title: Crop an image using multiple points and flexible size?
body: <p>I want to make a an application like a cam scanner for cropping a document.</p>
  <p>But I need same functionality like my two images..</p>
  <p>First Images shown image captured by camera..</p>
  <p><img src="https://i.stack.imgur.com/GzPNq.png" alt="enter image description here" /></p>
  <p>Second image recognize a captured image part like this..</p>
  <p><img src="https://i.stack.imgur.com/nlVyB.png" alt="enter image description here" /></p>
  <p>I research more and more but not getting any out put so, I ask here if,any one done this tell me..</p>
  <p>Thanks</p>