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Tip of the Day
Language: Visual Basic
Expertise: Intermediate
Dec 9, 1998

Enum API Constants Save Time Coding

You can simplify Win32 APIs by using enumerated types instead of constants. When you use enumerated types, VB provides you with a list of values when you define the API in your application:
 
Option Explicit

' define scrollbar constants as enumerations
Enum sb
	SB_BOTH = 3
	SB_CTL = 2
	SB_HORZ = 0
	SB_VERT = 1
End Enum

Enum esb
	ESB_DISABLE_BOTH = &H3
	ESB_DISABLE_DOWN = &H2
	ESB_DISABLE_LEFT = &H1
	ESB_ENABLE_BOTH = &H0
	ESB_DISABLE_RIGHT = &H2
	ESB_DISABLE_UP = &H1
End Enum
Note that you need to change the Declares to match the new Enums:
 
Private Declare Function EnableScrollBar Lib _
	"user32" (ByVal hWnd As Long, ByVal _
	wSBflags As sb, ByVal wArrows As esb) As _
	LongPrivate Declare Function _
	ShowScrollBar Lib "user32" (ByVal hWnd _
	As Long, ByVal wBar As sb, ByVal bShow _
	As Boolean) As Long
When coding up these API calls, VB displays enumerated lists for both the wSBflags and wArrows parameters to EnableScrollBar, and displays both the wBar and bShow parameters to ShowScrollBar:
 
Call EnableScrollBar(Me.hWnd, SB_BOTH, _
	ESB_ENABLE_BOTH)
Call ShowScrollBar(Me.hWnd, SB_BOTH, True)
Tom Domijan
 
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