动画CAShapeLayer Pie

Question

我正在尝试使用CAShapeLayer创建一个简单的动画饼图。我想让它从0动画到提供的百分比。

要创建形状图层，我使用：

CGMutablePathRef piePath = CGPathCreateMutable();
CGPathMoveToPoint(piePath, NULL, self.frame.size.width/2, self.frame.size.height/2);
CGPathAddLineToPoint(piePath, NULL, self.frame.size.width/2, 0);
CGPathAddArc(piePath, NULL, self.frame.size.width/2, self.frame.size.height/2, radius, DEGREES_TO_RADIANS(-90), DEGREES_TO_RADIANS(-90), 0);        
CGPathAddLineToPoint(piePath, NULL, self.frame.size.width/2 + radius * cos(DEGREES_TO_RADIANS(-90)), self.frame.size.height/2 + radius * sin(DEGREES_TO_RADIANS(-90)));

pie = [CAShapeLayer layer];
pie.fillColor = [UIColor redColor].CGColor;
pie.path = piePath;

[self.layer addSublayer:pie];

然后动画我使用：

CGMutablePathRef newPiePath = CGPathCreateMutable();
CGPathAddLineToPoint(newPiePath, NULL, self.frame.size.width/2, 0);    
CGPathMoveToPoint(newPiePath, NULL, self.frame.size.width/2, self.frame.size.height/2);
CGPathAddArc(newPiePath, NULL, self.frame.size.width/2, self.frame.size.height/2, radius, DEGREES_TO_RADIANS(-90), DEGREES_TO_RADIANS(125), 0);                
CGPathAddLineToPoint(newPiePath, NULL, self.frame.size.width/2 + radius * cos(DEGREES_TO_RADIANS(125)), self.frame.size.height/2 + radius * sin(DEGREES_TO_RADIANS(125)));    

CABasicAnimation *pieAnimation = [CABasicAnimation animationWithKeyPath:@"path"];
pieAnimation.duration = 1.0;
pieAnimation.removedOnCompletion = NO;
pieAnimation.fillMode = kCAFillModeForwards;
pieAnimation.fromValue = pie.path;
pieAnimation.toValue = newPiePath;

[pie addAnimation:pieAnimation forKey:@"animatePath"];

显然，这是以一种非常奇怪的方式制作动画。形状只是变成了最终状态。有没有一种简单的方法可以让这个动画跟随圆圈的方向？或者这是CAShapeLayer动画的限制吗？

Answer 1

我知道这个问题早已得到解答，但我不认为这是CAShapeLayer和CAKeyframeAnimation的好例子。 Core Animation有能力为我们做动画补间动画。这是一个类（包含UIView，如果你愿意的话），我用它来很好地完成效果。

图层子类为progress属性启用隐式动画，但视图类将其setter包装在UIView动画方法中。使用带有UIViewAnimationOptionBeginFromCurrentState的0.0长度动画的有趣（并且最终有用）副作用是每个动画取消前一个动画，从而产生平滑，快速，高帧率的饼图，如this（动画）和this（不动画，但递增）。

DZRoundProgressView.h

@interface DZRoundProgressLayer : CALayer

@property (nonatomic) CGFloat progress;

@end

@interface DZRoundProgressView : UIView

@property (nonatomic) CGFloat progress;

@end

DZRoundProgressView.m

#import "DZRoundProgressView.h"
#import <QuartzCore/QuartzCore.h>

@implementation DZRoundProgressLayer

// Using Core Animation's generated properties allows
// it to do tweening for us.
@dynamic progress;

// This is the core of what does animation for us. It
// tells CoreAnimation that it needs to redisplay on
// each new value of progress, including tweened ones.
+ (BOOL)needsDisplayForKey:(NSString *)key {
    return [key isEqualToString:@"progress"] || [super needsDisplayForKey:key];
}

