GridViewbuildergridDelegate

GridView.builder is a constructor that creates a scrollable, lazily built grid. The gridDelegate parameter specifies how the grid should arrange its tiles. It takes a SliverGridDelegate, an abstract class that describes the layout geometry used during the grid’s layout phase. Concrete implementations determine how many tiles fit in the cross axis and how much space each tile receives.

The two most commonly used delegates are SliverGridDelegateWithFixedCrossAxisCount and SliverGridDelegateWithMaxCrossAxisExtent. The first fixes the number of columns (crossAxisCount) and allows configuring spacing (mainAxisSpacing, crossAxisSpacing) and tile aspect ratio (childAspectRatio). The second fixes the maximum extent of a tile along the cross axis (maxCrossAxisExtent), and similarly supports spacing and aspect ratio. The result is a grid that adapts to screen size while obeying the specified constraints.

GridDelegate is consulted during layout and does not itself create widgets; GridView.builder provides itemBuilder to lazily instantiate tiles as they scroll into view. The grid delegate thus enables responsive, dynamic grids suitable for image galleries, product listings, and other grid-based UI.

Ensure the gridDelegate is supplied to GridView.builder; omitting it leaves the grid without a layout policy. Related concepts include GridView, SliverGridDelegate, and the concrete delegates mentioned above.