Flet v0.24.0 Release Announcement

I am very happy to announce the release of Flet version 0.24.0! It comes with a very long list of bug fixes, several enhancements and new features.

New Controls

• InteractiveViewer
• Placeholder

New Properties

• AudioRecorder: cancel_recording()
• Video: on_completed, on_track_changed
• InputFilter: unicode, case_sensitive, dot_all, multiline
• Geolocator: on_error, on_position_change
• Barchart, LineChart: tooltip_border_side, tooltip_direction, tooltip_fit_inside_horizontally, tooltip_fit_inside_vertically, tooltip_horizontal_offset, tooltip_margin, tooltip_max_content_width, tooltip_padding, tooltip_rounded_radius, tooltip_rotate_angle
• Container: decoration, foreground_decoration, ignore_interactions, image
• Page, View: decoration, foreground_decoration
• CupertinoTextField: enable_scribble, image, obscuring_character, padding, scroll_padding, on_click
• DataTable: heading_row_alignment
• TextField: counter, disabled_hint_content, options_fill_horizontally
• ExpansionTile: min_tile_height, show_trailing_icon
• Markdown: fit_content, img_error_content, md_style_sheet, shrink_wrap, soft_line_break, on_selection_change
• MenuItemButton: autofocus, overflow_axis, semantic_label
• Tabs: label_padding, label_text_style, padding, splash_border_radius, unselected_label_text_style, on_click
• and lot of new classes (enums, dataclasses, events)…

Enhancements

• Better string output of Events when printed
• Image.filter_quality now has a default of FilterQuality.MEDIUM (previously FilterQuality.LOW), which is a better default for downscaled images.
• Geolocator control has been improved to support location streaming through the newly added on_position_change event. When defined, you will be able to "listen" to location changes as they happen.
• When AppBar.adaptive=True and the app is running on an Apple platform, the AppBar.actions controls are now wrapped in a Row, then displayed. Before this, only the first item of AppBar.actions list was displayed.
• The Markdown control has been significantly improved. It can now display SVG images and be much more customized.
• A very requested feature was the ability to set a background image or gradient for the application. In #3820, we made this possible and easy to use.
• rtl (right-to-left) property has been added to more controls (NavigationRailDestination, NavigationRail, AppBar, CupertinoAppBar, and NavigationDrawer ) to improve support for right-to-left text directions.
• Introduced --no-rich-output flag (only in flet build command for now) to make it possible to disable rich output (mainly emojis) in the console. More information in #3708.
• Typing has been significantly improved, particularly for event-handler properties. In modern IDEs like PyCharm and VSCode, you can now easily determine the type of an event handler's argument by simply hovering over the event in the control. Additionally, the IDE will highlight errors when you attempt to access a non-existent property on the event handler argument, ensuring more robust and error-free code.

Bug Fixes

The below issues were successfully fixed:

• #3769: InputFilter clears the TextField text content when an invalid character is entered
• #3770: Theme.floating_action_button_theme non existent
• #3734: Ensure Dropdown.alignment is respected.
• #3730: UnicodeEncodeError raised when packaging on WindowOS
• #2160: Markdown control can't render svg images
• #2158: Markdown broken when an image is not found
• #3679: Broken Dismissible
• #3670: Switch.height and Switch.width not respected
• #3612, #3566: Broken OnScrollEvent
• #3564: Broken TextField.capitalization
• #3649: CupertinoPicker jumps-scroll on some platforms
• #3557: Impeller causes blank screen on mac Intel
• #3574: Geolocator not working on Android devices
• #3505: WindowEventType doesn't contain fullscreen all events

Thanks to all those who reported them!

Deprecations

All deprecated items from this release will be removed in version 0.27.0.

• ThemeVisualDensity is deprecated and has been renamed to VisualDensity
• CupertinoButton: disabled_color is deprecated and has been renamed to disabled_bgcolor, which better reflects its use
• Markdown: code_style is deprecated and should now be accessed as code_style_sheet.code_text_style
• Container: image_fit, image_opacity, image_repeat, image_src and image_src_base64 are deprecated and should now be accessed from image which is of type DecorationImage

Breaking Changes and Migration

Tooltip

The Tooltip class is no more a Flet control and is from now on a simple Python dataclass. The tooltip property (available in almost all controls) now supports both strings and Tooltip objects.

Below is how to migrate:

# before
page.add(
    ft.Tooltip(
        message="This is tooltip",
        content=ft.Text("Hover to see tooltip"),
        padding=20,
        border_radius=10,
    )
)

# after
page.add(
    ft.Text(
        "Hover to see tooltip",
        tooltip=ft.Tooltip(
            message="This is tooltip",
            padding=20,
            border_radius=10,
        )
    )
)

TextField InputFilter

We modified how InputFilter.regex_string is internally handled. As a result of this, you (might) now have to anchor your regex pattern. This simply implies using start (^) and end ($) regex anchors. For example: r"[0-9]" now becomes r"^[0-9]$". Using this new string will lead work as expected and only numbers/digits will be allowed, but you might notice another issue: the last character of the text field cannot be deleted. To resolve this, you need to add an asterisk (*) in the regex which in this case will simply mean "match zero or more digits (including an empty string)". The new regex now becomes r"^[0-9]*$". To ease this migration, you can use an AI tool with the following simple prompt: "update the following regex pattern: #### ensuring that the entire string matches the pattern and it allows for an empty string".

Event-Handler subscription

The possibility to "subscribe" more than one callback to an event handler has been removed, as this was somehow biased (was only possible on some, and not all). Below is a simple example:

import flet as ft

def main(page: ft.Page):
    def print_one(e):
        print("1")
    def print_two(e):
        print("2")
    def print_three(e):
        print("3")
    c = ft.Container(
        bgcolor=ft.Colors.random_color(),
        width=300,
        height=300,
    )
    
    # subscribe callbacks
    c.on_tap_down = print_one
    c.on_tap_down = print_two
    c.on_tap_down = print_three
    page.add(c)

ft.app(main)

In the above code, we subscribe multiple callbacks to the Container.on_tap_down event. Prior to Flet version 0.24.0, running this code and tapping on the Container, you will see all the callbacks getting called ("1", "2" and "3" are printed out). From Flet version 0.24.0 going forward, one event = one callback. Meaning only the lastly subscribed callback will get executed ("3" is printed out) So, if you still want the final output to resemble the first one you can simply create one callback which calls the others:

def main(page: ft.Page):
    #....
  
    def print_all(e):
            print_one(e)
            print_two(e)
            print_three(e)
    
    c = ft.Container(
            bgcolor=ft.Colors.random_color(),
            width=300,
            height=300,
            on_tap_down=print_all,
        )

    # OR
    c.on_tap_down = print_all

Conclusion

As you can see, we made a lot of changes in this release and as usual, your feedback is highly welcomed!

Upgrade to Flet 0.24.0, test your apps and let us know how you find the new features we added. If you have any questions, please join Flet Discord server or create a new thread on Flet GitHub discussions.

Happy Flet-ing! 👾