screencasting: implement intefraces to create dmabuf textures

plugins/platforms/drm/CMakeLists.txt

@@ -18,6 +18,7 @@ if (HAVE_GBM)
         egl_gbm_backend.cpp
         drm_buffer_gbm.cpp
         gbm_surface.cpp
+        gbm_dmabuf.cpp
         remoteaccess_manager.cpp
     )
 endif()

plugins/platforms/drm/drm_backend.cpp

@@ -34,6 +34,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #if HAVE_GBM
 #include "egl_gbm_backend.h"
 #include <gbm.h>
+#include "gbm_dmabuf.h"
 #endif
 #if HAVE_EGL_STREAMS
 #include "egl_stream_backend.h"
@@ -818,4 +819,13 @@ QString DrmBackend::supportInformation() const
     return supportInfo;
 }
 
+DmaBufTexture *DrmBackend::createDmaBufTexture(const QSize &size)
+{
+#if HAVE_GBM
+    return GbmDmaBuf::createBuffer(size, m_gbmDevice);
+#else
+    return nullptr;
+#endif
+}
+
 }

plugins/platforms/drm/drm_backend.h

@@ -55,7 +55,6 @@ class DrmConnector;
 class GbmSurface;
 class Cursor;
 
-
 class KWIN_EXPORT DrmBackend : public Platform
 {
     Q_OBJECT
@@ -68,6 +67,7 @@ public:
     Screens *createScreens(QObject *parent = nullptr) override;
     QPainterBackend *createQPainterBackend() override;
     OpenGLBackend* createOpenGLBackend() override;
+    DmaBufTexture *createDmaBufTexture(const QSize &size) override;
 
     void init() override;
     void prepareShutdown() override;

plugins/platforms/drm/gbm_dmabuf.cpp

@@ -0,0 +1,81 @@
+/*
+ * Copyright © 2020 Aleix Pol Gonzalez <aleixpol@kde.org>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors:
+ *       Aleix Pol Gonzalez <aleixpol@kde.org>
+ */
+
+#include "gbm_dmabuf.h"
+#include "kwineglimagetexture.h"
+#include "platformsupport/scenes/opengl/drm_fourcc.h"
+#include "main.h"
+#include "platform.h"
+#include <unistd.h>
+
+namespace KWin
+{
+
+GbmDmaBuf::GbmDmaBuf(GLTexture *texture, gbm_bo *bo, int fd)
+    : DmaBufTexture(texture)
+    , m_bo(bo)
+    , m_fd(fd)
+{}
+
+GbmDmaBuf::~GbmDmaBuf()
+{
+    m_texture.reset(nullptr);
+
+    close(m_fd);
+    gbm_bo_destroy(m_bo);
+}
+
+
+KWin::GbmDmaBuf *GbmDmaBuf::createBuffer(const QSize &size, gbm_device *device)
+{
+    auto bo = gbm_bo_create(device, size.width(), size.height(), GBM_BO_FORMAT_ARGB8888, GBM_BO_USE_RENDERING | GBM_BO_USE_LINEAR);
+
+    if (!bo) {
+        gbm_bo_destroy(bo);
+        return nullptr;
+    }
+
+    const int fd = gbm_bo_get_fd(bo);
+    if (fd < 0) {
+        gbm_bo_destroy(bo);
+        return nullptr;
+    }
+
+    EGLint importAttributes[] = {
+        EGL_WIDTH, EGLint(gbm_bo_get_width(bo)),
+        EGL_HEIGHT, EGLint(gbm_bo_get_height(bo)),
+        EGL_LINUX_DRM_FOURCC_EXT, DRM_FORMAT_ARGB8888,
+        EGL_DMA_BUF_PLANE0_FD_EXT, fd,
+        EGL_DMA_BUF_PLANE0_OFFSET_EXT, EGLint(gbm_bo_get_offset(bo, 0)),
+        EGL_DMA_BUF_PLANE0_PITCH_EXT, EGLint(gbm_bo_get_stride(bo)),
+        EGL_NONE
+    };
+
+    EGLDisplay display = kwinApp()->platform()->sceneEglDisplay();
+    EGLImageKHR destinationImage = eglCreateImageKHR(display, EGL_NO_CONTEXT, EGL_LINUX_DMA_BUF_EXT, nullptr, importAttributes);
+    if (destinationImage == EGL_NO_IMAGE_KHR) {
+        return nullptr;
+    }
+
+    return new GbmDmaBuf(new KWin::EGLImageTexture(display, destinationImage, GL_RGBA8, size), bo, fd);
+}
+
+}
+

