Support multiple null GL contexts on a thread.

src/gpu/gl/SkNullGLContext.cpp

 
 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "gl/SkNullGLContext.h"
+#include "gl/GrGLInterface.h"
+#include "GrGLDefines.h"
+#include "GrGLNoOpInterface.h"
+#include "SkTDArray.h"
+#include "SkTLS.h"
+
+static const SkNullGLContext* current_context();
+
+/////////////////////////////////////////////////////////////////////////////////////////////////
+
+class BufferObj {
+public:
+    SK_DECLARE_INST_COUNT(BufferObj);
+
+    BufferObj(GrGLuint id) : fID(id), fDataPtr(NULL), fSize(0), fMapped(false) {}
+    ~BufferObj() { SkDELETE_ARRAY(fDataPtr); }
+
+    void allocate(GrGLsizeiptr size, const GrGLchar* dataPtr) {
+        if (fDataPtr) {
+            SkASSERT(0 != fSize);
+            SkDELETE_ARRAY(fDataPtr);
+        }
+
+        fSize = size;
+        fDataPtr = SkNEW_ARRAY(char, size);
+    }
+
+    GrGLuint id() const          { return fID; }
+    GrGLchar* dataPtr()          { return fDataPtr; }
+    GrGLsizeiptr size() const    { return fSize; }
+
+    void setMapped(bool mapped)  { fMapped = mapped; }
+    bool mapped() const          { return fMapped; }
+
+private:
+    GrGLuint     fID;
+    GrGLchar*    fDataPtr;
+    GrGLsizeiptr fSize;         // size in bytes
+    bool         fMapped;
+};
+
+// This class maintains a sparsely populated array of buffer pointers.
+class BufferManager {
+public:
+    SK_DECLARE_INST_COUNT(BufferManager);
+
+    BufferManager() : fFreeListHead(kFreeListEnd) {}
+
+    ~BufferManager() {
+        // NULL out the entries that are really free list links rather than ptrs before deleting.
+        intptr_t curr = fFreeListHead;
+        while (kFreeListEnd != curr) {
+            intptr_t next = reinterpret_cast<intptr_t>(fBuffers[SkToS32(curr)]);
+            fBuffers[SkToS32(curr)] = NULL;
+            curr = next;
+        }
+
+        fBuffers.deleteAll();
+    }
+
+    BufferObj* lookUp(GrGLuint id) {
+        BufferObj* buffer = fBuffers[id];
+        SkASSERT(buffer && buffer->id() == id);
+        return buffer;
+    }
+
+    BufferObj* create() {
+        GrGLuint id;
+        BufferObj* buffer;
+
+        if (kFreeListEnd == fFreeListHead) {
+            // no free slots - create a new one
+            id = fBuffers.count();
+            buffer = SkNEW_ARGS(BufferObj, (id));
+            *fBuffers.append() = buffer;
+        } else {
+            // grab the head of the free list and advance the head to the next free slot.
+            id = static_cast<GrGLuint>(fFreeListHead);
+            fFreeListHead = reinterpret_cast<intptr_t>(fBuffers[id]);
+
+            buffer = SkNEW_ARGS(BufferObj, (id));
+            fBuffers[id] = buffer;
+        }
+
+        return buffer;
+    }
+
+    void free(BufferObj* buffer) {
+        SkASSERT(fBuffers.count() > 0);
+
+        GrGLuint id = buffer->id();
+        SkDELETE(buffer);
+
+        fBuffers[id] = reinterpret_cast<BufferObj*>(fFreeListHead);
+        fFreeListHead = id;
+    }
+
+private:
+    static const intptr_t kFreeListEnd = -1;
+    // Index of the first entry of fBuffers in the free list. Free slots in fBuffers are indices to
+    // the next free slot. The last free slot has a value of kFreeListEnd.
+    intptr_t                fFreeListHead;
+    SkTDArray<BufferObj*>   fBuffers;
+};
+
+/**
+ * The state object for the null interface.
