Add QT_IM_MODULES env to allows specify multi IM key

Like as QT_QPA_PLATFORM, supports specifying multiple keys, and can
perform fallback operations to prioritize the use of a certain plug-in.
This is useful when using Wayland and XWayland applications at the same
time. For an example, we can set "QT_IM_MODULES=wayland;fcitx", and the
wayland application will use the wayland input context plugin, the
xwayland application will use fcitx, which can't be done without adding
a new environment variable, if we specify "QT_IM_MODULE=wayland", the
XWayland applications may not be able to use the input method.

Fixes: QTBUG-120202
Change-Id: Iac408af241963147747a2fe685f1e27bf9d9ee64
Reviewed-by: Liang Qi <[email protected]>
Reviewed-by: Tor Arne Vestbø <[email protected]>
Reviewed-by: David Edmundson <[email protected]>

1 files changed, 26 insertions, 3 deletions

diff --git a/src/gui/kernel/qplatforminputcontextfactory.cpp b/src/gui/kernel/qplatforminputcontextfactory.cpp
index 7074de56afa..933d990f7c9 100644
--- a/src/gui/kernel/qplatforminputcontextfactory.cpp
+++ b/src/gui/kernel/qplatforminputcontextfactory.cpp
@@ -28,10 +28,33 @@ QStringList QPlatformInputContextFactory::keys()
 #endif
 }
 
-QString QPlatformInputContextFactory::requested()
+QStringList QPlatformInputContextFactory::requested()
 {
-    QByteArray env = qgetenv("QT_IM_MODULE");
-    return env.isNull() ? QString() : QString::fromLocal8Bit(env);
+    QStringList imList;
+    QByteArray env = qgetenv("QT_IM_MODULES");
+
+    if (!env.isEmpty())
+        imList = QString::fromLocal8Bit(env).split(QChar::fromLatin1(';'), Qt::SkipEmptyParts);
+
+    if (!imList.isEmpty())
+        return imList;
+
+    env = qgetenv("QT_IM_MODULE");
+    if (!env.isEmpty())
+        imList = {QString::fromLocal8Bit(env)};
+
+    return imList;
+}
+
+QPlatformInputContext *QPlatformInputContextFactory::create(const QStringList& keys)
+{
+    for (const QString &key : keys) {
+        auto plugin = create(key);
+        if (plugin)
+            return plugin;
+    }
+
+    return nullptr;
 }
 
 QPlatformInputContext *QPlatformInputContextFactory::create(const QString& key)