Thursday, August 23, 2012

Check orientation of images/captures

A lot of times, you would need your app to either pick an image from the gallery or use the device's camera for capturing a picture that your app could use. I have seen a lot of apps, do it plain wrong. Especially, the orientation of the images.

The default gallery app, reads the orientation properly, and displays the images/thumbnails properly. So, our apps can also handle images in various orientations properly. And the good news is, it's very easy to handle.

There's a class called ExifInterface. Most of the times, when you have a similar situation, you would almost never want a full-scaled image to be shown in your app. Most often, we use a thumbnail view for the purpose. The following code would get you a re-sized bitmap, from your original file.

Say for example, we have this path to the actual image file. imagePath

1. Create a Bitmap from the file

Bitmap b = BitmapFactory.decodeFile(imagePath);

2. Resize the Bitmap by scaling it to appropriate level
int width = b.getWidth();
int height = b.getHeight();
int newWidth = 150;
int newHeight = 150;
float scaleWidth = ((float) newWidth) / width;
float scaleHeight = ((float) newHeight) / height;
Matrix matrix = new Matrix();
matrix.postScale(scaleWidth, scaleHeight);
// Bitmap resizedBitmap = Bitmap.createBitmap(b, 0, 0, width, height, matrix, true);
// resizedBitmap.compress(Bitmap.CompressFormat.JPEG, 70, out);

3. Handle orientation of the image
ExifInterface exif = new ExifInterface(imagePath);
String orientation = exif.getAttribute(ExifInterface.TAG_ORIENTATION);
if (orientation.equals(ExifInterface.ORIENTATION_NORMAL)) {
        // Do nothing. The original image is fine.
} else if (orientation.equals(ExifInterface.ORIENTATION_ROTATE_90+"")) {
        matrix.postRotate(90);
} else if (orientation.equals(ExifInterface.ORIENTATION_ROTATE_180+"")) {
        matrix.postRotate(180);
} else if (orientation.equals(ExifInterface.ORIENTATION_ROTATE_270+"")) {
        matrix.postRotate(270);
}

4. Save the new bitmap 
out = new FileOutputStream(new File("some output file path"));
Bitmap resizedBitmap = Bitmap.createBitmap(b, 0, 0, width, height, matrix, true);
resizedBitmap.compress(Bitmap.CompressFormat.JPEG, 70, out);
Now your output file would be an image that is resized and handled properly for orientation of the images. You could directly use the "resized" bitmap, but I prefere files.