Hello
I'm trying to scroll a region of graphics, the best way I can see is to use
the ScrollWindowEx API because it is designed for doing this
However it doesn't work correctly, Why?
Here is my code:
Public Class Win32
<DllImport("use r32.dll")> _
Public Shared Function ScrollWindowEx( ByVal hWnd As IntPtr, ByVal dx As
Integer, ByVal dy As Integer, <MarshalAs(Unma nagedType.Struc t)> ByVal
prcScroll As Rectangle, <MarshalAs(Unma nagedType.Struc t)> ByVal prcClip As
Rectangle, ByVal hrgnUpdate As IntPtr,
<System.Runtime .InteropService s.Out(), MarshalAs(Unman agedType.Struct )>
ByRef prcUpdate As Rectangle, <MarshalAs(Unma nagedType.U4)> ByVal flags As
Integer) As Integer
End Function
End Class
Private Sub barScroll_Scrol l(ByVal sender As System.Object, ByVal e As
System.Windows. Forms.ScrollEve ntArgs) Handles barScroll.Scrol l
Dim rt As Rectangle = New Rectangle
Dim rtout As Rectangle = New Rectangle(0, 0, 10, 10)
Dim rtin As Rectangle = New Rectangle(20, 20, 100, 100)
Dim rr As Integer = Win32.ScrollWin dowEx(Handle, 0, 10, rtin, rt,
IntPtr.Zero, rtout, 0)
End Sub
rr is the return from the ScrollWindowEx function and this returns 0 but
nothing happens on the screen.
err.LastDllErro r returns 993 which means Invalid access to memory location.
If I change this:
Dim rr As Integer = Win32.ScrollWin dowEx(Handle, 0, 10, rtin, rt,
IntPtr.Zero, rtout, 0)
To this:
Dim rr As Integer = Win32.ScrollWin dowEx(Handle, 0, 10, rectangle.empty ,
rectangle.empty , IntPtr.Zero, rectangle.empty , 0)
the whole screen scrolls as it should do, which kinda says the parameters
are wrong.
Can anyone help?
Scott 0 1169 This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics |
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>Thanks Peter, it works. I have another question for you. What does the
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>
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