Gets or sets a value that indicates whether layout rounding should be applied to this element's size and position during layout.
Assembly: PresentationFramework (in PresentationFramework.dll)
XMLNS for XAML: http://schemas.microsoft.com/winfx/2006/xaml/presentation, http://schemas.microsoft.com/netfx/2007/xaml/presentation
This property is inherited by child elements.
You should set to true on the root element. The layout system adds child coordinates to the parent coordinates; therefore, if the parent coordinates are not on a pixel boundary, the child coordinates are also not on a pixel boundary. If cannot be set at the root, set SnapsToDevicePixels on the child to obtain the effect that you want.
Drawing objects on pixel boundaries eliminates the semi-transparent edges that are produced by anti-aliasing, when an edge falls in the middle of a device pixel. The following illustration shows the output of a single pixel-width line that falls in the middle of a device pixel. The line on the left does not use layout rounding and is anti-aliased. The line on the right uses layout rounding.
When you use layout rounding and Star sizing, the layout system creates small variations in the column or row measurements to avoid subpixel rendering. For example, if a grid has a total width of 100 with 3 columns each of size Star, instead of creating three columns that have an equal width of 33.3, the layout system creates 2 columns that have a width of 33 and one that has a width of 34.
The following example demonstrates the effect that the property has on a single pixel-width line. The line on the left does not use layout rounding and the line on the right uses layout rounding. If you slowly resize the window, you can see the difference that layout rounding makes.
<Page x:Class="LayoutRounding.Lines" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="Lines" Name="linesPage" > <StackPanel Width="150" Margin="7" Orientation="Horizontal"> <!-- Single pixel line with layout rounding turned OFF.--> <Rectangle UseLayoutRounding="False" Width="45.5" Margin="10" Height="1" Fill="Red"/> <!-- Single pixel line with layout rounding turned ON.--> <Rectangle UseLayoutRounding="True" Width="45.5" Margin="10" Height="1" Fill="Red"/> </StackPanel> <!-- Background Grid --> <Page.Background> <DrawingBrush Viewport="0,0,10,10" ViewportUnits="Absolute" TileMode="Tile"> <DrawingBrush.Drawing> <DrawingGroup> <GeometryDrawing Brush="White"> <GeometryDrawing.Geometry> <RectangleGeometry Rect="0,0,1,1" /> </GeometryDrawing.Geometry> </GeometryDrawing> <GeometryDrawing Geometry="M0,0 L1,0 1,0.1, 0,0.1Z " Brush="#CCCCFF" /> <GeometryDrawing Geometry="M0,0 L0,1 0.1,1, 0.1,0Z" Brush="#CCCCFF" /> </DrawingGroup> </DrawingBrush.Drawing> </DrawingBrush> </Page.Background> </Page>