TrianglePainter class

A custom painter that draws triangular shapes on a canvas.

Provides a flexible triangle drawing utility that can render both filled and outlined triangles with customizable colors and stroke widths. The triangle is drawn with its apex pointing downward.

Commonly used for:

  • Dropdown indicators
  • Arrow decorations
  • Custom geometric UI elements
  • Chart visualizations

Example:

// Filled triangle
CustomPaint(
  size: Size(50, 50),
  painter: TrianglePainter(
    strokeColor: Colors.blue,
    paintingStyle: PaintingStyle.fill,
  ),
)

// Outlined triangle
CustomPaint(
  size: Size(50, 50),
  painter: TrianglePainter(
    strokeColor: Colors.red,
    strokeWidth: 2,
    paintingStyle: PaintingStyle.stroke,
  ),
)
Inheritance

Constructors

TrianglePainter({Color strokeColor = Colors.black, double strokeWidth = 3, PaintingStyle paintingStyle = PaintingStyle.stroke})
Creates a triangle painter with customizable styling.

Properties

hashCode → int
The hash code for this object.
no setterinherited
paintingStyle → PaintingStyle
The painting style (fill or stroke)
final
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited
semanticsBuilder → SemanticsBuilderCallback?
Returns a function that builds semantic information for the picture drawn by this painter.
no setterinherited
strokeColor → Color
The color used for the triangle stroke or fill
final
strokeWidth → double
The width of the stroke (only applies when paintingStyle is stroke)
final

Methods

addListener(VoidCallback listener) → void
Register a closure to be notified when it is time to repaint.
inherited
getTrianglePath(double x, double y) → Path
Constructs the triangular path for the given dimensions.
hitTest(Offset position) → bool?
Called whenever a hit test is being performed on an object that is using this custom paint delegate.
inherited
noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
inherited
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 size argument.
override
removeListener(VoidCallback listener) → void
Remove a previously registered closure from the list of closures that the object notifies when it is time to repaint.
inherited
shouldRebuildSemantics(covariant 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).
inherited
shouldRepaint(covariant TrianglePainter oldDelegate) → bool
Determines whether the painter should repaint.
override
toString() → String
A string representation of this object.
inherited

Operators

operator ==(Object other) → bool
The equality operator.
inherited