壓縮圖像android

Question

我有一個應用程序，您可以在其中拍照或從圖庫中選擇圖像。 一次拍攝/選擇的照片必須上傳到服務器。
我的問題是，因爲有不同的設備具有不同的大小和分辨率，壓縮的圖像應該加載到服務器上的原始大小，還是應該放大並壓縮？
爲所有設備縮放圖像的最佳方式是什麼？

現在我使用這種算法，當用戶通過相機或畫廊

private void setPic() throws IOException { 
     // First decode with inJustDecodeBounds=true to check dimensions 
     final BitmapFactory.Options options = new BitmapFactory.Options(); 
     options.inJustDecodeBounds = true; 
     BitmapFactory.decodeFile(mCurrentPhotoPath, options); 
     // Calculate inSampleSize 
     int sampleSize = calculateInSampleSize(options, 720, 720); 
     Log.d("UserPanel", "Samplesize: " + sampleSize); 
     Log.d("SquareImage", ""+image.getWidth()); 
     options.inSampleSize = sampleSize; 

     // Decode bitmap with inSampleSize set 
     options.inJustDecodeBounds = false; 
     options.inPreferredConfig= Bitmap.Config.ARGB_8888; 
     Bitmap bitmap = BitmapFactory.decodeFile(mCurrentPhotoPath, options); 
     Log.d("UserPanel", "Bytebitmap: " + bitmap.getByteCount()); 
     ExifInterface exif = new ExifInterface(mCurrentPhotoPath); 
     String orientString = exif.getAttribute(ExifInterface.TAG_ORIENTATION); 
     int orientation = orientString != null ? Integer.parseInt(orientString) : ExifInterface.ORIENTATION_NORMAL; 

     int rotationAngle = 0; 
     if (orientation == ExifInterface.ORIENTATION_ROTATE_90) rotationAngle = 90; 
     if (orientation == ExifInterface.ORIENTATION_ROTATE_180) rotationAngle = 180; 
     if (orientation == ExifInterface.ORIENTATION_ROTATE_270) rotationAngle = 270; 

     Matrix matrix = new Matrix(); 
     matrix.setRotate(rotationAngle, (float) bitmap.getWidth()/2, (float) bitmap.getHeight()/2); 
     Bitmap rotatedBitmap = Bitmap.createBitmap(bitmap, 0, 0, options.outWidth, options.outHeight, matrix, true); 
     Log.d("UserPanel", "Bytebitmaprotate: " + rotatedBitmap.getByteCount()); 
     MediaStore.Images.Media.insertImage(getContentResolver(), rotatedBitmap, imageFileName, ""); 
     File fdelete = new File(mCurrentPhotoPath); 
     if (fdelete.delete()) Log.d("UserPanel", "Delete"); 
     imageToServer = getStringImage(rotatedBitmap); 
    } 

這是calculateSampleSize

public static int calculateInSampleSize(
      BitmapFactory.Options options, int reqWidth, int reqHeight) { 
     // Raw height and width of image 
     final int height = options.outHeight; 
     final int width = options.outWidth; 
     Log.d("UserPanel", "Width: " + width + " height: " + height); 
     int inSampleSize = 1; 

     if (height > reqHeight || width > reqWidth) { 

      final int halfHeight = height/2; 
      final int halfWidth = width/2; 

      // Calculate the largest inSampleSize value that is a power of 2 and keeps both 
      // height and width larger than the requested height and width. 
      while ((halfHeight/inSampleSize) >= reqHeight 
        && (halfWidth/inSampleSize) >= reqWidth) { 
       inSampleSize *= 2; 
      } 
     } 

     return inSampleSize; 
    } 

要壓縮圖像拍攝照片我固定的大小100KB

private String getStringImage(Bitmap bmp) { 
     int compressQuality = 100; 
     int streamLength = 0; 
     ByteArrayOutputStream baos = new ByteArrayOutputStream(); 
     do{ 
      ByteArrayOutputStream bmpStream = new ByteArrayOutputStream(); 
      Log.d("compressBitmap", "Quality: " + compressQuality); 
      bmp.compress(Bitmap.CompressFormat.JPEG, compressQuality, bmpStream); 
      byte[] bmpPicByteArray = bmpStream.toByteArray(); 
      streamLength = bmpPicByteArray.length; 
      compressQuality -= 5; 
      Log.d("compressBitmap", "Size: " + streamLength/1024+" kb"); 
     }while (streamLength >= 100000); 
     bmp.compress(Bitmap.CompressFormat.JPEG, compressQuality, baos); 
     byte[] imageBytes = baos.toByteArray(); 
     Log.d("UserPanel", "Bytebitmap compress: " + imageBytes.length); 
     String encodedImage = Base64.encodeToString(imageBytes, Base64.DEFAULT); 
     return encodedImage; 
    } 

Answer 1

嘗試壓縮圖像使用此類別

import android.content.Context; 
import android.database.Cursor; 
import android.graphics.Bitmap; 
import android.graphics.BitmapFactory; 
import android.graphics.Canvas; 
import android.graphics.Matrix; 
import android.graphics.Paint; 
import android.media.ExifInterface; 
import android.net.Uri; 
import android.os.Environment; 
import android.provider.MediaStore; 
import android.util.Log; 

import java.io.File; 
import java.io.FileNotFoundException; 
import java.io.FileOutputStream; 
import java.io.IOException; 
import java.text.SimpleDateFormat; 
import java.util.Date; 


public class CompressImage { 

    Context mContext; 

    public CompressImage(Context context) { 
     this.mContext = context; 
    } 

    public String compressImage(String imageUri) throws IOException { 

     String filePath = getRealPathFromURI(imageUri); 
     if(filePath == null) 
     { 
      filePath = imageUri; 
     } 
     Bitmap scaledBitmap = null; 

     BitmapFactory.Options options = new BitmapFactory.Options(); 

//  by setting this field as true, the actual bitmap pixels are not loaded in the memory. Just the bounds are loaded. If 
//  you try the use the bitmap here, you will get null. 
     options.inJustDecodeBounds = true; 
     Bitmap bmp = BitmapFactory.decodeFile(filePath, options); 

     int actualHeight = options.outHeight; 
     int actualWidth = options.outWidth; 

//  max Height and width values of the compressed image is taken as 816x612 

     float maxHeight = 816.0f; 
     float maxWidth = 612.0f; 
     float imgRatio = actualWidth/actualHeight; 
     float maxRatio = maxWidth/maxHeight; 

//  width and height values are set maintaining the aspect ratio of the image 

     if (actualHeight > maxHeight || actualWidth > maxWidth) { 
      if (imgRatio < maxRatio) { 
       imgRatio = maxHeight/actualHeight; 
       actualWidth = (int) (imgRatio * actualWidth); 
       actualHeight = (int) maxHeight; 
      } else if (imgRatio > maxRatio) { 
       imgRatio = maxWidth/actualWidth; 
       actualHeight = (int) (imgRatio * actualHeight); 
       actualWidth = (int) maxWidth; 
      } else { 
       actualHeight = (int) maxHeight; 
       actualWidth = (int) maxWidth; 

      } 
     } 

//  setting inSampleSize value allows to load a scaled down version of the original image 

     options.inSampleSize = calculateInSampleSize(options, actualWidth, actualHeight); 

//  inJustDecodeBounds set to false to load the actual bitmap 
     options.inJustDecodeBounds = false; 

//  this options allow android to claim the bitmap memory if it runs low on memory 
     options.inPurgeable = true; 
     options.inInputShareable = true; 
     options.inTempStorage = new byte[16 * 1024]; 

     try { 
//   load the bitmap from its path 
      bmp = BitmapFactory.decodeFile(filePath, options); 
     } catch (OutOfMemoryError exception) { 
      exception.printStackTrace(); 

     } 
     try { 
      scaledBitmap = Bitmap.createBitmap(actualWidth, actualHeight, Bitmap.Config.ARGB_8888); 
     } catch (OutOfMemoryError exception) { 
      exception.printStackTrace(); 
     } 

     float ratioX = actualWidth/(float) options.outWidth; 
     float ratioY = actualHeight/(float) options.outHeight; 
     float middleX = actualWidth/2.0f; 
     float middleY = actualHeight/2.0f; 

     Matrix scaleMatrix = new Matrix(); 
     scaleMatrix.setScale(ratioX, ratioY, middleX, middleY); 

     Canvas canvas = new Canvas(scaledBitmap); 
     canvas.setMatrix(scaleMatrix); 
     canvas.drawBitmap(bmp, middleX - bmp.getWidth()/2, middleY - bmp.getHeight()/2, new Paint(Paint.FILTER_BITMAP_FLAG)); 

//  check the rotation of the image and display it properly 
     ExifInterface exif; 
     try { 
      exif = new ExifInterface(filePath); 

      int orientation = exif.getAttributeInt(
        ExifInterface.TAG_ORIENTATION, 0); 
      Log.d("EXIF", "Exif: " + 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); 
      } 
      scaledBitmap = Bitmap.createBitmap(scaledBitmap, 0, 0, 
        scaledBitmap.getWidth(), scaledBitmap.getHeight(), matrix, 
        true); 
     } catch (IOException e) { 
      e.printStackTrace(); 
     } 

     FileOutputStream out = null; 
     String filename = imageUri; 
     File oldfile = new File(imageUri); 
     if (oldfile.exists()) { 
      oldfile.delete(); 
     } 
     try { 
      out = new FileOutputStream(filename); 

//   write the compressed bitmap at the destination specified by filename. 
      scaledBitmap.compress(Bitmap.CompressFormat.JPEG, 80, out); 

     } catch (FileNotFoundException e) { 
      e.printStackTrace(); 
     } 

     return filename; 

    } 

    public String getFilename() throws IOException { 
//  File file = new File(Environment.getExternalStorageDirectory().getPath(), "MyFolder/Images"); 
//  if (!file.exists()) { 
//   file.mkdirs(); 
//  } 
//  String uriSting = (file.getAbsolutePath() + "/" + System.currentTimeMillis() + ".jpg"); 

     String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss") 
       .format(new Date()); 
     String imageFileName = "twice_" + timeStamp + "_"; 
     File storageDir = Environment 
       .getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES); 
     File image = File.createTempFile(imageFileName, /* prefix */ 
       ".jpg", /* suffix */ 
       storageDir /* directory */ 
     ); 

//  ChatRoomFragment.picturePath= image.getAbsolutePath(); 
     return image.getAbsolutePath(); 

    } 

    private String getRealPathFromURI(String contentURI) { 
     Uri contentUri = Uri.parse(contentURI); 
     Cursor cursor = mContext.getContentResolver().query(contentUri, null, null, null, null); 
     if (cursor == null) { 
      return contentUri.getPath(); 
     } else { 
      cursor.moveToFirst(); 
      int index = cursor.getColumnIndex(MediaStore.Images.ImageColumns.DATA); 
      return cursor.getString(index); 
     } 
    } 

    public int calculateInSampleSize(BitmapFactory.Options options, int reqWidth, int reqHeight) { 
     final int height = options.outHeight; 
     final int width = options.outWidth; 
     int inSampleSize = 1; 

     if (height > reqHeight || width > reqWidth) { 
      final int heightRatio = Math.round((float) height/(float) reqHeight); 
      final int widthRatio = Math.round((float) width/(float) reqWidth); 
      inSampleSize = heightRatio < widthRatio ? heightRatio : widthRatio; 
     } 
     final float totalPixels = width * height; 
     final float totalReqPixelsCap = reqWidth * reqHeight * 2; 
     while (totalPixels/(inSampleSize * inSampleSize) > totalReqPixelsCap) { 
      inSampleSize++; 
     } 

     return inSampleSize; 
    } 


}