将RichTextBox设置为自动换行或非自动换行

近日研究文本控件和字符串，研究得头混脑胀，问题真是太多了。

这只是其中的一个问题，答案来自问专家网站和CSDN的TechnoFantasy(www.applevb.com) ，解决如下：

Public Const WM_USER = &H400

Public Const EM_SETTARGETDEVICE = (WM_USER + 72)

Public Declare Function GetDC Lib "user32" (ByVal hWnd As Long) As Long

Public Declare Function SendMessage Lib "user32" Alias "SendMessageA" _

(ByVal hWnd As Long, _

ByVal wMsg As Long, _

ByVal wParam As Long, _

lParam As Any) As Long

Public Sub AutoSwitchLine(ByRef RichText As Long, ByVal bSwitch As Boolean)

If bSwitch Then

'设置 RichTextBox 自动换行

Call SendMessage(RichText.hWnd, EM_SETTARGETDEVICE, _

GetDC(RichText.hWnd), RichText.Width / 15)

If RichText.RightMargin = 0 Then

RichText.RightMargin = 1

Else

RichText.RightMargin = 0

End If

Else

'设置 RichTextBox 不自动换行

Call SendMessage(RichText.hWnd, EM_SETTARGETDEVICE, 0, 1)

End If

End Sub