plugins/platforms/drm/gbm_dmabuf.h

@@ -0,0 +1,52 @@
+/*
+ * Copyright © 2020 Aleix Pol Gonzalez <aleixpol@kde.org>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors:
+ *       Aleix Pol Gonzalez <aleixpol@kde.org>
+ */
+
+#pragma once
+
+#include "dmabuftexture.h"
+#include <gbm.h>
+#include <QSize>
+#include <epoxy/egl.h>
+
+namespace KWin
+{
+
+class GbmDmaBuf : public DmaBufTexture
+{
+public:
+    ~GbmDmaBuf();
+
+    int fd() const override
+    {
+        return m_fd;
+    }
+    quint32 stride() const override {
+        return gbm_bo_get_stride(m_bo);
+    }
+
+    static GbmDmaBuf *createBuffer(const QSize &size, gbm_device *device);
+
+private:
+    GbmDmaBuf(GLTexture *texture, gbm_bo *bo, int fd);
+    struct gbm_bo *const m_bo;
+    const int m_fd;
+};
+
+}

plugins/platforms/wayland/CMakeLists.txt

@@ -3,6 +3,7 @@ set(WAYLAND_BACKEND_SOURCES
     scene_qpainter_wayland_backend.cpp
     wayland_backend.cpp
     wayland_output.cpp
+    ../drm/gbm_dmabuf.cpp
 )
 
 if (HAVE_WAYLAND_EGL)
@@ -15,7 +16,7 @@ set_target_properties(KWinWaylandWaylandBackend PROPERTIES LIBRARY_OUTPUT_DIRECT
 target_link_libraries(KWinWaylandWaylandBackend kwin KF5::WaylandClient SceneQPainterBackend)
 
 if (HAVE_WAYLAND_EGL)
-    target_link_libraries(KWinWaylandWaylandBackend SceneOpenGLBackend Wayland::Egl)
+    target_link_libraries(KWinWaylandWaylandBackend SceneOpenGLBackend Wayland::Egl gbm::gbm)
 endif()
 
 install(

plugins/platforms/wayland/wayland_backend.cpp

@@ -35,6 +35,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include "pointer_input.h"
 #include "screens.h"
 #include "wayland_server.h"
+#include "../drm/gbm_dmabuf.h"
 
 #include <config-kwin.h>
 
@@ -64,6 +65,9 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 #include <linux/input.h>
 #include <wayland-cursor.h>
+#include <unistd.h>
+#include <gbm.h>
+#include <fcntl.h>
 
 namespace KWin
 {
@@ -451,8 +455,18 @@ WaylandBackend::WaylandBackend(QObject *parent)
     , m_connectionThreadObject(new ConnectionThread(nullptr))
     , m_connectionThread(nullptr)
 {
-    connect(this, &WaylandBackend::connectionFailed, this, &WaylandBackend::initFailed);
     supportsOutputChanges();
+    connect(this, &WaylandBackend::connectionFailed, this, &WaylandBackend::initFailed);
+
+
+    char const *drm_render_node = "/dev/dri/renderD128";
+    m_drm_fd = open(drm_render_node, O_RDWR);
+    if (m_drm_fd < 0) {
+        qCWarning(KWIN_WAYLAND_BACKEND) << "Failed to open drm render node" << drm_render_node;
+        m_gbmDevice = nullptr;
+        return;
+    }
+    m_gbmDevice = gbm_create_device(m_drm_fd);
 }
 
 WaylandBackend::~WaylandBackend()
@@ -477,6 +491,8 @@ WaylandBackend::~WaylandBackend()
     m_connectionThread->quit();
     m_connectionThread->wait();
     m_connectionThreadObject->deleteLater();
+    gbm_device_destroy(m_gbmDevice);
+    close(m_drm_fd);
 
     qCDebug(KWIN_WAYLAND_BACKEND) << "Destroyed Wayland display";
 }
@@ -835,6 +851,11 @@ Outputs WaylandBackend::enabledOutputs() const
     return m_outputs;
 }
 
+DmaBufTexture *WaylandBackend::createDmaBufTexture(const QSize& size)
+{
+    return GbmDmaBuf::createBuffer(size, m_gbmDevice);
+}
+
 }
 
 } // KWin

plugins/platforms/wayland/wayland_backend.h

@@ -36,6 +36,7 @@ struct wl_buffer;
 struct wl_display;
 struct wl_event_queue;
 struct wl_seat;
+struct gbm_device;
 
 namespace KWayland
 {
@@ -184,6 +185,7 @@ public:
     Screens *createScreens(QObject *parent = nullptr) override;
     OpenGLBackend *createOpenGLBackend() override;
     QPainterBackend *createQPainterBackend() override;
+    DmaBufTexture *createDmaBufTexture(const QSize &size) override;
 
     void flush();
 
@@ -248,6 +250,8 @@ private:
     WaylandCursor *m_waylandCursor = nullptr;
 
     bool m_pointerLockRequested = false;
+    int m_drmFileDescriptor = 0;
+    gbm_device *m_gbmDevice;
 };
 
 inline