+ */
+struct SkNullGLContext::ContextState {
+public:
+    SK_DECLARE_INST_COUNT(ContextState);
+
+    BufferManager   fBufferManager;
+    GrGLuint        fCurrArrayBuffer;
+    GrGLuint        fCurrElementArrayBuffer;
+    GrGLuint        fCurrProgramID;
+    GrGLuint        fCurrShaderID;
+
+
+    ContextState()
+        : fCurrArrayBuffer(0)
+        , fCurrElementArrayBuffer(0)
+        , fCurrProgramID(0)
+        , fCurrShaderID(0) {}
+
+    static ContextState* Get() {
+        const SkNullGLContext* context = current_context();
+        SkASSERT(context);
+        return context->fState;
+    }
+};
+
+typedef SkNullGLContext::ContextState State;
+
+// Functions not declared in GrGLBogusInterface.h (not common with the Debug GL interface).
+
+namespace { // added to suppress 'no previous prototype' warning
+
+GrGLvoid GR_GL_FUNCTION_TYPE nullGLActiveTexture(GrGLenum texture) {}
+GrGLvoid GR_GL_FUNCTION_TYPE nullGLAttachShader(GrGLuint program, GrGLuint shader) {}
+GrGLvoid GR_GL_FUNCTION_TYPE nullGLBeginQuery(GrGLenum target, GrGLuint id) {}
+GrGLvoid GR_GL_FUNCTION_TYPE nullGLBindAttribLocation(GrGLuint program, GrGLuint index, const char* name) {}
+GrGLvoid GR_GL_FUNCTION_TYPE nullGLBindTexture(GrGLenum target, GrGLuint texture) {}
+GrGLvoid GR_GL_FUNCTION_TYPE nullGLBindVertexArray(GrGLuint id) {}
+
+GrGLvoid GR_GL_FUNCTION_TYPE nullGLGenBuffers(GrGLsizei n, GrGLuint* ids) {
+    State* state = State::Get();
+    for (int i = 0; i < n; ++i) {
+        BufferObj* buffer = state->fBufferManager.create();
+        ids[i] = buffer->id();
+    }
+}
+
+GrGLvoid GR_GL_FUNCTION_TYPE nullGLGenerateMipmap(GrGLenum target) {}
+
+GrGLvoid GR_GL_FUNCTION_TYPE nullGLBufferData(GrGLenum target,
+                                              GrGLsizeiptr size,
+                                              const GrGLvoid* data,
+                                              GrGLenum usage) {
+    State* state = State::Get();
+    GrGLuint id = 0;
+
+    switch (target) {
+    case GR_GL_ARRAY_BUFFER:
+        id = state->fCurrArrayBuffer;
+        break;
+    case GR_GL_ELEMENT_ARRAY_BUFFER:
+        id = state->fCurrElementArrayBuffer;
+        break;
+    default:
+        SkFAIL("Unexpected target to nullGLBufferData");
+        break;
+    }
+
+    if (id > 0) {
+        BufferObj* buffer = state->fBufferManager.lookUp(id);
+        buffer->allocate(size, (const GrGLchar*) data);
+    }
+}
+
+GrGLvoid GR_GL_FUNCTION_TYPE nullGLPixelStorei(GrGLenum pname, GrGLint param) {}
+GrGLvoid GR_GL_FUNCTION_TYPE nullGLReadPixels(GrGLint x, GrGLint y, GrGLsizei width, GrGLsizei height, GrGLenum format, GrGLenum type, GrGLvoid* pixels) {}
+GrGLvoid GR_GL_FUNCTION_TYPE nullGLUseProgram(GrGLuint program) {}
+GrGLvoid GR_GL_FUNCTION_TYPE nullGLViewport(GrGLint x, GrGLint y, GrGLsizei width, GrGLsizei height) {}
+GrGLvoid GR_GL_FUNCTION_TYPE nullGLBindFramebuffer(GrGLenum target, GrGLuint framebuffer) {}
+GrGLvoid GR_GL_FUNCTION_TYPE nullGLBindRenderbuffer(GrGLenum target, GrGLuint renderbuffer) {}
+GrGLvoid GR_GL_FUNCTION_TYPE nullGLDeleteFramebuffers(GrGLsizei n, const GrGLuint *framebuffers) {}
+GrGLvoid GR_GL_FUNCTION_TYPE nullGLDeleteRenderbuffers(GrGLsizei n, const GrGLuint *renderbuffers) {}
+GrGLvoid GR_GL_FUNCTION_TYPE nullGLFramebufferRenderbuffer(GrGLenum target, GrGLenum attachment, GrGLenum renderbuffertarget, GrGLuint renderbuffer) {}
