Table Of Contents

• Label
  • Sizing and text content
  • Text alignment and wrapping
  • Markup text
  • Interactive zone in text
  • Catering for Unicode languages
  • Usage example

Label

The Label widget is for rendering text:

# hello world text
l = Label(text='Hello world')

# unicode text; can only display glyphs that are available in the font
l = Label(text='Hello world ' + chr(2764))

# multiline text
l = Label(text='Multi\nLine')

# size
l = Label(text='Hello world', font_size='20sp')

Sizing and text content

By default, the size of Label is not affected by text content and the text is not affected by the size. In order to control sizing, you must specify text_size to constrain the text and/or bind size to texture_size to grow with the text.

For example, this label’s size will be set to the text content (plus padding):

Label:
    size: self.texture_size

This label’s text will wrap at the specified width and be clipped to the height:

Label:
    text_size: cm(6), cm(4)

Note

The shorten and max_lines attributes control how overflowing text behaves.

Combine these concepts to create a Label that can grow vertically but wraps the text at a certain width:

Label:
    text_size: root.width, None
    size: self.texture_size

How to have a custom background color in the label:

# Define your background color Template
<BackgroundColor@Widget>
    background_color: 1, 1, 1, 1
    canvas.before:
        Color:
            rgba: root.background_color
        Rectangle:
            size: self.size
            pos: self.pos
# Now you can simply Mix the `BackgroundColor` class with almost
# any other widget... to give it a background.
<BackgroundLabel@Label+BackgroundColor>
    background_color: 0, 0, 0, 0
    # Default the background color for this label
    # to r 0, g 0, b 0, a 0
# Use the BackgroundLabel any where in your kv code like below
BackgroundLabel
    text: 'Hello'
    background_color: 1, 0, 0, 1

Text alignment and wrapping

The Label has halign and valign properties to control the alignment of its text. However, by default the text image (texture) is only just large enough to contain the characters and is positioned in the center of the Label. The valign property will have no effect and halign will only have an effect if your text has newlines; a single line of text will appear to be centered even though halign is set to left (by default).

In order for the alignment properties to take effect, set the text_size, which specifies the size of the bounding box within which text is aligned. For instance, the following code binds this size to the size of the Label, so text will be aligned within the widget bounds. This will also automatically wrap the text of the Label to remain within this area.

Label:
    text_size: self.size
    halign: 'right'
    valign: 'middle'

Markup text

New in version 1.1.0.

You can change the style of the text using Text Markup. The syntax is similar to the bbcode syntax but only the inline styling is allowed:

# hello world with world in bold
l = Label(text='Hello [b]World[/b]', markup=True)

# hello in red, world in blue
l = Label(text='[color=ff3333]Hello[/color][color=3333ff]World[/color]',
    markup = True)

If you need to escape the markup from the current text, use kivy.utils.escape_markup():

text = 'This is an important message [1]'
l = Label(text='[b]' + escape_markup(text) + '[/b]', markup=True)

The following tags are available:

[b][/b]

Activate bold text

[i][/i]

Activate italic text

[u][/u]

Underlined text

[s][/s]

Strikethrough text

[font=<str>][/font]

Change the font (note: this refers to a TTF file or registered alias)

[font_context=<str>][/font_context]

Change context for the font, use string value “none” for isolated context (this is equivalent to None; if you created a font context named ‘none’, it cannot be referred to using markup)

[font_family=<str>][/font_family]

Font family to request for drawing. This is only valid when using a font context, see kivy.uix.label.Label for details.

[font_features=<str>][/font_features]

OpenType font features, in CSS format, this is passed straight through to Pango. The effects of requesting a feature depends on loaded fonts, library versions, etc. Pango only, requires v1.38 or later.

[size=<integer>][/size]

Change the font size

[color=#<color>][/color]

Change the text color

[ref=<str>][/ref]

Add an interactive zone. The reference + bounding box inside the reference will be available in Label.refs

[anchor=<str>]

Put an anchor in the text. You can get the position of your anchor within the text with Label.anchors

[sub][/sub]

Display the text at a subscript position relative to the text before it.

[sup][/sup]

Display the text at a superscript position relative to the text before it.

[text_language=<str>][/text_language]

Language of the text, this is an RFC-3066 format language tag (as string), for example “en_US”, “zh_CN”, “fr” or “ja”. This can impact font selection and metrics. Use the string “None” to revert to locale detection. Pango only.

