Android: Don't crash when displaying multiple top-levels

While the raster platform plugin supports multiple top
level windows, this is not supported on the GL plugin,
so if you use GL or QtQuick2 in your app and use several
top levels, the app would crash with an error message.

A problem is that the top-level SurfaceView is a special
overlay View and does not support being stacked in a
layout. So instead, we let all windows share the same
GL surface and draw on top of each other. This works
fine for simple use cases.

We implement a new platform capability to make sure no
top level windows (even combobox popups and dialogs)
get non-fullscreen geometries. That has never
worked properly with the eglfs plugin.

Task-number: QTBUG-30473
Change-Id: Ia1438019638fc739cc93ffe79b46b81631254df2
Reviewed-by: Paul Olav Tvete <paul.tvete@digia.com>

1 files changed, 6 insertions, 2 deletions

diff --git a/src/gui/kernel/qplatformintegration.cpp b/src/gui/kernel/qplatformintegration.cpp
index 70de75072c..8a0540efc2 100644
--- a/src/gui/kernel/qplatformintegration.cpp
+++ b/src/gui/kernel/qplatformintegration.cpp
@@ -210,6 +210,11 @@ QPlatformServices *QPlatformIntegration::services() const
     \value ForeignWindows The platform allows creating QWindows which represent
     native windows created by other processes or anyway created by using native
     libraries.
+
+    \value NonFullScreenWindows The platform supports top-level windows which do not
+    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.
  */
 
 
@@ -227,8 +232,7 @@ QPlatformServices *QPlatformIntegration::services() const
 
 bool QPlatformIntegration::hasCapability(Capability cap) const
 {
-    Q_UNUSED(cap);
-    return false;
+    return cap == NonFullScreenWindows;
 }
 
 QPlatformPixmap *QPlatformIntegration::createPlatformPixmap(QPlatformPixmap::PixelType type) const