This article was previously published under Q153929
Making use of the COMDLG32.DLL is a good reuse of resources under Windowsbecause Windows always has COMDLG32.DLL loaded. If you use the COMDLG32.OCXcontrol instead, your program must load the OCX into memory and you mustalso distribute an additional 90K file to your customers. The OCX controlprovides an easy-to-use interface to predefined dialog boxes, but is a moreexpensive hit on performance and resources. To optimize performance andreduce resource usage, you should minimize the use of controls in yourapplications and use the Win32 API calls directly. Below is a code sampleof how to use the Choose Color dialog box in the COMDLG32.DLL.
1a. Visual Basic: Start a new project. Form1 is created by default.
1b. Access: Open a database and create a new form.
Add a CommandButton (Command1) to the form.
Add the following code to the General Declarations section of the form:
Option Explicit Private Type CHOOSECOLOR lStructSize As Long hwndOwner As Long hInstance As Long rgbResult As Long lpCustColors As String flags As Long lCustData As Long lpfnHook As Long lpTemplateName As String End Type Private Declare Function ChooseColorAPI Lib "comdlg32.dll" Alias _ "ChooseColorA" (pChoosecolor As CHOOSECOLOR) As Long Dim CustomColors() As Byte Private Sub Command1_Click() Dim cc As CHOOSECOLOR Dim Custcolor(16) As Long Dim lReturn As Long cc.lStructSize = Len(cc) cc.hwndOwner = Me.hWnd cc.hInstance = 0 cc.lpCustColors = StrConv(CustomColors, vbUnicode) cc.flags = 0 lReturn = ChooseColorAPI(cc) If lReturn <> 0 Then Me.Caption = "RGB Value User Chose: " & Str$(cc.rgbResult) Me.BackColor = cc.rgbResult ' Visual Basic only **** Me.Section(0).BackColor = cc.rgbResult ' Access only ********** CustomColors = StrConv(cc.lpCustColors, vbFromUnicode) Else MsgBox "User chose the Cancel Button" End If End Sub Private Sub Form_Load() ReDim CustomColors(0 To 16 * 4 - 1) As Byte Dim i As Integer For i = LBound(CustomColors) To UBound(CustomColors) CustomColors(i) = 0 Next i End Sub
4a. Visual Basic: Press the F5 key to run the project.
4b. Access: Use the View|Form menu to open the form and run it.
Click the CommandButton and the Color dialog box will be displayed. When you choose a color and press OK, the background color of the form will change to your selected color.
The constant CC_PREVENTFULLOPEN, with a decimal value of 4, can be used inthe flags element of the CHOOSECOLOR structure if you wish to prevent theCustom Colors part of the Dialog from being displayed.
NOTE: In the Command1_Click routine above, the code to set the backgroundcolor of an Access form and a Visual Basic form is slightly different. Bothcommands are included and commented. Only type the command that isappropriate for the product you are using.
Microsoft Visual Basic Programmer's Guide, Chapter 11, P.325-332.
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