+GrGLvoid GR_GL_FUNCTION_TYPE nullGLFramebufferTexture2D(GrGLenum target, GrGLenum attachment, GrGLenum textarget, GrGLuint texture, GrGLint level) {}
+
+GrGLuint GR_GL_FUNCTION_TYPE nullGLCreateProgram() {
+    return ++State::Get()->fCurrProgramID;
+}
+
+GrGLuint GR_GL_FUNCTION_TYPE nullGLCreateShader(GrGLenum type) {
+    return ++State::Get()->fCurrShaderID;
+}
+
+// same delete used for shaders and programs
+GrGLvoid GR_GL_FUNCTION_TYPE nullGLDelete(GrGLuint program) {
+}
+
+GrGLvoid GR_GL_FUNCTION_TYPE nullGLBindBuffer(GrGLenum target, GrGLuint buffer) {
+    State* state = State::Get();
+    switch (target) {
+    case GR_GL_ARRAY_BUFFER:
+        state->fCurrArrayBuffer = buffer;
+        break;
+    case GR_GL_ELEMENT_ARRAY_BUFFER:
+        state->fCurrElementArrayBuffer = buffer;
+        break;
+    }
+}
+
+// deleting a bound buffer has the side effect of binding 0
+GrGLvoid GR_GL_FUNCTION_TYPE nullGLDeleteBuffers(GrGLsizei n, const GrGLuint* ids) {
+    State* state = State::Get();
+    for (int i = 0; i < n; ++i) {
+        if (ids[i] == state->fCurrArrayBuffer) {
+            state->fCurrArrayBuffer = 0;
+        }
+        if (ids[i] == state->fCurrElementArrayBuffer) {
+            state->fCurrElementArrayBuffer = 0;
+        }
+
+        BufferObj* buffer = state->fBufferManager.lookUp(ids[i]);
+        state->fBufferManager.free(buffer);
+    }
+}
+
+GrGLvoid* GR_GL_FUNCTION_TYPE nullGLMapBufferRange(GrGLenum target, GrGLintptr offset,
+                                                   GrGLsizeiptr length, GrGLbitfield access) {
+    State* state = State::Get();
+    GrGLuint id = 0;
+    switch (target) {
+        case GR_GL_ARRAY_BUFFER:
+            id = state->fCurrArrayBuffer;
+            break;
+        case GR_GL_ELEMENT_ARRAY_BUFFER:
+            id = state->fCurrElementArrayBuffer;
+            break;
+    }
+
+    if (id > 0) {
+        // We just ignore the offset and length here.
+        BufferObj* buffer = state->fBufferManager.lookUp(id);
+        SkASSERT(!buffer->mapped());
+        buffer->setMapped(true);
+        return buffer->dataPtr();
+    }
+    return NULL;
+}
+
+GrGLvoid* GR_GL_FUNCTION_TYPE nullGLMapBuffer(GrGLenum target, GrGLenum access) {
+    State* state = State::Get();
+    GrGLuint id = 0;
+    switch (target) {
+        case GR_GL_ARRAY_BUFFER:
+            id = state->fCurrArrayBuffer;
+            break;
+        case GR_GL_ELEMENT_ARRAY_BUFFER:
+            id = state->fCurrElementArrayBuffer;
+            break;
+    }
+
+    if (id > 0) {
+        BufferObj* buffer = state->fBufferManager.lookUp(id);
+        SkASSERT(!buffer->mapped());
+        buffer->setMapped(true);
+        return buffer->dataPtr();
+    }
+
+    SkASSERT(false);
+    return NULL;            // no buffer bound to target
+}
+
+GrGLvoid GR_GL_FUNCTION_TYPE nullGLFlushMappedBufferRange(GrGLenum target,
+                                                          GrGLintptr offset,
+                                                          GrGLsizeiptr length) {}
+
+
+GrGLboolean GR_GL_FUNCTION_TYPE nullGLUnmapBuffer(GrGLenum target) {
+    State* state = State::Get();
+    GrGLuint id = 0;
+    switch (target) {
+    case GR_GL_ARRAY_BUFFER:
+        id = state->fCurrArrayBuffer;
+        break;
+    case GR_GL_ELEMENT_ARRAY_BUFFER:
+        id = state->fCurrElementArrayBuffer;
+        break;
+    }
+    if (id > 0) {
+        BufferObj* buffer = state->fBufferManager.lookUp(id);
+        SkASSERT(buffer->mapped());
+        buffer->setMapped(false);