// This is the other crucial half to tweening.
// The animation we return is compatible with that
// used by UIView, but it also enables implicit
// filling-up-the-pie animations.
- (id)actionForKey:(NSString *) aKey {
    if ([aKey isEqualToString:@"progress"]) {
        CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:aKey];
        animation.fromValue = [self.presentationLayer valueForKey:aKey];
        return animation;
    }
    return [super actionForKey:aKey];
}

// This is the gold; the drawing of the pie itself.
// In this code, it draws in a "HUD"-y style, using
// the same color to fill as the border.
- (void)drawInContext:(CGContextRef)context {
    CGRect circleRect = CGRectInset(self.bounds, 1, 1);

    CGColorRef borderColor = [[UIColor whiteColor] CGColor];
    CGColorRef backgroundColor = [[UIColor colorWithWhite: 1.0 alpha: 0.15] CGColor];

    CGContextSetFillColorWithColor(context, backgroundColor);
    CGContextSetStrokeColorWithColor(context, borderColor);
    CGContextSetLineWidth(context, 2.0f);

    CGContextFillEllipseInRect(context, circleRect);
    CGContextStrokeEllipseInRect(context, circleRect);

    CGFloat radius = MIN(CGRectGetMidX(circleRect), CGRectGetMidY(circleRect));
    CGPoint center = CGPointMake(radius, CGRectGetMidY(circleRect));
    CGFloat startAngle = -M_PI / 2;
    CGFloat endAngle = self.progress * 2 * M_PI + startAngle;
    CGContextSetFillColorWithColor(context, borderColor);
    CGContextMoveToPoint(context, center.x, center.y);
    CGContextAddArc(context, center.x, center.y, radius, startAngle, endAngle, 0);
    CGContextClosePath(context);
    CGContextFillPath(context);

    [super drawInContext:context];
}

@end

@implementation DZRoundProgressView
+ (Class)layerClass {
    return [DZRoundProgressLayer class];
}

- (id)init {
    return [self initWithFrame:CGRectMake(0.0f, 0.0f, 37.0f, 37.0f)];
}

- (id)initWithFrame:(CGRect)frame {
    if ((self = [super initWithFrame:frame])) {
        self.opaque = NO;
        self.layer.contentsScale = [[UIScreen mainScreen] scale];
        [self.layer setNeedsDisplay];
    }
    return self;
}

- (void)setProgress:(CGFloat)progress {
    [(id)self.layer setProgress:progress];
}

- (CGFloat)progress {
    return [(id)self.layer progress];
}

@end

Answer 2

我建议您改为制作关键帧动画：

pie.bounds = CGRectMake(-0.5 * radius,
                        -0.5 * radius,
                        radius,
                        radius);

NSMutableArray *values = [NSMutableArray array];
for (int i = 0; i < nrSteps + 1; i++)
{
    UIBezierPath *path = [UIBezierPath bezierPath];
    [path moveToPoint:CGPointZero];
    [path addLineToPoint:CGPointMake(radius * cosf(startAngle),
                                     radius * sinf(startAngle))];
    [path addArcWithCenter:...
                  endAngle:startAngle + i * (endAngle - startAngle) / nrSteps
                           ...];
    [path closePath];
    [values addObject:(__bridge id)path.CGPath];
}

基本动画适用于标量/矢量。但是你想让它插入你的路径吗？

Answer 3

快速复制/粘贴this excellent Objective-C answer的快速翻译。

class ProgressView: UIView {

    required init(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        genericInit()
    }

    private func genericInit() {
        self.opaque = false;
        self.layer.contentsScale = UIScreen.mainScreen().scale
        self.layer.setNeedsDisplay()
    }

    var progress : CGFloat = 0 {
        didSet {
            (self.layer as! ProgressLayer).progress = progress
        }
    }

    override class func layerClass() -> AnyClass {
        return ProgressLayer.self
    }