If you want to render the markup text with a [ or ] or & character, you need to escape them. We created a simple syntax:

[   -> &bl;
]   -> &br;
&   -> &

Then you can write:

"[size=24]Hello &bl;World&br;[/size]"

Interactive zone in text

New in version 1.1.0.

You can now have definable “links” using text markup. The idea is to be able to detect when the user clicks on part of the text and to react. The tag [ref=xxx] is used for that.

In this example, we are creating a reference on the word “World”. When this word is clicked, the function print_it will be called with the name of the reference:

def print_it(instance, value):
    print('User clicked on', value)
widget = Label(text='Hello [ref=world]World[/ref]', markup=True)
widget.bind(on_ref_press=print_it)

For prettier rendering, you could add a color for the reference. Replace the text= in the previous example with:

'Hello [ref=world][color=0000ff]World[/color][/ref]'

Catering for Unicode languages

The font kivy uses does not contain all the characters required for displaying all languages. When you use the built-in widgets, this results in a block being drawn where you expect a character.

If you want to display such characters, you can chose a font that supports them and deploy it universally via kv:

<Label>:
    font_name: '/<path>/<to>/<font>'

Note that this needs to be done before your widgets are loaded as kv rules are only applied at load time.

Usage example

The following example marks the anchors and references contained in a label:

from kivy.app import App
from kivy.uix.label import Label
from kivy.clock import Clock
from kivy.graphics import Color, Rectangle


class TestApp(App):

    @staticmethod
    def get_x(label, ref_x):
        """ Return the x value of the ref/anchor relative to the canvas """
        return label.center_x - label.texture_size[0] * 0.5 + ref_x

    @staticmethod
    def get_y(label, ref_y):
        """ Return the y value of the ref/anchor relative to the canvas """
        # Note the inversion of direction, as y values start at the top of
        # the texture and increase downwards
        return label.center_y + label.texture_size[1] * 0.5 - ref_y

    def show_marks(self, label):

        # Indicate the position of the anchors with a red top marker
        for name, anc in label.anchors.items():
            with label.canvas:
                Color(1, 0, 0)
                Rectangle(pos=(self.get_x(label, anc[0]),
                               self.get_y(label, anc[1])),
                          size=(3, 3))

        # Draw a green surround around the refs. Note the sizes y inversion
        for name, boxes in label.refs.items():
            for box in boxes:
                with label.canvas:
                    Color(0, 1, 0, 0.25)
                    Rectangle(pos=(self.get_x(label, box[0]),
                                   self.get_y(label, box[1])),
                              size=(box[2] - box[0],
                                    box[1] - box[3]))

    def build(self):
        label = Label(
            text='[anchor=a]a\nChars [anchor=b]b\n[ref=myref]ref[/ref]',
            markup=True)
        Clock.schedule_once(lambda dt: self.show_marks(label), 1)
        return label

TestApp().run()

class kivy.uix.label.Label(**kwargs)

Bases: kivy.uix.widget.Widget

Label class, see module documentation for more information.

Events

on_ref_press

Fired when the user clicks on a word referenced with a [ref] tag in a text markup.

anchors

New in version 1.1.0.

Position of all the [anchor=xxx] markup in the text. These coordinates are relative to the top left corner of the text, with the y value increasing downwards. Anchors names should be unique and only the first occurrence of any duplicate anchors will be recorded.

You can place anchors in your markup text as follows:

text = """
    [anchor=title1][size=24]This is my Big title.[/size]
    [anchor=content]Hello world
"""

Then, all the [anchor=] references will be removed and you’ll get all the anchor positions in this property (only after rendering):

>>> widget = Label(text=text, markup=True)
>>> widget.texture_update()
>>> widget.anchors
{"content": (20, 32), "title1": (20, 16)}

Note

This works only with markup text. You need markup set to True.

base_direction

Base direction of text, this impacts horizontal alignment when halign is auto (the default). Available options are: None, “ltr” (left to right), “rtl” (right to left) plus “weak_ltr” and “weak_rtl”.

Note

This feature requires the Pango text provider.

Note

Weak modes are currently not implemented in Kivy text layout, and have the same effect as setting strong mode.

New in version 1.11.0.

base_direction is an OptionProperty and defaults to None (autodetect RTL if possible, otherwise LTR).

bold

Indicates use of the bold version of your font.

