gecko-dev/gfx/gl/GLScreenBuffer.h

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/* -*- Mode: c++; c-basic-offset: 4; indent-tabs-mode: nil; tab-width: 40; -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/* GLScreenBuffer is the abstraction for the "default framebuffer" used
* by an offscreen GLContext. Since it's only for offscreen GLContext's,
* it's only useful for things like WebGL, and is NOT used by the
* compositor's GLContext. Remember that GLContext provides an abstraction
* so that even if you want to draw to the 'screen', even if that's not
* actually the screen, just draw to 0. This GLScreenBuffer class takes the
* logic handling out of GLContext.
*/
#ifndef SCREEN_BUFFER_H_
#define SCREEN_BUFFER_H_
#include "GLContextTypes.h"
#include "GLDefs.h"
#include "mozilla/gfx/2D.h"
#include "mozilla/gfx/Point.h"
#include "mozilla/UniquePtr.h"
#include "SharedSurface.h"
#include "SurfaceTypes.h"
namespace mozilla {
namespace gl {
class GLContext;
class SharedSurface;
class ShSurfHandle;
class SurfaceFactory;
class DrawBuffer
{
public:
// Fallible!
// But it may return true with *out_buffer==nullptr if unneeded.
static bool Create(GLContext* const gl,
const SurfaceCaps& caps,
const GLFormats& formats,
const gfx::IntSize& size,
UniquePtr<DrawBuffer>* out_buffer);
protected:
GLContext* const mGL;
public:
const gfx::IntSize mSize;
const GLsizei mSamples;
const GLuint mFB;
protected:
const GLuint mColorMSRB;
const GLuint mDepthRB;
const GLuint mStencilRB;
DrawBuffer(GLContext* gl,
const gfx::IntSize& size,
GLsizei samples,
GLuint fb,
GLuint colorMSRB,
GLuint depthRB,
GLuint stencilRB)
: mGL(gl)
, mSize(size)
, mSamples(samples)
, mFB(fb)
, mColorMSRB(colorMSRB)
, mDepthRB(depthRB)
, mStencilRB(stencilRB)
{}
public:
virtual ~DrawBuffer();
};
class ReadBuffer
{
public:
// Infallible, always non-null.
static UniquePtr<ReadBuffer> Create(GLContext* gl,
const SurfaceCaps& caps,
const GLFormats& formats,
SharedSurface* surf);
protected:
GLContext* const mGL;
public:
const GLuint mFB;
protected:
// mFB has the following attachments:
const GLuint mDepthRB;
const GLuint mStencilRB;
// note no mColorRB here: this is provided by mSurf.
SharedSurface* mSurf;
ReadBuffer(GLContext* gl,
GLuint fb,
GLuint depthRB,
GLuint stencilRB,
SharedSurface* surf)
: mGL(gl)
, mFB(fb)
, mDepthRB(depthRB)
, mStencilRB(stencilRB)
, mSurf(surf)
{}
public:
virtual ~ReadBuffer();
// Cannot attach a surf of a different AttachType or Size than before.
void Attach(SharedSurface* surf);
const gfx::IntSize& Size() const;
SharedSurface* SharedSurf() const {
return mSurf;
}
void SetReadBuffer(GLenum mode) const;
};
class GLScreenBuffer
{
public:
// Infallible.
static UniquePtr<GLScreenBuffer> Create(GLContext* gl,
const gfx::IntSize& size,
const SurfaceCaps& caps);
protected:
GLContext* const mGL; // Owns us.
public:
const SurfaceCaps mCaps;
protected:
UniquePtr<SurfaceFactory> mFactory;
RefPtr<ShSurfHandle> mBack;
RefPtr<ShSurfHandle> mFront;
UniquePtr<DrawBuffer> mDraw;
UniquePtr<ReadBuffer> mRead;
bool mNeedsBlit;
GLenum mUserReadBufferMode;
// Below are the parts that help us pretend to be framebuffer 0:
GLuint mUserDrawFB;
GLuint mUserReadFB;
GLuint mInternalDrawFB;
GLuint mInternalReadFB;
#ifdef DEBUG
bool mInInternalMode_DrawFB;
bool mInInternalMode_ReadFB;
#endif
GLScreenBuffer(GLContext* gl,
const SurfaceCaps& caps,
UniquePtr<SurfaceFactory> factory)
: mGL(gl)
, mCaps(caps)
, mFactory(Move(factory))
, mNeedsBlit(true)
, mUserReadBufferMode(LOCAL_GL_BACK)
, mUserDrawFB(0)
, mUserReadFB(0)
, mInternalDrawFB(0)
, mInternalReadFB(0)
#ifdef DEBUG
, mInInternalMode_DrawFB(true)
, mInInternalMode_ReadFB(true)
#endif
{}
public:
virtual ~GLScreenBuffer();
SurfaceFactory* Factory() const {
return mFactory.get();
}
ShSurfHandle* Front() const {
return mFront;
}
SharedSurface* SharedSurf() const {
MOZ_ASSERT(mRead);
return mRead->SharedSurf();
}
bool ShouldPreserveBuffer() const {
return mCaps.preserve;
}
GLuint DrawFB() const {
if (!mDraw)
return ReadFB();
return mDraw->mFB;
}
GLuint ReadFB() const {
return mRead->mFB;
}
GLsizei Samples() const {
if (!mDraw)
return 1;
return mDraw->mSamples;
}
void DeletingFB(GLuint fb);
const gfx::IntSize& Size() const {
MOZ_ASSERT(mRead);
MOZ_ASSERT(!mDraw || mDraw->mSize == mRead->Size());
return mRead->Size();
}
void BindAsFramebuffer(GLContext* const gl, GLenum target) const;
void RequireBlit();
void AssureBlitted();
void AfterDrawCall();
void BeforeReadCall();
void SetReadBuffer(GLenum userMode);
/**
* Attempts to read pixels from the current bound framebuffer, if
* it is backed by a SharedSurface.
*
* Returns true if the pixel data has been read back, false
* otherwise.
*/
bool ReadPixels(GLint x, GLint y, GLsizei width, GLsizei height,
GLenum format, GLenum type, GLvoid *pixels);
// Morph changes the factory used to create surfaces.
void Morph(UniquePtr<SurfaceFactory> newFactory);
protected:
// Returns false on error or inability to resize.
bool Swap(const gfx::IntSize& size);
public:
bool PublishFrame(const gfx::IntSize& size);
bool Resize(const gfx::IntSize& size);
protected:
bool Attach(SharedSurface* surf, const gfx::IntSize& size);
bool CreateDraw(const gfx::IntSize& size, UniquePtr<DrawBuffer>* out_buffer);
UniquePtr<ReadBuffer> CreateRead(SharedSurface* surf);
public:
/* `fb` in these functions is the framebuffer the GLContext is hoping to
* bind. When this is 0, we intercept the call and bind our own
* framebuffers. As a client of these functions, just bind 0 when you want
* to draw to the default framebuffer/'screen'.
*/
void BindFB(GLuint fb);
void BindDrawFB(GLuint fb);
void BindReadFB(GLuint fb);
GLuint GetFB() const;
GLuint GetDrawFB() const;
GLuint GetReadFB() const;
// Here `fb` is the actual framebuffer you want bound. Binding 0 will
// bind the (generally useless) default framebuffer.
void BindFB_Internal(GLuint fb);
void BindDrawFB_Internal(GLuint fb);
void BindReadFB_Internal(GLuint fb);
bool IsDrawFramebufferDefault() const;
bool IsReadFramebufferDefault() const;
};
} // namespace gl
} // namespace mozilla
#endif // SCREEN_BUFFER_H_