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MessageBox with custom font?

由 女生的网名这么多〃 提交于 2019-12-06 13:05:41
Hans Passant

I already answered this question, the answer is here. You just need to tweak is slightly since you are not interested in changing the existing font:

if (hText != IntPtr.Zero) {
  // Get the current font
  IntPtr hFont = SendMessage(hText, WM_GETFONT, IntPtr.Zero, IntPtr.Zero);
  Font font = Font.FromHfont(hFont);
  mFont = new Font(new FontFamily("Arial"), font.SizeInPoints, FontStyle.Normal);
  SendMessage(hText, WM_SETFONT, mFont.ToHfont(), (IntPtr)1);
}

Only the 5th line is different. Change the font family you want. The same basic problem with this code, although not nearly as severe, the new font you pick must fit the calculated size of the static control. A calculation that was made for the original font. If your new font is "wide" then it won't fit, reducing the SizeInPoints is the only workaround.

First of all, I apologize for my answer not being in VB (Update - Ran the code through a C# to VB converter). Surely you can read C# well enough to make sense of this and I will happily answer any questions you have about it.

This solution is not generic, in terms of how you go about finding the window and the static control. You'll need to adapt it to your own situation, but the important piece about how to set the font is reusable.

The Thread.Sleep() at the beginning of the thread is a little arbitrary. You'll probably want to wait a bit (a half second is surely too long), but it will take time for the message box to be displayed and the message box will block execution. So, I fire off the thread, have it wait until the message box is definitely open, and then I start looking for it.

Also, be sure to call DeleteObject() on the HFont eventually.

Public Partial Class Form1
    Inherits Form
    Private Const WM_SETFONT As UInt32 = &H30

    Private Delegate Function EnumThreadDelegate(hwnd As IntPtr, lParam As IntPtr) As Boolean
    Private Delegate Function EnumWindowsProc(hWnd As IntPtr, lParam As IntPtr) As Boolean

    <DllImport("user32.dll")> _
    Private Shared Function EnumThreadWindows(dwThreadId As UInteger, lpfn As EnumThreadDelegate, lParam As IntPtr) As <MarshalAs(UnmanagedType.Bool)> Boolean
    End Function

    <DllImport("kernel32.dll")> _
    Private Shared Function GetCurrentThreadId() As UInteger
    End Function

    <DllImport("user32.dll", SetLastError := True, CharSet := CharSet.Auto)> _
    Private Shared Function GetClassName(hWnd As IntPtr, lpClassName As StringBuilder, nMaxCount As Integer) As Integer
    End Function

    <DllImport("user32.dll")> _
    Private Shared Function EnumChildWindows(hwndParent As IntPtr, lpEnumFunc As EnumWindowsProc, lParam As IntPtr) As <MarshalAs(UnmanagedType.Bool)> Boolean
    End Function

    <DllImport("user32.dll", CharSet := CharSet.Auto, SetLastError := True)> _
    Private Shared Function GetWindowText(hWnd As IntPtr, lpString As StringBuilder, nMaxCount As Integer) As Integer
    End Function

    <DllImport("user32.dll", CharSet := CharSet.Auto)> _
    Private Shared Function SendMessage(hWnd As IntPtr, Msg As UInt32, wParam As IntPtr, lParam As IntPtr) As IntPtr
    End Function

    Shared threadId As UInteger = GetCurrentThreadId()

    Public Sub New()
        InitializeComponent()
    End Sub

    Private Sub button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Dim t As New Thread(New ThreadStart(AddressOf FixMsgBoxFont))
        t.Start()
        MessageBox.Show(Me, "MyMsg", "Test")
    End Sub

    Private Sub FixMsgBoxFont()
        Thread.Sleep(500)
        EnumThreadWindows(threadId, New EnumThreadDelegate(Function(hWnd, lParam) 
        Dim className As New StringBuilder()
        GetClassName(hWnd, className, 1000)

        ' Look for the message box window
        If className.ToString() <> "#32770" Then
            Return True
        End If

        EnumChildWindows(hWnd, New EnumWindowsProc(Function(hWnd2, lParam2) 
        Dim wndText As New StringBuilder()
        GetWindowText(hWnd2, wndText, 1000)

        ' Look for the static control with our text
        If wndText.ToString() = "MyMsg" Then
            ' Replace the font being used with 8pt Comix Sans MS
            Dim f As New Font(New FontFamily("Comic Sans MS"), 8, FontStyle.Bold, GraphicsUnit.Pixel)

            ' In real life, you'll eventually want to eventually call 
            ' the Windows API DeleteObject() on the font handle
            ' below or it will leak.
            Dim fontHandle As IntPtr = f.ToHfont()
            SendMessage(hWnd2, WM_SETFONT, f.ToHfont(), New IntPtr(1))
            Return False
        End If
        Return True

End Function), IntPtr.Zero)

        Return False

End Function), IntPtr.Zero)
    End Sub
End Class

Here is the code!

