Luna UI Documentation

Unity UI Toolkit provides built-in support for auto-sizing text elements, allowing text to automatically scale to fit within its container.

Unity Documentation

For the most up-to-date information, see the official Unity documentation:

Unity Manual: Auto-sizing text elements

Overview

Auto-sizing text adjusts the font size dynamically based on the available space, ensuring text remains readable and fits within defined boundaries. This is useful for:

Responsive UI layouts
Localization (different languages have different text lengths)
Dynamic content that varies in length

USS Properties

Enable Auto-Sizing

css

.auto-size-label {
    -unity-font-size-auto-sizing: true;
}

Min/Max Font Size

Control the range of font sizes the auto-sizing algorithm will use:

css

.auto-size-label {
    -unity-font-size-auto-sizing: true;
    -unity-font-size-auto-sizing-min-size: 12px;
    -unity-font-size-auto-sizing-max-size: 48px;
}

Step Size

Controls the granularity of size adjustments:

css

.auto-size-label {
    -unity-font-size-auto-sizing: true;
    -unity-font-size-auto-sizing-step-size: 1px;
}

Complete Example

css

.dynamic-title {
    -unity-font-size-auto-sizing: true;
    -unity-font-size-auto-sizing-min-size: 16px;
    -unity-font-size-auto-sizing-max-size: 64px;
    -unity-font-size-auto-sizing-step-size: 2px;
    
    /* Container must have defined dimensions */
    width: 300px;
    height: 100px;
    
    /* Other styling */
    -unity-text-align: middle-center;
    white-space: normal;
}

UXML Usage

xml

<ui:Label 
    text="This text will auto-size" 
    class="dynamic-title" 
/>

Code Usage

csharp

Label label = new Label("Dynamic text");
label.style.unityFontSizeAutoSizing = true;
label.style.unityFontSizeAutoSizingMinSize = 12;
label.style.unityFontSizeAutoSizingMaxSize = 48;

Important Notes

Container Size Required: Auto-sizing only works when the container has defined dimensions. Without explicit width/height, the text cannot determine how to scale.
White Space: Set white-space: normal if you want text to wrap before scaling down.
Performance: Auto-sizing recalculates on layout changes. Avoid using it on rapidly changing text.
Rich Text: Works with rich text tags, but complex formatting may affect sizing calculations.

Best Practices

Set reasonable min/max bounds to maintain readability
Use larger step sizes (2-4px) for better performance
Test with your longest expected text strings
Consider localization requirements when setting bounds

Auto Size Text