chromium/ui/ozone/platform/wayland/gpu/gl_surface_egl_readback_wayland.h

// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef UI_OZONE_PLATFORM_WAYLAND_GPU_GL_SURFACE_EGL_READBACK_WAYLAND_H_
#define UI_OZONE_PLATFORM_WAYLAND_GPU_GL_SURFACE_EGL_READBACK_WAYLAND_H_

#include "base/containers/circular_deque.h"
#include "base/memory/raw_ptr.h"
#include "base/memory/shared_memory_mapping.h"
#include "ui/ozone/common/gl_surface_egl_readback.h"
#include "ui/ozone/platform/wayland/gpu/wayland_surface_gpu.h"

namespace ui {

class WaylandBufferManagerGpu;

// This is a GLSurface implementation that uses glReadPixels to populate a
// shared memory region with the contents of the surface, and then passes the
// shared memory region to Wayland for presentation.
//
// Basic control flow:
//   1. Resize() creates kMaxBuffers shared memory regions. These are added to
//   available_buffers_ and registered with Wayland via CreateShmBasedBuffer().
//   2. SwapBuffersAsync() calls glReadPixels() to read the contents of the
//   active GL context into the next available shared memory region. The shared
//   memory region is immediately sent to Wayland via CommitBuffer().
//   3. The buffer is not available for reuse until OnSubmission() is called.
//
// Note: This class relies on the assumption that kMaxBuffers is necessary and
// sufficient. The behavior is undefined if SwapBuffersAsync() is called and no
// buffers are available.
class GLSurfaceEglReadbackWayland : public GLSurfaceEglReadback,
                                    public WaylandSurfaceGpu { … };

}  // namespace ui

#endif  // UI_OZONE_PLATFORM_WAYLAND_GPU_GL_SURFACE_EGL_READBACK_WAYLAND_H_