如何在 VB.Net 中为 WebBrowser 设置透明背景色？

Question

我正在使用网络浏览器在 VB.Net 表单应用程序中自动从网络加载图像，但是，有一个白色背景，图像没有填满表单上的整个导航器对象.

如何在我的应用程序中为 Web 浏览器对象设置透明背景？

谢谢，
C.

Answer 1

将表单的透明度键设置为白色。 您选择作为透明度键的颜色是透明的。整个表单上具有该颜色的任何内容都会变成透明的。由于浏览器的背景是白色的，白色的透明度键将使其透明，您可以使用 Windows Aero Glass DWM 效果获得玻璃般的透明度，但它仅适用于 Windows Vista 及以上版本，对于以前版本的 Windows，您将拥有手动绘制它是一项漫长的工作。对您来说最简单、最快捷的方法是将透明键设置为白色 :)

Me.TransparencyKey = Color.White

如果您想使用 Aero Glass DWM，请使用以下代码：

Imports System.Drawing
Imports System.Drawing.Drawing2D
Imports System.Runtime.InteropServices

Private mExtendedFrameMargins As MARGINS

Protected Overrides Sub _
OnPaint(ByVal e As System.Windows.Forms.PaintEventArgs)
    e.Graphics.SmoothingMode = SmoothingMode.AntiAlias
    'use either one
    e.Graphics.SmoothingMode = SmoothingMode.HighQuality
End Sub

Private Sub Form1_Paint(ByVal sender As System.Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles MyBase.Paint
    If IsGlassEnabled() Then
        'You should paint the extended frame black for proper composition, but I'm painting it white as you need it
        e.Graphics.FillRectangle(Brushes.White, 0, 0, Me.ClientRectangle.Width, mExtendedFrameMargins.cyTopHeight)
    End If
End Sub

Private Function IsGlassEnabled() As Boolean
    If Environment.OSVersion.Version.Major < 6 Then
        Return False
    End If

    Dim isGlassSupported As Boolean = False
    DwmIsCompositionEnabled(isGlassSupported)
    Return isGlassSupported
End Function

<DllImport("dwmapi.dll")> _
Private Shared Function DwmIsCompositionEnabled(<MarshalAs(UnmanagedType.Bool)> ByRef pfEnabled As Boolean) As Integer
End Function

<DllImport("dwmapi.dll")> _
Private Shared Function DwmExtendFrameIntoClientArea(ByVal hwnd As IntPtr, ByRef pMarInset As MARGINS) As Integer
End Function


<StructLayout(LayoutKind.Sequential)> _
Private Structure MARGINS
    Public cxLeftWidth As Integer
    Public cxRightWidth As Integer
    Public cyTopHeight As Integer
    Public cyBottomHeight As Integer
End Structure



Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
 If IsGlassEnabled() Then
  mExtendedFrameMargins = New MARGINS
  mExtendedFrameMargins.cyTopHeight = Me.Height 'type height here, this is going to be a number (integer)
  DwmExtendFrameIntoClientArea(Me.Handle, mExtendedFrameMargins)
 End If
End Sub

我在我正在创建的应用程序中使用了此代码