Note

Depending of your font, the bold attribute may have no impact on your text rendering.

bold is a BooleanProperty and defaults to False.

color

Text color, in the format (r, g, b, a).

color is a ColorProperty and defaults to [1, 1, 1, 1].

Changed in version 2.0.0: Changed from ListProperty to ColorProperty.

disabled_color

The color of the text when the widget is disabled, in the (r, g, b, a) format.

New in version 1.8.0.

disabled_color is a ColorProperty and defaults to [1, 1, 1, .3].

Changed in version 2.0.0: Changed from ListProperty to ColorProperty.

disabled_outline_color

The color of the text outline when the widget is disabled, in the (r, g, b) format.

Note

This feature requires the SDL2 text provider.

New in version 1.10.0.

disabled_outline_color is a ColorProperty and defaults to [0, 0, 0].

Changed in version 2.0.0: Changed from ListProperty to ColorProperty. Alpha component is ignored and assigning value to it has no effect.

ellipsis_options

Font options for the ellipsis string(’…’) used to split the text.

Accepts a dict as option name with the value. Only applied when markup is true and text is shortened. All font options which work for Label will work for ellipsis_options. Defaults for the options not specified are taken from the surronding text.

Label:
    text: 'Some very long line which will be cut'
    markup: True
    shorten: True
    ellipsis_options: {'color':(1,0.5,0.5,1),'underline':True}

New in version 2.0.0.

ellipsis_options is a DictProperty and defaults to {} (the empty dict).

font_blended

Whether blended or solid font rendering should be used.

Note

This feature requires the SDL2 text provider.

New in version 1.10.0.

font_blended is a BooleanProperty and defaults to True.

font_context

Font context. None means the font is used in isolation, so you are guaranteed to be drawing with the TTF file resolved by font_name. Specifying a value here will load the font file into a named context, enabling fallback between all fonts in the same context. If a font context is set, you are not guaranteed that rendering will actually use the specified TTF file for all glyphs (Pango will pick the one it thinks is best).

If Kivy is linked against a system-wide installation of FontConfig, you can load the system fonts by specifying a font context starting with the special string system://. This will load the system fontconfig configuration, and add your application-specific fonts on top of it (this imposes a signifficant risk of family name collision, Pango may not use your custom font file, but pick one from the system)

Note

This feature requires the Pango text provider.

New in version 1.11.0.

font_context is a StringProperty and defaults to None.

font_family

Font family, this is only applicable when using font_context option. The specified font family will be requested, but note that it may not be available, or there could be multiple fonts registered with the same family. The value can be a family name (string) available in the font context (for example a system font in a system:// context, or a custom font file added using kivy.core.text.FontContextManager). If set to None, font selection is controlled by the font_name setting.

Note

If using font_name to reference a custom font file, you should leave this as None. The family name is managed automatically in this case.

Note

This feature requires the Pango text provider.

New in version 1.11.0.

font_family is a StringProperty and defaults to None.

font_features

OpenType font features, in CSS format, this is passed straight through to Pango. The effects of requesting a feature depends on loaded fonts, library versions, etc. For a complete list of features, see:

https://en.wikipedia.org/wiki/List_of_typographic_features

Note

This feature requires the Pango text provider, and Pango library v1.38 or later.

New in version 1.11.0.

font_features is a StringProperty and defaults to an empty string.

font_hinting

What hinting option to use for font rendering. Can be one of ‘normal’, ‘light’, ‘mono’ or None.

Note

This feature requires SDL2 or Pango text provider.

New in version 1.10.0.

font_hinting is an OptionProperty and defaults to ‘normal’.

font_kerning

Whether kerning is enabled for font rendering. You should normally only disable this if rendering is broken with a particular font file.

Note

This feature requires the SDL2 text provider.

New in version 1.10.0.

font_kerning is a BooleanProperty and defaults to True.

font_name

Filename of the font to use. The path can be absolute or relative. Relative paths are resolved by the resource_find() function.

Warning

Depending of your text provider, the font file can be ignored. However, you can mostly use this without problems.

