HOWTO: Use Color Dialog from COMDLG32.DLL in VB and Access

ID: Q153929

The information in this article applies to:

Microsoft Visual Basic Professional and Enterprise Editions for Windows, versions 5.0, 6.0
Microsoft Visual Basic Standard, Professional, and Enterprise Editions, 32-bit only, for Windows, version 4.0
Microsoft PowerPoint Viewer 98 Macintosh Edition, version 1.0

SUMMARY

Making use of the COMDLG32.DLL is a good reuse of resources under Windows because Windows always has COMDLG32.DLL loaded. If you use the COMDLG32.OCX control instead, your program must load the OCX into memory and you must also distribute an additional 90K file to your customers. The OCX control provides an easy-to-use interface to predefined dialog boxes, but is a more expensive hit on performance and resources. To optimize performance and reduce resource usage, you should minimize the use of controls in your applications and use the Win32 API calls directly. Below is a code sample of how to use the Choose Color dialog box in the COMDLG32.DLL.

MORE INFORMATION

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 in the flags element of the CHOOSECOLOR structure if you wish to prevent the Custom Colors part of the Dialog from being displayed.

NOTE: In the Command1_Click routine above, the code to set the background color of an Access form and a Visual Basic form is slightly different. Both commands are included and commented. Only type the command that is appropriate for the product you are using.

REFERENCES

Microsoft Visual Basic Programmer's Guide, Chapter 11, P.325-332.

Win32 SDK.

Additional query words: Common kbVBp400 kbVBp500 kbVBp600 kbVBp kbdsd kbDSupport knintluk
kbNoKeyWord

Keywords : kbGrpVB
Version : WINDOWS:4.0,5.0,6.0; :1.0
Platform : WINDOWS
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