IOS图片调整用法bitmap

学习链接：https://www.jianshu.com/p/8f508f4ffd2c

直接上代码吧

//将image图片转化为符合要求的图片

- (UIImage *)transformImage:(UIImage *)image WithTargetRect:(CGRect) targetRect {

    //将image改为50 * 50pt大小的

    CGSize smallImageSize = CGSizeMake(50.0f, 50.0f);

    //创建一个目标大小的画板

    UIGraphicsBeginImageContextWithOptions(smallImageSize, NO, [[UIScreen mainScreen] scale]);

    //将需要转换的图片画在上面

    [image drawInRect:CGRectMake(0, 0, smallImageSize.width, smallImageSize.height)];

    //保存下来

    UIImage *smallImage = UIGraphicsGetImageFromCurrentImageContext();

    //结束画板

    UIGraphicsEndImageContext();

    

    //创建一个纯色图片

    UIColor *backgroudColor =[UIColor whiteColor];

    UIGraphicsBeginImageContextWithOptions(targetRect.size, NO, [[UIScreen mainScreen] scale]);

    CGContextRef context = UIGraphicsGetCurrentContext();

    

    //设置圆角

    float radius = 8.0f;

    CGContextAddPath(context, [UIBezierPath bezierPathWithRoundedRect:targetRect cornerRadius:radius].CGPath);

    CGContextClip(context);

    

    CGContextSetFillColorWithColor(context, [backgroudColor CGColor]);//填充

    CGContextFillRect(context, targetRect);

    //将smallImage画到纯色背景上

    CGFloat margin = 4.0f;

    [smallImage drawAtPoint:CGPointMake(margin, margin)];

    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

    

    return newImage;

}