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中建立一個工程文件，然后在Form1中加入一個ListBox控件和兩個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) '獲得最后一個顯示模式之后EnumDisplaySettings會返回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)將會產(chǎn)生一個錯誤

　　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）