skia2/gpu/include/GrGLTexture.h

/*
    Copyright 2011 Google Inc.

    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
    You may obtain a copy of the License at

         http://www.apache.org/licenses/LICENSE-2.0

    Unless required by applicable law or agreed to in writing, software
    distributed under the License is distributed on an "AS IS" BASIS,
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the License.
 */

#ifndef GrGLTexture_DEFINED
#define GrGLTexture_DEFINED

#include "GrTexture.h"
#include "GrScalar.h"
#include "GrGLIRect.h"

class GrGpuGL;
class GrGLTexture;

/**
 * A ref counted tex id that deletes the texture in its destructor.
 */
class GrGLTexID : public GrRefCnt {

public:
    GrGLTexID(GrGLuint texID, bool ownsID) : fTexID(texID), fOwnsID(ownsID) {}

    virtual ~GrGLTexID() {
        if (0 != fTexID && fOwnsID) {
            GR_GL(DeleteTextures(1, &fTexID));
        }
    }

    void abandon() { fTexID = 0; }
    GrGLuint id() const { return fTexID; }

private:
    GrGLuint      fTexID;
    bool          fOwnsID;
};

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

class GrGLRenderTarget : public GrRenderTarget {

public:
    // set fTexFBOID to this value to indicate that it is multisampled but
    // Gr doesn't know how to resolve it.
    enum { kUnresolvableFBOID = 0 };

    struct GLRenderTargetIDs {
        GrGLuint      fRTFBOID;
        GrGLuint      fTexFBOID;
        GrGLuint      fStencilRenderbufferID;
        GrGLuint      fMSColorRenderbufferID;
        bool          fOwnIDs;
        void reset() { memset(this, 0, sizeof(GLRenderTargetIDs)); }
    };

    GrGLRenderTarget(GrGpuGL* gpu,
                     const GLRenderTargetIDs& ids,
                     GrGLTexID* texID,
                     GrGLuint stencilBits,
                     bool isMultisampled,
                     const GrGLIRect& fViewport,
                     GrGLTexture* texture);

    virtual ~GrGLRenderTarget() { this->release(); }

    void setViewport(const GrGLIRect& rect) { fViewport = rect; }
    const GrGLIRect& getViewport() const { return fViewport; }

    // The following two functions return the same ID when a 
    // texture-rendertarget is multisampled, and different IDs when
    // it is.
    // FBO ID used to render into
    GrGLuint renderFBOID() const { return fRTFBOID; }
    // FBO ID that has texture ID attached.
    GrGLuint textureFBOID() const { return fTexFBOID; }

    // override of GrRenderTarget 
    virtual ResolveType getResolveType() const {
        if (fRTFBOID == fTexFBOID) {
            // catches FBO 0 and non MSAA case
            return kAutoResolves_ResolveType;
        } else if (kUnresolvableFBOID == fTexFBOID) {
            return kCantResolve_ResolveType;
        } else {
            return kCanResolve_ResolveType;
        }
    }

protected:
    // override of GrResource
    virtual void onAbandon();
    virtual void onRelease();

private:
    GrGLuint      fRTFBOID;
    GrGLuint      fTexFBOID;
    GrGLuint      fStencilRenderbufferID;
    GrGLuint      fMSColorRenderbufferID;

    // Should this object delete IDs when it is destroyed or does someone
    // else own them.
    bool        fOwnIDs;

    // when we switch to this rendertarget we want to set the viewport to
    // only render to to content area (as opposed to the whole allocation) and
    // we want the rendering to be at top left (GL has origin in bottom left)
    GrGLIRect fViewport;

    // non-NULL if this RT was created by Gr with an associated GrGLTexture.
    GrGLTexID* fTexIDObj;

    typedef GrRenderTarget INHERITED;
};

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

class GrGLTexture : public GrTexture {

public:
    enum Orientation {
        kBottomUp_Orientation,
        kTopDown_Orientation,
    };

    struct TexParams {
        GrGLenum fFilter;
        GrGLenum fWrapS;
        GrGLenum fWrapT;
        void invalidate() { memset(this, 0xff, sizeof(TexParams)); }
    };

    struct GLTextureDesc {
        int             fContentWidth;
        int             fContentHeight;
        int             fAllocWidth;
        int             fAllocHeight;
        GrPixelConfig   fFormat;
        GrGLuint        fTextureID;
        bool            fOwnsID;
        GrGLenum        fUploadFormat;
        GrGLenum        fUploadByteCount;
        GrGLenum        fUploadType;
        GrGLuint        fStencilBits;
        Orientation     fOrientation;
    };

    typedef GrGLRenderTarget::GLRenderTargetIDs GLRenderTargetIDs;

    GrGLTexture(GrGpuGL* gpu,
                const GLTextureDesc& textureDesc,
                const GLRenderTargetIDs& rtIDs,
                const TexParams& initialTexParams);

    virtual ~GrGLTexture() { this->release(); }

    // overrides of GrTexture
    virtual void uploadTextureData(int x,
                                   int y,
                                   int width,
                                   int height,
                                   const void* srcData,
                                   size_t rowBytes);
    virtual intptr_t getTextureHandle();

    const TexParams& getTexParams() const { return fTexParams; }
    void setTexParams(const TexParams& texParams) { fTexParams = texParams; }
    GrGLuint textureID() const { return fTexIDObj->id(); }

    GrGLenum uploadFormat() const { return fUploadFormat; }
    GrGLenum uploadByteCount() const { return fUploadByteCount; }
    GrGLenum uploadType() const { return fUploadType; }

    /**
     * Retrieves the texture width actually allocated in texels.
     *
     * @return the width in texels
     */
    int allocWidth() const { return fAllocWidth; }

    /**
     * Retrieves the texture height actually allocated in texels.
     *
     * @return the height in texels
     */
    int allocHeight() const { return fAllocHeight; }

    /**
     * @return width() / allocWidth()
     */
    GrScalar contentScaleX() const { return fScaleX; }

    /**
     * @return height() / allocHeight()
     */
    GrScalar contentScaleY() const { return fScaleY; }

    // Ganesh assumes texture coordinates have their origin
    // in the top-left corner of the image. OpenGL, however,
    // has the origin in the lower-left corner. For content that
    // is loaded by Ganesh we just push the content "upside down"
    // (by GL's understanding of the world ) in glTex*Image and the
    // addressing just works out. However, content generated by GL
    // (FBO or externally imported texture) will be updside down
    // and it is up to the GrGpuGL derivative to handle y-mirroing.
    Orientation orientation() const { return fOrientation; }

    static const GrGLenum* WrapMode2GLWrap();

protected:

    // overrides of GrTexture
    virtual void onAbandon();
    virtual void onRelease();

private:
    TexParams           fTexParams;
    GrGLTexID*          fTexIDObj;
    GrGLenum            fUploadFormat;
    GrGLenum            fUploadByteCount;
    GrGLenum            fUploadType;
    int                 fAllocWidth;
    int                 fAllocHeight;
    // precomputed content / alloc ratios
    GrScalar            fScaleX;
    GrScalar            fScaleY;
    Orientation         fOrientation;
    GrGpuGL*            fGpuGL;

    typedef GrTexture INHERITED;
};

#endif