UIImage的一些扩展

今日的勤奋，只是为了明日拥有可以懒惰的权利！

图片拉伸

+ (UIImage *)resizableImage:(NSString *)name
{
 UIImage *normal = [UIImage imageNamed:name];
 CGFloat w = normal.size.width * 0.5;
 CGFloat h = normal.size.height * 0.5;
 return [normal resizableImageWithCapInsets:UIEdgeInsetsMake(h, w, h, w)];
}

圆形图片的裁剪

//此方法返回一张新的带圆环边框的圆形图片，参数为：图片名，圆环宽度，圆环颜色
+ (instancetype)circleImageWithName:(NSString *)name borderWidth:(CGFloat)borderWidth borderColor:(UIColor *)borderColor
{
    // 1.加载原图
    UIImage *oldImage = [UIImage imageNamed:name];
    
    // 2.开启上下文
    CGFloat imageW = oldImage.size.width + 2 * borderWidth;
    CGFloat imageH = oldImage.size.height + 2 * borderWidth;
    CGSize imageSize = CGSizeMake(imageW, imageH);
    UIGraphicsBeginImageContextWithOptions(imageSize, NO, 0.0);
    
    // 3.取得当前的上下文
    CGContextRef ctx = UIGraphicsGetCurrentContext();
    
    // 4.画边框(大圆)
    [borderColor set];
    CGFloat bigRadius = imageW * 0.5; // 大圆半径
    CGFloat centerX = bigRadius; // 圆心
    CGFloat centerY = bigRadius;
    CGContextAddArc(ctx, centerX, centerY, bigRadius, 0, M_PI * 2, 0);
    CGContextFillPath(ctx); // 画圆
    
    // 5.小圆
    CGFloat smallRadius = bigRadius - borderWidth;
    CGContextAddArc(ctx, centerX, centerY, smallRadius, 0, M_PI * 2, 0);
    // 裁剪(后面画的东西才会受裁剪的影响)
    CGContextClip(ctx);
    
    // 6.画图
    [oldImage drawInRect:CGRectMake(borderWidth, borderWidth, oldImage.size.width, oldImage.size.height)];
    
    // 7.取图
    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
    
    // 8.结束上下文
    UIGraphicsEndImageContext();
    
    return newImage;
}

屏幕截图

+ (instancetype)captureWithView:(UIView *)view
{
    // 1.开启上下文
    UIGraphicsBeginImageContextWithOptions(view.frame.size, NO, 0.0);
    
    // 2.将控制器view的layer渲染到上下文
    [view.layer renderInContext:UIGraphicsGetCurrentContext()];
    
    // 3.取出图片
    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
    
    // 4.结束上下文
    UIGraphicsEndImageContext();
    
    return newImage;
}

图片水印

//此方法用于制作带水印的图片
+ (instancetype)waterImageWithBg:(NSString *)bg logo:(NSString *)logo
{
    UIImage *bgImage = [UIImage imageNamed:bg];
    
    // 1.创建一个基于位图的上下文(开启一个基于位图的上下文)
    UIGraphicsBeginImageContextWithOptions(bgImage.size, NO, 0.0);
    
    // 2.画背景
    [bgImage drawInRect:CGRectMake(0, 0, bgImage.size.width, bgImage.size.height)];
    
    // 3.画右下角的水印
    UIImage *waterImage = [UIImage imageNamed:logo];
    CGFloat scale = 0.2;
    CGFloat margin = 5;
    CGFloat waterW = waterImage.size.width * scale;
    CGFloat waterH = waterImage.size.height * scale;
    CGFloat waterX = bgImage.size.width - waterW - margin;
    CGFloat waterY = bgImage.size.height - waterH - margin;
    [waterImage drawInRect:CGRectMake(waterX, waterY, waterW, waterH)];
    
    // 4.从上下文中取得制作完毕的UIImage对象
    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
    
    // 5.结束上下文
    UIGraphicsEndImageContext();
    
    return newImage;
}

图片存储

//将图片存储在沙盒中并返回该图片的二进制数据
+(NSData*)WriteImageToDocument:(NSString*)img Store:(NSString*)storeName{
    UIImage*image = [UIImage imageNamed:img];
    NSData*data = UIImagePNGRepresentation(image);
    NSString*path =  [[NSSearchPathForDirectoriesInDomains(NSDocumentationDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent: storeName];
    [data writeToFile:path atomically:YES];
    return data;
}