+        return GR_GL_TRUE;
+    }
+
+    GrAlwaysAssert(false);
+    return GR_GL_FALSE; // GR_GL_INVALID_OPERATION;
+}
+
+GrGLvoid GR_GL_FUNCTION_TYPE nullGLGetBufferParameteriv(GrGLenum target, GrGLenum pname, GrGLint* params) {
+    State* state = State::Get();
+    switch (pname) {
+        case GR_GL_BUFFER_MAPPED: {
+            *params = GR_GL_FALSE;
+            GrGLuint id = 0;
+            switch (target) {
+                case GR_GL_ARRAY_BUFFER:
+                    id = state->fCurrArrayBuffer;
+                    break;
+                case GR_GL_ELEMENT_ARRAY_BUFFER:
+                    id = state->fCurrElementArrayBuffer;
+                    break;
+            }
+            if (id > 0) {
+                BufferObj* buffer = state->fBufferManager.lookUp(id);
+                if (buffer->mapped()) {
+                    *params = GR_GL_TRUE;
+                }
+            }
+            break; }
+        default:
+            SkFAIL("Unexpected pname to GetBufferParamateriv");
+            break;
+    }
+};
+
+} // end anonymous namespace
+
+static const GrGLInterface* create_null_interface() {
+    GrGLInterface* interface = SkNEW(GrGLInterface);
+
+    interface->fStandard = kGL_GrGLStandard;
+
+    GrGLInterface::Functions* functions = &interface->fFunctions;
+    functions->fActiveTexture = nullGLActiveTexture;
+    functions->fAttachShader = nullGLAttachShader;
+    functions->fBeginQuery = nullGLBeginQuery;
+    functions->fBindAttribLocation = nullGLBindAttribLocation;
+    functions->fBindBuffer = nullGLBindBuffer;
+    functions->fBindFragDataLocation = noOpGLBindFragDataLocation;
+    functions->fBindTexture = nullGLBindTexture;
+    functions->fBindVertexArray = nullGLBindVertexArray;
+    functions->fBlendColor = noOpGLBlendColor;
+    functions->fBlendFunc = noOpGLBlendFunc;
+    functions->fBufferData = nullGLBufferData;
+    functions->fBufferSubData = noOpGLBufferSubData;
+    functions->fClear = noOpGLClear;
+    functions->fClearColor = noOpGLClearColor;
+    functions->fClearStencil = noOpGLClearStencil;
+    functions->fColorMask = noOpGLColorMask;
+    functions->fCompileShader = noOpGLCompileShader;
+    functions->fCompressedTexImage2D = noOpGLCompressedTexImage2D;
+    functions->fCompressedTexSubImage2D = noOpGLCompressedTexSubImage2D;
+    functions->fCopyTexSubImage2D = noOpGLCopyTexSubImage2D;
+    functions->fCreateProgram = nullGLCreateProgram;
+    functions->fCreateShader = nullGLCreateShader;
+    functions->fCullFace = noOpGLCullFace;
+    functions->fDeleteBuffers = nullGLDeleteBuffers;
+    functions->fDeleteProgram = nullGLDelete;
+    functions->fDeleteQueries = noOpGLDeleteIds;
+    functions->fDeleteShader = nullGLDelete;
+    functions->fDeleteTextures = noOpGLDeleteIds;
+    functions->fDeleteVertexArrays = noOpGLDeleteIds;
+    functions->fDepthMask = noOpGLDepthMask;
+    functions->fDisable = noOpGLDisable;
+    functions->fDisableVertexAttribArray = noOpGLDisableVertexAttribArray;
+    functions->fDrawArrays = noOpGLDrawArrays;
+    functions->fDrawBuffer = noOpGLDrawBuffer;
+    functions->fDrawBuffers = noOpGLDrawBuffers;
+    functions->fDrawElements = noOpGLDrawElements;
+    functions->fEnable = noOpGLEnable;
+    functions->fEnableVertexAttribArray = noOpGLEnableVertexAttribArray;
+    functions->fEndQuery = noOpGLEndQuery;
+    functions->fFinish = noOpGLFinish;
+    functions->fFlush = noOpGLFlush;
