Add a WindowManagement capability to QPlatformIntegration

To be set to false by eglfs and similar platforms where no real window
management is provided.

When this capability is not set, some of the changes done for
QTBUG-26903 will be disabled, allowing dialogs to show up at their
QDialog-chosen place on platforms where no WM is present and so
windows are never repositioned by the system.

Change-Id: If1dac3cd11f2a856913a51277431fe3ec644b719
Reviewed-by: Gunnar Sletta <gunnar.sletta@digia.com>

4 files changed, 13 insertions, 4 deletions

diff --git a/src/gui/kernel/qplatformintegration.cpp b/src/gui/kernel/qplatformintegration.cpp
index 06d2aa4fca..dc775bcb61 100644
--- a/src/gui/kernel/qplatformintegration.cpp
+++ b/src/gui/kernel/qplatformintegration.cpp
@@ -224,6 +224,11 @@ QPlatformServices *QPlatformIntegration::services() const
     fill the screen. The default implementation returns true. Returning false for
     this will cause all windows, including dialogs and popups, to be resized to fill the
     screen.
+
+    \value WindowManagement The platform is based on a system that performs window
+    management.  This includes the typical desktop platforms. Can be set to false on
+    platforms where no window management is available, meaning for example that windows
+    are never repositioned by the window manager. The default implementation returns true.
  */
 
 
@@ -241,7 +246,7 @@ QPlatformServices *QPlatformIntegration::services() const
 
 bool QPlatformIntegration::hasCapability(Capability cap) const
 {
-    return cap == NonFullScreenWindows || cap == NativeWidgets;
+    return cap == NonFullScreenWindows || cap == NativeWidgets || cap == WindowManagement;
 }
 
 QPlatformPixmap *QPlatformIntegration::createPlatformPixmap(QPlatformPixmap::PixelType type) const
diff --git a/src/gui/kernel/qplatformintegration.h b/src/gui/kernel/qplatformintegration.h
index a98d332356..0204181ca6 100644
--- a/src/gui/kernel/qplatformintegration.h
+++ b/src/gui/kernel/qplatformintegration.h
@@ -93,7 +93,8 @@ public:
         ApplicationState,
         ForeignWindows,
         NonFullScreenWindows,
-        NativeWidgets
+        NativeWidgets,
+        WindowManagement
     };
 
     virtual ~QPlatformIntegration() { }
diff --git a/src/plugins/platforms/eglfs/qeglfsintegration.cpp b/src/plugins/platforms/eglfs/qeglfsintegration.cpp
index 12658e6d01..14b839c2dd 100644
--- a/src/plugins/platforms/eglfs/qeglfsintegration.cpp
+++ b/src/plugins/platforms/eglfs/qeglfsintegration.cpp
@@ -134,6 +134,7 @@ bool QEglFSIntegration::hasCapability(QPlatformIntegration::Capability cap) cons
     case ThreadedPixmaps: return true;
     case OpenGL: return true;
     case ThreadedOpenGL: return true;
+    case WindowManagement: return false;
     default: return QPlatformIntegration::hasCapability(cap);
     }
 }
diff --git a/src/widgets/kernel/qwidget_qpa.cpp b/src/widgets/kernel/qwidget_qpa.cpp
index a06283be02..ae8a0b25b9 100644
--- a/src/widgets/kernel/qwidget_qpa.cpp
+++ b/src/widgets/kernel/qwidget_qpa.cpp
@@ -110,7 +110,8 @@ void QWidgetPrivate::create_sys(WId window, bool initializeWindow, bool destroyO
 
     win->setFlags(data.window_flags);
     fixPosIncludesFrame();
-    if (q->testAttribute(Qt::WA_Moved))
+    if (q->testAttribute(Qt::WA_Moved)
+        || !QGuiApplicationPrivate::platformIntegration()->hasCapability(QPlatformIntegration::WindowManagement))
         win->setGeometry(q->geometry());
     else
         win->resize(q->size());
@@ -530,7 +531,8 @@ void QWidgetPrivate::show_sys()
         }
         const QRect windowRect = window->geometry();
         if (windowRect != geomRect) {
-            if (q->testAttribute(Qt::WA_Moved))
+            if (q->testAttribute(Qt::WA_Moved)
+                || !QGuiApplicationPrivate::platformIntegration()->hasCapability(QPlatformIntegration::WindowManagement))
                 window->setGeometry(geomRect);
             else
                 window->resize(geomRect.size());