Question

C# 怎样实现窗体的悬浮效果

Answer 1

第一步：建立一个窗体，设置其属性：

this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.None;
this.MaximizeBox = false;
this.MinimizeBox = false;
this.Opacity = 0.5;

第二步：设置窗体的OnLoad事件：

private void Form2_Load(object sender, EventArgs e)
{
this.Top = 20;
this.Left = Screen.PrimaryScreen.Bounds.Width - 80;
this.Width = 60;
this.Height = 60;
}

第三步：修改窗体的Paint事件，美化界面，这里做一个渐变背景，需要引入System.Drawing.Drawing2D;

private void Form2_Paint(object sender, PaintEventArgs e)
{
Graphics g = e.Graphics;
Color FColor = Color.Red;
Color TColor = Color.Yellow;
Brush b = new LinearGradientBrush(this.ClientRectangle, FColor, TColor, LinearGradientMode.ForwardDiagonal);
g.FillRectangle(b, this.ClientRectangle);
}

第四步：需要实现鼠标拖动悬浮窗体，

const int WM_NCHITTEST = 0x0084;
const int HTCLIENT = 0x0001;
const int HTCAPTION = 0x0002;
protected override void WndProc(ref System.Windows.Forms.Message m)
{
switch(m.Msg)
{
case WM_NCHITTEST:
base.WndProc(ref m);
if (m.Result==(IntPtr)HTCLIENT)
m.Result=(IntPtr)HTCAPTION;
break;
default:
base.WndProc(ref m);
break;
}
}

关于这一步，愚翁不是这样处理的，他是处理鼠标事件来实现的，效果差不多，也贴在这里学习一下吧：
先定义几个类成员变量：
private Point ptMouseCurrrnetPos, ptMouseNewPos,ptFormPos, ptFormNewPos;
private bool blnMouseDown = false;

再添加三个鼠标事件：
private void Form2_MouseDown(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left)
{
blnMouseDown = true;
// Save window position and mouse position
ptMouseCurrrnetPos = Control.MousePosition;
ptFormPos = Location;
}

}

private void Form2_MouseMove(object sender, 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 Form2_MouseUp(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left)
//Return back signal
blnMouseDown = false;
}

第三种移动无标标题窗体的办法：
通过API来处理，需要引入System.Runtime.InteropServices;

[DllImport("user32.dll")]
public static extern bool ReleaseCapture();
[DllImport("user32.dll")]
public static extern bool SendMessage(IntPtr hwnd,int wMsg,int wParam,int lParam);

public const int WM_SYSCOMMAND=0x0112;
public const int SC_MOVE=0xF010;
public const int HTCAPTION=0x0002;

private void Form2_MouseDown(object sender, System.Windows.Forms.MouseEventArgs e)
{
ReleaseCapture();
SendMessage(this.Handle,WM_SYSCOMMAND,SC_MOVE+HTCAPTION, 0);
}

呵，这个看起来好像比较“正统”。