Small Problem...

[dcahrakos]

well im trying to get it so when a persons mouse goes into a picture box, which I have named as prender, a box is drawn around the mouse, and then it follows the mouse, the code I have is this

 

Private Sub prender_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles prender.MouseMove

Dim p As Pen

Dim g As Graphics

g.DrawRectangle(p, e.X, e.Y, 40, 40)

End Sub

 

this all builds, and everything, but when i try it in the app, I get a Object reference not set to an instance of an object error...

 

can someone help me with this I havent used GDI much, so im not firmiliar that much with it.

[thenerd]

You're not initializing G or P.

 

Try:

 

Private Sub prender_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles prender.MouseMove
Dim p As Pen
p = new pen(color.black)
Dim g As Graphics
g = new graphics(prender.creategraphics)
g.DrawRectangle(p, e.X, e.Y, 40, 40)
'Also, this won't draw the rectangle around the mouse.  to make the rectangle around the mouse, you'd want
'g.drawrectangle(p,e.x - 20,e.y - 20,40,40)
End Sub

[dcahrakos]

doh....I knew I was forgetting something, im still to use to VB6....oh well, thanks alot :)

 

edit, it doesnt really work, it gives me an error

'System.Drawing.Graphics.Private Sub New(nativeGraphics As System.IntPtr)' is not accessible in this context because it is 'Private'.

 

that happens at g = New Graphics(prender.CreateGraphics)

[snarfblam]

The CreateGraphics method, um, creates a graphics object for you. You do not have to use the New keyword.

'Wrong: You are passing a graphics object to the graphics constructor
'(If you look at intellisense or the object browser, you will see that graphics has no
' public constructor).
g = New Graphics(prender.CreateGraphics)
'Right
g = prender.CreateGraphics()

[dcahrakos]

thanks, that works perfectly, although its not the way I thought it would respond, but I got it to work the way I wanted now. :)

 

edit: actually, one other quick question while were still on the same subject, say if I wanted to draw the same rectangle when the mouse just stays in one spot, how would I do that, I tried mousehover, but it doesnt have any X,Y coordinates to draw the rectangle at.

Edited September 18, 2005 by dcahrakos

[Machaira]

The rectangle should stay there until you move the mouse.