android - How to get a Bitmap from VectorDrawable

Question

I'm still trying to solve the problem I've had since a couple of days ago and I still have not found a solution. However, I am getting there step by step. Now I have run into another roadblock.

I am trying to get Bitmap.getpixel(int x, int y) to return the Color of what the user has touched using OnTouchListener. The pie is a VectorDrawable resource, vectordrawable.xml I don't need to do anything with the pixel data yet, I just need to test it. So I made a TextView that will spit out the Color touched.

public class MainActivity extends AppCompatActivity {
    ImageView imageView;
    TextView textView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        imageView = (ImageView) findViewById(R.id.imageView);
        textView = (TextView) findViewById(R.id.textView);

        imageView.setOnTouchListener(imageViewOnTouchListener);
    }

    View.OnTouchListener imageViewOnTouchListener = new View.OnTouchListener() {
        @Override
        public boolean onTouch(View view, MotionEvent event) {

            Drawable drawable = ((ImageView)view).getDrawable();
            //Bitmap bitmap = BitmapFactory.decodeResource(imageView.getResources(),R.drawable.vectordrawable);
            Bitmap bitmap = ((BitmapDrawable)drawable).getBitmap();

            int x = (int)event.getX();
            int y = (int)event.getY();

            int pixel = bitmap.getPixel(x,y);

            textView.setText("touched color: " + "#" + Integer.toHexString(pixel));

            return true;
        }
    };
}

But my app encounters a fatal error as soon as I touch the ImageView, gives the "Unfortunately,..." message and quits. In the stack trace, I found this.

java.lang.ClassCastException: android.graphics.drawable.VectorDrawable cannot be cast to android.graphics.drawable.BitmapDrawable
    at com.skwear.colorthesaurus.MainActivity$1.onTouch(MainActivity.java:38)

and line 38 is this one,

Bitmap bitmap = ((BitmapDrawable)drawable).getBitmap();

I kind of followed this. What am I doing wrong? Is it because it's a VectorDrawable. What can I do to get the Color? You can see that I have also tried BitmapFactory to cast the Drawable. Could it also be a problem with the API level of VectorDrawable since it was added like API 21?

Answer 1

First of all, you cannot cast VectorDrawable to BitmapDrawable. They don't have a parent-child relationship. They both are direct subclasses of Drawable class.

Now, to get a bitmap from drawable, you will need to create a Bitmap from the drawable metadata.

Probably something like this in a separate method,

try {
    Bitmap bitmap;

    bitmap = Bitmap.createBitmap(drawable.getIntrinsicWidth(), drawable.getIntrinsicHeight(), Bitmap.Config.ARGB_8888);

    Canvas canvas = new Canvas(bitmap);
    drawable.setBounds(0, 0, canvas.getWidth(), canvas.getHeight());
    drawable.draw(canvas);
    return bitmap;
} catch (OutOfMemoryError e) {
    // Handle the error
    return null;
}

I hope this helps.