UI Toolkit uses a powerful layout system that automatically calculates the position and size of individual elements based on the layout parameters in their style properties. This is based on Flexbox, a web layout model. For more information, see Layout Engine.
UI Toolkit has two types of coordinates:
Each visual elementA node of a visual tree that instantiates or derives from the C# VisualElement
class. You can style the look, define the behaviour, and display it on screen as part of the UI. More info
See in Glossary determines the coordinate system used to calculate its position. You can configure which coordinate system to use in the element stylesheet.
The following code shows how to set the coordinate space and the position of a visual element through code:
var newElement = new VisualElement();
newElement.style.position = Position.Relative;
newElement.style.left = 15;
newElement.style.top = 35;
The origin of an element is its top left corner.
The layout system computes the VisualElement.layout
property (type Rect
) for each element, which includes the final position of the element. This takes the relative or absolute position of the element into account.
The layout.position
is expressed in points, relative to the coordinate space of its parent.
Each VisualElement
has a transform property (ITransform
) you can use to add an additional local offset to the position and rotation of an element. The offset isn’t represented in the calculated layout property. By default, the transform
is the identity.
Use the worldBound
property to retrieve the final window space coordinates of the VisualElement
, taking into account both the layout position and the transform. This position includes the height of the header of the window.
The VisualElement.layout.position
and VisualElement.transform
properties define how to transform between the local coordinate system and the parent coordinate system.
The VisualElementExtensions
static class provides the following extension methods that transform points and rectangles between coordinate systems:
WorldToLocal
transforms a Vector2
or Rect
from Panel
space to the referential within the element.LocalToWorld
transforms a Vector2
or Rect
to Panel
space referential.ChangeCoordinatesTo
transforms Vector2
or Rect
from the local space of one element to the local space of another.Did you find this page useful? Please give it a rating:
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