在吕毅大佬的文章中已经详细介绍了什么是AppBar: WPF 使用 AppBar 将窗口停靠在桌面上，让其他程序不占用此窗口的空间（附我封装的附加属性） - walterlv
即让窗口固定在屏幕某一边，并且保证其他窗口最大化后不会覆盖AppBar占据的区域（类似于Windows任务栏）。
但是在我的环境中测试时，上面的代码出现了一些问题，例如非100%缩放显示时的坐标计算异常、多窗口同时停靠时布局错乱等。所以我重写了AppBar在WPF上的实现，效果如图：
主要流程如图：
（图注：ABN_POSCHANGED消息在任何需要调整位置之时都会触发，括号只是举个例子）
核心代码其实在于如何计算停靠窗口的位置，要点是处理好一下几个方面：
1. 修改停靠位置时用原窗口的大小计算，被动告知需要调整位置时用即时大小计算
2. 像素单位与WPF单位之间的转换
3. 小心Windows的位置建议，并排停靠时会得到负值高宽，需要手动适配对齐方式
4. 有新的AppBar加入时，窗口会被系统强制移动到工作区(WorkArea)，这点我还没能找到解决方案，只能把移动窗口的命令通过Dispatcher延迟操作
1.下载我封装好的库：AppBarTest/AppBarCreator.cs at master · TwilightLemon/AppBarTest (github.com)
2. 在xaml中直接设置：
<Window ...> <local:AppBarCreator.AppBar> <local:AppBar x:Name="appBar" Location="Top" OnFullScreenStateChanged="AppBar_OnFullScreenStateChanged"/> </local:AppBarCreator.AppBar> ... </Window>
或者在后台创建：
private readonly AppBar appBar=new AppBar(); ...Window_Loaded... appBar.Location = AppBarLocation.Top; appBar.OnFullScreenStateChanged += AppBar_OnFullScreenStateChanged; AppBarCreator.SetAppBar(this, appBar);
3. 另外你可能注意到了，这里有一个OnFullScreenStateChanged事件：该事件由AppBarMsg注册，在有窗口进入或退出全屏时触发，参数bool为true指示进入全屏。
你需要手动在事件中设置全屏模式下的行为，例如在全屏时隐藏AppBar
private void AppBar_OnFullScreenStateChanged(object sender, bool e) { Debug.WriteLine("Full Screen State: "+e); Visibility = e ? Visibility.Collapsed : Visibility.Visible; }
我在官方的Flag上加了一个RegisterOnly，即只注册AppBarMsg而不真的停靠窗口，可以此用来作全屏模式监听。
4. 如果你需要在每个虚拟桌面都显示AppBar(像任务栏那样)，可以尝试为窗口使用SetWindowLong添加WS_EX_TOOLWINDOW标签（自行查找）
以下贴出完整的代码：
1 using System.ComponentModel; 2 using System.Diagnostics; 3 using System.Runtime.InteropServices; 4 using System.Windows; 5 using System.Windows.Interop; 6 using System.Windows.Threading; 7 8 namespace AppBarTest; 9 public static class AppBarCreator 10 { 11 public static readonly DependencyProperty AppBarProperty = 12 DependencyProperty.RegisterAttached( 13 "AppBar", 14 typeof(AppBar), 15 typeof(AppBarCreator), 16 new PropertyMetadata(null, OnAppBarChanged)); 17 private static void OnAppBarChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) 18 { 19 if (d is Window window && e.NewValue is AppBar appBar) 20 { 21 appBar.AttachedWindow = window; 22 } 23 } 24 public static void SetAppBar(Window element, AppBar value) 25 { 26 if (value == null) return; 27 element.SetValue(AppBarProperty, value); 28 } 29 30 public static AppBar GetAppBar(Window element) 31 { 32 return (AppBar)element.GetValue(AppBarProperty); 33 } 34 } 35 36 public class AppBar : DependencyObject 37 { 38 /// <summary> 39 /// 附加到的窗口 40 /// </summary> 41 public Window AttachedWindow 42 { 43 get => _window; 44 set 45 { 46 if (value == null) return; 47 _window = value; 48 _window.Closing += _window_Closing; 49 _window.LocationChanged += _window_LocationChanged; 50 //获取窗口句柄hWnd 51 var handle = new WindowInteropHelper(value).Handle; 52 if (handle == IntPtr.Zero) 53 { 54 //Win32窗口未创建 55 _window.SourceInitialized += _window_SourceInitialized; 56 } 57 else 58 { 59 _hWnd = handle; 60 CheckPending(); 61 } 62 } 63 } 64 65 private void _window_LocationChanged(object? sender, EventArgs e) 66 { 67 Debug.WriteLine(_window.Title+ " LocationChanged: Top: "+_window.Top+" Left: "+_window.Left); 68 } 69 70 private void _window_Closing(object? sender, CancelEventArgs e) 71 { 72 _window.Closing -= _window_Closing; 73 if (Location != AppBarLocation.None) 74 DisableAppBar(); 75 } 76 77 /// <summary> 78 /// 检查是否需要应用之前的Location更改 79 /// </summary> 80 private void CheckPending() 81 { 82 //创建AppBar时提前触发的LocationChanged 83 if (_locationChangePending) 84 { 85 _locationChangePending = false; 86 LoadAppBar(Location); 87 } 88 } 89 /// <summary> 90 /// 载入AppBar 91 /// </summary> 92 /// <param name="e"></param> 93 private void LoadAppBar(AppBarLocation e,AppBarLocation? previous=null) 94 { 95 96 if (e != AppBarLocation.None) 97 { 98 if (e == AppBarLocation.RegisterOnly) 99 { 100 //仅注册AppBarMsg 101 //如果之前注册过有效的AppBar则先注销，以还原位置 102 if (previous.HasValue && previous.Value != AppBarLocation.RegisterOnly) 103 { 104 if (previous.Value != AppBarLocation.None) 105 { 106 //由生效的AppBar转为RegisterOnly，还原为普通窗口再注册空AppBar 107 DisableAppBar(); 108 } 109 RegisterAppBarMsg(); 110 } 111 else 112 { 113 //之前未注册过AppBar，直接注册 114 RegisterAppBarMsg(); 115 } 116 } 117 else 118 { 119 if (previous.HasValue && previous.Value != AppBarLocation.None) 120 { 121 //之前为RegisterOnly才备份窗口信息 122 if(previous.Value == AppBarLocation.RegisterOnly) 123 { 124 BackupWindowInfo(); 125 } 126 SetAppBarPosition(_originalSize); 127 ForceWindowStyles(); 128 } 129 else 130 EnableAppBar(); 131 } 132 } 133 else 134 { 135 DisableAppBar(); 136 } 137 } 138 private void _window_SourceInitialized(object? sender, EventArgs e) 139 { 140 _window.SourceInitialized -= _window_SourceInitialized; 141 _hWnd = new WindowInteropHelper(_window).Handle; 142 CheckPending(); 143 } 144 145 /// <summary> 146 /// 当有窗口进入或退出全屏时触发 bool参数为true时表示全屏状态 147 /// </summary> 148 public event EventHandler<bool>? OnFullScreenStateChanged; 149 /// <summary> 150 /// 期望将AppBar停靠到的位置 151 /// </summary> 152 public AppBarLocation Location 153 { 154 get { return (AppBarLocation)GetValue(LocationProperty); } 155 set { SetValue(LocationProperty, value); } 156 } 157 158 public static readonly DependencyProperty LocationProperty = 159 DependencyProperty.Register( 160 "Location", 161 typeof(AppBarLocation), typeof(AppBar), 162 new PropertyMetadata(AppBarLocation.None, OnLocationChanged)); 163 164 private bool _locationChangePending = false; 165 private static void OnLocationChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) 166 { 167 if (DesignerProperties.GetIsInDesignMode(d)) 168 return; 169 if (d is not AppBar appBar) return; 170 if (appBar.AttachedWindow == null) 171 { 172 appBar._locationChangePending = true; 173 return; 174 } 175 appBar.LoadAppBar((AppBarLocation)e.NewValue,(AppBarLocation)e.OldValue); 176 } 177 178 private int _callbackId = 0; 179 private bool _isRegistered = false; 180 private Window _window = null; 181 private IntPtr _hWnd; 182 private WindowStyle _originalStyle; 183 private Point _originalPosition; 184 private Size _originalSize = Size.Empty; 185 private ResizeMode _originalResizeMode; 186 private bool _originalTopmost; 187 public Rect? DockedSize { get; set; } = null; 188 private IntPtr WndProc(IntPtr hwnd, int msg, IntPtr wParam, 189 IntPtr lParam, ref bool handled) 190 { 191 if (msg == _callbackId) 192 { 193 Debug.WriteLine(_window.Title + " AppBarMsg("+_callbackId+"): " + wParam.ToInt32() + " LParam: " + lParam.ToInt32()); 194 switch (wParam.ToInt32()) 195 { 196 case (int)Interop.AppBarNotify.ABN_POSCHANGED: 197 Debug.WriteLine("AppBarNotify.ABN_POSCHANGED ! "+_window.Title); 198 if (Location != AppBarLocation.RegisterOnly) 199 SetAppBarPosition(Size.Empty); 200 handled = true; 201 break; 202 case (int)Interop.AppBarNotify.ABN_FULLSCREENAPP: 203 OnFullScreenStateChanged?.Invoke(this, lParam.ToInt32() == 1); 204 handled = true; 205 break; 206 } 207 } 208 return IntPtr.Zero; 209 } 210 211 public void BackupWindowInfo() 212 { 213 _callbackId = 0; 214 DockedSize = null; 215 _originalStyle = _window.WindowStyle; 216 _originalSize = new Size(_window.ActualWidth, _window.ActualHeight); 217 _originalPosition = new Point(_window.Left, _window.Top); 218 _originalResizeMode = _window.ResizeMode; 219 _originalTopmost = _window.Topmost; 220 } 221 public void RestoreWindowInfo() 222 { 223 if (_originalSize != Size.Empty) 224 { 225 _window.WindowStyle = _originalStyle; 226 _window.ResizeMode = _originalResizeMode; 227 _window.Topmost = _originalTopmost; 228 _window.Left = _originalPosition.X; 229 _window.Top = _originalPosition.Y; 230 _window.Width = _originalSize.Width; 231 _window.Height = _originalSize.Height; 232 } 233 } 234 public void ForceWindowStyles() 235 { 236 _window.WindowStyle = WindowStyle.None; 237 _window.ResizeMode = ResizeMode.NoResize; 238 _window.Topmost = true; 239 } 240 241 public void RegisterAppBarMsg() 242 { 243 var data = new Interop.APPBARDATA(); 244 data.cbSize = Marshal.SizeOf(data); 245 data.hWnd = _hWnd; 246 247 _isRegistered = true; 248 _callbackId = Interop.RegisterWindowMessage(Guid.NewGuid().ToString()); 249 data.uCallbackMessage = _callbackId; 250 var success = Interop.SHAppBarMessage((int)Interop.AppBarMsg.ABM_NEW, ref data); 251 var source = HwndSource.FromHwnd(_hWnd); 252 Debug.WriteLineIf(source == null, "HwndSource is null!"); 253 source?.AddHook(WndProc); 254 Debug.WriteLine(_window.Title+" RegisterAppBarMsg: " + _callbackId); 255 } 256 public void EnableAppBar() 257 { 258 if (!