UIImage+Fit.m

//
//  UIImage+Fit.m
//  redstar
//
//  Created by admin on 15/12/28.
//  Copyright © 2015年 ZWF. All rights reserved.
//

#import "UIImage+Fit.h"

@implementation UIImage (Fit)
//计算适合的大小。并保留其原始图片大小

+ (CGSize) fitSize: (CGSize)thisSize inSize: (CGSize) aSize
{
    CGFloat scale;
    CGSize newsize = thisSize;
    
    if (newsize.height && (newsize.height > aSize.height))
    {
        scale = aSize.height / newsize.height;
        newsize.width *= scale;
        newsize.height *= scale;
    }
    
    if (newsize.width && (newsize.width >= aSize.width))
    {
        scale = aSize.width / newsize.width;
        newsize.width *= scale;
        newsize.height *= scale;
    }
    
    return newsize;
}

// 返回调整的缩略图

+ (UIImage *) image: (UIImage *) image fitInSize: (CGSize) viewsize
{
    // calculate the fitted size
    CGSize size = [self fitSize:image.size inSize:viewsize];
    
    UIGraphicsBeginImageContext(viewsize);
    
    float dwidth = (viewsize.width - size.width) / 2.0f;
    float dheight = (viewsize.height - size.height) / 2.0f;
    
    CGRect rect = CGRectMake(dwidth, dheight, size.width, size.height);
    [image drawInRect:rect];
    
    UIImage *newimg = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    
    return newimg;
}


//返回居中的缩略图

+ (UIImage *) image: (UIImage *) image centerInSize: (CGSize) viewsize {
    CGSize size = image.size;
    
    UIGraphicsBeginImageContext(viewsize);
    float dwidth = (viewsize.width - size.width) / 2.0f;
    float dheight = (viewsize.height - size.height) / 2.0f;
    
    CGRect rect = CGRectMake(dwidth, dheight, size.width, size.height);
    [image drawInRect:rect];
    
    UIImage *newimg = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    
    return newimg;
}


// 返回填充的缩略图

+ (UIImage *) image: (UIImage *) image fillSize: (CGSize) viewsize {
    CGSize size = image.size;
    
    CGFloat scalex = viewsize.width / size.width;
    CGFloat scaley = viewsize.height / size.height;
    CGFloat scale = MAX(scalex, scaley);
    
    UIGraphicsBeginImageContext(viewsize);
    
    CGFloat width = size.width * scale;
    CGFloat height = size.height * scale;
    
    float dwidth = ((viewsize.width - width) / 2.0f);
    float dheight = ((viewsize.height - height) / 2.0f);
    
    CGRect rect = CGRectMake(dwidth, dheight, size.width * scale, size.height * scale);
    [image drawInRect:rect];
    
    UIImage *newimg = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    
    return newimg;
}
@end