Geometry API

The Geometry APIs let you create interactive tools such as selection mechanisms and erasers.

This section shows how to use the Geometry APIs to implement an eraser.

private fun eraseIntersectingStrokes(
  currentX: Float,
  currentY: Float,
  currentStrokes: MutableList<Stroke>,
  ): Unit {
    val prev = previousPoint
    previousPoint = MutableVec(currentX, currentY)
    if (prev == null) return

    val segment = MutableSegment(prev, MutableVec(currentX, currentY))
    val parallelogram = MutableParallelogram().populateFromSegmentAndPadding(
      segment,
      eraserPadding
    )
    currentStrokes.removeAll {
        it.shape.intersects(parallelogram, AffineTransform.IDENTITY)
    }
}
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