful to use a
 * GrGLInterface initialized for the correct context. All functions that should
 * be available based on the OpenGL's version and extension string must be
 * non-NULL or GrContext creation will fail. This can be tested with the
 * validate() method when the OpenGL context has been made current.
 */
struct SK_API GrGLInterface : public SkRefCnt {
private:
    // simple wrapper class that exists only to initialize a pointer to NULL
    template <typename FNPTR_TYPE> class GLPtr {
    public:
        GLPtr() : fPtr(NULL) {}
        GLPtr operator =(FNPTR_TYPE ptr) { fPtr = ptr; return *this; }
        operator FNPTR_TYPE() const { return fPtr; }
    private:
        FNPTR_TYPE fPtr;
    };

    typedef SkRefCnt INHERITED;

public:
    SK_DECLARE_INST_COUNT(GrGLInterface)

    GrGLInterface();

    // Validates that the GrGLInterface supports a binding. This means that
    // the GrGLinterface advertises the binding in fBindingsExported and all
    // the necessary function pointers have been initialized. The interface is
    // validated for the current OpenGL context.
    bool validate(GrGLBinding binding) const;

    // Indicator variable specifying the type of GL implementation
    // exported:  GLES2 and/or Desktop.
    GrGLBinding fBindingsExported;

    GLPtr<GrGLActiveTextureProc> fActiveTexture;
    GLPtr<GrGLAttachShaderProc> fAttachShader;
    GLPtr<GrGLBeginQueryProc> fBeginQuery;
    GLPtr<GrGLBindAttribLocationProc> fBindAttribLocation;
    GLPtr<GrGLBindBufferProc> fBindBuffer;
    GLPtr<GrGLBindFragDataLocationProc> fBindFragDataLocation;
    GLPtr<GrGLBindFragDataLocationIndexedProc> fBindFragDataLocationIndexed;
    GLPtr<GrGLBindFramebufferProc> fBindFramebuffer;
    GLPtr<GrGLBindRenderbufferProc> fBindRenderbuffer;
    GLPtr<GrGLBindTextureProc> fBindTexture;
    GLPtr<GrGLBindVertexArrayProc> fBindVertexArray;
    GLPtr<GrGLBlendColorProc> fBlendColor;
    GLPtr<GrGLBlendFuncProc> fBlendFunc;
    GLPtr<GrGLBlitFramebufferProc> fBlitFramebuffer;
    GLPtr<GrGLBufferDataProc> fBufferData;
    GLPtr<GrGLBufferSubDataProc> fBufferSubData;
    GLPtr<GrGLCheckFramebufferStatusProc> fCheckFramebufferStatus;
    GLPtr<GrGLClearProc> fClear;
    GLPtr<GrGLClearColorProc> fClearColor;
    GLPtr<GrGLClearStencilProc> fClearStencil;
    GLPtr<GrGLClientActiveTextureProc> fClientActiveTexture;
    GLPtr<GrGLColorMaskProc> fColorMask;
    GLPtr<GrGLCompileShaderProc> fCompileShader;
    GLPtr<GrGLCompressedTexImage2DProc> fCompressedTexImage2D;
    GLPtr<GrGLCopyTexSubImage2DProc> fCopyTexSubImage2D;
    GLPtr<GrGLCreateProgramProc> fCreateProgram;
    GLPtr<GrGLCreateShaderProc> fCreateShader;
    GLPtr<GrGLCullFaceProc> fCullFace;
    GLPtr<GrGLDeleteBuffersProc> fDeleteBuffers;
    GLPtr<GrGLDeleteFramebuffersProc> fDeleteFramebuffers;
    GLPtr<GrGLDeleteProgramProc> fDeleteProgram;
    GLPtr<GrGLDeleteQueriesProc> fDeleteQueries;
    GLPtr<GrGLDeleteRenderbuffersProc> fDeleteRenderbuffers;
    GLPtr<GrGLDeleteShaderProc> fDeleteShader;
    GLPtr<GrGLDeleteTexturesProc> fDeleteTextures;
    GLPtr<GrGLDeleteVertexArraysProc> fDeleteVertexArrays;
    GLPtr<GrGLDepthMaskProc> fDepthMask;
    GLPtr<GrGLDisableProc> fDisable;
    GLPtr<GrGLDisableClientStateProc> fDisableClientState;
    GLPtr<GrGLDisableVertexAttribArrayProc> fDisableVertexAttribArray;
    GLPtr<GrGLDrawArraysProc> fDrawArrays;
    GLPtr<GrGLDrawBufferProc> fDrawBuffer;
    GLPtr<GrGLDrawBuffersProc> fDrawBuffers;
