Introduction - If you have any usage issues, please Google them yourself
1. draw a straight line with the left mouse button pressed for the " starting point" , keep it pressed, move the mouse until you release the mouse button as the " destination" , draw a straight line static. 2. In the process of moving the mouse should be the " starting point " to the mouse," draw a dynamic linear current location. " draw dynamic linear approach is a straight line before the first remove, and then draw a new line. in the mouse to move the process will continue to receive many WM_MOUSEMOVE message, which LOWORD ( lParam) and HIWORD (lParam) were stored the mouse' s current X, Y values.