如何在椭圆形或圆形上裁剪UIImage？

Question

请提供有关如何在椭圆形或圆形上裁剪UIImage的建议。请分享您的想法。

Answer 1

#import <QuartzCore/QuartzCore.h>

CALayer *imageLayer = YourImageview.layer;
        [imageLayer setCornerRadius:5];
        [imageLayer setBorderWidth:1];
        [imageLayer setMasksToBounds:YES];

通过增加半径，它将变得更加圆润。

只要图像是正方形，您可以通过将宽度的一半作为角半径来获得完美的圆形：

[imageView.layer setCornerRadius:imageView.frame.size.width/2]; 

您还需要添加

[imageView.layer setMasksToBounds:YES];

Swift 4.2

import QuartzCore

var imageLayer: CALayer? = YourImageview.layer
imageLayer?.cornerRadius = 5
imageLayer?.borderWidth = 1
imageLayer?.masksToBounds = true

Answer 2

几个星期前我开始研究这个问题。我在这里尝试了所有的建议，其中没有一个效果很好。在RTFM的伟大传统中，我去了Quartz 2D Programming阅读了Apple的文档并提出了这个问题。请试一试，让我知道你怎么走。

代码可以很容易地修改为裁剪为elipse，或者由路径定义的任何其他形状。

确保在项目中包含Quartz 2D。

#include <math.h>

+ (UIImage*)circularScaleAndCropImage:(UIImage*)image frame:(CGRect)frame {
    // This function returns a newImage, based on image, that has been:
    // - scaled to fit in (CGRect) rect
    // - and cropped within a circle of radius: rectWidth/2

    //Create the bitmap graphics context
    UIGraphicsBeginImageContextWithOptions(CGSizeMake(frame.size.width, frame.size.height), NO, 0.0);
    CGContextRef context = UIGraphicsGetCurrentContext();

    //Get the width and heights
    CGFloat imageWidth = image.size.width;
    CGFloat imageHeight = image.size.height;
    CGFloat rectWidth = frame.size.width;
    CGFloat rectHeight = frame.size.height;

    //Calculate the scale factor
    CGFloat scaleFactorX = rectWidth/imageWidth;
    CGFloat scaleFactorY = rectHeight/imageHeight;

    //Calculate the centre of the circle
    CGFloat imageCentreX = rectWidth/2;
    CGFloat imageCentreY = rectHeight/2;

    // Create and CLIP to a CIRCULAR Path
    // (This could be replaced with any closed path if you want a different shaped clip)
    CGFloat radius = rectWidth/2;
    CGContextBeginPath (context);
    CGContextAddArc (context, imageCentreX, imageCentreY, radius, 0, 2*M_PI, 0);
    CGContextClosePath (context);
    CGContextClip (context);

    //Set the SCALE factor for the graphics context
    //All future draw calls will be scaled by this factor
    CGContextScaleCTM (context, scaleFactorX, scaleFactorY);    

    // Draw the IMAGE
    CGRect myRect = CGRectMake(0, 0, imageWidth, imageHeight);
    [image drawInRect:myRect];

    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return newImage;
}

在您的UIView类中包含以下代码，将“monk2.png”替换为您自己的图像名称。

- (void)drawRect:(CGRect)rect {

    UIImage *originalImage = [UIImage imageNamed:[NSString stringWithFormat:@"monk2.png"]];
    CGFloat oImageWidth = originalImage.size.width;
    CGFloat oImageHeight = originalImage.size.height;
    // Draw the original image at the origin
    CGRect oRect = CGRectMake(0, 0, oImageWidth, oImageHeight);
    [originalImage drawInRect:oRect];

    // Set the newRect to half the size of the original image 
    CGRect newRect = CGRectMake(0, 0, oImageWidth/2, oImageHeight/2);
    UIImage *newImage = [self circularScaleAndCropImage:originalImage frame:newRect];

    CGFloat nImageWidth = newImage.size.width;
    CGFloat nImageHeight = newImage.size.height;

    //Draw the scaled and cropped image
    CGRect thisRect = CGRectMake(oImageWidth+10, 0, nImageWidth, nImageHeight);
    [newImage drawInRect:thisRect];

}

Answer 3

将imageView设为椭圆形并不困难。

您可以执行以下操作

UIBezierPath *path = [UIBezierPath bezierPathWithOvalInRect:yourImageView.bounds];
CAShapeLayer *maskLayer = [CAShapeLayer layer]; 
maskLayer.path = path.CGPath;
yourImageView.layer.mask = maskLayer;

