title: Draw a line on an Image using javascript
body: <p>I have an image in html img tag. My requirement is that when a user click on the image it will mark a point and draw a line while dragging the mouse. Then, While user finishes the drag and clicks on the image it should display the line also show the dimension of the line in millimeter/centimeter. ie , User has to draw a line on the image and show the distance/length (in millimeter/centimeter)of line he drawn.</p>
  
  <p>How can implement this feature in a web application? Can anyone please help me to implement this feature ?</p>