在UIView中剪切透明孔

Question

展望创建一个具有它里面的透明框架,使视图背后的意见,可以通过这个透明的框架中可以看出,但是这以外的地区将不显示通过视图.所以在视图中基本上是一个窗口.

希望能够做到这样的事情:

 CGRect hole = CGRectMake(100, 100, 250, 250);
CGContextRef context = UIGraphicsGetCurrentContext();

CGContextSetFillColorWithColor(context, [UIColor blackColor].CGColor);
CGContextFillRect(context, rect);

CGContextAddRect(context, hole);
CGContextClip(context);

CGContextSetFillColorWithColor(context, [UIColor clearColor].CGColor);
CGContextFillRect(context, rect);

但是清除不会覆盖黑色,所以整个背景都是黑色的.沿着这些方向的任何想法？

Answer 1

这是我的实现(因为我确实需要透明部分的视图):

标题(.h)文件:

// Subclasses UIview to draw transparent rects inside the view

#import <UIKit/UIKit.h>

@interface PartialTransparentView : UIView {
    NSArray *rectsArray;
    UIColor *backgroundColor;
}

- (id)initWithFrame:(CGRect)frame backgroundColor:(UIColor*)color andTransparentRects:(NSArray*)rects;

@end

实现(.m)文件:

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

@implementation PartialTransparentView

- (id)initWithFrame:(CGRect)frame backgroundColor:(UIColor*)color andTransparentRects:(NSArray*)rects
{
    backgroundColor = color;
    rectsArray = rects;
    self = [super initWithFrame:frame];
    if (self) {
        // Initialization code
        self.opaque = NO;
    }
    return self;
}

// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect
{
    // Drawing code
    [backgroundColor setFill];
    UIRectFill(rect);

    // clear the background in the given rectangles
    for (NSValue *holeRectValue in rectsArray) {
        CGRect holeRect = [holeRectValue CGRectValue];
        CGRect holeRectIntersection = CGRectIntersection( holeRect, rect );
        [[UIColor clearColor] setFill];
        UIRectFill(holeRectIntersection);
    }

}


@end

现在要添加具有部分透明度的视图,您需要导入PartialTransparentView自定义UIView子类,然后按如下方式使用它:

NSArray *transparentRects = [[NSArray alloc] initWithObjects:[NSValue valueWithCGRect:CGRectMake(0, 50, 100, 20)],[NSValue valueWithCGRect:CGRectMake(0, 150, 10, 20)], nil];
PartialTransparentView *transparentView = [[PartialTransparentView alloc] initWithFrame:CGRectMake(0,0,200,400) backgroundColor:[UIColor colorWithWhite:1 alpha:0.75] andTransparentRects:rects];
[self.view addSubview:backgroundView];

这将创建一个包含2个透明rects的视图.当然,您可以根据需要添加任意数量的rects,或者只使用一个.上面的代码只处理矩形,所以如果你想使用圆圈,你将不得不修改它.

Answer 2

Lefteris答案是绝对正确的,但它会创建透明的Rects.对于CIRCULAR透明层,将draw rect修改为

- (void)drawRect:(CGRect)rect {

    [backgroundColor setFill];
     UIRectFill(rect);

    for (NSValue *holeRectValue in rectsArray) {
        CGRect holeRect = [holeRectValue CGRectValue];
        CGRect holeRectIntersection = CGRectIntersection( holeRect, rect );

        CGContextRef context = UIGraphicsGetCurrentContext();

        if( CGRectIntersectsRect( holeRectIntersection, rect ) )
        {
            CGContextAddEllipseInRect(context, holeRectIntersection);
            CGContextClip(context);
            CGContextClearRect(context, holeRectIntersection);
            CGContextSetFillColorWithColor( context, [UIColor clearColor].CGColor );
            CGContextFillRect( context, holeRectIntersection);
        }
    }
}

Answer 3

我曾经UIBezierPath处理过切出透明孔.以下代码进入UIView要绘制透明孔的子类:

- (void)drawRect:(CGRect)rect {
    [super drawRect:rect];

    CGContextRef context = UIGraphicsGetCurrentContext();
    // Clear any existing drawing on this view
    // Remove this if the hole never changes on redraws of the UIView
    CGContextClearRect(context, self.bounds);

    // Create a path around the entire view
    UIBezierPath *clipPath = [UIBezierPath bezierPathWithRect:self.bounds];

    // Your transparent window. This is for reference, but set this either as a property of the class or some other way
    CGRect transparentFrame;
    // Add the transparent window
    UIBezierPath *path = [UIBezierPath bezierPathWithRoundedRect:transparentFrame cornerRadius:5.0f];
    [clipPath appendPath:path];

