Android: work around input method cursor position bug

Since the Qt input method queries only give us information
on the position within the block, moving to the same position
in a different block will be interpreted as not moving.

The quick fix is to send a fake position before the real one in
this case.

Task-number: QTBUG-34845
Change-Id: I5d62bdffc283e41d0384c60a0b69c01811caa629
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@digia.com>
Reviewed-by: BogDan Vatra <bogdan@kde.org>

1 files changed, 20 insertions, 0 deletions

diff --git a/src/plugins/platforms/android/src/androidjniinput.cpp b/src/plugins/platforms/android/src/androidjniinput.cpp
index 27d29129f8..8ce95532d3 100644
--- a/src/plugins/platforms/android/src/androidjniinput.cpp
+++ b/src/plugins/platforms/android/src/androidjniinput.cpp
@@ -67,12 +67,32 @@ namespace QtAndroidInput
 
     static QPointer<QWindow> m_mouseGrabber;
 
+    static int m_lastCursorPos = -1;
+
     void updateSelection(int selStart, int selEnd, int candidatesStart, int candidatesEnd)
     {
         AttachedJNIEnv env;
         if (!env.jniEnv)
             return;
 
+#ifdef QT_DEBUG_ANDROID_IM_PROTOCOL
+        qDebug() << ">>> UPDATESELECTION" << selStart << selEnd << candidatesStart << candidatesEnd;
+#endif
+        if (candidatesStart == -1 && candidatesEnd == -1 && selStart == selEnd) {
+            // Qt only gives us position inside the block, so if we move to the
+            // same position in another block, the Android keyboard will believe
+            // we have not changed position, and be terribly confused.
+            if (selStart == m_lastCursorPos) {
+#ifdef QT_DEBUG_ANDROID_IM_PROTOCOL
+                qDebug() << ">>> FAKEUPDATESELECTION" << selStart+1;
+#endif
+                env.jniEnv->CallStaticVoidMethod(applicationClass(), m_updateSelectionMethodID,
+                                         selStart+1, selEnd+1, candidatesStart, candidatesEnd);
+            }
+            m_lastCursorPos = selStart;
+        } else {
+            m_lastCursorPos = -1;
+        }
         env.jniEnv->CallStaticVoidMethod(applicationClass(), m_updateSelectionMethodID,
                                          selStart, selEnd, candidatesStart, candidatesEnd);
     }