How to Set Full-Screen Background Image in Flutter: Complete Guide

If your image fills the width of the screen but not the height, the issue lies in how the Image.asset() is placed inside the widget tree.

Column(
  mainAxisAlignment: MainAxisAlignment.start,
  children: [
    Image.asset("assets/images/bulb.jpg")
  ]
)

This shows the image only as much as it naturally fits, and doesn’t scale to the screen height.

Correct Way to Set Full-Screen Background Image

Use a Stack with Positioned.fill or make the Image.asset take full width and height using BoxFit.cover.

Example 1: Using Stack

Example 2: Using Container with decoration

Image Standards in Flutter

• Flutter supports raster images (PNG, JPG, etc.) from the assets/ directory.
• Images scale based on BoxFit and device resolution.
• Use 2x, 3x image assets in folders like assets/images/2.0x/ for better scaling on high-density screens.

Final Tips:

• Always use fit: BoxFit.cover or fit: BoxFit.fill to scale.
• Wrap images in a SizedBox, Positioned.fill, or Container with height/width if needed.
• Use MediaQuery.of(context).size if you want precise control.

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