Learn the Windows Programming day2 scroll bar using

Tag: Use a client message that requires a mouse pos Windows programming BSP INT

Related functions:

Setscrollrange,setscrollpos,getscrollrange,getscrollpos

What we need to do when using the scroll bar:

1. Initialize scroll bar range and position

The wm_create response can be completed when the window is created

00, TRUE);

2. Handling scroll bar messages for window procedures

Handling when responding to Wm_vscroll

Switch(LoWord (WParam)) { Casesb_lineup: .... Break;  Casesb_linedown: .... Break;  Casesb_pageup: .... Break;  Casesb_pagedown: .... Break;  Casesb_thumbtrack: .... Break;  Casesb_thumbposition: .... Break;} 

Note You can get the mouse action on the scrollbar by using the LoWord (WParam) in the low 16 bits of the WParam parameter.

When the scrollbar action is sb_thumbposition or sb_thumbtrack, the position can be obtained in the high 16 bits of the WParam parameter HiWord (wParam)

3. Update the slider position

SetScrollPos (hwnd, Sb_vert, XXX, TRUE);

4. Update client content based on scroll bar changes

You can set global parameters when processing a scrollbar message, and respond to an update when the WM_PAINT response is made

To update client content in a timely manner

can use

InvalidateRect (hwnd, NULL, TRUE);

Sends a message to the message queue WM_PAINT, which is placed behind the message queue, knowing that other messages have been processed before responding

or use

UpdateWindow (HWND);

Non-queued messages, skipping the message loop mechanism to process the update window directly

Learn the Windows Programming day2 scroll bar using