Microsoft KB Archive/109390

= ACC: Sample Function to Use the COMMDLG Color Dialog Box =

Article ID: 109390

Article Last Modified on 5/6/2003

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APPLIES TO


 * Microsoft Access 1.0 Standard Edition
 * Microsoft Access 1.1 Standard Edition
 * Microsoft Access 2.0 Standard Edition

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This article was previously published under Q109390



SUMMARY
Advanced: Requires expert coding, interoperability, and multiuser skills.

The Palette in Microsoft Access provides a limited selection of colors for database objects and does not allow you to create custom colors. However, the BackColor, ForeColor, and BorderColor properties of forms and reports will accept any valid RGB color value.

This article lists a sample Access Basic function called ChooseColor that uses the Microsoft Windows standard Color dialog box so that you can choose from a greater selection of colors or create your own custom color.

NOTE: In Access for Windows 95, the new Color Builder Wizard is included which replaces the functionality of the ChooseColor function. For more information about the Color Builder, search for "Color Builder" using the Microsoft Access for Windows 95 Help Index.

This article assumes that you are familiar with Access Basic and with creating Microsoft Access applications using the programming tools provided with Microsoft Access. For more information on Access Basic, please refer to the "Introduction to Programming" manual in Microsoft Access version 1.x, or the "Building Applications" manual, Chapter 3, "Introducing Access Basic" in version 2.0.



MORE INFORMATION
To set up the sample function ChooseColor, create a new module with the following Declarations section and function:

NOTE: In the following sample code, an underscore (_) is used as a line- continuation character. Remove the underscore when re-creating this code in Access Basic.

  '******************************************************************** ' MODULE DECLARATION SECTION '********************************************************************  Option Explicit

'  ' Required COMMDLG Declarations '  Type ChooseColor lStructSize As Long hwndOwner As Integer hInstance As Integer RgbResult As Long lpCustColors As Long Flags As Long lCustData As Long lpfnHook As Long lpTemplateName As Long End Type

Global Const CC_RGBINIT = &H1 Global Const CC_FULLOPEN = &H2

Declare Function ChooseColor_API Lib "COMMDLG.DLL" Alias _ "ChooseColor" (pCHOOSECOLOR As ChooseColor) As Integer Declare Function CommDlgExtendedError Lib "COMMDLG.DLL" As Long

'  ' Global Memory Declarations '  Declare Function GlobalAlloc Lib "Kernel" _ (ByVal wFlags As Integer, ByVal dwBytes As Long) As Integer Declare Function GlobalFree Lib "Kernel" _ (ByVal hMem As Integer) As Integer Declare Function GlobalLock Lib "Kernel" _ (ByVal hMem As Integer) As Long Declare Function GlobalUnlock Lib "Kernel" _ (ByVal hMem As Integer) As Integer

Global Const GMEM_MOVEABLE = &H2 Global Const GMEM_ZEROINIT = &H40 Global Const GHND = (GMEM_MOVEABLE Or GMEM_ZEROINIT)

Declare Sub hmemcpy Lib "Kernel" _ (lpDest As Any, lpSource As Any, ByVal dwBytes As Long)

'********************************************************************  ' FUNCTION: ChooseColor '  ' PURPOSE: '  Uses the standard Windows Color dialog box in COMMDLG.DLL to get '  a 256-color RGB value for use in Microsoft Access. The returned '  value can be used in the BackColor, ForeColor, or BorderColor '  properties. '  ' ARGUMENTS: '  DefaultColor - The default RGB color to be selected. '                 Black, 0, is usually the default. '  ' RETURN VALUE: '  >=0  The user-selected RGB value '  -1   Couldn't allocate global memory '  -2   Couldn't lock global memory '  -3   COMMDLG error occurred. A message box will display the '       number prior to this function exiting. '  ' ********************************************************************   Function ChooseColor (ByVal DefaultColor As Long) As Long Dim C As ChooseColor Dim MemHandle As Long Dim Result As Integer, i As Integer

' Define CustomColor array, address, size variables ReDim CustomColors(15) As Long Dim CustomColorsAddress As Long Dim CustomColorsSize As Integer

' Fill custom colors array with all white For i = 0 To UBound(CustomColors) CustomColors(i) = &HFFFFFF Next

' Get size of global memory needed for custom colors CustomColorsSize = Len(CustomColors(0)) * 16

' Get a global memory block to hold a copy of the custom colors MemHandle = GlobalAlloc(GHND, CustomColorsSize) If MemHandle = 0 Then ChooseColor = -1 Exit Function End If

' Lock the custom color's global memory block CustomColorsAddress = GlobalLock(MemHandle) If CustomColorsAddress = 0 Then ChooseColor = -2 Exit Function End If

' Copy custom colors to the global memory block Call hmemcpy(ByVal CustomColorsAddress, _        CustomColors(0), CustomColorsSize)

' Initialize Choose Color structure C.lStructSize = Len(C) C.hwndOwner = 0& C.lpCustColors = CustomColorsAddress C.RgbResult = DefaultColor C.Flags = CC_RGBINIT Or CC_FULLOPEN

' Call the Choose Color COMMDLG routine Result = ChooseColor_API(C)

' Did an error occur? If Result = 0 And CommDlgExtendedError <> 0 Then ChooseColor = -3 MsgBox Str$(CommDlgExtendedError), 16, "Choose Color Error" End If

' Copy the new custom colors to the CustomColors address locally ' .. CustomColor array will now contain list of new custom colors Call hmemcpy(CustomColors(0), _        ByVal CustomColorsAddress, CustomColorsSize)

' Unlock and free the global memory block Result = GlobalUnlock(MemHandle) Result = GlobalFree(MemHandle)

' Return the selected color ChooseColor = C.RgbResult

End Function

How to Use the ChooseColor Function
The following sample Access Basic function demonstrates how to use the ChooseColor function:

Function GetColor MsgBox Str$(ChooseColor(0)) End Function

The GetColor function calls the ChooseColor function and selects black as the default color. A message box will display the color selected in the Color dialog box.

The GetColor function can be called from a command button by entering the following for the button's OnPush property:

  =GetColor

Additional query words: commdlg.dll

Keywords: kbinfo kbprogramming KB109390

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