WPF是Windows作業系統中一次重大變革，與早期的GDI+/GDI不同。

WPF是基於DirectX引擎的，支援GPU硬體加速，在不支援硬體加速時也可以使用軟體繪製。

利用WPF建立無邊框的窗體：

第一種方式：設定WindowStyle="None" AllowsTransparency="True"

<Window x:Class="WpfApplication1.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="146" Width="637"  WindowStyle="None" AllowsTransparency="True"><!---->
    <Grid>
    </Grid>
</Window>
 

<Window x:Class="WpfApplication1.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="146" Width="637" Loaded="Window_Loaded" ><!---->
    <Grid>
    </Grid>
</Window>
 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Interop;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace WpfApplication1
{
    /// <summary>
    /// MainWindow.xaml 的互動邏輯
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }

        private void Window_Loaded(object sender, RoutedEventArgs e)
        {
            IntPtr hwnd = new WindowInteropHelper(this).Handle;
            NativeMethods.SetWindowNoBorder(hwnd);
        }
    }

    public class NativeMethods
    {

        /// <summary> 
        /// 帶有外邊框和標題的windows的樣式 
        /// </summary> 
        public const long WS_CAPTION = 0x00C00000L;
        public const long WS_CAPTION_2 = 0X00C0000L;

        // public const long WS_BORDER = 0X0080000L; 
        /// <summary> 
        /// window 擴充套件樣式 分層顯示 
        /// </summary> 
        public const long WS_EX_LAYERED = 0x00080000L;
        public const long WS_CHILD = 0x40000000L;

        /// <summary> 
        /// 帶有alpha的樣式 
        /// </summary> 
        public const long LWA_ALPHA = 0x00000002L;

        /// <summary> 
        /// 顏色設定 
        /// </summary> 
        public const long LWA_COLORKEY = 0x00000001L;

        /// <summary> 
        /// window的基本樣式 
        /// </summary> 
        public const int GWL_STYLE = -16;

        /// <summary> 
        /// window的擴充套件樣式 
        /// </summary> 
        public const int GWL_EXSTYLE = -20;

        /// <summary> 
        /// 設定窗體的樣式 
        /// </summary> 
        /// <param name="handle">操作窗體的控制代碼</param> 
        /// <param name="oldStyle">進行設定窗體的樣式型別.</param> 
        /// <param name="newStyle">新樣式</param> 
        [System.Runtime.InteropServices.DllImport("User32.dll")]
        public static extern void SetWindowLong(IntPtr handle, int oldStyle, long newStyle);

        /// <summary> 
        /// 獲取窗體指定的樣式. 
        /// </summary> 
        /// <param name="handle">操作窗體的控制代碼</param> 
        /// <param name="style">要進行返回的樣式</param> 
        /// <returns>當前window的樣式</returns> 
        [System.Runtime.InteropServices.DllImport("User32.dll")]
        public static extern long GetWindowLong(IntPtr handle, int style);

        /// <summary> 
        /// 設定窗體的工作區域. 
        /// </summary> 
        /// <param name="handle">操作窗體的控制代碼.</param> 
        /// <param name="handleRegion">操作窗體區域的控制代碼.</param> 
        /// <param name="regraw">if set to <c>true</c> [regraw].</param> 
        /// <returns>返回值</returns> 
        [System.Runtime.InteropServices.DllImport("User32.dll")]
        public static extern int SetWindowRgn(IntPtr handle, IntPtr handleRegion, bool regraw);

        /// <summary> 
        /// 建立帶有圓角的區域. 
        /// </summary> 
        /// <param name="x1">左上角座標的X值.</param> 
        /// <param name="y1">左上角座標的Y值.</param> 
        /// <param name="x2">右下角座標的X值.</param> 
        /// <param name="y2">右下角座標的Y值.</param> 
        /// <param name="width">圓角橢圓的width.</param> 
        /// <param name="height">圓角橢圓的height.</param> 
        /// <returns>hRgn的控制代碼</returns> 
        [System.Runtime.InteropServices.DllImport("gdi32.dll")]
        public static extern IntPtr CreateRoundRectRgn(int x1, int y1, int x2, int y2, int width, int height);

        /// <summary> 
        /// Sets the layered window attributes. 
        /// </summary> 
        /// <param name="handle">要進行操作的視窗控制代碼</param> 
        /// <param name="colorKey">RGB的值</param> 
        /// <param name="alpha">Alpha的值，透明度</param> 
        /// <param name="flags">附帶引數</param> 
        /// <returns>true or false</returns> 
        [System.Runtime.InteropServices.DllImport("User32.dll")]
        public static extern bool SetLayeredWindowAttributes(IntPtr handle, ulong colorKey, byte alpha, long flags);

        //=================================================================================
        /// <summary>
        /// 設定窗體為無邊框風格
        /// </summary>
        /// <param name="hWnd"></param>
        public static void SetWindowNoBorder(IntPtr hWnd)
        {
            long oldstyle = NativeMethods.GetWindowLong(hWnd, NativeMethods.GWL_STYLE);
            SetWindowLong(hWnd, GWL_STYLE, oldstyle & (~(WS_CAPTION | WS_CAPTION_2)));
        }
    }
}