Scale image without losing image quality did not work

Does anyone know how to scale the bitmap image without losing the image quality ? Currently I facing this problem, where the size of selected image maybe too big caused the app return to another activity.

So now I tried using this method to scale the selected image without losing its quality. I get the code from here.

 protected void onActivityResult(int requestCode, int resultCode,
                                    Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        switch (requestCode) {
            case RESULT_LOAD_IMAGE:
                if (requestCode == RESULT_LOAD_IMAGE && resultCode == RESULT_OK & null != data) {
                    Uri selectedImage = data.getData();
                    String[] filePathColumn = {MediaStore.Images.Media.DATA};
                    Cursor cursor = getContentResolver()
                            .query(selectedImage, filePathColumn, null, null,
                                    null);
                    cursor.moveToFirst();
                    int columnIndex = cursor.getColumnIndex(filePathColumn[0]);
                    String picturePath = cursor.getString(columnIndex);
                    cursor.close();
                    Bitmap a = (BitmapFactory.decodeFile(picturePath));
                    photo = scaleBitmap(a, 200, 200);
                    imageView.setImageBitmap(photo);
                }
                break;
}

  public static Bitmap scaleBitmap(Bitmap bitmap, int newWidth, int newHeight) {
        Bitmap scaledBitmap = Bitmap.createBitmap(newWidth, newHeight, Bitmap.Config.ARGB_8888);

        float scaleX = newWidth / (float) bitmap.getWidth();
        float scaleY = newHeight / (float) bitmap.getHeight();
        float pivotX = 0;
        float pivotY = 0;

        Matrix scaleMatrix = new Matrix();
        scaleMatrix.setScale(scaleX, scaleY, pivotX, pivotY);

        Canvas canvas = new Canvas(scaledBitmap);
        canvas.setMatrix(scaleMatrix);
        canvas.drawBitmap(bitmap, 0, 0, new Paint(Paint.FILTER_BITMAP_FLAG));

        return scaledBitmap;
    }

The answer seems helpful for most of the people, but why it doesn't work for me ? Have I missed anything?

original image

selected image display on imageView


请试试这个

public Bitmap scaleBitmap(Bitmap bitmap,int newWidth,int newHeight) {    
    Bitmap scaledBitmap = Bitmap.createBitmap(newWidth, newHeight, Config.ARGB_8888);

    float ratioX = newWidth / (float) bitmap.getWidth();
    float ratioY = newHeight / (float) bitmap.getHeight();
    float middleX = newWidth / 2.0f;
    float middleY = newHeight / 2.0f;

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

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

    return scaledBitmap;

    }

试试这个缩放位图

public static Bitmap scaleBitmap(Bitmap bitmap, int newWidth, int newHeight) {
    float scaleX = ((float)newWidth) /  bitmap.getWidth();
    float scaleY = ((float)newHeight) / bitmap.getHeight(); 
    Matrix scaleMatrix = new Matrix();
    scaleMatrix.postScale(scaleX, scaleY);
    Bitmap scaledBitmap = Bitmap.createBitmap(bitmap, 0, 0, bitmap.getWidth(), bitmap.getHeight() , scaleMatrix, true);
    return scaledBitmap;
}

Use this it will definitely help you to reduce the size without loosing quality.
public Bitmap compressImage(String imageUri) {

        String filePath = imageUri;
        // String filePath = getRealPathFromURI(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 maxHeight = 1080.0f;
        float maxWidth = 800.0f;

        float imgRatio = actualWidth / (float) actualHeight;
        float maxRatio = maxWidth / (float) 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);
            displayLogs("EXIF", "Exif: " + orientation);
            Matrix matrix = new Matrix();
            if (orientation == 6) {
                matrix.postRotate(90);
                displayLogs("EXIF", "Exif: " + orientation);
            } else if (orientation == 3) {
                matrix.postRotate(180);
                displayLogs("EXIF", "Exif: " + orientation);
            } else if (orientation == 8) {
                matrix.postRotate(270);
                displayLogs("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(filePath);
        // File image = new File(getFilename(), System.currentTimeMillis() +
        // ".jpg");
        try {
            out = new FileOutputStream(filename);

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

            out.close();

            System.out.println(didWrite);
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {

            e.printStackTrace();
        }

        return scaledBitmap;

    }

    private String getRealPathFromURI(String contentURI) {
        Uri contentUri = Uri.parse(contentURI);
        Cursor cursor = 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;
    }

    public String getFilename(String originalname) {

        ImageCache imageCache = new ImageCache(this);
        File file = new File("Your folder path");

        // return file;
        String uriSting = (file.getAbsolutePath() + "/" + "F_" + System.currentTimeMillis() + ".png");
        return uriSting;

    }
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