vb.net - 如何在 VB.Net 中为所有元素切换高对比度模式？

Question

无论如何有一个按钮（btnHCon）点击事件，在vb.net中启用高对比度模式（然后显然是再次关闭它）？

我希望在将其添加到我的项目时添加功能/可访问性（类似于在控制面板中切换高对比度）？

任何建议都非常感谢！

Answer 1

似乎做到这一点的唯一方法是在高对比度模式下为表单/控件使用系统默认颜色（因为只有那些会被高对比度模式更改）。¹ 要打开高对比度模式，您唯一的选择似乎是使用非托管代码——尤其是SystemParametersInfo()带有结构 的.uiAction SPI_SETHIGHCONTRASTHIGHCONTRASTpvParam

我不太擅长调用非托管代码，但幸运的是 VBForums 的 chris128 完成了艰苦的工作。不过，您只能靠自己来设置它！但我认为，如果您查看上面的参考资料，您可以找出适当的调整。

Imports System.Runtime.InteropServices

Public Class Form1
'
'API declarations
'

Public Const HCF_HIGHCONTRASTON As Integer = 1
Public Const SPI_SETHIGHCONTRAST As Integer = 67
Public Const SPIF_SENDWININICHANGE As Integer = 2

<System.Runtime.InteropServices.StructLayoutAttribute(System.Runtime.InteropServices.LayoutKind.Sequential)> _
Public Structure HIGHCONTRAST
    Public cbSize As UInteger
    Public dwFlags As UInteger
    <System.Runtime.InteropServices.MarshalAsAttribute(System.Runtime.InteropServices.UnmanagedType.LPWStr)> _
    Public lpszDefaultScheme As String
End Structure

<System.Runtime.InteropServices.DllImportAttribute("user32.dll", EntryPoint:="SystemParametersInfoW")> _
Public Shared Function SystemParametersInfoW(ByVal uiAction As UInteger, ByVal uiParam As UInteger, ByVal pvParam As System.IntPtr, ByVal fWinIni As UInteger) As <System.Runtime.InteropServices.MarshalAsAttribute(System.Runtime.InteropServices.UnmanagedType.Bool)> Boolean
End Function

'
'End of API declarations
'

'Some button click event
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

    Dim highcontraststruct As New HIGHCONTRAST
    highcontraststruct.dwFlags = HCF_HIGHCONTRASTON
    highcontraststruct.cbSize = CUInt(Marshal.SizeOf(highcontraststruct))
    Dim highcontrastptr As IntPtr = Marshal.AllocHGlobal(Marshal.SizeOf(highcontraststruct))
    Runtime.InteropServices.Marshal.StructureToPtr(highcontraststruct, highcontrastptr, False)

    SystemParametersInfoW(SPI_SETHIGHCONTRAST, CUInt(Marshal.SizeOf(highcontraststruct)), highcontrastptr, SPIF_SENDWININICHANGE)

End Sub
End Class