percentPath function
给定一个Path和路径百分比返回给定百分比路径
Implementation
Path percentPath(Path path, double percent) {
PathMetrics metrics = path.computeMetrics();
Path newPath = Path();
for (PathMetric metric in metrics) {
Path tmp = metric.extractPath(0, metric.length * percent);
newPath.addPath(tmp, Offset.zero);
}
return newPath;
}