ImageUtil.java

package com.sxjs.common.util.imagecompress;

import android.content.Context;
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.text.TextUtils;

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

/**
 * Created on : June 18, 2016
 */
class ImageUtil {

    private ImageUtil() {

    }

    static Bitmap getScaledBitmap(Context context, Uri imageUri, float maxWidth, float maxHeight, Bitmap.Config bitmapConfig) {
        String filePath = FileUtil.getRealPathFromURI(context, 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);
        if (bmp == null) {

            InputStream inputStream = null;
            try {
                inputStream = new FileInputStream(filePath);
                BitmapFactory.decodeStream(inputStream, null, options);
                inputStream.close();
            } catch (FileNotFoundException exception) {
                exception.printStackTrace();
            } catch (IOException exception) {
                exception.printStackTrace();
            }
        }

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

        if (actualWidth < 0 || actualHeight < 0) {
            Bitmap bitmap2 = BitmapFactory.decodeFile(filePath);
            actualWidth = bitmap2.getWidth();
            actualHeight = bitmap2.getHeight();
        }

        float imgRatio = (float) 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);
            if (bmp == null) {

                InputStream inputStream = null;
                try {
                    inputStream = new FileInputStream(filePath);
                    BitmapFactory.decodeStream(inputStream, null, options);
                    inputStream.close();
                } catch (FileNotFoundException exception) {
                    exception.printStackTrace();
                } catch (IOException exception) {
                    exception.printStackTrace();
                }
            }
        } catch (OutOfMemoryError exception) {
            exception.printStackTrace();
        }
        try {
            scaledBitmap = Bitmap.createBitmap(actualWidth, actualHeight, bitmapConfig);
        } catch (OutOfMemoryError exception) {
            exception.printStackTrace();
        }

        float ratioX = actualWidth / (float) options.outWidth;
        float ratioY = actualHeight / (float) options.outHeight;

        Matrix scaleMatrix = new Matrix();
        scaleMatrix.setScale(ratioX, ratioY, 0, 0);

        Canvas canvas = new Canvas(scaledBitmap);
        canvas.setMatrix(scaleMatrix);
        canvas.drawBitmap(bmp, 0, 0, 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);
            Matrix matrix = new Matrix();
            if (orientation == 6) {
                matrix.postRotate(90);
            } else if (orientation == 3) {
                matrix.postRotate(180);
            } else if (orientation == 8) {
                matrix.postRotate(270);
            }
            scaledBitmap = Bitmap.createBitmap(scaledBitmap, 0, 0,
                                               scaledBitmap.getWidth(), scaledBitmap.getHeight(),
                                               matrix, true);
        } catch (IOException e) {
            e.printStackTrace();
        }

        return scaledBitmap;
    }

    static File compressImage(Context context, Uri imageUri, float maxWidth, float maxHeight,
                              Bitmap.CompressFormat compressFormat, Bitmap.Config bitmapConfig,
                              int quality, String parentPath, String prefix, String fileName) {
        FileOutputStream out = null;
        String filename = generateFilePath(context, parentPath, imageUri, compressFormat.name().toLowerCase(), prefix, fileName);
        try {
            out = new FileOutputStream(filename);

            //write the compressed bitmap at the destination specified by filename.
            ImageUtil.getScaledBitmap(context, imageUri, maxWidth, maxHeight, bitmapConfig).compress(compressFormat, quality, out);

        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } finally {
            try {
                if (out != null) {
                    out.close();
                }
            } catch (IOException ignored) {
            }
        }

        return new File(filename);
    }

    private static String generateFilePath(Context context, String parentPath, Uri uri,
                                           String extension, String prefix, String fileName) {
        File file = new File(parentPath);
        if (!file.exists()) {
            file.mkdirs();
        }
        /** if prefix is null, set prefix "" */
        prefix = TextUtils.isEmpty(prefix) ? "" : prefix;
        /** reset fileName by prefix and custom file name */
        fileName = TextUtils.isEmpty(fileName) ? prefix + FileUtil.splitFileName(FileUtil.getFileName(context, uri))[0] : fileName;
        return file.getAbsolutePath() + File.separator + fileName + "." + extension;
    }

    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;
    }
}