+    functions->fFlushMappedBufferRange = nullGLFlushMappedBufferRange;
+    functions->fFrontFace = noOpGLFrontFace;
+    functions->fGenBuffers = nullGLGenBuffers;
+    functions->fGenerateMipmap = nullGLGenerateMipmap;
+    functions->fGenQueries = noOpGLGenIds;
+    functions->fGenTextures = noOpGLGenIds;
+    functions->fGenVertexArrays = noOpGLGenIds;
+    functions->fGetBufferParameteriv = nullGLGetBufferParameteriv;
+    functions->fGetError = noOpGLGetError;
+    functions->fGetIntegerv = noOpGLGetIntegerv;
+    functions->fGetQueryObjecti64v = noOpGLGetQueryObjecti64v;
+    functions->fGetQueryObjectiv = noOpGLGetQueryObjectiv;
+    functions->fGetQueryObjectui64v = noOpGLGetQueryObjectui64v;
+    functions->fGetQueryObjectuiv = noOpGLGetQueryObjectuiv;
+    functions->fGetQueryiv = noOpGLGetQueryiv;
+    functions->fGetProgramInfoLog = noOpGLGetInfoLog;
+    functions->fGetProgramiv = noOpGLGetShaderOrProgramiv;
+    functions->fGetShaderInfoLog = noOpGLGetInfoLog;
+    functions->fGetShaderiv = noOpGLGetShaderOrProgramiv;
+    functions->fGetString = noOpGLGetString;
+    functions->fGetStringi = noOpGLGetStringi;
+    functions->fGetTexLevelParameteriv = noOpGLGetTexLevelParameteriv;
+    functions->fGetUniformLocation = noOpGLGetUniformLocation;
+    functions->fInsertEventMarker = noOpGLInsertEventMarker;
+    functions->fLineWidth = noOpGLLineWidth;
+    functions->fLinkProgram = noOpGLLinkProgram;
+    functions->fMapBuffer = nullGLMapBuffer;
+    functions->fMapBufferRange = nullGLMapBufferRange;
+    functions->fPixelStorei = nullGLPixelStorei;
+    functions->fPopGroupMarker = noOpGLPopGroupMarker;
+    functions->fPushGroupMarker = noOpGLPushGroupMarker;
+    functions->fQueryCounter = noOpGLQueryCounter;
+    functions->fReadBuffer = noOpGLReadBuffer;
+    functions->fReadPixels = nullGLReadPixels;
+    functions->fScissor = noOpGLScissor;
+    functions->fShaderSource = noOpGLShaderSource;
+    functions->fStencilFunc = noOpGLStencilFunc;
+    functions->fStencilFuncSeparate = noOpGLStencilFuncSeparate;
+    functions->fStencilMask = noOpGLStencilMask;
+    functions->fStencilMaskSeparate = noOpGLStencilMaskSeparate;
+    functions->fStencilOp = noOpGLStencilOp;
+    functions->fStencilOpSeparate = noOpGLStencilOpSeparate;
+    functions->fTexImage2D = noOpGLTexImage2D;
+    functions->fTexParameteri = noOpGLTexParameteri;
+    functions->fTexParameteriv = noOpGLTexParameteriv;
+    functions->fTexSubImage2D = noOpGLTexSubImage2D;
+    functions->fTexStorage2D = noOpGLTexStorage2D;
+    functions->fDiscardFramebuffer = noOpGLDiscardFramebuffer;
+    functions->fUniform1f = noOpGLUniform1f;
+    functions->fUniform1i = noOpGLUniform1i;
+    functions->fUniform1fv = noOpGLUniform1fv;
+    functions->fUniform1iv = noOpGLUniform1iv;
+    functions->fUniform2f = noOpGLUniform2f;
+    functions->fUniform2i = noOpGLUniform2i;
+    functions->fUniform2fv = noOpGLUniform2fv;
+    functions->fUniform2iv = noOpGLUniform2iv;
+    functions->fUniform3f = noOpGLUniform3f;
+    functions->fUniform3i = noOpGLUniform3i;
+    functions->fUniform3fv = noOpGLUniform3fv;
+    functions->fUniform3iv = noOpGLUniform3iv;
+    functions->fUniform4f = noOpGLUniform4f;
+    functions->fUniform4i = noOpGLUniform4i;
+    functions->fUniform4fv = noOpGLUniform4fv;
+    functions->fUniform4iv = noOpGLUniform4iv;
+    functions->fUniformMatrix2fv = noOpGLUniformMatrix2fv;
+    functions->fUniformMatrix3fv = noOpGLUniformMatrix3fv;