    GLPtr<GrGLDrawElementsProc> fDrawElements;
    GLPtr<GrGLEnableProc> fEnable;
    GLPtr<GrGLEnableClientStateProc> fEnableClientState;
    GLPtr<GrGLEnableVertexAttribArrayProc> fEnableVertexAttribArray;
    GLPtr<GrGLEndQueryProc> fEndQuery;
    GLPtr<GrGLFinishProc> fFinish;
    GLPtr<GrGLFlushProc> fFlush;
    GLPtr<GrGLFramebufferRenderbufferProc> fFramebufferRenderbuffer;
    GLPtr<GrGLFramebufferTexture2DProc> fFramebufferTexture2D;
    GLPtr<GrGLFramebufferTexture2DMultisampleProc> fFramebufferTexture2DMultisample;
    GLPtr<GrGLFrontFaceProc> fFrontFace;
    GLPtr<GrGLGenBuffersProc> fGenBuffers;
    GLPtr<GrGLGenFramebuffersProc> fGenFramebuffers;
    GLPtr<GrGLGenerateMipmapProc> fGenerateMipmap;
    GLPtr<GrGLGenQueriesProc> fGenQueries;
    GLPtr<GrGLGenRenderbuffersProc> fGenRenderbuffers;
    GLPtr<GrGLGenTexturesProc> fGenTextures;
    GLPtr<GrGLGenVertexArraysProc> fGenVertexArrays;
    GLPtr<GrGLGetBufferParameterivProc> fGetBufferParameteriv;
    GLPtr<GrGLGetErrorProc> fGetError;
    GLPtr<GrGLGetFramebufferAttachmentParameterivProc> fGetFramebufferAttachmentParameteriv;
    GLPtr<GrGLGetIntegervProc> fGetIntegerv;
    GLPtr<GrGLGetQueryObjecti64vProc> fGetQueryObjecti64v;
    GLPtr<GrGLGetQueryObjectivProc> fGetQueryObjectiv;
    GLPtr<GrGLGetQueryObjectui64vProc> fGetQueryObjectui64v;
    GLPtr<GrGLGetQueryObjectuivProc> fGetQueryObjectuiv;
    GLPtr<GrGLGetQueryivProc> fGetQueryiv;
    GLPtr<GrGLGetProgramInfoLogProc> fGetProgramInfoLog;
    GLPtr<GrGLGetProgramivProc> fGetProgramiv;
    GLPtr<GrGLGetRenderbufferParameterivProc> fGetRenderbufferParameteriv;
    GLPtr<GrGLGetShaderInfoLogProc> fGetShaderInfoLog;
    GLPtr<GrGLGetShaderivProc> fGetShaderiv;
    GLPtr<GrGLGetStringProc> fGetString;
    GLPtr<GrGLGetStringiProc> fGetStringi;
    GLPtr<GrGLGetTexLevelParameterivProc> fGetTexLevelParameteriv;
    GLPtr<GrGLGetUniformLocationProc> fGetUniformLocation;
    GLPtr<GrGLLineWidthProc> fLineWidth;
    GLPtr<GrGLLinkProgramProc> fLinkProgram;
    GLPtr<GrGLLoadIdentityProc> fLoadIdentity;
    GLPtr<GrGLLoadMatrixfProc> fLoadMatrixf;
    GLPtr<GrGLMapBufferProc> fMapBuffer;
    GLPtr<GrGLMatrixModeProc> fMatrixMode;
    GLPtr<GrGLPixelStoreiProc> fPixelStorei;
    GLPtr<GrGLQueryCounterProc> fQueryCounter;
    GLPtr<GrGLReadBufferProc> fReadBuffer;
    GLPtr<GrGLReadPixelsProc> fReadPixels;
    GLPtr<GrGLRenderbufferStorageProc> fRenderbufferStorage;

#if !GR_GL_IGNORE_ES3_MSAA
    //  On OpenGL ES there are multiple incompatible extensions that add support for MSAA
    //  and ES3 adds MSAA support to the standard. On an ES3 driver we may still use the
    //  older extensions for performance reasons or due to ES3 driver bugs. We want the function
    //  that creates the GrGLInterface to provide all available functions and internally
    //  we will select among them. They all have a method called glRenderbufferStorageMultisample*.
    //  So we have separate function pointers for GL_IMG/EXT_multisampled_to_texture,
    //  GL_CHROMIUM/ANGLE_framebuffer_multisample/ES3, and GL_APPLE_framebuffer_multisample
    //  variations.
    //
    //  If a driver supports multiple GL_ARB_framebuffer_multisample-style extensions then we will
    //  assume the function pointers for the standard (or equivalent GL_ARB) version have
    //  been preferred over GL_EXT, GL_CHROMIUM, or GL_ANGLE variations that have reduced
    //  functionality.

