overlayMatrix function

Implementation

Matrix4 overlayMatrix({
  required Offset origin,
  required Size size,
  required Alignment alignment,
  required bool rotate,
  double mapRotationRad = 0.0,
  EdgeInsets margin = EdgeInsets.zero,
  Offset pixelOffset = Offset.zero,
}) {
  final f = _computeFrame(
    origin: origin,
    size: size,
    alignment: alignment,
    mapRotationRad: mapRotationRad,
    rotate: rotate,
    margin: margin,
  );

  final m = Matrix4.identity();

  if (f.counter) {
    final c = math.cos(-mapRotationRad);
    final s = math.sin(-mapRotationRad);
    final dx = f.tl.dx + pixelOffset.dx;
    final dy = f.tl.dy + pixelOffset.dy;
    final ax = f.ax;
    final ay = f.ay;

    // Col 0
    m[0] = c;
    m[1] = s;
    // Col 1
    m[4] = -s;
    m[5] = c;
    // Col 3 (Translation)
    m[12] = ax * (1 - c) + ay * s + dx;
    m[13] = ay * (1 - c) - ax * s + dy;
  } else {
    m.translateByDouble(
      f.tl.dx + pixelOffset.dx,
      f.tl.dy + pixelOffset.dy,
      0.0,
      1.0,
    );
  }

  return m;
}