在VB.NET中改变显示器的分辩率

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出处：ttp://www.microsoft.com/china/community/Column/28.mspx
作者：李洪根

在VB.NET中，我们很容易获得显示器的分辩率，但是，要改变显示器的分辩率就比较麻烦了。由于.NET的类库没有将EnumDisplaySettings 和ChangeDisplaySettings这两个API函数进行封装，但是我们得调用它们函数，相对于VB6来说，VB.NET调用API函数是有一些小的改动！
下面，我们就尝试一下在VB.NET中，使用这两个API函数。
新建一个项目，在Form1上添加两个按钮，一个名为btnGetDisp，将其Text属性设置为“得到分辩率”；另一个按钮名为btnSetDisp，Text属性为“设置分辩率”。然后在代码窗口里添加以下代码： 

    Private Const CCDEVICENAME As Short = 32
    Private Const CCFORMNAME As Short = 32
    Private Const DM_PELSWIDTH As Integer = &H80000
    Private Const DM_PELSHEIGHT As Integer = &H100000

'刷新频率常量
Private Const DM_DISPLAYFREQUENCY As Integer = &H400000

    '调用API函数
    Private Declare Function EnumDisplaySettings Lib "user32" Alias "EnumDisplaySettingsA" 
    (ByVal lpszDeviceName As Integer, ByVal iModeNum As Integer, ByRef lpDevMode As DEVMODE) As Boolean
    '调用API函数
    Private Declare Function ChangeDisplaySettings Lib "user32" Alias "ChangeDisplaySettingsA" 
    (ByRef lpDevMode As DEVMODE, ByVal dwflags As Integer) As Integer

    '定义结构
    Private Structure DEVMODE
        <VBFixedString(CCDEVICENAME), System.Runtime.InteropServices.MarshalAs
        (System.Runtime.InteropServices.UnmanagedType.ByValTStr, SizeConst:=CCDEVICENAME)> Public dmDeviceName As String
        Dim dmSpecVersion As Short
        Dim dmDriverVersion As Short
        Dim dmSize As Short
        Dim dmDriverExtra As Short
        Dim dmFields As Integer
        Dim dmOrientation As Short
        Dim dmPaperSize As Short
        Dim dmPaperLength As Short
        Dim dmPaperWidth As Short
        Dim dmScale As Short
        Dim dmCopies As Short
        Dim dmDefaultSource As Short
        Dim dmPrintQuality As Short
        Dim dmColor As Short
        Dim dmDuplex As Short
        Dim dmYResolution As Short
        Dim dmTTOption As Short
        Dim dmCollate As Short
        <VBFixedString(CCFORMNAME), System.Runtime.InteropServices.MarshalAs
        (System.Runtime.InteropServices.UnmanagedType.ByValTStr, SizeConst:=CCFORMNAME)> Public dmFormName As String
        Dim dmUnusedPadding As Short
        Dim dmBitsPerPel As Short
        Dim dmPelsWidth As Integer
        Dim dmPelsHeight As Integer
        Dim dmDisplayFlags As Integer
        Dim dmDisplayFrequency As Integer
    End Structure

    '改变分辩率过程，参数一宽度，参数二高度
    Private Sub ChangeDisp(ByRef iWidth As Single, ByRef iHeight As Single)
        Dim blnWorked As Boolean
        Dim i As Integer
        Dim DevM As Form1.DEVMODE
        i = 0
        Do
            blnWorked = EnumDisplaySettings(0, i, DevM)
            i = i + 1
        Loop Until (blnWorked = False)

        With DevM
            .dmFields = DM_PELSWIDTH Or DM_PELSHEIGHT  Or DM_DISPLAYFREQUENCY
            .dmPelsWidth = iWidth
            .dmPelsHeight = iHeight
'刷新频率为85
.dmDisplayFrequency = 85       
        End With
        Call ChangeDisplaySettings(DevM, 0)
    End Sub

    Private Sub btnGetDisp_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnGetDisp.Click
        Dim X As Short = System.Windows.Forms.Screen.PrimaryScreen.Bounds.Width
        Dim Y As Short = System.Windows.Forms.Screen.PrimaryScreen.Bounds.Height
        MsgBox("您的显示器分辨率是" & X & " X " & Y)
    End Sub

    Private Sub btnSetDisp_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSetDisp.Click
        If MsgBox("您确认要将显示器分辨率改为1024x768吗？", MsgBoxStyle.OKCancel, "系统消息") = MsgBoxResult.OK Then
            '调用改变分辩率过程
            ChangeDisp(1024, 768)
        End If
    End Sub