It has the font-size problem which I need to resolve but by now this is solved!

' The author of this code is Hand Passant: 
' http://stackoverflow.com/questions/2259027/bold-text-in-messagebox/2259213#2259213
'
' I've just translated it to VB.NET and made very little modifications.

Imports System.Drawing
Imports System.Runtime.InteropServices
Imports System.Text
Imports System.Windows.Forms

Class CustomMessageBox : Implements IDisposable

Private mTries As Integer = 0
Private mOwner As Form
Private mFont As Font

' P/Invoke declarations
Private Const WM_SETFONT As Integer = &H30
Private Const WM_GETFONT As Integer = &H31

Private Delegate Function EnumThreadWndProc(hWnd As IntPtr, lp As IntPtr) As Boolean

<DllImport("user32.dll")> _
Private Shared Function EnumThreadWindows(tid As Integer, callback As EnumThreadWndProc, lp As IntPtr) As Boolean
End Function

<DllImport("kernel32.dll")> _
Private Shared Function GetCurrentThreadId() As Integer
End Function

<DllImport("user32.dll")> _
Private Shared Function GetClassName(hWnd As IntPtr, buffer As StringBuilder, buflen As Integer) As Integer
End Function

<DllImport("user32.dll")> _
Private Shared Function GetDlgItem(hWnd As IntPtr, item As Integer) As IntPtr
End Function

<DllImport("user32.dll")> _
Private Shared Function SendMessage(hWnd As IntPtr, msg As Integer, wp As IntPtr, lp As IntPtr) As IntPtr
End Function

<DllImport("user32.dll")> _
Shared Function GetWindowRect(hWnd As IntPtr, ByRef rc As RECT) As Boolean
End Function

<DllImport("user32.dll")> _
Shared Function MoveWindow(hWnd As IntPtr, x As Integer, y As Integer, w As Integer, h As Integer, repaint As Boolean) As Boolean
End Function

Structure RECT
    Public Left As Integer
    Public Top As Integer
    Public Right As Integer
    Public Bottom As Integer
End Structure

Public Sub New(owner As Form, Optional Custom_Font As Font = Nothing)
    mOwner = owner
    mFont = Custom_Font
    owner.BeginInvoke(New MethodInvoker(AddressOf findDialog))
End Sub

Private Sub findDialog()

    ' Enumerate windows to find the message box
    If mTries < 0 Then
        Return
    End If

    Dim callback As New EnumThreadWndProc(AddressOf checkWindow)

    If EnumThreadWindows(GetCurrentThreadId(), callback, IntPtr.Zero) Then
        If System.Threading.Interlocked.Increment(mTries) < 10 Then
            mOwner.BeginInvoke(New MethodInvoker(AddressOf findDialog))
        End If
    End If

End Sub

Private Function checkWindow(hWnd As IntPtr, lp As IntPtr) As Boolean

    ' Checks if <hWnd> is a dialog
    Dim sb As New StringBuilder(260)
    GetClassName(hWnd, sb, sb.Capacity)
    If sb.ToString() <> "#32770" Then Return True

    ' Got it, get the STATIC control that displays the text
    Dim hText As IntPtr = GetDlgItem(hWnd, &HFFFF)

    Dim frmRect As New Rectangle(mOwner.Location, mOwner.Size)
    Dim dlgRect As RECT
    GetWindowRect(hWnd, dlgRect)
    MoveWindow(hWnd, frmRect.Left + (frmRect.Width - dlgRect.Right + dlgRect.Left) \ 2, frmRect.Top + (frmRect.Height - dlgRect.Bottom + dlgRect.Top) \ 2, dlgRect.Right - dlgRect.Left, dlgRect.Bottom - dlgRect.Top, True)
    If hText <> IntPtr.Zero Then

        If mFont Is Nothing Then
            ' Get the current font
            mFont = Font.FromHfont(SendMessage(hText, WM_GETFONT, IntPtr.Zero, IntPtr.Zero))
        End If

        SendMessage(hText, WM_SETFONT, mFont.ToHfont(), New IntPtr(1))

    End If

    ' Done
    Return False

End Function

Public Sub Dispose() Implements IDisposable.Dispose
    mTries = -1
    mOwner = Nothing
    If mFont IsNot Nothing Then mFont.Dispose()
End Sub

End Class

Usage:

Using New CustomMessageBox(Me, New Font(New FontFamily("Lucida Console"), Font.SizeInPoints, FontStyle.Bold))
    MessageBox.Show("Test Text", "Test Title", MessageBoxButtons.OK)
End Using
标签
.net
vb.net
winforms
fonts
messagebox
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