_isRegistered) 259 { 260 //备份窗口信息并设置窗口样式 261 BackupWindowInfo(); 262 //注册成为AppBar窗口 263 RegisterAppBarMsg(); 264 ForceWindowStyles(); 265 } 266 //成为AppBar窗口之后(或已经是)只需要注册并移动窗口位置即可 267 SetAppBarPosition(_originalSize); 268 } 269 public void SetAppBarPosition(Size WindowSize) 270 { 271 var data = new Interop.APPBARDATA(); 272 data.cbSize = Marshal.SizeOf(data); 273 data.hWnd = _hWnd; 274 data.uEdge = (int)Location; 275 data.uCallbackMessage = _callbackId; 276 Debug.WriteLine("\r\nWindow: "+_window.Title); 277 278 //获取WPF单位与像素的转换矩阵 279 var compositionTarget = PresentationSource.FromVisual(_window)?.CompositionTarget; 280 if (compositionTarget == null) 281 throw new Exception("居然获取不到CompositionTarget?!"); 282 var toPixel = compositionTarget.TransformToDevice; 283 var toWpfUnit = compositionTarget.TransformFromDevice; 284 285 //窗口在屏幕的实际大小 286 if(WindowSize== Size.Empty) 287 WindowSize = new Size(_window.ActualWidth, _window.ActualHeight); 288 var actualSize = toPixel.Transform(new Vector(WindowSize.Width, WindowSize.Height)); 289 //屏幕的真实像素 290 var workArea = toPixel.Transform(new Vector(SystemParameters.PrimaryScreenWidth, SystemParameters.PrimaryScreenHeight)); 291 Debug.WriteLine("WorkArea Width: {0}, Height: {1}", workArea.X, workArea.Y); 292 293 if (Location is AppBarLocation.Left or AppBarLocation.Right) 294 { 295 data.rc.top = 0; 296 data.rc.bottom = (int)workArea.Y; 297 if (Location == AppBarLocation.Left) 298 { 299 data.rc.left = 0; 300 data.rc.right = (int)Math.Round(actualSize.X); 301 } 302 else 303 { 304 data.rc.right = (int)workArea.X; 305 data.rc.left = (int)workArea.X - (int)Math.Round(actualSize.X); 306 } 307 } 308 else 309 { 310 data.rc.left = 0; 311 data.rc.right = (int)workArea.X; 312 if (Location == AppBarLocation.Top) 313 { 314 data.rc.top = 0; 315 data.rc.bottom = (int)Math.Round(actualSize.Y); 316 } 317 else 318 { 319 data.rc.bottom = (int)workArea.Y; 320 data.rc.top = (int)workArea.Y - (int)Math.Round(actualSize.Y); 321 } 322 } 323 //以上生成的是四周都没有其他AppBar时的理想位置 324 //系统将自动调整位置以适应其他AppBar 325 Debug.WriteLine("Before QueryPos: Left: {0}, Top: {1}, Right: {2}, Bottom: {3}", data.rc.left, data.rc.top, data.rc.right, data.rc.bottom); 326 Interop.SHAppBarMessage((int)Interop.AppBarMsg.ABM_QUERYPOS, ref data); 327 Debug.WriteLine("After QueryPos: Left: {0}, Top: {1}, Right: {2}, Bottom: {3}", data.rc.left, data.rc.top, data.rc.right, data.rc.bottom); 328 //自定义对齐方式，确保Height和Width不会小于0 329 if (data.rc.bottom - data.rc.top < 0) 330 { 331 if (Location == AppBarLocation.Top) 332 data.rc.bottom = data.rc.top + (int)Math.Round(actualSize.Y);//上对齐 333 else if (Location == AppBarLocation.Bottom) 334 data.rc.top = data.rc.bottom - (int)Math.Round(actualSize.Y);//下对齐 335 } 336 if(data.rc.right - data.rc.left < 0) 337 { 338 if (Location == AppBarLocation.Left) 339 data.rc.right = data.rc.left + (int)Math.Round(actualSize.X);//左对齐 340 else if (Location == AppBarLocation.Right) 341 data.rc.left = data.rc.right - (int)Math.Round(actualSize.X);//右对齐 342 } 343 //调整完毕，设置为最终位置 344 Interop.SHAppBarMessage((int)Interop.AppBarMsg.ABM_SETPOS, ref data); 345 //应用到窗口 346 var location = toWpfUnit.Transform(new Point(data.rc.left, data.rc.top)); 347 var dimension = toWpfUnit.Transform(new Vector(data.rc.right - data.rc.left, 348 data.rc.bottom - data.rc.top)); 349 var rect = new Rect(location, new Size(dimension.X, dimension.Y)); 350 DockedSize = rect; 