blob: 54629b95d557927d681d52739187d8d88036c8c9 [file] [log] [blame]
 // 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(); }