Patrick Steele's .NET Blog

I needed to capture mouse clicks before my windows app got a hold of them.  Seeing that the Form class has a PreProcessMessage method I thought I was all set.  As the documentation stated:

First was Don Box.  Then Tim Ewald, Chris Sells and Robert Scoble.  Now Ingo Rammer is posting that his first "assignment" will be in mid-August and he'll be in Redmond the last week of June.  Hmmm....  Could the remoting guru be Microsoft's next big catch?

From a Visual Studio Magazine HotTip:

... to Hungarian Notation:

Alex Lowe asks: Do you miss ASPToday.com?

You've seen applications that allow you to move the form around by simply clicking anywhere on the form (not just the caption bar). Can you do this in .NET? Yes! And it's very easy. All you have to do is handle the proper windows message and the rest is easy.

Option Strict On
Option Explicit On


Imports System
Imports System.Windows.Forms
Imports System.Drawing


Public Class Form1
    Inherits Form


    Private Declare Function ReleaseCapture Lib "user32" () As Long
    Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As IntPtr, ByVal wMsg As Integer, ByVal wParam As Integer, ByVal lParam As Integer) As Integer


    Private Const WM_NCLBUTTONDOWN  As Integer = &HA1
    Private Const HTCAPTION         As Integer = 2


    Public Sub New()
        Me.Text = "Drag anywhere to move"
        AddHandler Me.MouseDown, AddressOf frmMain_MouseDown
    End Sub


    <STAThread()> _
    Shared Sub Main()
        Application.Run(New Form1())
    End Sub


    Private Sub frmMain_MouseDown(ByVal sender As Object, ByVal e As MouseEventArgs)
        'Don't drag the sceen if it is the right button or the wheel.
        If e.Button = MouseButtons.Left Then
            ReleaseCapture()
            SendMessage(Me.Handle, WM_NCLBUTTONDOWN, HTCAPTION, 0)
        End If


    End Sub


End Class

Still using the .NET 1.0 framework and need a "browse for folder" dialog? You'll need to resort to platform invoke (p/invoke) using the Win32 API's. Here's a class that encapsulates all of it.

Here's an example of pulling a bitmap off the clipboard and displaying it in a windows form.

Option Strict On
Option Explicit On 

Imports System
Imports System.Windows.Forms
Imports System.Drawing

Public Class WinApp
    Inherits System.Windows.Forms.Form

    Private m_PB As PictureBox

    <STAThread()> _
    Shared Sub Main()
        Application.Run(New WinApp())
    End Sub

    Public Sub New()
        Me.Text = "This is my form"
        m_PB = New PictureBox()
        m_PB.Location = New Point(0, 0)
        m_PB.Size = Me.Size

        m_PB.Image = GetImageFromClipboard()
        If Not m_PB.Image Is Nothing Then
            Me.ClientSize = New Size(m_PB.Image.Width, m_PB.Image.Height)
            m_PB.Size = Me.ClientSize
        End If

        Me.Controls.Add(m_PB)
    End Sub

    Public Function GetImageFromClipboard() As Image
        If Not Clipboard.GetDataObject() Is Nothing Then
            Dim dobj As IDataObject = Clipboard.GetDataObject()
            If dobj.GetDataPresent(DataFormats.Bitmap) Then
                Dim img_obj As Object = dobj.GetData(DataFormats.Bitmap)
                Return CType(img_obj, Bitmap)
            End If
        End If
    End Function

End Class