Harmonize input context selection

Input context selection works differently across platforms. On some
platforms it is not possible to request a specific context at all
(e.g. Wayland). This will be unified, depending on the environment
variable "QT_IM_MODULE", you will get:
- null:  default (platform) context, if defined (otherwise no context)
- empty: no context
- set:   set one, if it exists and is valid (otherwise no context)

[ChangeLog][Platform Specific Changes] Haromnized input context selection.
QT_IM_MODULE environment variable will be taken into account.

Change-Id: Ic8f826fbc6ace25941cd19b9b086943e848fbe01
Reviewed-by: Lars Knoll <lars.knoll@theqtcompany.com>
Reviewed-by: Nedim Hadzic <nedim.hadzic@pelagicore.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/src/plugins/platforms/xcb/qxcbintegration.cpp b/src/plugins/platforms/xcb/qxcbintegration.cpp
index fc06f1a7b0..9cedfa77ad 100644
--- a/src/plugins/platforms/xcb/qxcbintegration.cpp
+++ b/src/plugins/platforms/xcb/qxcbintegration.cpp
@@ -268,7 +268,10 @@ void QXcbIntegration::initialize()
 {
     // Perform everything that may potentially need the event dispatcher (timers, socket
     // notifiers) here instead of the constructor.
-    m_inputContext.reset(QPlatformInputContextFactory::create());
+    QString icStr = QPlatformInputContextFactory::requested();
+    if (icStr.isNull())
+        icStr = QLatin1String("compose");
+    m_inputContext.reset(QPlatformInputContextFactory::create(icStr));
 }
 
 void QXcbIntegration::moveToScreen(QWindow *window, int screen)