Line Number❖

Module path❖

kivydk.uix.line_number

Overview❖

This module provides the LineNumber widget, a companion component for TextInput that renders synchronized line numbers alongside editable text.

Is intended for use in text editors, code editors and any UI component where visible line numbering is required. The widget integrates cleanly with both standalone TextInput instances and TextInputs embedded inside a ScrollView.

The LineNumber widget handles automatic sizing, vertical alignment and scroll synchronization, ensuring that the displayed line numbers always match the visible portion of the associated TextInput.

Example❖

Sample demonstrating how LineNumber can be used to draw the line numbers.

#// IMPORT
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.codeinput import CodeInput
from kivy.uix.scrollview import ScrollView

from kivydk.uix import LineNumber


#// LOGIC
class TestLineNumber(BoxLayout):
    def __init__(self, **kwargs):
        super().__init__(**kwargs)

        # Components
        self.scroll_view = ScrollView(scroll_type=['bars', 'content'], bar_width="11dp")
        self.text_input = CodeInput(size_hint_y=None)
        self.line_number = LineNumber(
            self.text_input,
            background_color=[0.3,0.3,0.3, 1.0], foreground_color=[1.0,1.0,1.0, 1.0]
        )

        # Packing
        self.scroll_view.add_widget(self.text_input)

        self.add_widget(self.line_number)
        self.add_widget(self.scroll_view)

        # Binds
        self.text_input.bind(text=self._update_text_height)
        self.scroll_view.bind(size=self._update_text_height)

    def _update_text_height(self, *args):
        height = len(self.text_input._lines_rects) * self.text_input.line_height
        height += self.text_input.padding[1] + self.text_input.padding[3]

        self.text_input.height = max(height, self.scroll_view.height)
        self.line_number.refresh()


#// RUN FILE
if __name__ == "__main__":
    from kivydk.app import App

    class Example(App):
        def build(self):
            return TestLineNumber()

    Example().run()

Reference❖

class LineNumber(text_input: TextInput, **kwargs)❖

Bases: Widget

Widget that displays line numbers for a linked TextInput.

A TextInput instance must be provided as the text_input argument. It is used to extract line information, wrapping state, scroll position and all metrics required to compute the widget’s size and vertical placement.

When used together with a ScrollView, the LineNumber widget must be placed outside the ScrollView. Its height and vertical offset are calculated automatically so that the visible line numbers remain synchronized with the associated TextInput, regardless of whether the TextInput is scrollable or not.

The widget updates dynamically based on the state of the linked TextInput, including text changes, wrapping, scrolling and font metrics.

align: OptionProperty❖

Horizontal alignment of the line numbers.

Default value❖

"right"

background_color: ColorProperty❖

Tint color applied to the background_texture.

Default value❖

[1.0, 1.0, 1.0, 1.0]

background_texture: StringProperty❖

Background image applied to the entire widget.

Default value❖

"atlas://data/images/defaulttheme/textinput"

background_border: VariableListProperty❖

Border definition used when rendering background_texture. This controls how the texture is sliced, allowing custom backgrounds to be applied.

The background_border may be specified as one , two or four values. These are expanded into a list of four values: [left, top, right, bottom].

Default value❖

[4, 4, 4, 4]

foreground_color: ColorProperty❖

Color used to render the line numbers, in RGBA format.

Default value❖

[0.0, 0.0, 0.0, 1.0]

font_context: StringProperty❖

Font context used to render the line numbers.

Default value❖

None

font_family: StringProperty❖

Font family used to render the line numbers.

Default value❖

None

font_name: StringProperty❖

Font name or file used to render the line numbers.

Default value❖

None

font_size: NumericProperty❖

Font size used to render the line numbers.

Default value❖

"15sp"

padding: VariableListProperty❖

Horizontal padding applied to the line numbers.

The padding may be specified as one or two values. These are expanded into a list of two values: [left, right].

Default value❖

[4, 4]

width_min: NumericProperty❖

Minimum desired width of the widget.

The actual width is computed automatically based on padding, font_size, the active font and the current line‑number context. This property ensures that the computed width is never smaller than the specified minimum.

Default value❖

"18sp"

refresh(delay: int | float = -1) → None❖

Schedule a re-render of the line numbers.

Note

A delay of 0 schedules the update for the next frame, while a negative value triggers the update immediately within the current frame.

Name	Description
delay	Delays the refresh by the given number of seconds.