如果传递给bezierPathWithOvalInRect的矩形为方形，则图像将被裁剪为圆形。

Swift Code

let path = UIBezierPath(ovalIn: yourImageView.bounds)
let maskLayer = CAShapeLayer()
maskLayer.path = path.cgPath
yourImageView.layer.mask = maskLayer

Answer 4

经过长时间的搜索，我找到了正确的方法来圈选图像

从网址http://vocaro.com/trevor/blog/2009/10/12/resize-a-uiimage-the-right-way/

下载支持存档文件

#import "UIImage+RoundedCorner.h"
#import "UIImage+Resize.h"

以下行用于调整图像大小并转换为半径为圆形

UIImage *mask = [UIImage imageNamed:@"mask.jpg"];

mask = [mask resizedImage:CGSizeMake(47, 47) interpolationQuality:kCGInterpolationHigh ];
mask = [mask roundedCornerImage:23.5 borderSize:1];

Answer 5

制作圆形图像

第1步：在.h文件中

@property (strong, nonatomic) IBOutlet UIImageView *songImage;

第2步：在.m文件中

- (void)viewDidLoad
{
    self.songImage.layer.cornerRadius = self.songImage.frame.size.width / 2;
    self.songImage.clipsToBounds = YES;

     //To give the Border and Border color of imageview

   self.songImage.layer.borderWidth = 1.0f;
   self.songImage.layer.borderColor = [UIColor colorWithRed:249/255.0f green:117/255.0f blue:44/255.0f alpha:1.0f].CGColor;

}

或者对于Swift

cell.songImage.layer.cornerRadius = cell.songImage.frame.size.width / 2;
cell.songImage.clipsToBounds = true

//To give the Border and Border color of imageview
cell.songImage.layer.borderWidth = 1.0
cell.songImage.layer.borderColor = UIColor(red: 50.0/255, green: 150.0/255, blue: 65.0/255, alpha: 1.0).CGColor

Answer 6

<强> SWIFT

var vwImage = UIImageView(image: UIImage(named: "Btn_PinIt_Normal.png"))
vwImage.frame = CGRectMake(0, 0, 100, 100)
vwImage.layer.cornerRadius = vwImage.frame.size.width/2

Answer 7

如果你只需要一个完美的圆圈，改变UIImageView的形状可能有所帮助。 只需将QuartzCore框架添加到项目中，并在显示imageView之前在生命周期的某处添加这些代码行：

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

//to crop your UIImageView to show only a circle
yourImageView.layer.cornerRadius = yourImageView.frame.size.width/2;
yourImageView.clipsToBounds = YES;

Answer 8

结帐CGImageCreateWithMask。创建椭圆形的蒙版，然后将其应用于图像。

Answer 9

你应该参考This ...

// Create the image from a png file
UIImage *image = [UIImage imageNamed:@"prgBinary.jpg"];
UIImageView *imageView = [[UIImageView alloc] initWithImage:image];

// Get size of current image
CGSize size = [image size];

// Frame location in view to show original image
[imageView setFrame:CGRectMake(0, 0, size.width, size.height)];
[[self view] addSubview:imageView];
[imageView release];    

// Create rectangle that represents a cropped image  
// from the middle of the existing image
CGRect rect = CGRectMake(size.width / 4, size.height / 4 , 
(size.width / 2), (size.height / 2)); //oval logic goes here

// Create bitmap image from original image data,
// using rectangle to specify desired crop area
CGImageRef imageRef = CGImageCreateWithImageInRect([image CGImage], rect);
UIImage *img = [UIImage imageWithCGImage:imageRef]; 
CGImageRelease(imageRef);

// Create and show the new image from bitmap data
imageView = [[UIImageView alloc] initWithImage:img];
[imageView setFrame:CGRectMake(0, 200, (size.width / 2), (size.height / 2))];
[[self view] addSubview:imageView];
[imageView release];

Answer 10

SWIFT 3 答案来自@Mohammad Sadiq

let path = UIBezierPath.init(ovalIn: workingImgaeView.bounds)
let maskLayer = CAShapeLayer(layer: layer)
maskLayer.path = path.cgPath
workingImgaeView.layer.mask = maskLayer

Answer 11

这应该有效， 尝试将以下代码粘贴到viewDidLoad（）中。

self.myImage.layer.cornerRadius = self.myImage.frame.size.width / 2;
self.myImage.clipsToBounds = YES;