    // NOTE: If you want to add more holes, simply create another UIBezierPath and call [clipPath appendPath:anotherPath];

    // This sets the algorithm used to determine what gets filled and what doesn't
    clipPath.usesEvenOddFillRule = YES;
    // Add the clipping to the graphics context
    [clipPath addClip];

    // set your color
    UIColor *tintColor = [UIColor blackColor];

    // (optional) set transparency alpha
    CGContextSetAlpha(context, 0.7f);
    // tell the color to be a fill color
    [tintColor setFill];
    // fill the path
    [clipPath fill];
}

Answer 4

另一个解决方案:大矩形是所有视图(黄色),小是透明矩形.颜色不透明度是可设置的.

let pathBigRect = UIBezierPath(rect: bigRect)
let pathSmallRect = UIBezierPath(rect: smallRect)

pathBigRect.appendPath(pathSmallRect)
pathBigRect.usesEvenOddFillRule = true

let fillLayer = CAShapeLayer()
fillLayer.path = pathBigRect.CGPath
fillLayer.fillRule = kCAFillRuleEvenOdd
fillLayer.fillColor = UIColor.yellowColor().CGColor
//fillLayer.opacity = 0.4
view.layer.addSublayer(fillLayer)

Answer 5

@ mosib的回答对我来说很有帮助,直到我想在我的视图中绘制多个圆形剪纸.经过一段时间的努力,我更新了我的drawRect(swift中的代码......对不起编辑错误):

override func drawRect(rect: CGRect)
{     
    backgroundColor.setFill()   
    UIRectFill(rect)

    let layer = CAShapeLayer()
    let path = CGPathCreateMutable()

    for aRect in self.rects
    {
        let holeEnclosingRect = aRect
        CGPathAddEllipseInRect(path, nil, holeEnclosingRect) // use CGPathAddRect() for rectangular hole
        /*
        // Draws only one circular hole
        let holeRectIntersection = CGRectIntersection(holeRect, rect)
        let context = UIGraphicsGetCurrentContext()

        if( CGRectIntersectsRect(holeRectIntersection, rect))
        {
        CGContextBeginPath(context);
        CGContextAddEllipseInRect(context, holeRectIntersection)
        //CGContextDrawPath(context, kCGPathFillStroke)
        CGContextClip(context)
        //CGContextClearRect(context, holeRectIntersection)
        CGContextSetFillColorWithColor(context, UIColor.clearColor().CGColor)
        CGContextFillRect(context, holeRectIntersection)
        CGContextClearRect(context, holeRectIntersection)
        }*/
    }
    CGPathAddRect(path, nil, self.bounds)
    layer.path = path
    layer.fillRule = kCAFillRuleEvenOdd
    self.layer.mask = layer

}

Answer 6

这将做剪辑:

CGContextRef context = UIGraphicsGetCurrentContext();

CGContextSetFillColorWithColor( context, [UIColor blueColor].CGColor );
CGContextFillRect( context, rect );

CGRect holeRectIntersection = CGRectIntersection( CGRectMake(50, 50, 50, 50), rect );

if( CGRectIntersectsRect( holeRectIntersection, rect ) )
{
    CGContextAddEllipseInRect(context, holeRectIntersection);
    CGContextClip(context);
    CGContextClearRect(context, holeRectIntersection);
    CGContextSetFillColorWithColor( context, [UIColor clearColor].CGColor );
    CGContextFillRect( context, holeRectIntersection);
}

Answer 7

在 Swift 4 上实现 @Lefteris答案 ：

import UIKit

class PartialTransparentView: UIView {
    var rectsArray: [CGRect]?

    convenience init(rectsArray: [CGRect]) {
        self.init()

        self.rectsArray = rectsArray

        backgroundColor = UIColor.black.withAlphaComponent(0.6)
        isOpaque = false
    }

    override func draw(_ rect: CGRect) {
        backgroundColor?.setFill()
        UIRectFill(rect)

        guard let rectsArray = rectsArray else {
            return
        }

        for holeRect in rectsArray {
            let holeRectIntersection = rect.intersection(holeRect)
            UIColor.clear.setFill()
            UIRectFill(holeRectIntersection)
        }
    }
}

Answer 8

反过来做！将您想要通过“洞”看到的视图放置在尺寸合适的单独视图中。然后将“clipsToBounds”设置为 YES 并将该视图放在顶部。带有“透明”框架的视图是最下面的。“clipsToBounds”意味着盒子/孔之外的所有内容都被切断。

然后你可能必须处理如何处理触摸。但这是另一个问题了。也许在相应的视图上设置 userInteractionEnabled 就足够了。