eglfs: Add support for raster content rotation

Running QWidget or other raster window-based apps with
QT_QPA_EGLFS_ROTATION=180 will now flip the screen as expected.

In addition, 90 and -90 are supported too. These will affect the
reported screen geometry as well.

The OpenGL mouse cursor is repositioned and rotated accordingly. For
true OpenGL content the rotation is ignored. Hardware mouse cursors
(DRM) ignore it as well for the time being.

[ChangeLog][Platform Specific Changes] QWidget-based applications
running on the eglfs platform plugin can now request 180 or 90 degrees
rotated output by setting the QT_QPA_EGLFS_ROTATION environment
variable.

Task-number: QTBUG-39959
Change-Id: I3570b515d0233c6c6a0e813899b935ee222eab62
Reviewed-by: Andy Nichols <andy.nichols@qt.io>

1 files changed, 25 insertions, 0 deletions

diff --git a/src/plugins/platforms/eglfs/api/qeglfsscreen.cpp b/src/plugins/platforms/eglfs/api/qeglfsscreen.cpp
index d636a783ec..47ef2f64e7 100644
--- a/src/plugins/platforms/eglfs/api/qeglfsscreen.cpp
+++ b/src/plugins/platforms/eglfs/api/qeglfsscreen.cpp
@@ -65,6 +65,31 @@ QEglFSScreen::~QEglFSScreen()
 
 QRect QEglFSScreen::geometry() const
 {
+    QRect r = geometryForSurface();
+
+    static int rotation = qEnvironmentVariableIntValue("QT_QPA_EGLFS_ROTATION");
+    switch (rotation) {
+    case 0:
+    case 180:
+    case -180:
+        break;
+    case 90:
+    case -90: {
+        int h = r.height();
+        r.setHeight(r.width());
+        r.setWidth(h);
+        break;
+    }
+    default:
+        qWarning("Invalid rotation %d specified in QT_QPA_EGLFS_ROTATION", rotation);
+        break;
+    }
+
+    return r;
+}
+
+QRect QEglFSScreen::geometryForSurface() const
+{
     return QRect(QPoint(0, 0), qt_egl_device_integration()->screenSize());
 }