CompressUtils.java

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.os.Environment;
import android.util.Log;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;

/**
 * Created by abdulla on 11/11/15.
 */
public class CompressUtils{
    public static final float MAX_HEIGHT = 816.0f;
    public static final float MAX_WIDTH = 612.0f;

    public static String compressImage(String filePath) {
        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 = MAX_HEIGHT;
        float maxWidth = MAX_WIDTH;
        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 = getFilename();
        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;

    }

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

    }

    private static 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;
    }
}