利用VB动态改变Windows显示模式的两种方法 - 水木森林(专业电脑教程网)|itus...
要改变显示模式,首先要获得显示系统支持的显示模式。显示系统支持的所有的显示模式是利用API函数EnumDisplaySettings获得的。然后有两种方法切换显示模式,一种是利用Windows API函数ChangeDisplaySettings另外一种方法是利用Windows附带的一个QuickRES库,通过调用QuickRES库实现显示模式的切换。
首先在VB中建立一个工程文件,然后在Form1中加入一个ListBox控件和两个CommandButton控件,然后在Form1的代码窗口中加入以下代码:
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 (“无法建立程序图标!")
End
End If
End Sub
Sub LoadDisplayMode()
Dim i As Long
Dim l1 As Long
Dim astr As String
i = 0
'遍历所有的显示模式并在List1中显示出来
Do
ModeCube(i).dmFields = DM_BITSPERPEL Or DM_PELSWIDTH Or DM_PELSHEIGHT Or _
DM_DISPLAYFLAGS Or DM_DISPLAYFREQUENCY
ModeCube(i).dmSize = Len(ModeCube(i))
'获得显示模式并保存到数组中
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) '获得最后一个显示模式之后EnumDisplaySettings会返回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的开发文档中没有说明
b = ChangeDisplaySettings(aDev, CDS_FORCE)
'改变完显示模式设置之后向所有的窗口发送显示模式改变消息
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
'调用Windows中的QuickRes库来改变显示模式,如果你的系统中没有安装QuickRes系统将会产生一个错误
RetVal = Shell(shellString, 1)
End Sub
Private Sub Form_Load()
Command1.Caption = “使用API函数改变分辨率"
Command2.Caption =“使用QuickRes库"
LoadDisplayMode
End Sub
运行程序,点击选择ListBox中的显示模式,然后按下“使用API函数改变分辨率”键或者“使用QuickRes库”键,就可以切换显示模式到所需要的模式了。
需要说明的一点是,在程序中的改变显示模式的语句 b = ChangeDisplaySettings(aDev, CDS_FORCE) 中的常量CDS_FORCE是一个未公开(UnDocument)的定义,在微软的帮助文档是没有有关的说明的。
以上的程序在Win98、VB6下运行通过。(长沙 陈锐)