If the font used lacks the glyphs for the particular language/symbols you are using, you will see ‘[]’ blank box characters instead of the actual glyphs. The solution is to use a font that has the glyphs you need to display. For example, to display , use a font such as freesans.ttf that has the glyph.

font_name is a StringProperty and defaults to ‘Roboto’. This value is taken from Config.

font_size

Font size of the text, in pixels.

font_size is a NumericProperty and defaults to 15sp.

halign

Horizontal alignment of the text.

halign is an OptionProperty and defaults to ‘auto’. Available options are : auto, left, center, right and justify. Auto will attempt to autodetect horizontal alignment for RTL text (Pango only), otherwise it behaves like left.

Warning

This doesn’t change the position of the text texture of the Label (centered), only the position of the text in this texture. You probably want to bind the size of the Label to the texture_size or set a text_size.

Changed in version 1.10.1: Added auto option

Changed in version 1.6.0: A new option was added to halign, namely justify.

is_shortened

This property indicates if text was rendered with or without shortening when shorten is True.

New in version 1.10.0.

is_shortened is a BooleanProperty and defaults to False.

italic

Indicates use of the italic version of your font.

Note

Depending of your font, the italic attribute may have no impact on your text rendering.

italic is a BooleanProperty and defaults to False.

line_height

Line Height for the text. e.g. line_height = 2 will cause the spacing between lines to be twice the size.

line_height is a NumericProperty and defaults to 1.0.

New in version 1.5.0.

markup

New in version 1.1.0.

If True, the text will be rendered using the MarkupLabel: you can change the style of the text using tags. Check the Text Markup documentation for more information.

markup is a BooleanProperty and defaults to False.

max_lines

Maximum number of lines to use, defaults to 0, which means unlimited. Please note that shorten take over this property. (with shorten, the text is always one line.)

New in version 1.8.0.

max_lines is a NumericProperty and defaults to 0.

mipmap

Indicates whether OpenGL mipmapping is applied to the texture or not. Read Mipmapping for more information.

New in version 1.0.7.

mipmap is a BooleanProperty and defaults to False.

on_touch_down(touch)

Receive a touch down event.

Parameters

touch: MotionEvent class

Touch received. The touch is in parent coordinates. See relativelayout for a discussion on coordinate systems.

Returns

bool If True, the dispatching of the touch event will stop. If False, the event will continue to be dispatched to the rest of the widget tree.

outline_color

The color of the text outline, in the (r, g, b) format.

Note

This feature requires the SDL2 text provider.

New in version 1.10.0.

outline_color is a ColorProperty and defaults to [0, 0, 0, 1].

Changed in version 2.0.0: Changed from ListProperty to ColorProperty. Alpha component is ignored and assigning value to it has no effect.

outline_width

Width in pixels for the outline around the text. No outline will be rendered if the value is None.

Note

This feature requires the SDL2 text provider.

New in version 1.10.0.

outline_width is a NumericProperty and defaults to None.

padding

Padding of the text in the format (padding_x, padding_y)

padding is a ReferenceListProperty of (padding_x, padding_y) properties.

padding_x

Horizontal padding of the text inside the widget box.

padding_x is a NumericProperty and defaults to 0.

Changed in version 1.9.0: padding_x has been fixed to work as expected. In the past, the text was padded by the negative of its values.

padding_y

Vertical padding of the text inside the widget box.

padding_y is a NumericProperty and defaults to 0.

Changed in version 1.9.0: padding_y has been fixed to work as expected. In the past, the text was padded by the negative of its values.

refs

New in version 1.1.0.

List of [ref=xxx] markup items in the text with the bounding box of all the words contained in a ref, available only after rendering.

For example, if you wrote:

Check out my [ref=hello]link[/ref]

The refs will be set with:

{'hello': ((64, 0, 78, 16), )}

The references marked “hello” have a bounding box at (x1, y1, x2, y2). These coordinates are relative to the top left corner of the text, with the y value increasing downwards. You can define multiple refs with the same name: each occurrence will be added as another (x1, y1, x2, y2) tuple to this list.

The current Label implementation uses these references if they exist in your markup text, automatically doing the collision with the touch and dispatching an on_ref_press event.

You can bind a ref event like this:

def print_it(instance, value):
    print('User click on', value)
widget = Label(text='Hello [ref=world]World[/ref]', markup=True)
widget.bind(on_ref_press=print_it)

Note

This works only with markup text. You need markup set to True.

shorten

Indicates whether the label should attempt to shorten its textual contents as much as possible if a text_size is given. Setting this to True without an appropriately set text_size will lead to unexpected results.

shorten_from and split_str control the direction from which the text is split, as well as where in the text we are allowed to split.

shorten is a BooleanProperty and defaults to False.

shorten_from

The side from which we should shorten the text from, can be left, right, or center.

