WM_MOUSEWHEEL problems

[Bill83]

Hi all,

I am using the WM_MOUSEWHEEL message in my program, but I am having trouble detecting two things: the direction of scrolling and checking whether or not the mouse wheel itself was pressed/clicked.

I read that the high-order word of the WPARAM parameter returns positive if the user rotated the mouse wheel forward and negative if he/she rotated it backwards. So this is what I did:

case WM_MOUSEWHEEL:
if(HIWORD(wParam) > 0)  //if user rotated the wheel forward
{//handle it accordingly}
if(HIWORD(wParam) < 0)  //if user rotated the wheel backward
{//handle it accordingly}

I also read that pressing the mouse wheel is equivalent to the WM_MBUTTONDOWN message, but that is not working in my program.

Thanks to you all.

Bill

[Bill83]

Ok I solved the first problem. I had to do an explicit type cast of short:

if ((short)HIWORD(wParam) > 0)
   {// handle it accordingly}
if ((short)HIWORD(wParam) < 0)
   {//handle it accordingly}

All I have left is the last problem: how do I detect whether or not the mouse wheel itself was clicked?

Thanks again.

Bill

[anonytmouse]

I also read that pressing the mouse wheel is equivalent to the WM_MBUTTONDOWN message, but that is not working in my program.

WM_MBUTTONDOWN/WM_MBUTTONUP should work. Do you get correct behaviour when you click the mouse wheel in other applications? For example, in Firefox and IE, you should get a up/down scroller symbol.

[Bill83]

Thanks for your reply. I actually do get the scroller symbol in IE, but I do not know why it is not responding to WM_MBUTTONDOWN in my program.

[Bill83]

I'm sorry you're right. Looks like I have to debug my program, because it works with other programs.

Thanks again.