我将尝试实现一个有趣的事情:
我有几个点,我想用正弦波将它们连接起来。
下一个方法返回制作图表的点数组:
之后我创建了特殊的
下一个方法返回制作图表的点数组:
- (NSArray *)plotPointsBetweenPoint:(CGPoint)pointA andPoint:(CGPoint)pointB {
double H = fabs(pointB.y - pointA.y);
double L = fabs(pointB.x - pointA.x);
NSInteger granularity = 40;
NSMutableArray *array = [NSMutableArray arrayWithCapacity:granularity + 1];
for (int i = 0; i <= granularity; ++i) {
CGFloat x = M_PI*(float)i/(granularity);
CGFloat y = -cosf(x);
CGFloat multiplier = pointA.y > pointB.y ? 1 : -1;
CGPoint newPoint = CGPointMake(pointA.x + L*(float)i/granularity, pointA.y - multiplier*H*(1.0 + y)/2.0);
[array addObject:[NSValue valueWithCGPoint:newPoint]];
}
return array;
}
之后我创建了特殊的
UIBezierPath
:- (UIBezierPath *)sineWaveWithPoints:(NSArray *)points {
UIBezierPath *path = [[UIBezierPath alloc] init];
NSMutableArray *array = [NSMutableArray array];
for (int i = 0; i < points.count - 1; ++i) {
[array addObjectsFromArray:[self plotPointsBetweenPoint:[points[i] CGPointValue] andPoint:[points[i+1] CGPointValue]]];
}
[path moveToPoint:[array[0] CGPointValue]];
for (NSValue *value in array) {
CGPoint point = [value CGPointValue];
[path addLineToPoint:point];
}
[path closePath];
path.lineWidth = 2.0;
[path stroke];
return path;
}
接下来我将使用CAShapeLayer添加这条路径:
CAGradientLayer *gradientLayer = [self gradientLayer];
CAShapeLayer *maskLine = [CAShapeLayer layer];
maskLine.path = [self sineWaveWithPoints:pointsArray].CGPath;
maskLine.lineWidth = self.plotWidth;
gradientLayer.mask = maskLine;
[self.view.layer addSublayer:gradientLayer];
所以我想在这些点之间有梯度正弦波。我的操作有什么问题呢?
理想情况下应该是这样的: