用C#做一個像FlashGet的懸浮窗口，其實很簡單，不像以前需要調用很多系統API。大致的步驟如下。
首先是主窗體部分，即要判斷窗體的狀態來決定是否顯示懸浮窗口。
局部成員聲明：
private FormWindowState fwsPrevious;
private frmTopMost myTopMost;
主窗體的Load事件：
private void frmMain_Load(object sender, System.EventArgs e)
{
// Save window state
fwsPrevious = this.WindowState;
// Create top most window
myTopMost = new frmTopMost( this );
}
主窗體的SizeChanged事件：
private void frmMain_SizeChanged(object sender, System.EventArgs e)
{
if( this.WindowState == FormWindowState.Minimized )
{
// Window minimized
// Show top most window
myTopMost.Show();
this.ShowInTaskbar = false;
}
else if( this.WindowState != fwsPrevious )
{
// Save current window state
fwsPrevious = this.WindowState;
}
}
然后，就是還原窗口方法，即供懸浮窗口進行調用的。
/// <summary>
/// Restore window state
/// </summary>
public void RestoreWindow()
{
this.WindowState = fwsPrevious;
this.ShowInTaskbar = true;
}
下來就是懸浮窗口部分代碼，首先要設置其窗體的FormBorderStyle為None，然后設置其的TopMost為true，接下來，就是主要是三個鼠標事件的處理，以下，具體說明如何實現的。
局部成員聲明。
private Point ptMouseCurrrnetPos, ptMouseNewPos,
ptFormPos, ptFormNewPos;
private bool blnMouseDown=false;
private frmMain pParent;
懸浮窗口的構造函數。
public frmTopMost( frmMain pMain )
{
//
// Required for Windows Form Designer support
//
InitializeComponent();
// Init main window object
pParent = pMain;
}
懸浮窗口的Load事件。
private void frmTopMost_Load(object sender, System.EventArgs e)
{
this.Show();
// Init window size and position
this.Top = 100;
this.Left = Screen.PrimaryScreen.Bounds.Width - 100;
this.Width = 80;
this.Height = 80;
}
主要的三個鼠標事件，即MouseDown、 MouseMove、 MouseUp三個事件。
private void frmTopMost_MouseMove(object sender, System.Windows.Forms.MouseEventArgs e)
{
if( blnMouseDown )
{
//Get the current position of the mouse in the screen
ptMouseNewPos = Control.MousePosition;
//Set window position
ptFormNewPos.X = ptMouseNewPos.X - ptMouseCurrrnetPos.X + ptFormPos.X;
ptFormNewPos.Y = ptMouseNewPos.Y - ptMouseCurrrnetPos.Y + ptFormPos.Y;
//Save window position
Location = ptFormNewPos;
ptFormPos = ptFormNewPos;
//Save mouse position
ptMouseCurrrnetPos = ptMouseNewPos;
}
}
private void frmTopMost_MouseDown(object sender, System.Windows.Forms.MouseEventArgs e)
{
if(e.Button==MouseButtons.Left)
{
blnMouseDown = true;
// Save window position and mouse position
ptMouseCurrrnetPos = Control.MousePosition;
ptFormPos = Location;
}
}
private void frmTopMost_MouseUp(object sender, System.Windows.Forms.MouseEventArgs e)
{
if( e.Button == MouseButtons.Left)
//Return back signal
blnMouseDown = false;
}
然后就是雙擊懸浮窗體，進行恢復主窗體。
private void frmTopMost_DoubleClick(object sender, System.EventArgs e)
{
SwitchToMain();
}
private void SwitchToMain()
{
//Change main window status here
pParent.RestoreWindow();
//Hide top most window
this.Hide();
}
此外，還可以給懸浮窗口添加ContextMenu，來輔助操作，這里就不細說了。
private System.Windows.Forms.ContextMenu mnuPopup;
private System.Windows.Forms.MenuItem mnuMainWindow;
private System.Windows.Forms.MenuItem mnuExit;
private void mnuMainWindow_Click(object sender, System.EventArgs e)
{
SwitchToMain();
}
private void mnuExit_Click(object sender, System.EventArgs e)
{
Application.Exit();
}