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//
// Created by mo on 2020/3/7.
//
#import "ThumbnailHelper.h"
@implementation ThumbnailHelper
+ (NSData *)compressImageData:(NSData *)imageData toByte:(NSUInteger)maxLength {
// Compress by quality
CGFloat compression = 1;
NSData *data = imageData;
NSLog(@"压缩前 %lu %lu ",(unsigned long)data.length,maxLength);
if (data.length < maxLength) return data;
UIImage *image = [UIImage imageWithData:imageData];
CGFloat max = 1;
CGFloat min = 0;
for (int i = 0; i < 6; ++i) {
compression = (max + min) / 2;
data = UIImageJPEGRepresentation(image, compression);
if (data.length < maxLength * 0.9) {
min = compression;
} else if (data.length > maxLength) {
max = compression;
} else {
break;
}
}
NSLog(@"压缩第一次 %lu %lu ",(unsigned long)data.length,maxLength);
if (data.length < maxLength) return data;
UIImage *resultImage;
resultImage = [UIImage imageWithData:data];
// Compress by size
NSUInteger lastDataLength = 0;
while (data.length > maxLength && data.length != lastDataLength) {
lastDataLength = data.length;
CGFloat ratio = (CGFloat) maxLength / data.length;
CGSize size = CGSizeMake((NSUInteger) (resultImage.size.width * sqrtf(ratio)),
(NSUInteger) (resultImage.size.height * sqrtf(ratio))); // Use NSUInteger to prevent white blank
UIGraphicsBeginImageContext(size);
[resultImage drawInRect:CGRectMake(0, 0, size.width, size.height)];
resultImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
data = UIImageJPEGRepresentation(resultImage, compression);
}
NSLog(@"压缩第二次%lu %lu ",(unsigned long)data.length,maxLength);
return data;
}
+ (UIImage *)compressImage:(UIImage *)image toByte:(NSUInteger)maxLength isPNG:(BOOL)isPNG {
// Compress by quality
CGFloat compression = 1;
NSData *data = UIImageJPEGRepresentation(image, compression);
if (data.length < maxLength) return image;
CGFloat max = 1;
CGFloat min = 0;
for (int i = 0; i < 6; ++i) {
compression = (max + min) / 2;
data = UIImageJPEGRepresentation(image, compression);
if (data.length < maxLength * 0.9) {
min = compression;
} else if (data.length > maxLength) {
max = compression;
} else {
break;
}
}
UIImage *resultImage;
if (isPNG) {
NSData *tmp = UIImagePNGRepresentation([UIImage imageWithData:data]);
resultImage = [UIImage imageWithData:tmp];
} else {
resultImage = [UIImage imageWithData:data];
}
if (data.length < maxLength) return resultImage;
// Compress by size
NSUInteger lastDataLength = 0;
while (data.length > maxLength && data.length != lastDataLength) {
lastDataLength = data.length;
CGFloat ratio = (CGFloat) maxLength / data.length;
CGSize size = CGSizeMake((NSUInteger) (resultImage.size.width * sqrtf(ratio)),
(NSUInteger) (resultImage.size.height * sqrtf(ratio))); // Use NSUInteger to prevent white blank
UIGraphicsBeginImageContext(size);
[resultImage drawInRect:CGRectMake(0, 0, size.width, size.height)];
resultImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
data = UIImageJPEGRepresentation(resultImage, compression);
}
return resultImage;
}
- (UIImage *)scaleFromImage:(UIImage *)image width:(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;
}
@end