Fix UI mismatch when QPrinter::setDuplex

Amends fa854f214a3c812e5548ff55d179dd07ef99053b. If user call
QPrinter::setDuplex method, the QPrintDialog explicitDuplexMode value
won't update.

Fix this by:
1) handle device-specific default and value set in QPrinter in
QCupsPrintEngine(Private)
2) handle the explicitly user-selected value in QPrintDialog(Private)

Done-with: Michael Weghorn <m.weghorn@posteo.de>
Fixes: QTBUG-99504
Change-Id: I1a471a8554e83aa4bec8bb95fcc95f9135b0ac8c
Reviewed-by: Michael Weghorn <m.weghorn@posteo.de>
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
(cherry picked from commit 72931f492092a67c39cd7fb124d54e8752ee4933)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

1 files changed, 4 insertions, 3 deletions

diff --git a/src/printsupport/dialogs/qprintdialog_unix.cpp b/src/printsupport/dialogs/qprintdialog_unix.cpp
index 7de8ec05f3..dbebd03719 100644
--- a/src/printsupport/dialogs/qprintdialog_unix.cpp
+++ b/src/printsupport/dialogs/qprintdialog_unix.cpp
@@ -708,13 +708,14 @@ void QPrintDialogPrivate::selectPrinter(const QPrinter::OutputFormat outputForma
         else
             options.grayscale->setChecked(true);
 
-        // keep duplex value explicitly set by user, if any, and selected printer supports it;
-        // use device default otherwise
+        // duplex priorities to be as follows:
+        // 1) a user-selected duplex value in the dialog has highest prority
+        // 2) duplex value set in the QPrinter
         QPrint::DuplexMode duplex;
         if (explicitDuplexMode != QPrint::DuplexAuto && supportedDuplexMode.contains(explicitDuplexMode))
             duplex = explicitDuplexMode;
         else
-            duplex = top->d->m_currentPrintDevice.defaultDuplexMode();
+            duplex = static_cast<QPrint::DuplexMode>(p->duplex());
         switch (duplex) {
         case QPrint::DuplexNone:
             options.noDuplex->setChecked(true); break;