103 lines
3.7 KiB
Mathematica
103 lines
3.7 KiB
Mathematica
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//
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// UIImage+Scale.m
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// Meet
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//
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// Created by yuqingyuan on 2018/9/28.
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// Copyright © 2018年 ko1o. All rights reserved.
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//
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#import "UIImage+Scale.h"
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@implementation UIImage (Scale)
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+ (UIImage *)imageWithImage:(UIImage *)image scaledToSize:(CGSize)size
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{
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if ([[UIScreen mainScreen] respondsToSelector:@selector(scale)]) {
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UIGraphicsBeginImageContextWithOptions(size, NO, [[UIScreen mainScreen] scale]);
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} else {
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UIGraphicsBeginImageContext(size);
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}
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[image drawInRect:CGRectMake(0, 0, size.width, size.height)];
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UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
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UIGraphicsEndImageContext();
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return newImage;
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}
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+ (UIImage *)imageWithImage:(UIImage *)image scaledToMaxWidth:(CGFloat)width maxHeight:(CGFloat)height
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{
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CGSize newSize = [self sizeWithImageSize:image.size scaledToMaxWidth:width maxHeight:height];
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return [self imageWithImage:image scaledToSize:newSize];
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}
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+ (CGSize)sizeWithImageSize:(CGSize)size scaledToMaxWidth:(CGFloat)width maxHeight:(CGFloat)height
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{
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CGFloat oldWidth = size.width;
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CGFloat oldHeight = size.height;
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CGFloat scaleFactor = (oldWidth > oldHeight) ? width / oldWidth : height / oldHeight;
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CGFloat newHeight = oldHeight * scaleFactor;
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CGFloat newWidth = oldWidth * scaleFactor;
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CGSize newSize = CGSizeMake(newWidth, newHeight);
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return newSize;
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}
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NSData *comprossImageToSize(UIImage *image, int size) {
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int maxLength = size; // 最大500k
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//首先判断原图大小是否在要求内，如果满足要求则不进行压缩，over
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CGFloat compression = 1;
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NSData *data = UIImageJPEGRepresentation(image, compression);
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if (data.length < maxLength) return UIImageJPEGRepresentation(image, 1.0);
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//原图大小超过范围，先进行“压处理”，这里 压缩比 采用二分法进行处理，6次二分后的最小压缩比是0.015625，已经够小了
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CGFloat max = 1;
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CGFloat min = 0;
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for (int i = 0; i < 6; ++i) {
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compression = (max + min) / 2;
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data = UIImageJPEGRepresentation(image, compression);
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if (data.length < maxLength * 0.9) {
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min = compression;
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} else if (data.length > maxLength) {
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max = compression;
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} else {
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break;
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}
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}
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//判断“压处理”的结果是否符合要求，符合要求就over
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UIImage *resultImage = [UIImage imageWithData:data];
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if (data.length < maxLength) return data;
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//缩处理，直接用大小的比例作为缩处理的比例进行处理，因为有取整处理，所以一般是需要两次处理
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NSUInteger lastDataLength = 0;
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while (data.length > maxLength && data.length != lastDataLength) {
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lastDataLength = data.length;
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//获取处理后的尺寸
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CGFloat ratio = (CGFloat)maxLength / data.length;
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CGSize size = CGSizeMake((NSUInteger)(resultImage.size.width * sqrtf(ratio)),
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(NSUInteger)(resultImage.size.height * sqrtf(ratio)));
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//通过图片上下文进行处理图片
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UIGraphicsBeginImageContext(size);
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[resultImage drawInRect:CGRectMake(0, 0, size.width, size.height)];
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resultImage = UIGraphicsGetImageFromCurrentImageContext();
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UIGraphicsEndImageContext();
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//获取处理后图片的大小
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data = UIImageJPEGRepresentation(resultImage, compression);
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}
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return data;
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}
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NSData *compressImageToDataIfNeed(UIImage *image)
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{
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return comprossImageToSize(image, 500 * 1000);
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}
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UIImage *compressImageToSizeIfNeed(UIImage *image, int size)
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{
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NSData *data = comprossImageToSize(image, size);
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return [[UIImage alloc] initWithData:data];
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}
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@end
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