backends/drm: port qpainter to layers

src/backends/drm/CMakeLists.txt

@@ -18,6 +18,7 @@ set(DRM_SOURCES
     drm_abstract_output.cpp
     drm_virtual_output.cpp
     drm_lease_output.cpp
+    drm_qpainter_layer.cpp
     egl_gbm_backend.cpp
     egl_gbm_layer.cpp
     drm_buffer_gbm.cpp

src/backends/drm/drm_layer.h

@@ -0,0 +1,47 @@
+/*
+    KWin - the KDE window manager
+    This file is part of the KDE project.
+
+    SPDX-FileCopyrightText: 2022 Xaver Hugl <xaver.hugl@gmail.com>
+
+    SPDX-License-Identifier: GPL-2.0-or-later
+*/
+#pragma once
+
+#include <optional>
+#include <QRegion>
+#include <QSharedPointer>
+
+namespace KWin
+{
+
+class SurfaceItem;
+class DrmBuffer;
+class DrmAbstractOutput;
+
+class DrmLayer
+{
+public:
+    virtual ~DrmLayer() = default;
+
+    virtual std::optional<QRegion> startRendering() = 0;
+    virtual bool endRendering(const QRegion &damagedRegion) = 0;
+
+    /**
+     * attempts to directly scan out the current buffer of the surfaceItem
+     * @returns true if scanout was successful
+     *          false if rendering is required
+     */
+    virtual bool scanout(SurfaceItem *surfaceItem) = 0;
+
+    /**
+     * @returns a buffer for atomic test commits
+     * If no fitting buffer is available, a new current buffer is created
+     */
+    virtual QSharedPointer<DrmBuffer> testBuffer() = 0;
+
+    virtual QSharedPointer<DrmBuffer> currentBuffer() const = 0;
+    virtual DrmAbstractOutput *output() const = 0;
+};
+
+}

src/backends/drm/drm_qpainter_layer.cpp

@@ -0,0 +1,71 @@
+/*
+    KWin - the KDE window manager
+    This file is part of the KDE project.
+
+    SPDX-FileCopyrightText: 2022 Xaver Hugl <xaver.hugl@gmail.com>
+
+    SPDX-License-Identifier: GPL-2.0-or-later
+*/
+#include "drm_qpainter_layer.h"
+#include "dumb_swapchain.h"
+#include "drm_abstract_output.h"
+#include "drm_buffer.h"
+
+#include <drm_fourcc.h>
+
+namespace KWin
+{
+
+DrmQPainterLayer::DrmQPainterLayer(DrmAbstractOutput *output)
+    : m_output(output)
+{
+}
+
+std::optional<QRegion> DrmQPainterLayer::startRendering()
+{
+    if (!doesSwapchainFit()) {
+        m_swapchain = QSharedPointer<DumbSwapchain>::create(m_output->gpu(), m_output->sourceSize(), DRM_FORMAT_XRGB8888);
+    }
+    QRegion needsRepaint;
+    if (!m_swapchain->acquireBuffer(m_output->geometry(), &needsRepaint)) {
+        return std::optional<QRegion>();
+    }
+    return needsRepaint;
+}
+
+bool DrmQPainterLayer::endRendering(const QRegion &damagedRegion)
+{
+    m_swapchain->releaseBuffer(m_swapchain->currentBuffer(), damagedRegion);
+    return true;
+}
+
+bool DrmQPainterLayer::scanout(SurfaceItem *surfaceItem)
+{
+    Q_UNUSED(surfaceItem);
+    return false;
+}
+
+QSharedPointer<DrmBuffer> DrmQPainterLayer::testBuffer()
+{
+    if (!doesSwapchainFit()) {
+        m_swapchain = QSharedPointer<DumbSwapchain>::create(m_output->gpu(), m_output->sourceSize(), DRM_FORMAT_XRGB8888);
+    }
+    return m_swapchain->currentBuffer();
+}
+
+bool DrmQPainterLayer::doesSwapchainFit() const
+{
+    return m_swapchain && m_swapchain->size() == m_output->sourceSize();
+}
+
+QSharedPointer<DrmBuffer> DrmQPainterLayer::currentBuffer() const
+{
+    return m_swapchain ? m_swapchain->currentBuffer() : nullptr;
+}
+
+DrmAbstractOutput *DrmQPainterLayer::output() const
+{
+    return m_output;
+}
+
+}

src/backends/drm/drm_qpainter_layer.h

@@ -0,0 +1,35 @@
+/*
+    KWin - the KDE window manager
+    This file is part of the KDE project.
+
+    SPDX-FileCopyrightText: 2022 Xaver Hugl <xaver.hugl@gmail.com>
+
+    SPDX-License-Identifier: GPL-2.0-or-later
+*/
+#pragma once
+#include "drm_layer.h"
+
+namespace KWin
+{
+
+class DumbSwapchain;
+
+class DrmQPainterLayer : public DrmLayer {
+public:
+    DrmQPainterLayer(DrmAbstractOutput *output);
+
+    std::optional<QRegion> startRendering() override;
+    bool endRendering(const QRegion &damagedRegion) override;
+    bool scanout(SurfaceItem *surfaceItem) override;
+    QSharedPointer<DrmBuffer> testBuffer() override;
+    QSharedPointer<DrmBuffer> currentBuffer() const override;
+    DrmAbstractOutput *output() const override;
+
+private:
+    bool doesSwapchainFit() const;
+
+    QSharedPointer<DumbSwapchain> m_swapchain;
+    DrmAbstractOutput *const m_output;
+};
+
+}

src/backends/drm/egl_gbm_layer.h

@@ -7,6 +7,7 @@
     SPDX-License-Identifier: GPL-2.0-or-later
 */
 #pragma once
+#include "drm_layer.h"
 
