| // Copyright 2014 The Flutter Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| import 'dart:math' as math; |
| |
| import 'basic_types.dart'; |
| |
| /// Draw a line between two points, which cuts diagonally back and forth across |
| /// the line that connects the two points. |
| /// |
| /// The line will cross the line `zigs - 1` times. |
| /// |
| /// If `zigs` is 1, then this will draw two sides of a triangle from `start` to |
| /// `end`, with the third point being `width` away from the line, as measured |
| /// perpendicular to that line. |
| /// |
| /// If `width` is positive, the first `zig` will be to the left of the `start` |
| /// point when facing the `end` point. To reverse the zigging polarity, provide |
| /// a negative `width`. |
| /// |
| /// The line is drawn using the provided `paint` on the provided `canvas`. |
| void paintZigZag(Canvas canvas, Paint paint, Offset start, Offset end, int zigs, double width) { |
| assert(zigs.isFinite); |
| assert(zigs > 0); |
| canvas.save(); |
| canvas.translate(start.dx, start.dy); |
| end = end - start; |
| canvas.rotate(math.atan2(end.dy, end.dx)); |
| final double length = end.distance; |
| final double spacing = length / (zigs * 2.0); |
| final Path path = Path() |
| ..moveTo(0.0, 0.0); |
| for (int index = 0; index < zigs; index += 1) { |
| final double x = (index * 2.0 + 1.0) * spacing; |
| final double y = width * ((index % 2.0) * 2.0 - 1.0); |
| path.lineTo(x, y); |
| } |
| path.lineTo(length, 0.0); |
| canvas.drawPath(path, paint); |
| canvas.restore(); |
| } |