Private Declare Function SetWindowRgn Lib "USER32" (ByVal hWnd As Long, ByVal hRgn As Long, ByVal bRedraw As Boolean) As Long
Private Declare Function CreateRoundRectRgn Lib "gdi32" (ByVal X1 As Long, ByVal Y1 As Long, ByVal X2 As Long, ByVal Y2 As Long, ByVal X3 As Long, ByVal Y3 As Long) As Long
Private Declare Function DeleteObject Lib "gdi32" (ByVal hObject As Long) As Long

Dim outrgn As Long

Private Sub Form_Activate()
    Call rgnform(Me, 20, 20) '修改后面两个参数可调整圆角弧度
End Sub
Private Sub Form_Unload(Cancel As Integer)
    DeleteObject outrgn '将圆角区域使用的所有系统资源释放
End Sub

Private Sub rgnform(ByVal frmbox As Form, ByVal fw As Long, ByVal fh As Long)
    Dim w As Long, h As Long
    w = frmbox.ScaleX(frmbox.Width, vbTwips, vbPixels)
    h = frmbox.ScaleY(frmbox.Height, vbTwips, vbPixels)
    outrgn = CreateRoundRectRgn(0, 0, w, h, fw, fh)
    Call SetWindowRgn(frmbox.hWnd, outrgn, True)
End Sub

<form>
<input type="file" name="userfile">
<input type="text" name="filetitle">
<input type="submit" value="Upload">
</form>

Private Sub Form_Load()
    Command1.caption="测试"
End Sub

Private Sub Command1_Click()
    Const CF_TEXT = 1      '定义剪贴板内容类型
    Clipboard.Clear

    '把文件路径发送到剪贴板
    Clipboard.SetText "E:\Picture\mm.jpg"
    
    WebBrowser1.Navigate (App.path & "demo.html")
End Sub

Private Sub WebBrowser1_DocumentComplete(ByVal pDisp As Object, URL As Variant)
    Dim vDoc, vTag
    Dim i As Integer

    Set vDoc = WebBrowser1.Document
    For i = 0 To vDoc.All.length - 1
        If UCase(vDoc.All(i).tagName) = "INPUT" Then
            Set vTag = vDoc.All(i)
            If vTag.Type = "file" Then
                vTag.focus            '使type="file"表单项获得焦点
                SendKeys "^{v}", True   '向其发送粘贴命令
                
            ElseIf vTag.Type = "text" Then
                vTag.Value = "www.Maiter.com.cn"    '自动填写type="text"的表单项
            
            '这里是自动点击提交按钮，为方便演示type="file"表单项的自动填写将忽略运行
            'ElseIf vTag.Type = "submit" Then
                'vtag.click
                
            End If
        End If
    Next
End Sub