    //  GL_EXT_multisampled_render_to_texture (preferred) or GL_IMG_multisampled_render_to_texture
    GLPtr<GrGLRenderbufferStorageMultisampleProc> fRenderbufferStorageMultisampleES2EXT;
    //  GL_APPLE_framebuffer_multisample
    GLPtr<GrGLRenderbufferStorageMultisampleProc> fRenderbufferStorageMultisampleES2APPLE;
#endif
    //  This is used to store the pointer for GL_ARB/EXT/ANGLE/CHROMIUM_framebuffer_multisample or
    //  the standard function in ES3+ or GL 3.0+.
    GLPtr<GrGLRenderbufferStorageMultisampleProc> fRenderbufferStorageMultisample;

    GLPtr<GrGLResolveMultisampleFramebufferProc> fResolveMultisampleFramebuffer;
    GLPtr<GrGLScissorProc> fScissor;
    GLPtr<GrGLShaderSourceProc> fShaderSource;
    GLPtr<GrGLStencilFuncProc> fStencilFunc;
    GLPtr<GrGLStencilFuncSeparateProc> fStencilFuncSeparate;
    GLPtr<GrGLStencilMaskProc> fStencilMask;
    GLPtr<GrGLStencilMaskSeparateProc> fStencilMaskSeparate;
    GLPtr<GrGLStencilOpProc> fStencilOp;
    GLPtr<GrGLStencilOpSeparateProc> fStencilOpSeparate;
    GLPtr<GrGLTexGenfProc> fTexGenf;
    GLPtr<GrGLTexGenfvProc> fTexGenfv;
    GLPtr<GrGLTexGeniProc> fTexGeni;
    GLPtr<GrGLTexImage2DProc> fTexImage2D;
    GLPtr<GrGLTexParameteriProc> fTexParameteri;
    GLPtr<GrGLTexParameterivProc> fTexParameteriv;
    GLPtr<GrGLTexSubImage2DProc> fTexSubImage2D;
    GLPtr<GrGLTexStorage2DProc> fTexStorage2D;
    GLPtr<GrGLDiscardFramebufferProc> fDiscardFramebuffer;
    GLPtr<GrGLUniform1fProc> fUniform1f;
    GLPtr<GrGLUniform1iProc> fUniform1i;
    GLPtr<GrGLUniform1fvProc> fUniform1fv;
    GLPtr<GrGLUniform1ivProc> fUniform1iv;
    GLPtr<GrGLUniform2fProc> fUniform2f;
    GLPtr<GrGLUniform2iProc> fUniform2i;
    GLPtr<GrGLUniform2fvProc> fUniform2fv;
    GLPtr<GrGLUniform2ivProc> fUniform2iv;
    GLPtr<GrGLUniform3fProc> fUniform3f;
    GLPtr<GrGLUniform3iProc> fUniform3i;
    GLPtr<GrGLUniform3fvProc> fUniform3fv;
    GLPtr<GrGLUniform3ivProc> fUniform3iv;
    GLPtr<GrGLUniform4fProc> fUniform4f;
    GLPtr<GrGLUniform4iProc> fUniform4i;
    GLPtr<GrGLUniform4fvProc> fUniform4fv;
    GLPtr<GrGLUniform4ivProc> fUniform4iv;
    GLPtr<GrGLUniformMatrix2fvProc> fUniformMatrix2fv;
    GLPtr<GrGLUniformMatrix3fvProc> fUniformMatrix3fv;
    GLPtr<GrGLUniformMatrix4fvProc> fUniformMatrix4fv;
    GLPtr<GrGLUnmapBufferProc> fUnmapBuffer;
    GLPtr<GrGLUseProgramProc> fUseProgram;
    GLPtr<GrGLVertexAttrib4fvProc> fVertexAttrib4fv;
    GLPtr<GrGLVertexAttribPointerProc> fVertexAttribPointer;
    GLPtr<GrGLVertexPointerProc> fVertexPointer;
    GLPtr<GrGLViewportProc> fViewport;

