image
最近碰到一个需求，需要画一个仪表盘的页面。图上所示。
计算角度
圆弧部分还好，用CAShapeLayer+UIBezierPath曲线，只要确定好圆心部分和左右两边的角度就行。这里正好说明一下
- (void)addArcWithCenter:(CGPoint)center radius:(CGFloat)radius startAngle:(CGFloat)startAngle endAngle:(CGFloat)endAngle clockwise:(BOOL)clockwise API_AVAILABLE(ios(4.0));
这个接口startAngle、endAngle和clockwise的关系，之前一直记不太清。
我们需要看一下下面这张图
在这里插入图片描述
clockwise为true的时候，就会从startAngle按顺时针方向画弧。为false的时候，按逆时针方向画弧。
这里有一个要注意的地方是
- 顺时针的360°表示的值，必须是0~2*M_PI，
- 逆时针的360°表示的值必须是0~-2*M_PI。
- 同一个角度表示的值，在clockwise取true或者false的情况下，是需要转换的。
了解了上面的注意点之后，三条圆弧还是能很方便的画出来的。
接下来就是动态的显示进度。即白色圆弧每次数值变化，弧线动态增长或减少。
StrokeEnd
一开始想的是每次都重新绘制贝塞尔曲线，但是发现从动画效果上来看，每次重新绘制，都会从起点位置绘制到终点位置。不是想要的效果。
然后又想着设置layer.masksToBounds=true然后，画一条半圆，通过旋转来达到左右移动的效果，这样超出layer的部分就不会显示了，但是又发现背景的圆弧不是一块半圆，会存在覆盖不全的情况。
后来查看CAShaperLayer的说明，发现这样一个属性
/* These values define the subregion of the path used to draw the
* stroked outline. The values must be in the range [0,1] with zero
* representing the start of the path and one the end. Values in
* between zero and one are interpolated linearly along the path
* length. strokeStart defaults to zero and strokeEnd to one. Both are
* animatable. */
@property CGFloat strokeStart;
@property CGFloat strokeEnd;
这两个值默认是0和1，对应的就是起始点和终点的比例，当storkeEnd=0.5的时候，原来圆弧终点的值就会减少为原来的一半
那么我就可以这样了，我先画一套完整的覆盖背景圆弧的实线圆弧，设置strokeEnd=0，这样圆弧长度就为0了。当值变化的时候，在调整strokeEnd的值。就可以动态的变化圆弧长度了。
CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"strokeEnd"];
animation.duration = 1;
animation.fromValue = @(oldValue/100.0);
animation.toValue = @(value/100.0);
animation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear];
animation.removedOnCompletion = NO;
animation.fillMode = kCAFillModeForwards;
[self.valueLayer addAnimation:animation forKey:@"valueProgress"];
绘制移动路径
搞定了圆弧的变化之后，还有一部分是小圆点的移动，它是按照圆弧的轨迹移动的，那么在做动画效果的时候，就要让小圆点按照圆弧的轨迹移动位置。
UIBezierPath *bezierPath = [UIBezierPath bezierPath];
CGFloat outerWidth = 226;
if (oldValue > value) { // <-
CGFloat valueAngle = value/100.0 * (2*M_PI - (self.startAngle - self.endAngle)) + self.startAngle;
CGFloat oldAngle = oldValue/100.0 * (2*M_PI - (self.startAngle - self.endAngle)) + self.startAngle;
valueAngle = valueAngle - 2*M_PI;
oldAngle = oldAngle - 2*M_PI;
[bezierPath addArcWithCenter:CGPointMake(outerWidth/2, outerWidth/2) radius:outerWidth/2 startAngle:oldAngle endAngle:valueAngle clockwise:NO];
} else if (oldValue < value) { // ->
CGFloat valueAngle = value/100.0 * (2*M_PI - (self.startAngle - self.endAngle)) + self.startAngle;
CGFloat oldAngle = oldValue/100.0 * (2*M_PI - (self.startAngle - self.endAngle)) + self.startAngle;
[bezierPath addArcWithCenter:CGPointMake(outerWidth/2, outerWidth/2) radius:outerWidth/2 startAngle:oldAngle endAngle:valueAngle clockwise:YES];
} else {
return;
}
CAKeyframeAnimation *positionKF = [CAKeyframeAnimation animationWithKeyPath:`@"position"`];
positionKF.duration = 1;
positionKF.path = bezierPath.CGPath;
positionKF.calculationMode = kCAAnimationPaced;
positionKF.removedOnCompletion = NO;
positionKF.fillMode = kCAFillModeForwards;
[self.cursorLayer addAnimation:positionKF forKey:`@"rotateCursorAnimated"`];
