动画绘制线条

Question

我试图通过以下方式为线条绘制动画:

.H

CAShapeLayer *rootLayer;
CAShapeLayer *lineLayer;
CGMutablePathRef path;

.M

 path = CGPathCreateMutable();
 CGPathMoveToPoint(path, nil, self.frame.size.width/2-100, 260);
 CGPathAddLineToPoint(path, nil, self.frame.size.width/2+100.0, 260);    
 CGPathCloseSubpath(path);

 self.rootLayer = [CALayer layer];
 rootLayer.frame = self.bounds;
[self.layer addSublayer:rootLayer];

 self.lineLayer = [CAShapeLayer layer];
[lineLayer setPath:path];
[lineLayer setFillColor:[UIColor redColor].CGColor];
[lineLayer setStrokeColor:[UIColor blueColor].CGColor];
[lineLayer setLineWidth:1.5];
[lineLayer setFillRule:kCAFillRuleNonZero];
[rootLayer addSublayer:lineLayer];

[self performSelector:@selector(startTotalLine) withObject:nil afterDelay:1.5];

- (void)startTotalLine
{    
      CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"animatePath"];
      [animation setDuration:3.5];
       animation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
      [animation setAutoreverses:NO];
      [animation setFromValue:(id)path];
      [animation setToValue:(id)path];
      [lineLayer addAnimation:animation forKey:@"animatePath"];    
}

在startTotalLine调用方法之前绘制了该行.此外,该startTotalLine方法不会影响该行.

我想让它从右到左为线条图画设置动画.

Answer 1

我会用动画属性来做.

为了实现这一点,我将创建一个自定义CALayer类 - 让我们称之为LineLayer.定义startPoint属性和length属性.然后我将length属性配置为"动画".

该代码看起来如下所示:

// LineLayer.h
@interface LineLayer: CALayer

@property (nonatomic, assign) int length;
// This was omitted from the SO code snippet.
@property (nonatomic, assign) CGPoint startPoint;

@end

// LineLayer.m
@implementation LineLayer

@synthesize length = _length;
// This was omitted from the SO code snippet.
@synthesize startPoint= _startPoint;

- (id) initWithLayer:(id)layer 
{
    if(self = [super initWithLayer:layer]) 
    {
        if([layer isKindOfClass:[LineLayer class]]) 
        {
            // This bit is required for when we CA is interpolating the values.
            LineLayer *other = (LineLayer*)layer;
            self.length = other.length;
            self.startPoint = other.startPoint; // This was omitted.
        }
    }
    return self;
}

+ (BOOL)needsDisplayForKey:(NSString *)key 
{
    if ([key isEqualToString:@"length"]) {
        return YES;
    }
    return [super needsDisplayForKey:key];
}

- (void) setLength:(int)newLength
{
    if (newLength < 0) {
        return; // Fail early.
    }
    _length = newLength; 
    [self setNeedsDisplay]; 
} 

/*
    This should have been drawInContext:(CGContextRef)context
    - (void) drawRect:(CGRect) rect 
*/
- (void) drawInContext:(CGContextRef)context
{
    //...Do your regular drawing here.

    // This was omitted from the SO code snippet.
    CGContextSetStrokeColorWithColor(context, [UIColor redColor].CGColor);
    CGContextSetLineWidth(context, 2);
    CGContextMoveToPoint(context, _startPoint.x, _startPoint.y);
    CGContextAddLineToPoint(context, _startPoint.x + _length, _startPoint.y);
    CGContextStrokePath(context);
}

@end

然后在您的视图控制器中,您可以LineLayer像这样使用:

- (void)viewDidLoad
{
    [super viewDidLoad];

    LineLayer *lineLayer = [LineLayer new];

    // This was omitted from the SO code snippet.
    lineLayer.frame = CGRectMake(0, 0, 320, 480);
    [lineLayer setNeedsDisplay];
    // ---

    lineLayer.startPoint = CGPointMake(0, 100);
    lineLayer.length = 0;

    [self.view.layer addSublayer:lineLayer];

    // Now animate the changes to the length property
    CABasicAnimation *anim = [CABasicAnimation animationWithKeyPath:@"length"];
    anim.duration = 5; // Change should table about 5 mins.
    anim.fromValue = [NSNumber numberWithInt:0];
    anim.toValue = [NSNumber numberWithInt:200];

    [lineLayer addAnimation:anim forKey:@"animateLength"];
    lineLayer.length = 200;
    //Do clean up below...
}

快乐编码:)

Answer 2

我认为做你想要的最简单的方法是呈现一些 1.5 像素高度的 UIView 并为其宽度设置动画。如果我不清楚就问我。

我认为您的代码不起作用，因为您的变量path不是图层属性。阅读手册：

CABasicAnimation 为图层属性提供基本的单关键帧动画功能。

你在这里做了一些奇怪的事情：

[animation setFromValue:(id)path];
[animation setToValue:(id)path];

编辑：我偶然发现了一篇文章，并理解您想要实现的目标！现在我认为你失败的原因是你可以为不改变点数的路径设置动画。现在我认为你可以创建一条有两点的路径线。起初它们位于同一个地方，而另一条路径是您想要结束的线。现在从第一条路径到第二条路径进行动画处理。我认为它应该有效，但我不确定。

编辑：当然！你需要这个人的密码。git 链接.