Quartz2D 实例应用

裁剪一个圆形的图片的分类

#import 
@interface UIImage (Image)
+ (UIImage *)imageWithClipImage:(UIImage *)image borderWidth:(CGFloat)borderWidth borderColor:(UIColor *)color;
@end

#import "UIImage+Image.h"
@implementation UIImage (Image)
+ (UIImage *)imageWithClipImage:(UIImage *)image borderWidth:(CGFloat)borderWidth borderColor:(UIColor *)color
{
    // 图片的宽度和高度
    CGFloat imageWH = image.size.width;
    
    // 设置圆环的宽度
    CGFloat border = borderWidth;
    
    // 圆形的宽度和高度
    CGFloat ovalWH = imageWH + 2 * border;
    
    // 1.开启上下文
    UIGraphicsBeginImageContextWithOptions(CGSizeMake(ovalWH, ovalWH), NO, 0);
    
    // 2.画大圆
    UIBezierPath *path = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(0, 0, ovalWH, ovalWH)];
    
    [color set];
    
    [path fill];
    
    // 3.设置裁剪区域
    UIBezierPath *clipPath = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(border, border, imageWH, imageWH)];
    [clipPath addClip];
    
    // 4.绘制图片
    [image drawAtPoint:CGPointMake(border, border)];
    
    // 5.获取图片
    UIImage *clipImage = UIGraphicsGetImageFromCurrentImageContext();
    
    // 6.关闭上下文
    UIGraphicsEndImageContext();
    
    return clipImage;
  
}
@end

截图

+ (UIImage *)imageWithCaputureView:(UIView *)view
{
    // 开启位图上下文
    UIGraphicsBeginImageContextWithOptions(view.bounds.size, NO, 0);
    
    // 获取上下文
    CGContextRef ctx = UIGraphicsGetCurrentContext();
    
    // 把控件上的图层渲染到上下文,layer只能渲染
    [view.layer renderInContext:ctx];
    
    // 生成一张图片
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    
    // 关闭上下文
    UIGraphicsEndImageContext();
    
    return image;
}

• 调用

 // 生成一张新的图片
    
     UIImage *image =  [UIImage imageWithCaputureView:self.view];
    
    // image转data
    // compressionQuality： 图片质量 1:最高质量
    
     NSData *data = UIImageJPEGRepresentation(image,1);
    
    [data writeToFile:@"/Users/liudunhui/Desktop/view.png" atomically:YES];

自定义图片的截取

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    
    // 给控制器的view添加一个pan手势
    UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(pan:)];
    
    [self.view addGestureRecognizer:pan];
}

- (void)pan:(UIPanGestureRecognizer *)pan
{
    CGPoint endA = CGPointZero;
    
    if (pan.state == UIGestureRecognizerStateBegan) { // 一开始拖动的时候
        
        // 获取一开始触摸点
      _startP = [pan locationInView:self.view];
        
        
    }else if(pan.state == UIGestureRecognizerStateChanged){ // 一直拖动
        
        // 获取结束点
         endA = [pan locationInView:self.view];
        
        CGFloat w = endA.x - _startP.x;
        CGFloat h = endA.y - _startP.y;
        
        // 获取截取范围
        CGRect clipRect = CGRectMake(_startP.x, _startP.y, w, h);

        // 生成截屏的view
        self.clipView.frame = clipRect;
        
        
    }else if (pan.state == UIGestureRecognizerStateEnded){ // 拖动结束
        
        
        // 图片裁剪，生成一张新的图片
        
        // 开启上下文
        // 如果不透明，默认超出裁剪区域会变成黑色，通常都是透明
        UIGraphicsBeginImageContextWithOptions(_imageV.bounds.size, NO, 0);
        
        // 设置裁剪区域
       UIBezierPath *path =  [UIBezierPath bezierPathWithRect:_clipView.frame];
        
        [path addClip];
        
        // 获取上下文
        CGContextRef ctx = UIGraphicsGetCurrentContext();
        
        // 把控件上的内容渲染到上下文
        [_imageV.layer renderInContext:ctx];
        
        
        // 生成一张新的图片
        _imageV.image = UIGraphicsGetImageFromCurrentImageContext();
        
        
        // 关闭上下文
        UIGraphicsEndImageContext();
        
        
        // 先移除
        [_clipView removeFromSuperview];
        // 截取的view设置为nil
        _clipView = nil;
        
    }
    
}

擦除图片

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    
    UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(pan:)];
    
    [self.view addGestureRecognizer:pan];
}


- (void)pan:(UIPanGestureRecognizer *)pan
{
    // 获取当前点
    CGPoint curP = [pan locationInView:self.view];
    
    // 获取擦除的矩形范围
    CGFloat wh = 100;
    CGFloat x = curP.x - wh * 0.5;
    CGFloat y = curP.y - wh * 0.5;
    
    CGRect rect = CGRectMake(x, y, wh, wh);
    
    // 开启上下文
    UIGraphicsBeginImageContextWithOptions(self.view.bounds.size, NO, 0);
    
    CGContextRef ctx = UIGraphicsGetCurrentContext();
    
    // 控件的layer渲染上去
    [_imageView.layer renderInContext:ctx];
    
    // 擦除图片
    CGContextClearRect(ctx, rect);
    
    // 生成一张图片
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    
    _imageView.image = image;
    
    // 关闭上下文
    UIGraphicsEndImageContext();
   
}