我们根据起点和终点绘制一段小圆点移动的路径，设置CAKeyframAnimation即可。这里比较绕的时候，当小圆点从左往右移动和从右往左移动，一个是顺时针clock=YES一个是逆时针clock=NO，这里就要注意我们前面说的了，相同角度下，顺时针和逆时针需要换算一下。参考上面的代码。
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代码部分
完整代码如下，仅供参考
#import "PointView.h"
@interface PointView ()
@property (nonatomic, strong) CAShapeLayer *valueLayer;
@property (nonatomic, strong) CALayer *cursorLayer;
@property (nonatomic, strong) UIBezierPath *valuePath;
@property (nonatomic, assign) CGFloat startAngle;
@property (nonatomic, assign) CGFloat endAngle;
@property (nonatomic, assign) CGFloat currenAngle;
@property (nonatomic, strong) CADisplayLink *link;
@property (nonatomic, strong) UILabel *numberLabel;
@property (nonatomic, assign) NSInteger oldValue;
@end
@implementation PointView
- (instancetype)initWithFrame:(CGRect)frame {
self = [super initWithFrame:frame];
if (self) {
_startAngle = M_PI*15.2/18;
_endAngle = M_PI*2.8/18;
[self setupViews];
}
return self;
}
- (void)dealloc {
[self.link invalidate];
self.link = nil;
}
/**
p1********************************************p6
* *
* *
* *
* *
p2******************p3 p4******************p5
p3.1 * p4.1
*/
- (void)setupViews {
CGFloat x = 0;
CGFloat y = 0;
CGFloat width = self.frame.size.width;
CGFloat height = self.frame.size.height;
CGFloat radius = 15;
CGPoint p1 = CGPointMake(x, y);
CGPoint p2 = CGPointMake(x, height-radius);
CGPoint p3 = CGPointMake(width/2-radius, height-radius);
CGPoint p3_1 = CGPointMake(width/2-radius, height);
CGPoint p4 = CGPointMake(width/2+radius, height-radius);
CGPoint p4_1 = CGPointMake(width/2+radius, height);
CGPoint p5 = CGPointMake(width, height-radius);
CGPoint p6 = CGPointMake(width, y);
CAGradientLayer *gradientLayer = [[CAGradientLayer alloc] init];
UIColor *startColor = [UIColor colorWithRed:225/255.0 green:187/255.0 blue:118/255.0 alpha:1];
UIColor *endColor = [UIColor colorWithRed:209/255.0 green:162/255.0 blue:92/255.0 alpha:1];
gradientLayer.colors = @[(__bridge id)startColor.CGColor, (__bridge id)endColor.CGColor];
gradientLayer.startPoint = CGPointMake(0.5, 0);
gradientLayer.endPoint = CGPointMake(0.5, 1);
gradientLayer.frame = self.bounds;
[self.layer addSublayer:gradientLayer];
CAShapeLayer *shapeLayer = [CAShapeLayer layer];
UIBezierPath *bezierPath = [UIBezierPath bezierPath];
[bezierPath moveToPoint:p1];
[bezierPath addLineToPoint:p2];
[bezierPath addLineToPoint:p3];
[bezierPath addArcWithCenter:p3_1 radius:radius startAngle:1.5*M_PI endAngle:0 clockwise:YES];
[bezierPath addArcWithCenter:p4_1 radius:radius startAngle:-1*M_PI endAngle:-0.5*M_PI clockwise:YES];
[bezierPath moveToPoint:p4];
[bezierPath addLineToPoint:p5];
[bezierPath addLineToPoint:p6];
[bezierPath addLineToPoint:p1];
shapeLayer.path = bezierPath.CGPath;
self.layer.mask = shapeLayer;
// inner circle
CAShapeLayer *innerLayer = [CAShapeLayer layer];
CGFloat innerWidth = 170;
CGFloat innerHeight = 135;
innerLayer.frame = CGRectMake(width/2-innerWidth/2, 54, innerWidth, innerHeight);
UIBezierPath *innerPath = [UIBezierPath bezierPath];
[innerPath addArcWithCenter:CGPointMake(innerWidth/2, innerWidth/2) radius:innerWidth/2 startAngle:M_PI*14.4/18 endAngle:M_PI*3.6/18 clockwise:YES];
innerLayer.path = innerPath.CGPath;
