Suppress mouse-movement

0
votes

I need to freeze the windows mouse cursor on the screen, so it stays hovered over a specific UI element. While the mouse is in this frozen state, I would still like to be able to interact with the UI using a "fake" mouse pointer.

Currently, I've got a low level mouse hook that prevents WM_MOUSEMOVE messages from being passed along, effectively stopping all real mouse movement. However, when I don't pass along the updated coordinates, windows actually sends me the old coordinates in a separate WM_MOUSEMOVE message, as if to correct for the fact that the mouse didn't move.

Any idea on either how to prevent Windows from sending me these corrected coordinates, or another approach of how I can freeze the actual mouse curosr and still allow the physical mouse to control a "Fake" cursor?

4
c#windowsmouse
When you have finished writing this most useful app please could you let me have a copy! Only joking, I'm sure you've got a perfectly good reason for wanting to do this. - David Heffernan
If you are not passing them along, could you just ignore them? (Piskvor reminds self never to buy whatever that will be, as he'd possibly break the mouse in frustration). Also, could you do the other interactions via SendMessage() ? Not sure if this is a better poison, but at least the mouse remains controllable. - Piskvor left the building
Granted it sounds like a horrible idea, believe me I know. But the reason for this is I would like to freeze the mouse over an html element (say, a popup javascript menu), but then be able to inspect the dom at this point. - jaws
No reason can justify this horrible idea. There are other ways to indicate a selection. Use a color for example. Look at the Firebug addon for Firefox for ideas. - Hans Passant

4 Answers

1
votes

You can suppress mouse cursor movement by using DirectInput exclusive mode. You should acquire mouse input device when cursor movement must be suppressed. This will block windows cursor movement but you can get messages for your fake cursor using DirectInput API.

0
votes

If you move the mouse cursor position in response to a WM_MOUSEMOVE message, to put the mouse back to where you want it, you will get another mouse move message because the mouse has been moved again (because you moved it). To stop this, don't set the mouse position if it is already in the right place.

You may also want to clip the mouse position to your window and get exclusive access to it.

0
votes

Why don't you just draw an image of the cursor at the place you want it frozen, then set the real mouse cursor to be hidden (Cursor.Hide IIRC).

0
votes

It's not clear to me what you are trying to do, perhaps making a tutorial for your app and you want to show mouse movements, etc. Perhaps this library will be useful:

http://www.codeproject.com/KB/system/globalmousekeyboardlib.aspx