要改變顯示模式，首先要獲得顯示系統(tǒng)支持的顯示模式。顯示系統(tǒng)支持的所有的顯示模式是利用API函數(shù)EnumDisplaySettings獲得的。然后有兩種方法切換顯示模式，一種是利用Windows API函數(shù)ChangeDisplaySettings另外一種方法是利用Windows附帶的一個(gè)QuickRES庫，通過調(diào)用QuickRES庫實(shí)現(xiàn)顯示模式的切換。
首先在VB中建立一個(gè)工程文件，然后在Form1中加入一個(gè)ListBox控件和兩個(gè)CommandButton控件，然后在Form1的代碼窗口中加入以下代碼：
Option Explicit
Private Type RECT
Left As Long
Top As Long
Right As Long
Bottom As Long
End Type
Private Declare Function ChangeDisplaySettings Lib “user32" Alias “ChangeDisplaySettingsA" _
(lpDevMode As Any, ByVal dwflags As Long) As Long
Private Declare Function EnumDisplaySettings Lib“user32" Alias“EnumDisplaySettingsA" _
(ByVal lpszDeviceName As String, ByVal iModeNum As Long, lpDevMode As Any) As Long
Private Declare Function SendMessageByLong＆ Lib“user32" Alias“SendMessageA" _
(ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, ByVal lParam As Long)
Private Declare Function InvalidateRect Lib “user32" (ByVal hwnd As Long, lprect As Any, _
ByVal bErase As Long) As Long
Private Declare Function PostMessage Lib “user32" Alias “PostMessageA" (ByVal hwnd As Long, _
ByVal wMsg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
Private Type DEVMODE
dmDeviceName As String ＊ 32
dmSpecVersion As Integer
dmDriverVersion As Integer
dmSize As Integer
dmDriverExtra As Integer
dmFields As Long
dmOrientation As Integer
dmPaperSize As Integer
dmPaperLength As Integer
dmPaperWidth As Integer
dmScale As Integer
dmCopies As Integer
dmDefaultSource As Integer
dmPrintQuality As Integer
dmColor As Integer
dmDuplex As Integer
dmYResolution As Integer
dmTTOption As Integer
dmCollate As Integer
dmFormName(1 To 32) As Byte
dmLogPixels As Integer
dmBitsPerPel As Long
dmPelsWidth As Long
dmPelsHeight As Long
dmDisplayFlags As Long
dmDisplayFrequency As Long
dmICMMethod As Long
'Windows 95 only
dmICMIntent As Long
’ Windows 95 only
dmMediaType As Long
' Windows 95 only
dmDitherType As Long
' Windows 95 only
dmReserved1 As Long
' Windows 95 only
dmReserved2 As Long
' Windows 95 only
End Type
Const DM_BITSPERPEL = ＆H40000
Const DM_PELSWIDTH = ＆H80000
Const DM_PELSHEIGHT = ＆H100000
Const DM_DISPLAYFLAGS = ＆H200000
Const DM_DISPLAYFREQUENCY = ＆H400000
Const DISP_CHANGE_SUCCESSFUL = 0
Const DISP_CHANGE_RESTART = 1
Const DISP_CHANGE_FAILED = －1
Const DISP_CHANGE_BADMODE = －2
Const DISP_CHANGE_NOTUPDATED = －3
Const DISP_CHANGE_BADFLAGS = －4
Const DISP_CHANGE_BADPARAM = －5
Const CDS_UPDATEREGISTRY = 1
Const CDS_FORCE As Long = ＆H80000000
Const CDS_RESET = ＆H40000000
Const HWND_BROADCAST = ＆HFFFF＆
Const WM_SYSCOLORCHANGE = ＆H15
Const WM_PALETTECHANGED = ＆H311
Const WM_DISPLAYCHANGE = ＆H7E
