kwin/plugins/screencast/eglnativefence.h

/*
    SPDX-FileCopyrightText: 2020 Vlad Zahorodnii <vlad.zahorodnii@kde.org>

    SPDX-License-Identifier: GPL-2.0-or-later
*/

#pragma once

#include <QtGlobal>

#include <epoxy/egl.h>

namespace KWin
{

class EGLNativeFence
{
public:
    explicit EGLNativeFence(EGLDisplay display);
    ~EGLNativeFence();

    bool isValid() const;
    int fileDescriptor() const;

private:
    EGLSyncKHR m_sync = EGL_NO_SYNC_KHR;
    EGLDisplay m_display = EGL_NO_DISPLAY;
    int m_fileDescriptor = -1;

    Q_DISABLE_COPY(EGLNativeFence)
};

} // namespace KWin
screencast: Use fences to avoid stalling the graphics pipeline Currently, we use glFinish() to ensure that stream consumers don't see corrupted or rather incomplete buffers. This is a serious issue because glFinish() not only prevents the gpu from processing new GL commands, but it also blocks the compositor. This change addresses the blocking issue by using native fences. With the proposed change, after finishing recording a frame, a fence is inserted in the command stream. When the native fence is signaled, the pending pipewire buffer will be enqueued. If the EGL_ANDROID_native_fence_sync extension is not supported, we'll fall back to using glFinish(). 2020-10-15 09:27:00 +00:00			`/*`
			`SPDX-FileCopyrightText: 2020 Vlad Zahorodnii <vlad.zahorodnii@kde.org>`

			`SPDX-License-Identifier: GPL-2.0-or-later`
			`*/`

			`#pragma once`

Prevent EGL headers from including Xlib headers One of the annoying things about EGL headers is that they include platform headers by default, e.g. on X11, it's Xlib.h, etc. The problem with Xlib.h is that it uses the define compiler directive to declare constants and those constants have very generic names, e.g. 'None', which typically conflict with enums, etc. In order to work around bad things coming from Xlib.h, we include fixx11.h file that contains some workarounds to redefine some Xlib's types. There's a flag or rather two flags (EGL_NO_PLATFORM_SPECIFIC_TYPES and EGL_NO_X11) that are cross-vendor and they can be used to prevent EGL headers from including platform specific headers, such as Xlib.h [1] The benefit of setting those two flags is that you can simply include EGL/egl.h or epoxy/egl.h and the world won't explode due to Xlib.h MESA_EGL_NO_X11_HEADERS is set to support older versions of Mesa. [1] https://github.com/KhronosGroup/EGL-Registry/pull/111 2020-12-10 09:01:12 +00:00			`#include <QtGlobal>`

screencast: Use fences to avoid stalling the graphics pipeline Currently, we use glFinish() to ensure that stream consumers don't see corrupted or rather incomplete buffers. This is a serious issue because glFinish() not only prevents the gpu from processing new GL commands, but it also blocks the compositor. This change addresses the blocking issue by using native fences. With the proposed change, after finishing recording a frame, a fence is inserted in the command stream. When the native fence is signaled, the pending pipewire buffer will be enqueued. If the EGL_ANDROID_native_fence_sync extension is not supported, we'll fall back to using glFinish(). 2020-10-15 09:27:00 +00:00			`#include <epoxy/egl.h>`

			`namespace KWin`
			`{`

			`class EGLNativeFence`
			`{`
			`public:`
			`explicit EGLNativeFence(EGLDisplay display);`
			`~EGLNativeFence();`

			`bool isValid() const;`
			`int fileDescriptor() const;`

			`private:`
			`EGLSyncKHR m_sync = EGL_NO_SYNC_KHR;`
			`EGLDisplay m_display = EGL_NO_DISPLAY;`
			`int m_fileDescriptor = -1;`

			`Q_DISABLE_COPY(EGLNativeFence)`
			`};`

			`} // namespace KWin`