WM_MOUSEWHEEL problems

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:

Code:

---

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

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

Code:

---

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

Quote:

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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.

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.

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

Thanks again.