innerLayer.strokeColor = [[UIColor whiteColor] colorWithAlphaComponent:0.4].CGColor;
innerLayer.fillColor = [UIColor clearColor].CGColor;
innerLayer.lineDashPattern = @[@4, @3];
[self.layer addSublayer:innerLayer];
// middle circle
CAShapeLayer *middleLayer = [CAShapeLayer layer];
CGFloat middleWidth = 199;
CGFloat middleHeight = 158;
middleLayer.frame = CGRectMake(width/2-middleWidth/2, 37, middleWidth, middleHeight);
UIBezierPath *middlePath = [UIBezierPath bezierPath];
[middlePath addArcWithCenter:CGPointMake(middleWidth/2, middleWidth/2) radius:middleWidth/2 startAngle:M_PI*15/18 endAngle:M_PI*3/18 clockwise:YES];
middleLayer.path = middlePath.CGPath;
middleLayer.strokeColor = [[UIColor whiteColor] colorWithAlphaComponent:0.4].CGColor;
middleLayer.fillColor = [UIColor clearColor].CGColor;
middleLayer.lineWidth = 10;
middleLayer.lineCap = kCALineCapRound;
[self.layer addSublayer:middleLayer];
// outer circle
CAShapeLayer *outerLayer = [CAShapeLayer layer];
CGFloat outerWidth = 226;
CGFloat outerHeight = 165;
outerLayer.frame = CGRectMake(width/2-outerWidth/2, 24, outerWidth, outerHeight);
UIBezierPath *outerPath = [UIBezierPath bezierPath];
[outerPath addArcWithCenter:CGPointMake(outerWidth/2, outerWidth/2) radius:outerWidth/2 startAngle:M_PI*15.2/18 endAngle:M_PI*2.8/18 clockwise:YES];
outerLayer.path = outerPath.CGPath;
outerLayer.strokeColor = [[UIColor whiteColor] colorWithAlphaComponent:0.4].CGColor;
outerLayer.fillColor = [UIColor clearColor].CGColor;
outerLayer.lineWidth = 3;
outerLayer.lineCap = kCALineCapRound;
[self.layer addSublayer:outerLayer];
// value circle
CAShapeLayer *valueLayer = [CAShapeLayer layer];
valueLayer.frame = CGRectMake(width/2-outerWidth/2, 24, outerWidth, outerHeight);
self.valuePath = [UIBezierPath bezierPath];
[self.valuePath addArcWithCenter:CGPointMake(outerWidth/2, outerWidth/2) radius:outerWidth/2 startAngle:self.startAngle endAngle:self.endAngle clockwise:YES];
valueLayer.path = self.valuePath.CGPath;
valueLayer.strokeColor = [UIColor whiteColor].CGColor;
valueLayer.fillColor = [UIColor clearColor].CGColor;
valueLayer.lineWidth = 3;
valueLayer.lineCap = kCALineCapRound;
self.cursorLayer = [CALayer layer];
self.cursorLayer.backgroundColor = [UIColor whiteColor].CGColor;
self.cursorLayer.cornerRadius = 4;
self.cursorLayer.masksToBounds = YES;
CGPoint startPoint = [[self pointsFromBezierPath:self.valuePath].firstObject CGPointValue];
self.cursorLayer.frame = CGRectMake(startPoint.x, startPoint.y, 8, 8);
[valueLayer addSublayer:self.cursorLayer];
[self.layer addSublayer:valueLayer];
self.valueLayer = valueLayer;
self.valueLayer.strokeEnd = 0;
self.value = 0;
self.numberLabel = [[UILabel alloc] initWithFrame:CGRectMake(width/2-100/2, 102, 100, 63)];
self.numberLabel.textColor = [UIColor whiteColor];
self.numberLabel.font = [UIFont systemFontOfSize:45];
self.numberLabel.textAlignment = NSTextAlignmentCenter;
self.numberLabel.text = @"0";
[self addSubview:self.numberLabel];
self.link = [CADisplayLink displayLinkWithTarget:self selector:@selector(displayNumber)];
[self.link addToRunLoop:[NSRunLoop mainRunLoop] forMode:NSDefaultRunLoopMode];
