title: create bitmap to screen size keeping ratio
body: <p><img src="https://i.stack.imgur.com/G2cJB.png" alt="original_Bitmap to new_Bitmap"></p>
  
  <p>I'm trying to make a Wallpaper Application. And I had big trouble during set wallpaper with bitmap. I have tried to figure out the answer for a week.</p>
  
  <p>I want to set Bitmap in to wallpaper like</p>
  
  <ol>
  <li>avoid crop</li>
  <li>scaleType:fit_center(align center vertical, keep original bitmap's ratio)</li>
  </ol>
  
  <p>How can I make it? Do I have to create new bitmap?</p>