File Picker Options

Common PickerOptions

Title

Gets or sets the text that appears in the title bar of a picker.

SuggestedStartLocation

Gets or sets the initial location where the file open picker looks for files to present to the user. Can be obtained from previously picked folder or using StorageProvider.TryGetFolderFromPathAsync or StorageProvider.TryGetWellKnownFolderAsync.

note

This is a suggestion for the system, that can ignore this parameter, if application doesn't have access to the folder or it doesn't exist.

note

On Linux some DBus file picker don't support start location. For using GTK Free Desktop disable UseDBusFilePicker in X11PlatformOptions

FilePickerOpenOptions

AllowMultiple

Gets or sets an option indicating whether open picker allows users to select multiple files.

FileTypeFilter

Gets or sets the collection of file types that the file open picker displays.

To create a list of file types for the file picker:

//This can also be applied for SaveFilePicker.
var files = await _target.StorageProvider.OpenFilePickerAsync(new FilePickerOpenOptions()
{
 Title = title,
//You can add either custom or from the built-in file types. See "Defining custom file types" on how to create a custom one.
 FileTypeFilter = new[] { ImageAll, FilePickerFileTypes.TextPlain }
});

FilePickerSaveOptions

SuggestedFileName

Gets or sets the file name that the file save picker suggests to the user.

DefaultExtension

Gets or sets the default extension to be used to save the file.

FileTypeChoices

Gets or sets the collection of valid file types that the user can choose to assign to a file.

ShowOverwritePrompt

Gets or sets a value indicating whether file open picker displays a warning if the user specifies the name of a file that already exists.

FolderPickerOpenOptions

AllowMultiple

Gets or sets an option indicating whether open picker allows users to select multiple folders.

Platform compatibility:

Feature	Managed	Windows	macOS	Linux	Browser	Android	iOS
Title	✔	✔	✔	✔	✖	✔	✔
SuggestedStartLocation	✔	✔	✔	✔	✔	✔	✔
AllowMultiple	✔	✔	✔	✔	✔	✔	✔
FileTypeFilter	✔	✔	✔	✔	✔	✔	✔
SuggestedFileName	✔	✔	✔	✔	✔	✔	✖
DefaultExtension	✔	✔	✔	✔	✔	✔	✖
FileTypeChoices	✔	✔	✔	✔	✔	✔	✖
ShowOverwritePrompt	✔	✔	✖	✔	✖	✖	✖

Defining custom file types

Avalonia has set of built-in file types:

• FilePickerFileTypes.All - all files
• FilePickerFileTypes.TextPlain - txt files
• FilePickerFileTypes.ImageAll - all images
• FilePickerFileTypes.ImageJpg - jpg images
• FilePickerFileTypes.ImagePng - png images
• FilePickerFileTypes.ImageWebP - webp images
• FilePickerFileTypes.Pdf - pdf documents

However it is possible to define custom file types that can be used by the picker.

For instance, the built-in ImageAll type is defined as:

public static FilePickerFileType ImageAll { get; } = new("All Images")
{
    Patterns = new[] { "*.png", "*.jpg", "*.jpeg", "*.gif", "*.bmp", "*.webp" },
    AppleUniformTypeIdentifiers = new[] { "public.image" },
    MimeTypes = new[] { "image/*" }
};

Where each file type has the following hints that are used by the different platforms:

• Patterns are used by most Windows, Linux and Browser platforms, and is a basic GLOB patten that can be matched on types.
• AppleUniformTypeIdentifiers is a standard identifier defined by Apple and is used on macOS and iOS platforms. You can find the correct value for a given file in the macOS terminal with mdls -name kMDItemContentType yourfile.ext.
• MimeTypes is a web identifier for the files used on most platforms, but not Windows and iOS.

Defining all hints is recommended if the information is known.

note

If specific hint is not known, don't set random values or "." wildcard, instead keep this collection null. It will tell the platform to ignore this collection and instead try to use another one.

WebP Inclusion in Options v11.1

Keep in mind that FilePickerFileTypes.ImageWebP and the addition of "*.webp" to the "All Images" patterns were introduced in version 11.1. You can still create custom file picker types in older versions to incorporate WebP images. For example, to allow only a WebP image to be picked, you can use this:

var customWebPFileType = new FilePickerFileType("Only WebP Images")
{
    Patterns = new[] { "*.webp" },
    AppleUniformTypeIdentifiers = new[] { "org.webmproject.webp" },
    MimeTypes = new[] { "image/webp" }
};

And if you want to include WebP as one of the file types you consider to be an image, you can use the "ImageAll" example shown above.