最近一直在学习 WPF，看着别人做的WPF程序那么漂亮，眼红啊～ 很多漂亮的程序都是无边框的。于是无边框窗口操作就是最重要的了。无边框窗口的操作一直以来相关的资料就很少。WPF 下的就更少了，有的大多是无边框窗体的移动。在得到群里高人的指点，再查了一些资料之后，终于把问题解决了。
废话不多说，直接来看看如何实现吧!其实现原理很简单：拦截并处理 Windows 消息：WM_NCHITTEST。
WPF 处理 Windows 消息的模式和 WinForm 不一样了。Window 类里没有 WndProc 函数了，想要截取 Windows 消息必须借助 HwndSource 添加 Hook。
借助 HwndSource 注册 WndProc
1
protected override void OnSourceInitialized(EventArgs e)
2
{
3
base.OnSourceInitialized(e);
4 HwndSource hwndSource = PresentationSource.FromVisual(this) as HwndSource;
5 if (hwndSource != null)
6
{
7 hwndSource.AddHook(new HwndSourceHook(this.WndProc));
8
}
9
}
10
11protected virtual IntPtr WndProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
12{
13 return IntPtr.Zero;
14}
OK，WndProc 注册完成之后就可以通过 WndProc 函数完成对Windows消息的处理了。可以发现，这里的 WndProc 和标准的 Win32 消息循环很像，只是多了一个 ref bool handled 参数，对于该参数MSDN是这样说明的：指示该消息是否已处理的值。如果该消息已处理，请将值设置为 true；否则请将其设置为 false。 在下面我们将会使用到这个参数数。
通过 WndProc 实现无边框窗体改变大小和拖动
1private const int WM_NCHITTEST = 0x0084;
2private readonly int agWidth = 12; //拐角宽度
3private readonly int bThickness = 4; // 边框宽度
4private Point mousePoint = new Point(); //鼠标坐标
5
6protected virtual IntPtr WndProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
7{
8 switch (msg)
9 {
10 case WM_NCHITTEST:
11 this.mousePoint.X = (lParam.ToInt32() &0xFFFF);
12 this.mousePoint.Y = (lParam.ToInt32() >> 16);
13
14 测试鼠标位置#region 测试鼠标位置
15
16 // 窗口左上角
17 if (this.mousePoint.Y - this.Top <= this.agWidth
18 && this.mousePoint.X - this.Left <= this.agWidth)
19 {
20 handled = true;
21 return new IntPtr((int)HitTest.HTTOPLEFT);
22 }
23 // 窗口左下角
24 else if (this.ActualHeight + this.Top - this.mousePoint.Y <= this.agWidth
25 && this.mousePoint.X - this.Left <= this.agWidth)
26 {
27 handled = true;
28 return new IntPtr((int)HitTest.HTBOTTOMLEFT);
29 }
30 // 窗口右上角
31 else if (this.mousePoint.Y - this.Top <= this.agWidth
32 && this.ActualWidth + this.Left - this.mousePoint.X <= this.agWidth)
33 {
34 handled = true;
35 return new IntPtr((int)HitTest.HTTOPRIGHT);
36 }
37 // 窗口右下角
38 else if (this.ActualWidth + this.Left - this.mousePoint.X <= this.agWidth
39 && this.ActualHeight + this.Top - this.mousePoint.Y <= this.agWidth)
40 {
41 handled = true;
42 return new IntPtr((int)HitTest.HTBOTTOMRIGHT);
43 }
44 // 窗口左侧
45 else if (this.mousePoint.X - this.Left <= this.bThickness)
46 {
47 handled = true;
48 return new IntPtr((int)HitTest.HTLEFT);
49 }
50 // 窗口右侧
51 else if (this.ActualWidth + this.Left - this.mousePoint.X <= this.bThickness)
52 {
53 handled = true;
54 return new IntPtr((int)HitTest.HTRIGHT);
55 }
56 // 窗口上方
57 else if (this.mousePoint.Y - this.Top <= this.bThickness)
58 {
59 handled = true;
60 return new IntPtr((int)HitTest.HTTOP);
61 }
62 // 窗口下方
63 else if (this.ActualHeight + this.Top - this.mousePoint.Y <= this.bThickness)
64 {
65 handled = true;
66 return new IntPtr((int)HitTest.HTBOTTOM);
67 }
68 else // 窗口移动
69 {
70 handled = true;
71 return new IntPtr((int)HitTest.HTCAPTION);
72 }
73 #endregion
74 }
75 return IntPtr.Zero;
76}
从上面的代码可以看出，工作原理很简单：截取 WM_NCHITTEST 消息，获得鼠标坐标，再在你希望的地方返回不同的消息以模拟鼠标的状态即可。需要注意的是，返回消息之前必须将handled 设为 true。告诉系统你已经处理过该消息，不然无效果。
关于 HitTest 是自定义的枚举类，里面包含了鼠标的各种消息。
HitTest
1public enum HitTest:int
2{
3 HTERROR = -2,
4 HTTRANSPARENT = -1,
5 HTNOWHERE = 0,
6 HTCLIENT = 1,
7 HTCAPTION = 2,
8 HTSYSMENU = 3,
9 HTGROWBOX = 4,
10 HTSIZE = HTGROWBOX,
11 HTMENU = 5,
12 HTHSCROLL = 6,
13 HTVSCROLL = 7,
14 HTMINBUTTON = 8,
15 HTMAXBUTTON = 9,
16 HTLEFT = 10,
17 HTRIGHT = 11,
18 HTTOP = 12,
19 HTTOPLEFT = 13,
20 HTTOPRIGHT = 14,
21 HTBOTTOM = 15,
22 HTBOTTOMLEFT = 16,
23 HTBOTTOMRIGHT = 17,
24 HTBORDER = 18,
25 HTREDUCE = HTMINBUTTON,
26 HTZOOM = HTMAXBUTTON,
27 HTSIZEFIRST = HTLEFT,
28 HTSIZELAST = HTBOTTOMRIGHT,
29 HTOBJECT = 19,
30 HTCLOSE = 20,
31 HTHELP = 21,
32}
在结束之前，先要感谢一下 WPF SL 技术超级群(10458228) 和群主 法拉力 还有高手 萧长老 是 法拉力 提供了一个非常好的交流环境，群里的朋友都很热情。这篇文章的完成得益于萧长老 的指点和提供的资料(http://social.msdn.microsoft.com/Forums/en-US/wpf/thread/77b566aa-be88-47a4-8c29-b1e44946348e/)。萧长老 的Blog http://www.cnblogs.com/jinkeungsiu。
再次感谢他们～！
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