The Width Units variable controls how a unit is horizontally sized, which may be relative to its parent. By default an object uses Absolute width, where each unit represents 1 pixel of width in absolute terms. When using Absolute, an object ignores its parents’ With.
The following shows a child ColoredRectangle with 50 Absolute Width:
The following shows a child ColoredRectangle with 100 Percentage Width, which means it will have 100% of the width of its parent. Note that 100 Percentage is the same as 0 RelativeToContainer:
The following image shows a child ColoredRectangle with -10 RelativeToContainer Width, which means it will always be 10 pixels less wide than its parent.
The following image shows a child ColoredRectangle with 50 RelativeToChildren Width, which means that it will always be 50 pixels wider than is necessary to contain its children. Since the rectangle has no children, this is the same as having 50 Absolute Width:
RelativeToChildren can be used to size an object based on the position and sizes of a container’s children. The following image shows a container with 0 RelativeToChildren Width, which mans that its width is set just large enough to contain its children. Since the rectangle on the right is the furthest-right rectangle, the width of the container is set to be wide enough to contain the right-edge of the furthest-right blue rectangle.
A non-zero Width when using RelativeToChildren can be used to add additional padding to a parent container. The following image shows a container with 20 pixels of padding width:
RelativeToChildren will dynamically adjust to changes in properties on the children. In the following animation the container has a Children Layout of LeftToRightStack. Adding additional children expands the container automatically:
For more information on relative layout in regards to absolute vs. relative unit types, see the Relative Layout Unit Type page.
Setting a Text instance’s Width Units to RelativeToChildren results in the Text object adjusting according to its text contents. For example, setting the Width Units to RelativeToChildren and setting the Width to 0 results in the Text object automatically adjusting its actual width according to the text it contains.
PercentageOfOtherDimension will adjust the object’s effective width so it remains proportional to the Height value multiplied by the Width value (as a percentage). For example, if a Width value of 200 is entered, then the effective width will be 200% (2x) of the height.
The following image shows a child ColoredRectangle with a Width of 200 PercentageOfOtherDimension. In this image, the Height value is 50 units, so the effective width is 100 units:
The Sprite type has an extra With Unit called PercentageOfSourceFile, which will set the width of the Sprite according to the file that it is displaying. This is the default Width Unit for Sprites.
The following image shows a child Sprite with 200 PercentageOfSourceFile Width, which means it will draw two times as wide as its source image: