Missing FileDialog filter options

[b2soft]

There are only 2 options that can be used in filters for FileDialog - InitialFileName and Extensions

In WPF I can specify filter to choose only files named as "Name.exe" in this way:

OpenFileDialog dlg = new OpenFileDialog();

dlg.Filter = "Name.exe|Name.exe";

if (dlg.ShowDialog() == true)
{
...
}

Requesting to add missing FileDialog's filter options (based on WPF) to Avalonia

[grokys]

@kekekeks @danwalmsley can this reasonably be implemented on all our dialog backends?

[kekekeks]

OSX file dialogs don't use glob patterns and need a list of accepted file extensions or UTIs

[b2soft]

Is there any workaround to such a problem?

[kekekeks]

On OSX? No, I don't think we can restrict the system file dialog to use a fixed name.

[b2soft]

I'm targeting only Win and Linux, so OSX is not the case. What will be the best solution to have a strict filename inside file dialog (and not swtiching to WPF instead of avalonia)?

[kekekeks]

Copy-pasting dialog implementations and altering them to fit your needs, I guess.

https://github.com/AvaloniaUI/Avalonia/blob/master/src/Windows/Avalonia.Win32/SystemDialogImpl.cs

https://github.com/AvaloniaUI/Avalonia/blob/master/src/Avalonia.X11/NativeDialogs/GtkNativeFileDialogs.cs

[Toemsel]

            var fileExtensions = new List<string>() { $"dump|*.{fileExtension};" };
            var extensionFilter = new FileDialogFilter() { Extensions = fileExtensions };

            var dialog = new OpenFileDialog();
            dialog.AllowMultiple = false;
            dialog.Filters.Add(extensionFilter);
            await dialog.ShowAsync(DjiWindow.Instance);

Will throw an ArgumentException, as a filter has been defined. Without the filter it works just fine.

[chyyran]

Copy-pasting dialog implementations and altering them to fit your needs, I guess.

https://github.com/AvaloniaUI/Avalonia/blob/master/src/Windows/Avalonia.Win32/SystemDialogImpl.cs

https://github.com/AvaloniaUI/Avalonia/blob/master/src/Avalonia.X11/NativeDialogs/GtkNativeFileDialogs.cs

This is untenable because many of the internal APIs used are protected and inaccessible, and we end up needing to vendor a large chunk of Avalonia, not to mention requiring unsafe in the project just for fixed name filters.

A proper solution is needed on Windows and GTK for this. The alternative here is to drop down to WPF just for an OpenFileDialog that supports fixed name filters.

Edit: It seems like <UseWPF> is not necessary as long as the project targets `.netX.0-windows'. Doing so bloats the file size of a single file deployment though.

[maxkatz6]

Filter as it is in WPF won't be supported in Avalonia.
Instead, special FilePickerFileType will be used (as opposite of what's currently available):

class FilePickerFileType
{
    string Title { get; init; }
    // For desktop
    IReadOnlyList<string> Extensions {get; init; }
    // For web and android
    IReadOnlyList<string> MimeTypes {get; init; }
    // For Apple platforms
    IReadOnlyList<string> AppleUniformTypeIdentifiers {get; init; }
}

For more details see #7234 and #8303

[chyyran]

Will FilePickerFileType allow a fixed filename on supported platforms? There is already a specialization for Apple platforms for UTIs, so I don't see why this functionality would be left out when targeting only platforms where fixed filename filters are supported.

[maxkatz6]

You can set suggested file name and a type extension. Not much flexibility here with non-windows platforms.

[chyyran]

In addition to Windows, GTK also allows glob-style filters. It is only macOS and mobile/web platforms that do not support this.

There is already a specialization for Apple platforms with UTIs that are only relevant on macOS. It would not be difficult to add a property to support fixed filename filters on platforms that support it, which does not just include Windows.

[chyyran]

To be clear here I am not asking for full support of WPF style globs. Simply allowing the file picker to filter on a fixed name will already go a long way, and is well supported on both Windows and GTK.

[maxkatz6]

Well, I suppose glob pattern support won't be a problem as part of new API.

[chyyran]

If full support for globs made it in that would be great as well but just having support for fixed file names would already cover 95% of use cases when including the existing extension based filter.

The only thing is if extensions are only relevant for non-macOS desktop environments, then all such environments already support globs.