Set orientation from DRM on fallback

Summary:
In case of a failed atomic commit the previous mode should be fallen back to.
For orientation provide again a setter that DRM backend can use to set the
transform back to the last working one.

Test Plan: Compiles, fallback works, cursor still messed up somewhat (scaling issue?).

Reviewers: #kwin

Subscribers: zzag, kwin

Tags: #kwin

Maniphest Tasks: T11670

Differential Revision: https://phabricator.kde.org/D25507

abstract_wayland_output.cpp

@@ -308,6 +308,47 @@ QSize AbstractWaylandOutput::orientateSize(const QSize &size) const
     return size;
 }
 
+DeviceInterface::Transform toTransform(Qt::ScreenOrientations orientation)
+{
+    if (orientation | Qt::LandscapeOrientation) {
+        if (orientation | Qt::InvertedPortraitOrientation) {
+            return DeviceInterface::Transform::Flipped;
+        }
+        return DeviceInterface::Transform::Normal;
+    }
+
+    if (orientation | Qt::PortraitOrientation) {
+        if (orientation | Qt::InvertedLandscapeOrientation) {
+            if (orientation | Qt::InvertedPortraitOrientation) {
+                return DeviceInterface::Transform::Flipped270;
+            }
+            return DeviceInterface::Transform::Flipped90;
+        }
+        return DeviceInterface::Transform::Rotated90;
+    }
+
+    if (orientation | Qt::InvertedLandscapeOrientation) {
+        return DeviceInterface::Transform::Rotated180;
+    }
+
+    if (orientation | Qt::InvertedPortraitOrientation) {
+        return DeviceInterface::Transform::Rotated270;
+    }
+
+    Q_ASSERT(orientation == Qt::PrimaryOrientation);
+    return DeviceInterface::Transform::Normal;
+}
+
+void AbstractWaylandOutput::setOrientation(Qt::ScreenOrientations orientation)
+{
+    const auto transform = toTransform(orientation);
+    if (transform == m_waylandOutputDevice->transform()) {
+        return;
+    }
+    setTransform(transform);
+    emit modeChanged();
+}
+
 Qt::ScreenOrientations AbstractWaylandOutput::orientation() const
 {
     const DeviceInterface::Transform transform = m_waylandOutputDevice->transform();

abstract_wayland_output.h

@@ -141,7 +141,7 @@ protected:
 
     void setWaylandMode(const QSize &size, int refreshRate);
 
-    void setTransform(KWayland::Server::OutputDeviceInterface::Transform transform);
+    void setOrientation(Qt::ScreenOrientations orientation);
     QSize orientateSize(const QSize &size) const;
 
     /**
@@ -159,6 +159,8 @@ private:
     void createWaylandOutput();
     void createXdgOutput();
 
+    void setTransform(KWayland::Server::OutputDeviceInterface::Transform transform);
+
     QPointer<KWayland::Server::OutputInterface> m_waylandOutput;
     QPointer<KWayland::Server::XdgOutputInterface> m_xdgOutput;
     QPointer<KWayland::Server::OutputDeviceInterface> m_waylandOutputDevice;

plugins/platforms/drm/drm_output.cpp

@@ -841,10 +841,7 @@ bool DrmOutput::presentAtomically(DrmBuffer *buffer)
         // go back to previous state
         if (m_lastWorkingState.valid) {
             m_mode = m_lastWorkingState.mode;
-
-            // TODO: Add API back to set orientation from backend
-//            setOrientation(m_lastWorkingState.orientation);
-
+            setOrientation(m_lastWorkingState.orientation);
             setGlobalPos(m_lastWorkingState.globalPos);
             if (m_primaryPlane) {
                 m_primaryPlane->setTransformation(m_lastWorkingState.planeTransformations);