For example, if left, the ellipsis will appear towards the left side and we will display as much text starting from the right as possible. Similar to shorten, this option only applies when text_size [0] is not None, In this case, the string is shortened to fit within the specified width.

New in version 1.9.0.

shorten_from is a OptionProperty and defaults to center.

split_str

The string used to split the text while shortening the string when shorten is True.

For example, if it’s a space, the string will be broken into words and as many whole words that can fit into a single line will be displayed. If split_str is the empty string, ‘’, we split on every character fitting as much text as possible into the line.

New in version 1.9.0.

split_str is a StringProperty and defaults to ‘’ (the empty string).

strikethrough

Adds a strikethrough line to the text.

Note

This feature requires the SDL2 text provider.

New in version 1.10.0.

strikethrough is a BooleanProperty and defaults to False.

strip

Whether leading and trailing spaces and newlines should be stripped from each displayed line. If True, every line will start at the right or left edge, depending on halign. If halign is justify it is implicitly True.

New in version 1.9.0.

strip is a BooleanProperty and defaults to False.

text

Text of the label.

Creation of a simple hello world:

widget = Label(text='Hello world')

text is a StringProperty and defaults to ‘’.

text_language

Language of the text, if None Pango will determine it from locale. This is an RFC-3066 format language tag (as a string), for example “en_US”, “zh_CN”, “fr” or “ja”. This can impact font selection, metrics and rendering. For example, the same bytes of text can look different for ur and ar languages, though both use Arabic script.

Note

This feature requires the Pango text provider.

New in version 1.11.0.

text_language is a StringProperty and defaults to None.

text_size

By default, the label is not constrained to any bounding box. You can set the size constraint of the label with this property. The text will autoflow into the constraints. So although the font size will not be reduced, the text will be arranged to fit into the box as best as possible, with any text still outside the box clipped.

This sets and clips texture_size to text_size if not None.

New in version 1.0.4.

For example, whatever your current widget size is, if you want the label to be created in a box with width=200 and unlimited height:

Label(text='Very big big line', text_size=(200, None))

Note

This text_size property is the same as the usersize property in the Label class. (It is named size= in the constructor.)

text_size is a ListProperty and defaults to (None, None), meaning no size restriction by default.

texture

Texture object of the text. The text is rendered automatically when a property changes. The OpenGL texture created in this operation is stored in this property. You can use this texture for any graphics elements.

Depending on the texture creation, the value will be a Texture or TextureRegion object.

Warning

The texture update is scheduled for the next frame. If you need the texture immediately after changing a property, you have to call the texture_update() method before accessing texture:

l = Label(text='Hello world')
# l.texture is good
l.font_size = '50sp'
# l.texture is not updated yet
l.texture_update()
# l.texture is good now.

texture is an ObjectProperty and defaults to None.

texture_size

Texture size of the text. The size is determined by the font size and text. If text_size is [None, None], the texture will be the size required to fit the text, otherwise it’s clipped to fit text_size.

When text_size is [None, None], one can bind to texture_size and rescale it proportionally to fit the size of the label in order to make the text fit maximally in the label.

Warning

The texture_size is set after the texture property. If you listen for changes to texture, texture_size will not be up-to-date in your callback. Bind to texture_size instead.

texture_update(*largs)

Force texture recreation with the current Label properties.

After this function call, the texture and texture_size will be updated in this order.

underline

Adds an underline to the text.

Note

This feature requires the SDL2 text provider.

New in version 1.10.0.

underline is a BooleanProperty and defaults to False.

unicode_errors

How to handle unicode decode errors. Can be ‘strict’, ‘replace’ or ‘ignore’.

New in version 1.9.0.

unicode_errors is an OptionProperty and defaults to ‘replace’.

valign

Vertical alignment of the text.

valign is an OptionProperty and defaults to ‘bottom’. Available options are : ‘bottom’, ‘middle’ (or ‘center’) and ‘top’.

Changed in version 1.10.0: The ‘center’ option has been added as an alias of ‘middle’.

Warning

This doesn’t change the position of the text texture of the Label (centered), only the position of the text within this texture. You probably want to bind the size of the Label to the texture_size or set a text_size to change this behavior.

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