351 352 _window.Dispatcher.Invoke(DispatcherPriority.ApplicationIdle, () =>{ 353 _window.Left = rect.Left; 354 _window.Top = rect.Top; 355 _window.Width = rect.Width; 356 _window.Height = rect.Height; 357 }); 358 359 Debug.WriteLine("Set {0} Left: {1} ,Top: {2}, Width: {3}, Height: {4}", _window.Title, _window.Left, _window.Top, _window.Width, _window.Height); 360 } 361 public void DisableAppBar() 362 { 363 if (_isRegistered) 364 { 365 _isRegistered = false; 366 var data = new Interop.APPBARDATA(); 367 data.cbSize = Marshal.SizeOf(data); 368 data.hWnd = _hWnd; 369 data.uCallbackMessage = _callbackId; 370 Interop.SHAppBarMessage((int)Interop.AppBarMsg.ABM_REMOVE, ref data); 371 _isRegistered = false; 372 RestoreWindowInfo(); 373 Debug.WriteLine(_window.Title + " DisableAppBar"); 374 } 375 } 376 } 377 378 public enum AppBarLocation : int 379 { 380 Left = 0, 381 Top, 382 Right, 383 Bottom, 384 None, 385 RegisterOnly=99 386 } 387 388 internal static class Interop 389 { 390 #region Structures & Flags 391 [StructLayout(LayoutKind.Sequential)] 392 internal struct RECT 393 { 394 public int left; 395 public int top; 396 public int right; 397 public int bottom; 398 } 399 400 [StructLayout(LayoutKind.Sequential)] 401 internal struct APPBARDATA 402 { 403 public int cbSize; 404 public IntPtr hWnd; 405 public int uCallbackMessage; 406 public int uEdge; 407 public RECT rc; 408 public IntPtr lParam; 409 } 410 411 internal enum AppBarMsg : int 412 { 413 ABM_NEW = 0, 414 ABM_REMOVE, 415 ABM_QUERYPOS, 416 ABM_SETPOS, 417 ABM_GETSTATE, 418 ABM_GETTASKBARPOS, 419 ABM_ACTIVATE, 420 ABM_GETAUTOHIDEBAR, 421 ABM_SETAUTOHIDEBAR, 422 ABM_WINDOWPOSCHANGED, 423 ABM_SETSTATE 424 } 425 internal enum AppBarNotify : int 426 { 427 ABN_STATECHANGE = 0, 428 ABN_POSCHANGED, 429 ABN_FULLSCREENAPP, 430 ABN_WINDOWARRANGE 431 } 432 #endregion 433 434 #region Win32 API 435 [DllImport("SHELL32", CallingConvention = CallingConvention.StdCall)] 436 internal static extern uint SHAppBarMessage(int dwMessage, ref APPBARDATA pData); 437 438 [DllImport("User32.dll", CharSet = CharSet.Auto)] 439 internal static extern int RegisterWindowMessage(string msg); 440 #endregion 441 }
1.在我的github上的实例程序中，如果你将两个同进程的窗口并排叠放的话，会导致explorer和你的进程双双爆栈，windows似乎不能很好地处理这两个并排放置的窗口，一直在左右调整位置，疯狂发送ABN_POSCHANGED消息。(快去clone试试，死机了不要打我) 但是并排放置示例窗口和OneNote的Dock窗口就没有问题。
2.计算停靠窗口时，如果选择停靠位置为Bottom，则系统建议的bottom位置值会比实际的高，测试发现是任务栏窗口占据了部分空间，应该是预留给平板模式的更大图标任务栏（猜测，很不合理的设计）
自动隐藏任务栏就没有这个问题：
3. 没有实现自动隐藏AppBar，故没有处理与之相关的WM_ACTIVATE等消息，有需要的可以参考官方文档。（嘻 我懒）
参考文档：
1). SHAppBarMessage function (shellapi.h) - Win32 apps | Microsoft Learn
2). ABM_QUERYPOS message (Shellapi.h) - Win32 apps | Microsoft Learn ABM_NEW & ABM_SETPOS etc..
3). 使用应用程序桌面工具栏 - Win32 apps | Microsoft Learn
4). 判断是否有全屏程序正在运行（C#）_c# 判断程序当前窗口是否全屏如果是返回原来-CSDN博客
[打个广告] [入门AppBar的最佳实践]
看这里，如果你也需要一个高度可自定义的沉浸式顶部栏(Preview): TwilightLemon/MyToolBar: 为Surface Pro而生的顶部工具栏 支持触控和笔快捷方式 (github.com)
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