PROSAGA码农传奇-swift/objective-C-使用绘图在UIScrollView中缩放UIView

<div class =“post-text”itemprop =“text”>
  
    你可能最好放上盒子和线条
     <code>
 CAShapeLayer
 </code>
    s，您可以根据缩放比例更新线宽。
  
  
    您只需要创建和定义一次线形。但是，对于您的盒子，您需要在更改缩放时重新创建路径（以使盒子的宽度/高度保持恒定的非缩放点大小。
  
  
    试一试。你应该能够简单地替换你的当前
     <code>
 ZoomingView.m
 </code>
     class - 不需要更改视图控制器。
  
   <pre>
 <code>
 //
// ZoomingView.m
//
// modified by Don Mag
//

#import "ZoomingView.h"

@interface ZoomingView()

@property (strong, nonatomic) CAShapeLayer *shapeLayer;
@property (strong, nonatomic) CAShapeLayer *boxesLayer;

@property (strong, nonatomic) NSArray *points;

@end

@implementation ZoomingView

{
    CGFloat _zoomScale;
    CGFloat _kPointSize;
}

- (instancetype)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        [self setup];
    }
    return self;
}

- (void)setup
{
    self.backgroundColor = [UIColor orangeColor];

_points = @[[NSValue valueWithCGPoint:CGPointMake(30, 30)],
                [NSValue valueWithCGPoint:CGPointMake(200, 40)],
                [NSValue valueWithCGPoint:CGPointMake(180, 200)],
                [NSValue valueWithCGPoint:CGPointMake(70, 180)]];

_zoomScale = 1;

_kPointSize = 10.0;

// create and setup boxes layer
    _boxesLayer = [CAShapeLayer new];
    [self.layer addSublayer:_boxesLayer];
    _boxesLayer.strokeColor = [UIColor redColor].CGColor;
    _boxesLayer.fillColor = [UIColor clearColor].CGColor;
    _boxesLayer.lineWidth = 1.0;
    _boxesLayer.frame = self.bounds;

// create and setup shape layer
    _shapeLayer = [CAShapeLayer new];
    [self.layer addSublayer:_shapeLayer];
    _shapeLayer.strokeColor = [UIColor greenColor].CGColor;
    _shapeLayer.fillColor = [UIColor clearColor].CGColor;
    _shapeLayer.lineWidth = 1.0;
    _shapeLayer.frame = self.bounds;

// new path for shape
    UIBezierPath *thePath = [UIBezierPath new];

for (NSValue *value in _points) {

CGPoint point = [value CGPointValue];

if ([value isEqualToValue:_points.firstObject]) {
            [thePath moveToPoint:point];
        } else {
            [thePath addLineToPoint:point];
        }

}

[thePath closePath];

[_shapeLayer setPath:thePath.CGPath];

// trigger the boxes update
    [self updateWithZoomScale:_zoomScale];
}

- (void)drawRect:(CGRect)rect
{
    // text

NSAttributedString *str = [[NSAttributedString alloc] initWithString:[NSString stringWithFormat:@"%f", _zoomScale] attributes:@{NSFontAttributeName : [UIFont systemFontOfSize:12]}];
    [str drawAtPoint:CGPointMake(5, 5)];
}

- (void)updateWithZoomScale:(CGFloat)zoomScale
{
    _zoomScale = zoomScale;

CGFloat scaledPointSize = _kPointSize * (1.0 / zoomScale);

// create a path for the boxes
    //  needs to be done here, because the width/height of the boxes
    //  must change with the scale
    UIBezierPath *thePath = [UIBezierPath new];

for (NSValue *value in _points) {

CGPoint point = [value CGPointValue];

CGRect r = CGRectMake(point.x - scaledPointSize / 2.0,
                              point.y - scaledPointSize / 2.0,
                              scaledPointSize,
                              scaledPointSize);

[thePath appendPath:[UIBezierPath bezierPathWithRect:r]];

}

[_boxesLayer setPath:thePath.CGPath];

_boxesLayer.lineWidth = 1.0 / zoomScale;
    _shapeLayer.lineWidth = 1.0 / zoomScale;

[self setNeedsDisplay];
}

@end

</code>
 </pre>
  
    结果：
  
  
    <a href="https://i.stack.imgur.com/IIKjd.png" rel="nofollow noreferrer">
      <img src =“https://i.stack.imgur.com/IIKjd.png”alt =“在此处输入图片说明”/>
    </A>
    <a href="https://i.stack.imgur.com/iSUQI.png" rel="nofollow noreferrer">
      <img src =“https://i.stack.imgur.com/iSUQI.png”alt =“在此处输入图片说明”/>
    </A>
  
  
    
      注意：
    
     应该不用多说，但是......这是一个与你合作的起点，而不是“生产代码”。
  
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