Lines 

You may draw freehand with the Freehand tool, a straight line with the Line tool, or a curved line with the Spline tool. 

The Freehand Tool allows you to draw freehand, just like using a pencil. Each time you press the mouse button (or push down on the pen), you begin a new line. 

The Line Tool allows you draw a line at any angle you want. Whether or not the angle measurement persists on the screen is determined by a software option. Hold down the Shift or Ctrl key on your keyboard to “snap” to a perfectly vertical, horizontal, or 45 degree line. 

The Spline Tool automatically draws a smooth curve between the points you click, in the order that you click them. When drawing a spline, you may click on the video to add new points, or click and drag the white rectangles that designate existing points.