+    functions->fUniformMatrix4fv = noOpGLUniformMatrix4fv;
+    functions->fUnmapBuffer = nullGLUnmapBuffer;
+    functions->fUseProgram = nullGLUseProgram;
+    functions->fVertexAttrib1f = noOpGLVertexAttrib1f;
+    functions->fVertexAttrib2fv = noOpGLVertexAttrib2fv;
+    functions->fVertexAttrib3fv = noOpGLVertexAttrib3fv;
+    functions->fVertexAttrib4fv = noOpGLVertexAttrib4fv;
+    functions->fVertexAttribPointer = noOpGLVertexAttribPointer;
+    functions->fViewport = nullGLViewport;
+    functions->fBindFramebuffer = nullGLBindFramebuffer;
+    functions->fBindRenderbuffer = nullGLBindRenderbuffer;
+    functions->fCheckFramebufferStatus = noOpGLCheckFramebufferStatus;
+    functions->fDeleteFramebuffers = nullGLDeleteFramebuffers;
+    functions->fDeleteRenderbuffers = nullGLDeleteRenderbuffers;
+    functions->fFramebufferRenderbuffer = nullGLFramebufferRenderbuffer;
+    functions->fFramebufferTexture2D = nullGLFramebufferTexture2D;
+    functions->fGenFramebuffers = noOpGLGenIds;
+    functions->fGenRenderbuffers = noOpGLGenIds;
+    functions->fGetFramebufferAttachmentParameteriv = noOpGLGetFramebufferAttachmentParameteriv;
+    functions->fGetRenderbufferParameteriv = noOpGLGetRenderbufferParameteriv;
+    functions->fRenderbufferStorage = noOpGLRenderbufferStorage;
+    functions->fRenderbufferStorageMultisample = noOpGLRenderbufferStorageMultisample;
+    functions->fBlitFramebuffer = noOpGLBlitFramebuffer;
+    functions->fResolveMultisampleFramebuffer = noOpGLResolveMultisampleFramebuffer;
+    functions->fMatrixLoadf = noOpGLMatrixLoadf;
+    functions->fMatrixLoadIdentity = noOpGLMatrixLoadIdentity;
+    functions->fBindFragDataLocationIndexed = noOpGLBindFragDataLocationIndexed;
+
+    interface->fExtensions.init(kGL_GrGLStandard, functions->fGetString, functions->fGetStringi,
+                                functions->fGetIntegerv);
+    return interface;
+}
+
+//////////////////////////////////////////////////////////////////////////////
+
+static void* create_tls() {
+    const SkNullGLContext** current = SkNEW(const SkNullGLContext*);
+    *current = NULL;
+    return current;
+}
+
+static void delete_tls(void* ctx) {
+    const SkNullGLContext** current = static_cast<const SkNullGLContext**>(ctx);
+    if (*current) {
+        (*current)->unref();
+    }
+    SkDELETE(current);
+}
+
+static const SkNullGLContext* current_context() {
+    return *static_cast<const SkNullGLContext**>(SkTLS::Get(create_tls, delete_tls));
+}
+
+static void set_current_context(const SkNullGLContext* context) {
+    const SkNullGLContext** current =
+        static_cast<const SkNullGLContext**>(SkTLS::Get(create_tls, delete_tls));
+    if (*current) {
+        (*current)->unref();
+    }
+    *current = context;
+    if (context) {
+        context->ref();
+    }
+}
+
+SkNullGLContext* SkNullGLContext::Create(GrGLStandard forcedGpuAPI) {
+    if (kGLES_GrGLStandard == forcedGpuAPI) {
+        return NULL;
+    }
+    SkNullGLContext* ctx = SkNEW(SkNullGLContext);
+    if (!ctx->isValid()) {
+        SkDELETE(ctx);
+        return NULL;
+    }
+    return ctx;
+}
 
 SkNullGLContext::SkNullGLContext() {
-    fGL.reset(GrGLCreateNullInterface());
+    fGL.reset(create_null_interface());
+    fState = SkNEW(ContextState);
 }
 
 SkNullGLContext::~SkNullGLContext() {
     fGL.reset(NULL);
-}
-
+    SkDELETE(fState);
+}
+
+void SkNullGLContext::makeCurrent() const { set_current_context(this); }