图像优化，例如iOS和android中的whatsapp和instagram [英] Image optimization like whatsapp and instagram in ios and android

问题描述

任务:- 优化像Facebook和WhatApp这样的图像? 在Android和ios中以最佳大小将图像上传到服务器，而不会丢失图像质量和尺寸.

Task :- optimize image like Facebook and WhatApp does? Upload image to server with optimize size in android and ios without losing image quality and dimension.

我已经看到很多代码，例如本机图像压缩(UIImageJPEGRepresentation(viewImage，0.8))，但是我无法获得正确的结果.

I have seen many code like native image compression (UIImageJPEGRepresentation(viewImage, 0.8)) but I am not able to get proper result.

有人可以建议我使用iOS和android中的任何算法或库，通过这些算法或库我们可以优化图像而不会降低质量.

Can someone suggest me any algorithm or library in iOS and android through which we can optimise the image without losing quality.

我已经访问过的链接:

iOS

1. Android
   1. https://abdelhady.net/2015/03/28/android-loading-images-super-fast-like-whatsapp-part-2/
   2. https://gist.github.com/vipulasri/0cd97d012934531f1266
   3. http://voidcanvas.com/whatsapp-like-image-在Android/
   中压缩
   1. https://abdelhady.net/2015/03/28/android-loading-images-super-fast-like-whatsapp-part-2/
   2. https://gist.github.com/vipulasri/0cd97d012934531f1266
   3. http://voidcanvas.com/whatsapp-like-image-compression-in-android/

   推荐答案

   尝试以下代码:

   +(UIImage *)scaleAndRotateImage:(UIImage *)image {
   int kMaxResolution = 640; // Or whatever
   
   CGImageRef imgRef = image.CGImage;
   
   CGFloat width = CGImageGetWidth(imgRef);
   CGFloat height = CGImageGetHeight(imgRef);
   
   
   CGAffineTransform transform = CGAffineTransformIdentity;
   CGRect bounds = CGRectMake(0, 0, width, height);
   if (width > kMaxResolution || height > kMaxResolution) {
       CGFloat ratio = width/height;
       if (ratio > 1) {
           bounds.size.width = kMaxResolution;
           bounds.size.height = roundf(bounds.size.width / ratio);
       }
       else {
           bounds.size.height = kMaxResolution;
           bounds.size.width = roundf(bounds.size.height * ratio);
       }
   }
   
   CGFloat scaleRatio = bounds.size.width / width;
   CGSize imageSize = CGSizeMake(CGImageGetWidth(imgRef), CGImageGetHeight(imgRef));
   CGFloat boundHeight;
   UIImageOrientation orient = image.imageOrientation;
   switch(orient) {
   
       case UIImageOrientationUp: //EXIF = 1
           transform = CGAffineTransformIdentity;
           break;
   
       case UIImageOrientationUpMirrored: //EXIF = 2
           transform = CGAffineTransformMakeTranslation(imageSize.width, 0.0);
           transform = CGAffineTransformScale(transform, -1.0, 1.0);
           break;
   
       case UIImageOrientationDown: //EXIF = 3
           transform = CGAffineTransformMakeTranslation(imageSize.width, imageSize.height);
           transform = CGAffineTransformRotate(transform, M_PI);
           break;
   
       case UIImageOrientationDownMirrored: //EXIF = 4
           transform = CGAffineTransformMakeTranslation(0.0, imageSize.height);
           transform = CGAffineTransformScale(transform, 1.0, -1.0);
           break;
   
       case UIImageOrientationLeftMirrored: //EXIF = 5
           boundHeight = bounds.size.height;
           bounds.size.height = bounds.size.width;
           bounds.size.width = boundHeight;
           transform = CGAffineTransformMakeTranslation(imageSize.height, imageSize.width);
           transform = CGAffineTransformScale(transform, -1.0, 1.0);
           transform = CGAffineTransformRotate(transform, 3.0 * M_PI / 2.0);
           break;
   
       case UIImageOrientationLeft: //EXIF = 6
           boundHeight = bounds.size.height;
           bounds.size.height = bounds.size.width;
           bounds.size.width = boundHeight;
           transform = CGAffineTransformMakeTranslation(0.0, imageSize.width);
           transform = CGAffineTransformRotate(transform, 3.0 * M_PI / 2.0);
           break;
   
       case UIImageOrientationRightMirrored: //EXIF = 7
           boundHeight = bounds.size.height;
           bounds.size.height = bounds.size.width;
           bounds.size.width = boundHeight;
           transform = CGAffineTransformMakeScale(-1.0, 1.0);
           transform = CGAffineTransformRotate(transform, M_PI / 2.0);
           break;
   
       case UIImageOrientationRight: //EXIF = 8
           boundHeight = bounds.size.height;
           bounds.size.height = bounds.size.width;
           bounds.size.width = boundHeight;
           transform = CGAffineTransformMakeTranslation(imageSize.height, 0.0);
           transform = CGAffineTransformRotate(transform, M_PI / 2.0);
           break;
   
       default:
           [NSException raise:NSInternalInconsistencyException format:@"Invalid image orientation"];
   
   }
   
   UIGraphicsBeginImageContext(bounds.size);
   CGContextRef context = UIGraphicsGetCurrentContext();
   
   if (orient == UIImageOrientationRight || orient == UIImageOrientationLeft) {
       CGContextScaleCTM(context, -scaleRatio, scaleRatio);
       CGContextTranslateCTM(context, -height, 0);
   }
   else {
       CGContextScaleCTM(context, scaleRatio, -scaleRatio);
       CGContextTranslateCTM(context, 0, -height);
   }
   
   CGContextConcatCTM(context, transform);
   
   CGContextDrawImage(UIGraphicsGetCurrentContext(), CGRectMake(0, 0, width, height), imgRef);
   UIImage *imageCopy = UIGraphicsGetImageFromCurrentImageContext();
   UIGraphicsEndImageContext();
   
   CGFloat scaleSize = 0.2f;
   UIImage *smallImage = [UIImage imageWithCGImage:imageCopy.CGImage
                                             scale:scaleSize
                                       orientation:imageCopy.imageOrientation];
   
   return smallImage;
   }
   

   这篇关于图像优化，例如iOS和android中的whatsapp和instagram的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！