1、WPF使用画像画刷（ImageBrush）

<Grid>
        <Grid.Background>
            <ImageBrush ImageSource="1.png" 
                        Stretch="None" 
                        TileMode="Tile" 
                        ViewportUnits="Absolute">
                <ImageBrush.Viewport>
                    <Rect X="0" Y="0" Width="20" Height="20"/>
                </ImageBrush.Viewport>
            </ImageBrush>
        </Grid.Background>    
    </Grid>

具体可阅读：TileBrush 概述 - WPF .NET Framework | Microsoft Learn

2、WPF使用DrawingBrush画刷

 <Grid>
        <Grid.Background>
            <DrawingBrush Stretch="Fill" TileMode="Tile"
                          Viewport="0,0,20,20" ViewportUnits="Absolute" >
                <DrawingBrush.Drawing>
                    <GeometryDrawing Brush="#333333" Geometry="M0,2 L1,2 1,3 0,3 Z M1,1 L2,1 2,2 1,2 z"/>
                </DrawingBrush.Drawing>
            </DrawingBrush>
        </Grid.Background>
    </Grid>

具体可阅读：DrawingBrush 类 (System.Windows.Media) | Microsoft Learn
效果图如下：