SetCustomPaintFunction method
Remarks
Provides a pointer to a custom drawing functions that will be called immediately before completing the button's rendering.
Syntax
Visual Basic
control.SetCustomPaintFunction pFunction as long
Visual C++
void control.SetCustomPaintFunction (long pFunction);
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Parameter
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Description
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pFunction
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Pointer to a custom drawing functions
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Return value
None
Let's see a sample that demonstrates how to paint a flicker free red circle over the button surface:
Visual Basic example
Inside a BAS module, add the following declarations that will allow accessing the Windows GDI primitives
Public Declare Function SelectObject Lib "gdi32" (ByVal hDC As Long, ByVal hObject As Long) As Long
Public Declare Function Ellipse Lib "gdi32" (ByVal hDC As Long, ByVal X1 As Long, ByVal Y1 As Long, ByVal X2 As Long, ByVal Y2 As Long) As Long
Public Declare Function DeleteObject Lib "gdi32" (ByVal hObject&) As Long
Public Declare Function CreateSolidBrush Lib "gdi32" (ByVal crColor As Long) As Long
Inside the same BAS module add the following subroutine that will perform our custom rendering
Sub MyPaintFunction(ByVal hDC As Long)
Dim brushColor As Long
Dim brushOld As Long
brushColor = CreateSolidBrush(RGB(255, 0, 0))
brushOld = SelectObject(hDC, brushColor)
Ellipse hDC, 10, 10, 50, 50
SelectObject hDC, brushOld
DeleteObject brushColor
End Sub
Inside the Form_Load subroutine, call the SetCustomPaintFunction method passing the pointer to the MyPaintFunction subroutine, obtained through the AddressOf function.
Private Sub Form_Load()
BtnEnh1.SetCustomPaintFunction AddressOf MyPaintFunction
End Sub
Note that you can call the SetCustomPaintFunction method from wherever you want, also passing different drawing function depending upon your rendering needs.
Visual C++ example
Write your own function like the one below (note that the function must have the _stdcall declaration)
void _stdcall MyPaintFunction (long hDC)
{
HBRUSH brushColor = ::CreateSolidBrush (RGB (255,0,0));
HBRUSH brushOld = (HBRUSH) ::SelectObject ((HDC) hDC, brushColor);
::Ellipse((HDC) hDC, 10, 10, 50, 50);
::SelectObject ((HDC) hDC, brushOld);
::DeleteObject (brushColor);
}
Supposing that we have created a member variable m_btn1 for one of our controls, we will have to call the following line
m_btn1.SetCustomPaintFunction ((long) MyPaintFunction);
