C# Class Sparrow.Display.DisplayObject

The DisplayObject class is the base class for all objects that are rendered on the screen. In Sparrow, all displayable objects are organized in a display tree. Only objects that are part of the display tree will be displayed (rendered). The display tree consists of leaf nodes (Image, Quad) that will be rendered directly to the screen, and of container nodes (subclasses of DisplayObjectContainer, like Sprite). A container is simply a display object that has child nodes - which can, again, be either leaf nodes or other containers. A display object has properties that define its position in relation to its parent ('X', 'Y'), as well as its rotation, skewing and scaling factors. Use the 'Alpha' and 'Visible' properties to make an object translucent or invisible. Every display object may be the target of touch events. If you don't want an object to be touchable, you can disable the `Touchable` property. When it's disabled, neither the object nor its children will receive any more touch events. **Points vs. Pixels** All sizes and distances are measured in points. What this means in pixels depends on the contentScaleFactor of the device. **Transforming coordinates** Within the display tree, each object has its own local coordinate system. If you rotate a container, you rotate that coordinate system - and thus all the children of the container. Sometimes you need to know where a certain point lies relative to another coordinate system. That's the purpose of the method 'TransformationMatrixToSpace'. It will create a matrix that represents the transformation of a point in one coordinate system to another. **Subclassing DisplayObject** As DisplayObject is an abstract class, you can't instantiate it directly, but have to use one of its subclasses instead. However, you can create custom display objects as well. That's especially useful when you want to create an object with a custom render function. You will need to implement the following methods when you subclass DisplayObject: - void Render ( RenderSupport support); - Rectangle BoundsInSpace ( DisplayObject targetSpace); Have a look at Quad for a sample implementation of those methods.