    // Experimental: Functions for GL_NV_path_rendering. These will be
    // alphabetized with the above functions once this is fully supported
    // (and functions we are unlikely to use will possibly be omitted).
    GLPtr<GrGLPathCommandsProc> fPathCommands;
    GLPtr<GrGLPathCoordsProc> fPathCoords;
    GLPtr<GrGLPathSubCommandsProc> fPathSubCommands;
    GLPtr<GrGLPathSubCoordsProc> fPathSubCoords;
    GLPtr<GrGLPathStringProc> fPathString;
    GLPtr<GrGLPathGlyphsProc> fPathGlyphs;
    GLPtr<GrGLPathGlyphRangeProc> fPathGlyphRange;
    GLPtr<GrGLWeightPathsProc> fWeightPaths;
    GLPtr<GrGLCopyPathProc> fCopyPath;
    GLPtr<GrGLInterpolatePathsProc> fInterpolatePaths;
    GLPtr<GrGLTransformPathProc> fTransformPath;
    GLPtr<GrGLPathParameterivProc> fPathParameteriv;
    GLPtr<GrGLPathParameteriProc> fPathParameteri;
    GLPtr<GrGLPathParameterfvProc> fPathParameterfv;
    GLPtr<GrGLPathParameterfProc> fPathParameterf;
    GLPtr<GrGLPathDashArrayProc> fPathDashArray;
    GLPtr<GrGLGenPathsProc> fGenPaths;
    GLPtr<GrGLDeletePathsProc> fDeletePaths;
    GLPtr<GrGLIsPathProc> fIsPath;
    GLPtr<GrGLPathStencilFuncProc> fPathStencilFunc;
    GLPtr<GrGLPathStencilDepthOffsetProc> fPathStencilDepthOffset;
    GLPtr<GrGLStencilFillPathProc> fStencilFillPath;
    GLPtr<GrGLStencilStrokePathProc> fStencilStrokePath;
    GLPtr<GrGLStencilFillPathInstancedProc> fStencilFillPathInstanced;
    GLPtr<GrGLStencilStrokePathInstancedProc> fStencilStrokePathInstanced;
    GLPtr<GrGLPathCoverDepthFuncProc> fPathCoverDepthFunc;
    GLPtr<GrGLPathColorGenProc> fPathColorGen;
    GLPtr<GrGLPathTexGenProc> fPathTexGen;
    GLPtr<GrGLPathFogGenProc> fPathFogGen;
    GLPtr<GrGLCoverFillPathProc> fCoverFillPath;
    GLPtr<GrGLCoverStrokePathProc> fCoverStrokePath;
    GLPtr<GrGLCoverFillPathInstancedProc> fCoverFillPathInstanced;
    GLPtr<GrGLCoverStrokePathInstancedProc> fCoverStrokePathInstanced;
    GLPtr<GrGLGetPathParameterivProc> fGetPathParameteriv;
    GLPtr<GrGLGetPathParameterfvProc> fGetPathParameterfv;
    GLPtr<GrGLGetPathCommandsProc> fGetPathCommands;
    GLPtr<GrGLGetPathCoordsProc> fGetPathCoords;
    GLPtr<GrGLGetPathDashArrayProc> fGetPathDashArray;
    GLPtr<GrGLGetPathMetricsProc> fGetPathMetrics;
    GLPtr<GrGLGetPathMetricRangeProc> fGetPathMetricRange;
    GLPtr<GrGLGetPathSpacingProc> fGetPathSpacing;
    GLPtr<GrGLGetPathColorGenivProc> fGetPathColorGeniv;
    GLPtr<GrGLGetPathColorGenfvProc> fGetPathColorGenfv;
    GLPtr<GrGLGetPathTexGenivProc> fGetPathTexGeniv;
    GLPtr<GrGLGetPathTexGenfvProc> fGetPathTexGenfv;
    GLPtr<GrGLIsPointInFillPathProc> fIsPointInFillPath;
    GLPtr<GrGLIsPointInStrokePathProc> fIsPointInStrokePath;
    GLPtr<GrGLGetPathLengthProc> fGetPathLength;
    GLPtr<GrGLPointAlongPathProc> fPointAlongPath;

    // Per-GL func callback
#if GR_GL_PER_GL_FUNC_CALLBACK
    GrGLInterfaceCallbackProc fCallback;
    GrGLInterfaceCallbackData fCallbackData;
#endif

};

#endif