From 6972b8deea403261006714d9d7ab937bb39b792c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Tor=20Arne=20Vestb=C3=B8?= <tor.arne.vestbo@qt.io>
Date: Wed, 3 Jan 2024 19:08:02 +0100
Subject: [PATCH] macOS: Reset save dialog extension when resetting file name
 filter

We map QFileDialog name filters to NSSavePanel.allowedFileTypes, for
example turning "Text Files (*.txt)" into allowedFileTypes = @[@"txt"].
In this case, the NSSavePanel will automatically add the extension to
the user's file name, if they just type "foo".

When a filter allows all files, we reset the allowedFileTypes to nil,
but this does not reset the automatically added extension, so if the
user switches from one filter (*.txt) to another (*.*), the file name
will still have a .txt extension.

This is problematic when the save panel's file name field does not
show the extension to the user, which can happen automatically if
the user types an initial file name without an extension, overriding
what we've asked by setting extensionHidden=NO. When that happens,
the user is shown "foo", but the actual file name is "foo.txt".

To mitigate this confusing situation we do a round-trip via the
UTTypeDirectory content type, which is a valid type without any
extension. This forces the save panel to remove any extensions
added automatically by previous filters.

Change-Id: Ia17a8c2734eff656116ef77a9813113a5076e9cc
Reviewed-by: Timur Pocheptsov <timur.pocheptsov@qt.io>
(cherry picked from commit 40506954979fa7cdd34da8251f179557eb9be4f3)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
---
 cmake/QtFrameworkHelpers.cmake                |  1 +
 src/plugins/platforms/cocoa/CMakeLists.txt    |  1 +
 .../platforms/cocoa/qcocoafiledialoghelper.mm | 20 +++++++++++++++++++
 3 files changed, 22 insertions(+)

diff --git a/cmake/QtFrameworkHelpers.cmake b/cmake/QtFrameworkHelpers.cmake
index c546dcd5b87..c15f74e5422 100644
--- a/cmake/QtFrameworkHelpers.cmake
+++ b/cmake/QtFrameworkHelpers.cmake
@@ -37,6 +37,7 @@ macro(qt_find_apple_system_frameworks)
         qt_internal_find_apple_system_framework(FWContacts Contacts)
         qt_internal_find_apple_system_framework(FWEventKit EventKit)
         qt_internal_find_apple_system_framework(FWHealthKit HealthKit)
+        qt_internal_find_apple_system_framework(FWUniformTypeIdentifiers UniformTypeIdentifiers)
     endif()
 endmacro()
 
diff --git a/src/plugins/platforms/cocoa/CMakeLists.txt b/src/plugins/platforms/cocoa/CMakeLists.txt
index af8434daaa5..92e681d8fb7 100644
--- a/src/plugins/platforms/cocoa/CMakeLists.txt
+++ b/src/plugins/platforms/cocoa/CMakeLists.txt
@@ -56,6 +56,7 @@ qt_internal_add_plugin(QCocoaIntegrationPlugin
         ${FWIOSurface}
         ${FWMetal}
         ${FWQuartzCore}
+        ${FWUniformTypeIdentifiers}
         Qt::Core
         Qt::CorePrivate
         Qt::Gui
diff --git a/src/plugins/platforms/cocoa/qcocoafiledialoghelper.mm b/src/plugins/platforms/cocoa/qcocoafiledialoghelper.mm
index 24579c6c9a8..6a9612e73f8 100644
--- a/src/plugins/platforms/cocoa/qcocoafiledialoghelper.mm
+++ b/src/plugins/platforms/cocoa/qcocoafiledialoghelper.mm
@@ -27,6 +27,8 @@
 #include <qpa/qplatformtheme.h>
 #include <qpa/qplatformnativeinterface.h>
 
+#include <UniformTypeIdentifiers/UniformTypeIdentifiers.h>
+
 QT_USE_NAMESPACE
 
 using namespace Qt::StringLiterals;
@@ -438,6 +440,24 @@ typedef QSharedPointer<QFileDialogOptions> SharedPointerFileDialogOptions;
 
     m_panel.allowedFileTypes = [self computeAllowedFileTypes];
 
+    // Setting allowedFileTypes to nil is not enough to reset any
+    // automatically added extension based on a previous filter.
+    // This is problematic because extensions can in some cases
+    // be hidden from the user, resulting in confusion when the
+    // resulting file name doesn't match the current empty filter.
+    // We work around this by temporarily resetting the allowed
+    // content type to one without an extension, which forces
+    // the save panel to update and remove the extension.
+    const bool nameFieldHasExtension = m_panel.nameFieldStringValue.pathExtension.length > 0;
+    if (!m_panel.allowedFileTypes && !nameFieldHasExtension && !openpanel_cast(m_panel)) {
+        if (!UTTypeDirectory.preferredFilenameExtension) {
+            m_panel.allowedContentTypes = @[ UTTypeDirectory ];
+            m_panel.allowedFileTypes = nil;
+        } else {
+            qWarning() << "UTTypeDirectory unexpectedly reported an extension";
+        }
+    }
+
     m_panel.showsHiddenFiles = m_options->filter().testFlag(QDir::Hidden);
 
     if (m_panel.visible)