macOS: Handle replacement range during marking of text

The input method may include already committed text when marking text,
in which case the replacement range reflects the position and length
of the existing text.

We handle this the same way we do replacement ranges in insertText.

Change-Id: I148e4701318a59c7e0d9441d157199d7c8606f43
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
(cherry picked from commit a56b915f71eb5ceb10b6c2c585eefb88657f4abf)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

1 files changed, 16 insertions, 0 deletions

diff --git a/src/plugins/platforms/cocoa/qnsview_complextext.mm b/src/plugins/platforms/cocoa/qnsview_complextext.mm
index d9df96e0cd..2d9a42cd74 100644
--- a/src/plugins/platforms/cocoa/qnsview_complextext.mm
+++ b/src/plugins/platforms/cocoa/qnsview_complextext.mm
@@ -228,12 +228,28 @@
         index = range.location + range.length;
     }
 
+    // Ensure we have a valid replacement range
+    replacementRange = [self sanitizeReplacementRange:replacementRange];
+
+    // Qt's QInputMethodEvent has different semantics for the replacement
+    // range than AppKit does, so we need to sanitize the range first.
+    auto [replaceFrom, replaceLength] = [self inputMethodRangeForRange:replacementRange];
+
+    // Update the composition, now that we've computed the replacement range
     m_composingText = preeditString;
 
     if (QObject *focusObject = m_platformWindow->window()->focusObject()) {
         m_composingFocusObject = focusObject;
         if (queryInputMethod(focusObject)) {
             QInputMethodEvent event(preeditString, preeditAttributes);
+            if (replaceLength > 0) {
+                // The input method may extend the preedit into already
+                // committed text. If so, we need to replace existing text
+                // by committing an empty string.
+                qCDebug(lcQpaKeys) << "Replacing from" << replaceFrom << "with length"
+                    << replaceLength << "based on replacement range" << replacementRange;
+                event.setCommitString(QString(), replaceFrom, replaceLength);
+            }
             QCoreApplication::sendEvent(focusObject, &event);
             // prevent handleKeyEvent from sending a key event
             m_sendKeyEvent = false;