    func updateWith(progress : CGFloat) {
        self.progress = progress
    }
}

class ProgressLayer: CALayer {

    @NSManaged var progress : CGFloat

    override class func needsDisplayForKey(key: String!) -> Bool{

        return key == "progress" || super.needsDisplayForKey(key);
    }

    override func actionForKey(event: String!) -> CAAction! {

        if event == "progress" {
            let animation = CABasicAnimation(keyPath: event)
            animation.duration = 0.2
            animation.fromValue = self.presentationLayer().valueForKey(event)
            return animation
        }

        return super.actionForKey(event)
    }

    override func drawInContext(ctx: CGContext!) {

        if progress != 0 {

            let circleRect = CGRectInset(self.bounds, 1, 1)
            let borderColor = UIColor.whiteColor().CGColor
            let backgroundColor = UIColor.clearColor().CGColor

            CGContextSetFillColorWithColor(ctx, backgroundColor)
            CGContextSetStrokeColorWithColor(ctx, borderColor)
            CGContextSetLineWidth(ctx, 2)

            CGContextFillEllipseInRect(ctx, circleRect)
            CGContextStrokeEllipseInRect(ctx, circleRect)

            let radius = min(CGRectGetMidX(circleRect), CGRectGetMidY(circleRect))
            let center = CGPointMake(radius, CGRectGetMidY(circleRect))
            let startAngle = CGFloat(-(M_PI/2))
            let endAngle = CGFloat(startAngle + 2 * CGFloat(M_PI * Double(progress)))

            CGContextSetFillColorWithColor(ctx, borderColor)
            CGContextMoveToPoint(ctx, center.x, center.y)
            CGContextAddArc(ctx, center.x, center.y, radius, startAngle, endAngle, 0)
            CGContextClosePath(ctx)
            CGContextFillPath(ctx)
        }
    }
}

Answer 4

在Swift 3中

class ProgressView: UIView {

    required init(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)!
        genericInit()
    }

    private func genericInit() {
        self.isOpaque = false;
        self.layer.contentsScale = UIScreen.main.scale
        self.layer.setNeedsDisplay()
    }

    var progress : CGFloat = 0 {
        didSet {
            (self.layer as! ProgressLayer).progress = progress
        }
    }

    override class var layerClass: AnyClass {
        return ProgressLayer.self
    }

    func updateWith(progress : CGFloat) {
        self.progress = progress
    }
}

class ProgressLayer: CALayer {

    @NSManaged var progress : CGFloat

    override class func needsDisplay(forKey key: String) -> Bool{

        return key == "progress" || super.needsDisplay(forKey: key);
    }

    override func action(forKey event: String) -> CAAction? {

        if event == "progress" {

            let animation = CABasicAnimation(keyPath: event)
            animation.duration = 0.2
            animation.fromValue = self.presentation()?.value(forKey: event) ?? 0
            return animation

        }

        return super.action(forKey: event)
    }

    override func draw(in ctx: CGContext) {

        if progress != 0 {

            let circleRect = self.bounds.insetBy(dx: 1, dy: 1)
            let borderColor = UIColor.white.cgColor
            let backgroundColor = UIColor.red.cgColor

            ctx.setFillColor(backgroundColor)
            ctx.setStrokeColor(borderColor)
            ctx.setLineWidth(2)

            ctx.fillEllipse(in: circleRect)
            ctx.strokeEllipse(in: circleRect)

            let radius = min(circleRect.midX, circleRect.midY)
            let center = CGPoint(x: radius, y: circleRect.midY)
            let startAngle = CGFloat(-(Double.pi/2))
            let endAngle = CGFloat(startAngle + 2 * CGFloat(Double.pi * Double(progress)))

            ctx.setFillColor(borderColor)
            ctx.move(to: CGPoint(x:center.x , y: center.y))
            ctx.addArc(center: CGPoint(x:center.x, y: center.y), radius: radius, startAngle: startAngle, endAngle: endAngle, clockwise: true)
            ctx.closePath()
            ctx.fillPath()
        }
    }
}