host/gl/EmulatedEglWindowSurface.h

/*
* Copyright (C) 2011 The Android Open Source Project
*
* 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.
*/

#pragma once

#include <EGL/egl.h>
#include <GLES/gl.h>

#include <memory>
#include <unordered_map>
#include <unordered_set>

#include "ColorBuffer.h"
#include "Handle.h"
#include "gl/ColorBufferGl.h"
#include "gl/EmulatedEglContext.h"

namespace gfxstream {
namespace gl {

// A class used to model a guest-side window surface. The implementation
// uses a host Pbuffer to act as the EGL rendering surface instead.
class EmulatedEglWindowSurface {
  public:
    // Create a new EmulatedEglWindowSurface instance.
    // |display| is the host EGLDisplay value.
    // |config| is the host EGLConfig value.
    // |width| and |height| are the initial size of the Pbuffer.
    // Return a new EmulatedEglWindowSurface instance on success, or NULL on
    // failure.
    static std::unique_ptr<EmulatedEglWindowSurface> create(EGLDisplay display,
                                                            EGLConfig config,
                                                            int width,
                                                            int height,
                                                            HandleType hndl);

    // Destructor.
    ~EmulatedEglWindowSurface();

    // Retrieve the host EGLSurface of the EmulatedEglWindowSurface's Pbuffer.
    EGLSurface getEGLSurface() const { return mSurface; }

    // Attach a ColorBuffer to this EmulatedEglWindowSurface.
    // Once attached, calling flushColorBuffer() will copy the Pbuffer's
    // pixels to the color buffer.
    //
    // IMPORTANT: This automatically resizes the Pbuffer's to the ColorBuffer's
    // dimensions. Potentially losing pixel values in the process.
    void setColorBuffer(ColorBufferPtr p_colorBuffer);

    // Retrieves a pointer to the attached color buffer.
    ColorBuffer* getAttachedColorBuffer() const {
        return mAttachedColorBuffer.get();
    }

    // Copy the Pbuffer's pixels to the attached color buffer.
    // Returns true on success, or false on error (e.g. if there is no
    // attached color buffer).
    bool flushColorBuffer();

    // Used by bind() below.
    enum BindType {
        BIND_READ,
        BIND_DRAW,
        BIND_READDRAW
    };

    // TODO(digit): What is this used for exactly? For example, the
    // mReadContext is never used by this class. The mDrawContext is only
    // used temporarily during flushColorBuffer() operation, and could be
    // passed as a parameter to the function instead. Maybe this is only used
    // to increment reference counts on the smart pointers.
    //
    // Bind a context to the EmulatedEglWindowSurface (huh? Normally you would bind a
    // surface to the context, not the other way around)
    //
    // |p_ctx| is a EmulatedEglContext pointer.
    // |p_bindType| is the type of bind. For BIND_READ, this assigns |p_ctx|
    // to mReadContext, for BIND_DRAW, it assigns it to mDrawContext, and for
    // for BIND_READDRAW, it assigns it to both.
    void bind(EmulatedEglContextPtr p_ctx, BindType p_bindType);

    GLuint getWidth() const;
    GLuint getHeight() const;

    void onSave(android::base::Stream* stream) const;
    static std::unique_ptr<EmulatedEglWindowSurface> onLoad(
      android::base::Stream* stream,
      EGLDisplay display,
      const ColorBufferMap& colorBuffers,
      const EmulatedEglContextMap& contexts);

    HandleType getHndl() const;

  private:
    EmulatedEglWindowSurface(const EmulatedEglWindowSurface& other) = delete;

    EmulatedEglWindowSurface(EGLDisplay display, EGLConfig config, HandleType hndl);

    bool resize(unsigned int p_width, unsigned int p_height);

    EGLSurface mSurface = EGL_NO_SURFACE;
    ColorBufferPtr mAttachedColorBuffer;
    EmulatedEglContextPtr mReadContext;
    EmulatedEglContextPtr mDrawContext;
    GLuint mWidth = 0;
    GLuint mHeight = 0;
    EGLConfig mConfig = nullptr;
    EGLDisplay mDisplay = EGL_NO_DISPLAY;
    HandleType mHndl;
};

typedef std::shared_ptr<EmulatedEglWindowSurface> EmulatedEglWindowSurfacePtr;
typedef std::unordered_map<HandleType, std::pair<EmulatedEglWindowSurfacePtr, HandleType>> EmulatedEglWindowSurfaceMap;
typedef std::unordered_set<HandleType> EmulatedEglWindowSurfaceSet;

}  // namespace gl
}  // namespace gfxstream