This article was previously published under Q161286
This article provides a code sample and demonstrates how to use the FileOpen dialog box in the Comdlg32.dll. Making use of Comdlg32.OCX is a goodreuse of resources under Windows, because Windows always has its dependentfile, Comdlg32.dll, loaded. It provides an easy-to-use interface, but canbe a performance hit. If you use the OCX control, you have to load themodule into memory and also distribute a 90K OCX control to users of yoursoftware. To improve performance, you should minimize the use of controlsin your applications. Instead, you can use the Win32 API calls directly.
If you use the API calls, you may lose some of the functionality thatComdlg32.OCX offers, such as the Help button. If you require the Helpbutton, you will need to use the Comdlg32.OCX control.
Start Visual Basic 5.0 and select Standard EXE. If Visual Basic 5.0 is already running, click New Project on the File menu and select Standard EXE. Form1 is created by default.
Place a CommandButton on Form1.
Add the following code to the Form1 code window:
Option Explicit Private Declare Function GetOpenFileName Lib "comdlg32.dll" Alias _ "GetOpenFileNameA" (pOpenfilename As OPENFILENAME) As Long Private Type OPENFILENAME lStructSize As Long hwndOwner As Long hInstance As Long lpstrFilter As String lpstrCustomFilter As String nMaxCustFilter As Long nFilterIndex As Long lpstrFile As String nMaxFile As Long lpstrFileTitle As String nMaxFileTitle As Long lpstrInitialDir As String lpstrTitle As String flags As Long nFileOffset As Integer nFileExtension As Integer lpstrDefExt As String lCustData As Long lpfnHook As Long lpTemplateName As String End Type Private Sub Command1_Click() Dim OpenFile As OPENFILENAME Dim lReturn As Long Dim sFilter As String OpenFile.lStructSize = Len(OpenFile) OpenFile.hwndOwner = Form1.hWnd OpenFile.hInstance = App.hInstance sFilter = "Batch Files (*.bat)" & Chr(0) & "*.BAT" & Chr(0) OpenFile.lpstrFilter = sFilter OpenFile.nFilterIndex = 1 OpenFile.lpstrFile = String(257, 0) OpenFile.nMaxFile = Len(OpenFile.lpstrFile) - 1 OpenFile.lpstrFileTitle = OpenFile.lpstrFile OpenFile.nMaxFileTitle = OpenFile.nMaxFile OpenFile.lpstrInitialDir = "C:\" OpenFile.lpstrTitle = "Use the Comdlg API not the OCX" OpenFile.flags = 0 lReturn = GetOpenFileName(OpenFile) If lReturn = 0 Then MsgBox "The User pressed the Cancel Button" Else MsgBox "The user Chose " & Trim(OpenFile.lpstrFile) End If End Sub
Press the F5 key to run the project, and click the CommandButton. You should see the File Open dialog box appear with the options set.
The Win32 SDK documents other calls to the Comdlg32.dll such asChooseColor, ChooseFont, and GetSaveFileName.
For more information, please see the following article in the MicrosoftKnowledge Base:
106682 : Default Extension Ignores File Type in VB Common Dialog