Trap Mouse Cursor

Question

I'm writing a Pong game for fun.

It's going well, the game is playable, but I've got a slight problem.
The player's paddle follows the mouse cursor up and down the form. My problem here is that as soon as the cursor leaves the form, the paddle stops, sometimes prematurely.

My solution is to trap the cursor in the game window, but I don't know how. Is there anyone who can point me in the right direction? Maybe supply some sample code...

Thanks in advance!!!

---

Logan Young, MCPD Web Developer hopeful

Answer 1

You could use a Global Mouse Hook

---

Listing SPEC's is not a review !!! :-)

Answer 2

But it should keep possible of course to leave your form, otherwize you cannot do almost anything anymore beside unplugging the power

On the other hands should a mouse click outside the mouse area be not any problem, therefore you should have done some extremely strange, check those things is the only advice I can give you.

 

Answer 3

I'm not saying there isn't a better way to accomplish this - one idea, might be to monitor when your mouse leaves the client area to automatically pause the game...   But, if you want to pursue the capture idea, then you might look at the SetCapture/ReleaseCapture api methods.

---

Tom Shelton

Answer 4

I'm not too worried about not being able to do anything outside the game window. This isn't the type of game that's going to be played for very long. More like the kind of thing you'd do during a tea break.

Tom, can you give me a link to a "crash course" on using the SetCapture/ReleaseCapture api methods? I googled it, but I didn't find anything useful

---

Logan Young, MCPD Web Developer hopeful

Answer 5

LoganY...  After playing with this, I don't think it accomplishes what you want - at least not exactly.  Sorry.

---

Tom Shelton

Answer 6

Ok.  The api's I was thinking of was GetClipCursor and ClipCursor - which I don't think you actually need in .NET :)  There is a property on the Cursor object - Cursor.Clip that should allow you to manipulate this.  But, they don't seem to work on Windows 7 at all - or I'm doing something wrong :)  Anyway, if I get time then I'll try them out latter on my Vista box.

---

Tom Shelton

Answer 7

Based on your post, you want to handle the mouse move event on the screen, here 
you could look this link and will be able to get current point coordinate wherever the Cursor points to. it works fine on my computer and please take it a try.
mouse position + mousehook
link:http://social.msdn.microsoft.com/forums/en-US/vbgeneral/thread/6ac8e418-f91a-40a2-9ac4-084288144ef3/

Prerequisites: Create a form named Form1 and copy all code to Form1.vb.

Public Class Form1

Private Structure MSLLHOOKSTRUCT

Public pt As Point

Public mouseData As Int32

Public flags As Int32

Public time As Int32

Public extra As IntPtr

End Structure

Private _mouseHook As IntPtr

Private Const WH_MOUSE_LL As Int32 = 14

Private Delegate Function CallBack(ByVal nCode As Int32, ByVal wParam As IntPtr, ByRef lParam As MSLLHOOKSTRUCT) As Int32

Private _mouseProc As CallBack

Private Declare Function SetWindowsHookExW Lib "user32.dll" (ByVal idHook As Int32, ByVal HookProc As CallBack, ByVal hInstance As IntPtr, ByVal wParam As Int32) As IntPtr

Private Declare Function UnhookWindowsHookEx Lib "user32.dll" (ByVal hook As IntPtr) As Boolean

Private Declare Function CallNextHookEx Lib "user32.dll" (ByVal idHook As Int32, ByVal nCode As Int32, ByVal wParam As IntPtr, ByRef lParam As MSLLHOOKSTRUCT) As Int32

Private Declare Function GetCurrentThreadId Lib "kernel32.dll" () As Integer

Private Declare Function GetModuleHandleW Lib "kernel32.dll" (ByVal fakezero As IntPtr) As IntPtr

Public Function InstallHook() As Boolean

If _mouseHook = IntPtr.Zero Then

_mouseProc = New CallBack(AddressOf MouseHookProc)

_mouseHook = SetWindowsHookExW(WH_MOUSE_LL, _mouseProc, GetModuleHandleW(IntPtr.Zero), 0)

End If

Return _mouseHook <> IntPtr.Zero

End Function

Public Sub RemoveHook()

If _mouseHook = IntPtr.Zero Then Return

UnhookWindowsHookEx(_mouseHook)

_mouseHook = IntPtr.Zero

End Sub

Private Shared Function MouseHookProc(ByVal nCode As Int32, ByVal wParam As IntPtr, ByRef lParam As MSLLHOOKSTRUCT) As Int32

Debug.Print("Message = {0}, x={1}, y={2}", wParam.ToInt32, lParam.pt.X, lParam.pt.Y)

' Get the current cursor coordinate

Form2.Text = "Current Point: " & lParam.pt.X & " " & lParam.pt.Y         '

Return CallNextHookEx(WH_MOUSE_LL, nCode, wParam, lParam)

End Function

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

InstallHook()

End Sub

Private Sub Form1_FormClosed(ByVal sender As System.Object, ByVal e As System.Windows.Forms.FormClosedEventArgs) Handles MyBase.FormClosed

RemoveHook()

End Sub

End Class

Otherwise, you could look this article "How to develop a screen saver “and i beileve it could give you some help.
http://www.codeproject.com/KB/cs/scrframework.aspx?display=Print

This article explains:

the basics of a screensaver
loading a screensaver
filling the whole screen
handling multiple monitors
handling events
some little intricacies

you could look the step4:

Once you have loaded your screensaver, you have to handle events. This is because when the user uses the mouse or hits the keyboard, you probably want to do something, like ending the screensaver. To do this, you add event handlers to the KeyDown, MouseMove and MoveDown events of the screensaver form. In the event handlers, you could use the form's Close method to end the screensaver.

There is one point to note here. When an application is executed, the current mouse parameters are passed to it by Windows. This naturally triggers a mouse event, which would close the screensaver. To handle this, add a Point variable in the class, initialize it when the application executes, and check the mouse position and mouse clicks when mouse events occur. If there happens to be any change, then call Close. The code would look something like:

If you have any issue please feel free to tell us

Bese wishes
XIngwei Hu

---

Please remember to mark the replies as answers if they help and unmark them if they provide no help.
Welcome to the All-In-One Code Framework! If you have any feedback, please tell us.