自制控件方面的有关知识

使用：

If RegComCtl32 = ERROR_SUCCESS Then
MsgBox "Registration Successful"
Else
MsgBox "Registration Unsuccessful"
End If

If UnRegComCtl32 = ERROR_SUCCESS Then
MsgBox "UnRegistration Successful"
Else
MsgBox "UnRegistration Unsuccessful"
End If

2.建立可下拉选择的属性
例如在 BorderStyle 中有以下的四个选择：
0 - None
1 - Dashed
2 - Single Line
3 - Double Line
4 - 3D
首先在控件中定义以下的集合：
Enum BorderType
None
Dashed
[Single Line]
[Double Line]
[3D]
End Enum
然后就可以把属性的类型设置好：
Public Property Get BorderStyle() As BorderType
Border = m_BorderStyle
End Property

Public Property Let BorderStyle(ByVal New_BorderStyle As BorderType)
m_BorderStyle = New_BorderStyle
PropertyChanged "BorderStyle"
End Property

3.缺省值和可选参数
VB5 加强了函数参数方面，可用以下的代码实现参数缺省：

Property Get Value(Optional index As Long = 1)
...
End Property
也可使用另一个方法（慢）：

Property Get Value(Optional index As Long)
If IsMissing(index) Then index = 1
...
End Property

4.多个参数的属性
在自制的控件中，可能需要对某个属性传递多个值：

Property Let Test (arg1 As String, arg2 As String, arg3 As Integer)
End Property

用以下的方法传递参数：
Test(arg1,arg2) = arg3

5.使用数组做属性
定义一个 variant 类型的属性，即可用它来做数组。
下面定义了一个 CArray 类。

Private m_MyArray As Variant

Public Property Get MyArray() As Variant
MyArray = m_MyArray
End Property

Public Property Let MyArray As Variant)
m_MyArray = a
End Property

可用以下的方法使用：

Private m_Array As CArray
Private mArr(3) As String

Private Sub Form_Load()
Set m_Array = New CArray
mArr(1) = "One"
mArr(2) = "Two"
mArr(3) = "Three"
m_Array.MyArray = mArr()
或者
m_Array.MyArray = Array("One", "Two", "Three")
End Sub

Private Sub Form_Unload(Cancel As Integer)
Dim i As Integer
For i = 1 To UBound(m_Array.MyArray)
MsgBox m_Array.MyArray(i)
Next
End Sub 

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