在VB.NET中改变显示器的分辩率

 

在VB.NET中改变显示器的分辩率

 

微软MVP 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

 

程序运行如下图所示，点击设置分辩率，将会把显示器分辨率改为1024x768，刷新频率为85，是不是很简单？