 #include <QSharedPointer>
 #include <QPointer>
@@ -33,35 +34,20 @@ class DrmGpu;
 class SurfaceItem;
 class GLTexture;
 
-class EglGbmLayer {
+class EglGbmLayer : public DrmLayer
+{
 public:
     EglGbmLayer(DrmGpu *renderGpu, DrmAbstractOutput *output);
     ~EglGbmLayer();
 
-    std::optional<QRegion> startRendering();
-    bool endRendering(const QRegion &damagedRegion);
-
-    /**
-     * attempts to directly scan out the current buffer of the surfaceItem
-     * @returns true if scanout was successful
-     *          false if rendering is required
-     */
-    bool scanout(SurfaceItem *surfaceItem);
-
-    /**
-     * @returns a buffer for atomic test commits
-     * If no fitting buffer is available, one is created
-     */
-    QSharedPointer<DrmBuffer> testBuffer();
-
-    /**
-     * only temporarily here, should be migrated out!
-     */
+    std::optional<QRegion> startRendering() override;
+    bool endRendering(const QRegion &damagedRegion) override;
+    bool scanout(SurfaceItem *surfaceItem) override;
+    QSharedPointer<DrmBuffer> testBuffer() override;
+    QSharedPointer<DrmBuffer> currentBuffer() const override;
     QSharedPointer<GLTexture> texture() const;
 
-    QSharedPointer<DrmBuffer> currentBuffer() const;
-
-    DrmAbstractOutput *output() const;
+    DrmAbstractOutput *output() const override;
     int bufferAge() const;
     EGLSurface eglSurface() const;
 

src/backends/drm/scene_qpainter_drm_backend.cpp

@@ -12,6 +12,7 @@
 #include "drm_gpu.h"
 #include "drm_buffer.h"
 #include "renderloop_p.h"
+#include "drm_qpainter_layer.h"
 
 #include <drm_fourcc.h>
 
@@ -22,6 +23,9 @@ DrmQPainterBackend::DrmQPainterBackend(DrmBackend *backend)
     : QPainterBackend()
     , m_backend(backend)
 {
+    connect(m_backend, &DrmBackend::outputEnabled, this, [this] (const auto output) {
+        m_swapchains[output] = QSharedPointer<DrmQPainterLayer>::create(static_cast<DrmAbstractOutput*>(output));
+    });
     connect(m_backend, &DrmBackend::outputDisabled, this, [this] (const auto output) {
         m_swapchains.remove(output);
     });
@@ -29,26 +33,19 @@ DrmQPainterBackend::DrmQPainterBackend(DrmBackend *backend)
 
 QImage *DrmQPainterBackend::bufferForScreen(AbstractOutput *output)
 {
-    return m_swapchains[output]->currentBuffer()->image();
+    return static_cast<DrmDumbBuffer*>(m_swapchains[output]->currentBuffer().data())->image();
 }
 
 QRegion DrmQPainterBackend::beginFrame(AbstractOutput *output)
 {
-    const auto drmOutput = static_cast<DrmAbstractOutput*>(output);
-    if (!m_swapchains[output] || m_swapchains[output]->size() != drmOutput->sourceSize()) {
-        m_swapchains[output] = QSharedPointer<DumbSwapchain>::create(drmOutput->gpu(), drmOutput->sourceSize(), DRM_FORMAT_XRGB8888);
-    }
-    QRegion needsRepainting;
-    m_swapchains[output]->acquireBuffer(output->geometry(), &needsRepainting);
-    return needsRepainting;
+    return m_swapchains[output]->startRendering().value_or(QRegion());
 }
 
 void DrmQPainterBackend::endFrame(AbstractOutput *output, const QRegion &renderedRegion, const QRegion &damage)
 {
     Q_UNUSED(renderedRegion)
-    QSharedPointer<DrmDumbBuffer> back = m_swapchains[output]->currentBuffer();
-    m_swapchains[output]->releaseBuffer(back, damage);
-    static_cast<DrmAbstractOutput*>(output)->present(back, output->geometry());
+    m_swapchains[output]->endRendering(damage);
+    static_cast<DrmAbstractOutput*>(output)->present(m_swapchains[output]->currentBuffer(), output->geometry());
 }
 
 }

src/backends/drm/scene_qpainter_drm_backend.h

@@ -20,9 +20,8 @@ namespace KWin
 {
 
 class DrmBackend;
-class DrmDumbBuffer;
 class DrmAbstractOutput;
-class DrmGpu;
+class DrmQPainterLayer;
 
 class DrmQPainterBackend : public QPainterBackend
 {
@@ -35,7 +34,7 @@ public:
     void endFrame(AbstractOutput *output, const QRegion &renderedRegion, const QRegion &damagedRegion) override;
 
 private:
-    QMap<AbstractOutput *, QSharedPointer<DumbSwapchain>> m_swapchains;
+    QMap<AbstractOutput *, QSharedPointer<DrmQPainterLayer>> m_swapchains;
     DrmBackend *m_backend;
 };
 }