像ios和Android中的WhatsApp和Instagram圖像優化

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任務： - 像Facebook和WhatApp那樣優化圖像？在Android和ios中將圖像上傳到優化大小的服務器，而不會丟失圖像質量和尺寸。像ios和Android中的WhatsApp和Instagram圖像優化

我見過很多代碼像本地圖像壓縮（UIImageJPEGRepresentation（viewImage，0.8）），但我無法得到正確的結果。

有人可以建議我在iOS和Android的任何算法或庫，通過它我們可以優化圖像，而不會丟失質量。

鏈接我已經訪問過：

的iOS

What's the easiest way to resize/optimize an image size with the iPhone SDK?

的Android

來源

2016-10-19 Dhaval Patel

到這裏看看，如果能有解決你的問題。 http://stackoverflow.com/questions/40129215/shrink-image-without-affecting-the-quality-in-objective-c/40129673#40129673 – Janmenjaya

試試這個代碼：

+(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; 
}

來源

2016-10-19 11:50:30

這是我使用Android中的：

public class ImageCompresser { 

    public static void compressImage(String inputFilePath, String outputFilePath) { 
     try { 

      final BitmapFactory.Options options = new BitmapFactory.Options(); 
      options.inJustDecodeBounds = true; 

      BitmapFactory.decodeFile(inputFilePath, options); 

      //options.inSampleSize = calculateInSampleSize(options,400,300); 
      options.inSampleSize = calculateInSampleSize(options,800,1000);//Specify Minimum Height, Width of the resulting bitmap maintaining the aspect ratio 

      options.inJustDecodeBounds = false; 

      Bitmap bm = BitmapFactory.decodeFile(inputFilePath, options); 

      FileOutputStream fileOutputStream; 

      fileOutputStream = new FileOutputStream(outputFilePath); 

      ExifInterface exif; 
      try { 
       exif = new ExifInterface(inputFilePath); 

       Log.d("EXIF", "Make : " + exif.getAttribute(ExifInterface.TAG_MAKE)); 

       int orientation = exif.getAttributeInt(
         ExifInterface.TAG_ORIENTATION, 0); 
       Log.d("EXIF", "Exif Orientation : " + orientation); 
       Matrix matrix = new Matrix(); 
       if (orientation == 6) { 
        matrix.postRotate(90); 
        Log.d("EXIF", "Exif: " + orientation); 
       } else if (orientation == 3) { 
        matrix.postRotate(180); 
        Log.d("EXIF", "Exif: " + orientation); 
       } else if (orientation == 8) { 
        matrix.postRotate(270); 
        Log.d("EXIF", "Exif: " + orientation); 
       } 
       Bitmap scaledBitmap = Bitmap.createBitmap(bm, 0, 0, 
         bm.getWidth(), bm.getHeight(), matrix, 
         true); 

       scaledBitmap.compress(Bitmap.CompressFormat.JPEG, 100, fileOutputStream);//Instead of 100, you can provide any value. But it will reduce the image quality 
       scaledBitmap.recycle(); 
      } catch (IOException e) { 
       e.printStackTrace(); 
      } 

      fileOutputStream.flush(); 
      fileOutputStream.close(); 
      bm.recycle(); 
     } catch (FileNotFoundException e) { 
      e.printStackTrace(); 
     } catch (IOException e) { 
      e.printStackTrace(); 
     } 
    } 

    private static int calculateInSampleSize(BitmapFactory.Options options, int reqWidth, int reqHeight) { 
     final int imageWidth = options.outWidth; 
     final int imageHeight = options.outHeight; 
     Log.d("Test", "imageWidth : " + imageWidth); 
     Log.d("Test", "imageHeight : " + imageHeight); 

     int inSampleSize = 1; 

     if(imageWidth > reqWidth || imageHeight > reqHeight) { 
      final int halfWidth = imageWidth/2; 
      final int halfHeight = imageHeight/2; 

      while((halfWidth/inSampleSize) > reqWidth 
        && (halfHeight/inSampleSize) > reqHeight) { 
       inSampleSize *= 2; 
      } 
     } 

     return inSampleSize; 
    } 
}

參考文獻：

來源

2016-10-19 12:05:12

像ios和Android中的WhatsApp和Instagram圖像優化

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