self.link.paused = YES;
}
- (void)displayNumber {
NSLog(@"display link变化");
NSInteger currentNumber = [self.numberLabel.text integerValue];
if (self.value < currentNumber) {
currentNumber -= 1;
} else if (self.value > currentNumber) {
currentNumber += 1;
}
if (currentNumber == self.value) {
self.link.paused = YES;
}
self.numberLabel.text = [NSString stringWithFormat:@"%ld", currentNumber];
}
- (void)setValue:(NSInteger)value {
NSInteger oldValue = _value;
_oldValue = oldValue;
_value = value;
NSLog(@"旧值：%f | 新值：%f", oldValue/100.0, value/100.0);
CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"strokeEnd"];
animation.duration = 1;
animation.fromValue = @(oldValue/100.0);
animation.toValue = @(value/100.0);
animation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear];
animation.removedOnCompletion = NO;
animation.fillMode = kCAFillModeForwards;
[self.valueLayer addAnimation:animation forKey:@"valueProgress"];
// self.valueLayer.strokeEnd = value/100.0;
self.link.paused = NO;
// [CATransaction begin];
UIBezierPath *bezierPath = [UIBezierPath bezierPath];
CGFloat outerWidth = 226;
if (oldValue > value) { // <-
CGFloat valueAngle = value/100.0 * (2*M_PI - (self.startAngle - self.endAngle)) + self.startAngle;
CGFloat oldAngle = oldValue/100.0 * (2*M_PI - (self.startAngle - self.endAngle)) + self.startAngle;
valueAngle = valueAngle - 2*M_PI;
oldAngle = oldAngle - 2*M_PI;
[bezierPath addArcWithCenter:CGPointMake(outerWidth/2, outerWidth/2) radius:outerWidth/2 startAngle:oldAngle endAngle:valueAngle clockwise:NO];
} else if (oldValue < value) { // ->
CGFloat valueAngle = value/100.0 * (2*M_PI - (self.startAngle - self.endAngle)) + self.startAngle;
CGFloat oldAngle = oldValue/100.0 * (2*M_PI - (self.startAngle - self.endAngle)) + self.startAngle;
[bezierPath addArcWithCenter:CGPointMake(outerWidth/2, outerWidth/2) radius:outerWidth/2 startAngle:oldAngle endAngle:valueAngle clockwise:YES];
} else {
return;
}
CAKeyframeAnimation *positionKF = [CAKeyframeAnimation animationWithKeyPath:@"position"];
positionKF.duration = 1;
positionKF.path = bezierPath.CGPath;
positionKF.calculationMode = kCAAnimationPaced;
positionKF.removedOnCompletion = NO;
positionKF.fillMode = kCAFillModeForwards;
[self.cursorLayer addAnimation:positionKF forKey:@"rotateCursorAnimated"];
}
void getPointsFromBezier(void *info, const CGPathElement *element) {
NSMutableArray *bezierPoints = (__bridge NSMutableArray *)info;
CGPathElementType type = element->type;
CGPoint *points = element->points;
if (type != kCGPathElementCloseSubpath) {
[bezierPoints addObject:[NSValue valueWithCGPoint:points[0]]];
if (type != kCGPathElementAddLineToPoint && type != kCGPathElementMoveToPoint) {
[bezierPoints addObject:[NSValue valueWithCGPoint:points[1]]];
}
}
if (type == kCGPathElementAddCurveToPoint) {
[bezierPoints addObject:[NSValue valueWithCGPoint:points[2]]];
}
}
- (NSArray *)pointsFromBezierPath:(UIBezierPath *)path {
NSMutableArray *points = [NSMutableArray array];
CGPathApply(path.CGPath, (__bridge void *)points, getPointsFromBezier);
return points;
}
@end
作者：神奇奶盖
链接：https://juejin.cn/post/6896859284295188488
