macOS: Report preedit cursor position and cursor visibility correctly

Unfortunately QInputMethodEvent::Cursor defines length == 0 as the
cursor being hidden, and length > 0 as being visible. This is the
opposite of what native macOS application do.

A future improvement here would be to base the QInputMethodEvent
logic on QStyle::SH_BlinkCursorWhenTextSelected, which we already
respect for normal selections. That would also allow us to use
QInputMethodEvent::Cursor to set the preedit selection, which
we currently have to fake via QInputMethodEvent::TextFormat.

Pick-to: 6.2
Change-Id: I75b5d8c5403283a0988355e440a98b4df35ec995
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

1 files changed, 9 insertions, 2 deletions

diff --git a/src/plugins/platforms/cocoa/qnsview_complextext.mm b/src/plugins/platforms/cocoa/qnsview_complextext.mm
index 05c0418ee7..39739d9725 100644
--- a/src/plugins/platforms/cocoa/qnsview_complextext.mm
+++ b/src/plugins/platforms/cocoa/qnsview_complextext.mm
@@ -185,9 +185,16 @@
     QString preeditString = QString::fromNSString(isAttributedString ? [text string] : text);
 
     QList<QInputMethodEvent::Attribute> preeditAttributes;
-    preeditAttributes << QInputMethodEvent::Attribute(
-        QInputMethodEvent::Cursor, selectedRange.location + selectedRange.length, true);
 
+    // The QInputMethodEvent::Cursor specifies that the length
+    // determines whether the cursor is visible or not, but uses
+    // logic opposite of that of native AppKit application, where
+    // the cursor is visible if there's no selection, and hidden
+    // if there's a selection. Instead of passing on the length
+    // directly we need to inverse the logic.
+    const bool showCursor = !selectedRange.length;
+    preeditAttributes << QInputMethodEvent::Attribute(
+        QInputMethodEvent::Cursor, selectedRange.location, showCursor);
 
     // QInputMethodEvent::Selection unfortunately doesn't apply to the
     // preedit text, and QInputMethodEvent::Cursor which does, doesn't