图片的相关处理

#define WIDTH [UIScreen mainScreen].bounds.size.width
#define HEIGHT [UIScreen mainScreen].bounds.size.height

1.图片转化为base64字符串

+ (NSString *)ImageTobase64:(UIImage *)image {

    CGSize size = image.size;

    size.width = WIDTH;
    size.height = HEIGHT;
    UIImage *newImage = [self scaleFromImage:image scaledToSize:size];
    NSData *data = [self reduceImage:newImage];
    NSString *encodedImageStr = [data base64EncodedStringWithOptions:NSDataBase64Encoding64CharacterLineLength];
    //NSString *photoStr1 = [encodedImageStr stringByReplacingOccurrencesOfString:@"+" withString:@"%2B"];
    return photoStr1;

}

2.压缩图片质量
+(NSData *)reduceImage:(UIImage *)image
{
    NSData *imageData = UIImageJPEGRepresentation(image, 0.3);
    return imageData;
}

3.压缩图片尺寸

+ (UIImage*)scaleFromImage:(UIImage*)image scaledToSize:(CGSize)newSize
{
    CGSize imageSize = image.size;
    CGFloat width = imageSize.width;
    CGFloat height = imageSize.height;
    
    if (width <= newSize.width && height <= newSize.height){
        return image;
    }
    
    if (width == 0 || height == 0){
        return image;
    }
    
    CGFloat widthFactor = newSize.width / width;
    CGFloat heightFactor = newSize.height / height;
    CGFloat scaleFactor = (widthFactor<heightFactor?widthFactor:heightFactor);
    
    CGFloat scaledWidth = width * scaleFactor;
    CGFloat scaledHeight = height * scaleFactor;
    CGSize targetSize = CGSizeMake(scaledWidth,scaledHeight);
    
    UIGraphicsBeginImageContext(targetSize);
    [image drawInRect:CGRectMake(0,0,scaledWidth,scaledHeight)];
    UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return newImage;
}

4.base64转成uiimage

+ (UIImage *)base64ToImage:(NSString *)_encodedImageStr {
   // _encodedImageStr = [_encodedImageStr stringByReplacingOccurrencesOfString:@"%2B" withString:@"+"];
    NSData *_decodedImageData  = [[NSData alloc] initWithBase64EncodedString:_encodedImageStr options:NSDataBase64DecodingIgnoreUnknownCharacters];
    UIImage *_decodedImage  = [UIImage imageWithData:_decodedImageData];
    NSLog(@"===Decoded image size: %@", NSStringFromCGSize(_decodedImage.size));
    return _decodedImage;
}

5.照片水印
+(UIImage *)watermarkImage:(UIImage *)img withName:(NSString *)name{
    
    NSString* mark = name;
    
    int w = img.size.width;
    
    int h = img.size.height;
    
    UIGraphicsBeginImageContext(img.size);
    
    [img drawInRect:CGRectMake(0, 0, w, h)];
    
    NSDictionary *attr = @{
                           NSFontAttributeName: [UIFont boldSystemFontOfSize:40],   //设置字体
                           NSForegroundColorAttributeName : [UIColor whiteColor]      //设置字体颜色
                           };
    
    //         [mark drawInRect:CGRectMake(0, 30, 500, 50) withAttributes:attr];                 //左上角
    //
    //         [mark drawInRect:CGRectMake(w - 500, 30, 500, 50) withAttributes:attr];            //右上角
    //
    [mark drawInRect:CGRectMake(w - 500, h - 32 - 30, 500, 50) withAttributes:attr];   //右下角
    
    //         [mark drawInRect:CGRectMake(0, h - 32 - 30, 500, 50) withAttributes:attr];        //左下角
    
    UIImage *aimg = UIGraphicsGetImageFromCurrentImageContext();
    
    UIGraphicsEndImageContext();
    
    return aimg;
    
}