Scaled Bitmap maintaining aspect ratio

Question

I would like to scale a Bitmap to a runtime dependant width and height, where the aspect ratio is maintained and the Bitmap fills the entire width

Answer 1

public static Bitmap scaleBitmap(Bitmap bitmap, int wantedWidth, int wantedHeight) {
    float originalWidth = bitmap.getWidth();
    float originalHeight = bitmap.getHeight();
    Bitmap output = Bitmap.createBitmap(wantedWidth, wantedHeight, Config.ARGB_8888);
    Canvas canvas = new Canvas(output);
    Matrix m = new Matrix();

    float scalex = wantedWidth/originalWidth;
    float scaley = wantedHeight/originalHeight;
    float xTranslation = 0.0f, yTranslation = (wantedHeight - originalHeight * scaley)/2.0f;

    m.postTranslate(xTranslation, yTranslation);
    m.preScale(scalex, scaley);
    // m.setScale((float) wantedWidth / bitmap.getWidth(), (float) wantedHeight / bitmap.getHeight());
    Paint paint = new Paint();
    paint.setFilterBitmap(true);
    canvas.drawBitmap(bitmap, m, paint);

    return output;
}