The interface used by CustomPaint (in the widgets library) and RenderCustomPaint (in the rendering library).
To implement a custom painter, subclass this interface to define your custom paint delegate. CustomPaint subclasses must implement the paint and shouldRepaint methods, and may optionally also implement the hitTest method.
The paint method is called whenever the custom object needs to be repainted.
The shouldRepaint method is called when a new instance of the class is provided, to check if the new instance actually represents different information.
The most efficient way to trigger a repaint is to supply a repaint argument to the constructor of the CustomPainter. The custom object will listen to this animation and repaint whenever the animation ticks, avoiding both the build and layout phases of the pipeline.
The hitTest method is called when the user interacts with the underlying render object, to determine if the user hit the object or missed it.
Constructors
- CustomPainter({Listenable repaint })
-
Creates a custom painter.
const
Properties
- hashCode → int
-
Get a hash code for this object.
read-only, inherited - runtimeType → Type
-
A representation of the runtime type of the object.
read-only, inherited
Operators
-
operator ==(
other) → bool -
The equality operator.
inherited
Methods
-
hitTest(
Point position) → bool -
Called whenever a hit test is being performed on an object that is using this custom paint delegate.
-
paint(
Canvas canvas, Size size) → void -
Called whenever the object needs to paint. The given Canvas has its coordinate space configured such that the origin is at the top left of the box. The area of the box is the size of the
sizeargument. -
shouldRepaint(
CustomPainter oldDelegate) → bool -
Called whenever a new instance of the custom painter delegate class is provided to the RenderCustomPaint object, or any time that a new CustomPaint object is created with a new instance of the custom painter delegate class (which amounts to the same thing, because the latter is implemented in terms of the former).
-
noSuchMethod(
Invocation invocation) → dynamic -
Invoked when a non-existent method or property is accessed.
inherited -
toString(
) → String -
Returns a string representation of this object.
inherited