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' Width.
The following shows a child ColoredRectangle with 50 Absolute Width:
The following image shows a child ColoredRectangle with -10 RelativeToContainer Width, so it sizes itself 10 pixels less wide than its parent.
Despite the name referring to a "Container", the size is relative to the parent regardless of the parent's type. If the instance has no parent, then the size is relative to the canvas.
The following shows a child ColoredRectangle with 100 Percentage of Container Width, which means it has 100% of the width of its parent. Note that 100 Percentage is the same as 0 Relative to Container:
Despite the name referring to a "Container", the size is relative to the parent regardless of the parent's type. If the instance has no parent, then the size is relative to the canvas.
Ratio of Container can be used to fill available space or to share available space with other objects using a ratio. It behaves similar to a Height Units of Ratio of Container, but operates horizontally rather than vertically.
Despite the name referring to a "Container", the total size available for ratios is relative to the parent regardless of the parent's type. If the instance has no parent, then the size is relative to the canvas.
The following image shows a child ColoredRectangle with 50 Relative to Children Width, which means that it is sized 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:
Relative to Children 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 Relative to Children Width, which means that its width is set just large enough to contain its children.
A non-zero Width when using Relative to Children can be used to add additional padding to a parent container. The following image shows a container with 20 pixels of padding width:
Relative to Children dynamically adjusts to changes in properties on the children. In the following animation the container has a Children Layout of Left to Right Stack. Adding additional children expands the container automatically:
If a parent sets its Width Units to Relative to Children, then it must resize itself to contain its children. Normally the width of the entire parent is determined by the child which needs the most space horizontally. If the parent uses an Auto Grid Horizontal layout, then the children control the size of the cells rather than the entire parent. Since all cells must be the same size, the child which needs the most amount of space horizontally determines the width of all cells.
For example, the following image shows a four by four grid, each containing one white rectangle. The first rectangle has an absolute width and height of 100, so each cell is sized to be 100x100. Note that the other rectangles are 50x50.
The largest child determines the cell size for all other children. Therefore, if a child is moved or resized so it outgrows its cell, then the parent width adjusts in response.
Setting a Text instance's Width Units to Relative to Children results in the Text object adjusting according to its text contents. For example, setting the Width Units to Relative to Children and setting the Width to 0 results in the Text object automatically adjusting its actual width according to the text it contains.
Percentage of Other Dimension adjusts 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 is 200% (2x) of the height.
The following image shows a child ColoredRectangle with a Width of 200 Percentage of Other Dimension. 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 Percentage of Source File, which sets 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 Percentage of Source File Width, which means it draws two times as wide as its source image:
Absolute Multiplied by Font Scale is a property which multiplies the Font Scale property at runtime with the width value. This can be used to create widths which are responsive to font scales for devices which may have variable text sizes.
At the time of this writing, the Gum tool always uses a Font Scale of 1, so this cannot be previewed in the tool. However, when a Gum project is loaded at runtime, the runtime may apply a Font Scale value such as using the Text size from Windows.