Const WM_SETTINGCHANGE = ＆H1A
Dim ModeCube(63) As DEVMODE
Dim lproc As Long
Sub EndApp()
Icon_Del (Form1.Command1.hwnd)
End
End Sub
Sub ShowIcon()
Dim l As Long
If (Icon_Add(Form1.Command1.hwnd, Form1.Picture)) Then
lproc = SetWindowLong(Form1.Command1.hwnd, GWL_WNDPROC, AddressOf DialogProc)
Else
MsgBox (“無法建立程序圖標(biāo)！")
End
End If
End Sub
Sub LoadDisplayMode()
Dim i As Long
Dim l1 As Long
Dim astr As String
i = 0
'遍歷所有的顯示模式并在List1中顯示出來
Do
ModeCube(i).dmFields = DM_BITSPERPEL Or DM_PELSWIDTH Or DM_PELSHEIGHT Or _
DM_DISPLAYFLAGS Or DM_DISPLAYFREQUENCY
ModeCube(i).dmSize = Len(ModeCube(i))
'獲得顯示模式并保存到數(shù)組中
l1 = EnumDisplaySettings(vbNullString, i, ModeCube(i))
If l1 Then
astr = Str＄(ModeCube(i).dmPelsWidth) ＋ “＊" ＋ Trim＄(Str＄(ModeCube(i).dmPelsHeight)) ＋“ "
Select Case ModeCube(i).dmBitsPerPel
Case 4
astr = astr ＋ “16色"
Case 8
astr = astr ＋ “256色"
Case 16
astr = astr ＋“16位高彩"
Case 24
astr = astr ＋ “24位真彩"
Case Else
astr = astr ＋ Str＄(ModeCube(i).dmBitsPerPel)
End Select
i = i ＋ 1
End If
List1.AddItem astr
Loop Until (l1 = False) '獲得最后一個(gè)顯示模式之后EnumDisplaySettings會(huì)返回False
End Sub
Private Sub Command1_Click()
Dim aDev As DEVMODE
Dim b, xxa, xxb, xxc, xxd As Long
If List1.ListIndex < 0 Then Exit Sub
aDev = ModeCube(List1.ListIndex)
'CDS_FORCE在Microsoft的開發(fā)文檔中沒有說明
b = ChangeDisplaySettings(aDev, CDS_FORCE)
'改變完顯示模式設(shè)置之后向所有的窗口發(fā)送顯示模式改變消息
xxc= Send Message ByLong(HWND_BROADCAST, WM_SYSCOLORCHANGE, 0＆, 0＆)
xxa = SendMessageByLong(HWND_BROADCAST, WM_PALETTECHANGED, Me.hwnd, 0＆)
xxb = PostMessage(HWND_BROADCAST, WM_SYSCOLORCHANGE, 0＆, 0＆)
xxd = InvalidateRect(0＆, ByVal 0, 1＆)
End Sub
Private Sub Command2_Click()
Dim aDev As DEVMODE
Dim tempVar As String
Dim RetVal
Dim shellString As String
If List1.ListIndex < 0 Then Exit Sub
aDev = ModeCube(List1.ListIndex)
tempVar = LTrim＄(Str(aDev.dmPelsWidth)) ＋ “x" ＋ LTrim＄(Str(aDev.dmPelsHeight)) ＋
“x" ＋ LTrim＄(Str(aDev.dmBitsPerPel))
Debug.Print tempVar
shellString =“Rundll.exe DeskCp16.dll,QUICKRES_RUNDLLENTRY "
shellString = shellString ＋ tempVar
'調(diào)用Windows中的QuickRes庫來改變顯示模式，如果你的系統(tǒng)中沒有安裝QuickRes系統(tǒng)將會(huì)產(chǎn)生一個(gè)錯(cuò)誤
RetVal = Shell(shellString, 1)
End Sub
Private Sub Form_Load()
Command1.Caption = “使用API函數(shù)改變分辨率"
Command2.Caption =“使用QuickRes庫"
LoadDisplayMode
End Sub
運(yùn)行程序，點(diǎn)擊選擇ListBox中的顯示模式，然后按下“使用API函數(shù)改變分辨率”鍵或者“使用QuickRes庫”鍵，就可以切換顯示模式到所需要的模式了。
需要說明的一點(diǎn)是，在程序中的改變顯示模式的語句 b = ChangeDisplaySettings(aDev, CDS_FORCE) 中的常量CDS_FORCE是一個(gè)未公開（UnDocument）的定義，在微軟的幫助文檔是沒有有關(guān)的說明的。
以上的程序在Win98、VB6下運(yùn)行通過。（長沙 陳銳）
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