How do you do AppBar docking (to screen edge, like

Question

Is there any complete guidance on doing AppBar docking (such as locking to the screen edge) in WPF? I understand there are InterOp calls that need to be made, but I'm looking for either a proof of concept based on a simple WPF form, or a componentized version that can be consumed.

Related resources:

• http://www.codeproject.com/KB/dotnet/AppBar.aspx
• http://social.msdn.microsoft.com/Forums/en-US/wpf/thread/05c73c9c-e85d-4ecd-b9b6-4c714a65e72b/

Answer 1

Please Note: This question gathered a good amount of feedback, and some people below have made great points or fixes. Therefore, while I'll keep the code here (and possibly update it), I've also created a WpfAppBar project on github. Feel free to send pull requests.

That same project also builds to a WpfAppBar nuget package

---

I took the code from the first link provided in the question ( http://www.codeproject.com/KB/dotnet/AppBar.aspx ) and modified it to do two things:

1. Work with WPF
2. Be "standalone" - if you put this single file in your project, you can call AppBarFunctions.SetAppBar(...) without any further modification to the window.

This approach doesn't create a base class.

To use, just call this code from anywhere within a normal wpf window (say a button click or the initialize). Note that you can not call this until AFTER the window is initialized, if the HWND hasn't been created yet (like in the constructor), an error will occur.

Make the window an appbar:

AppBarFunctions.SetAppBar( this, ABEdge.Right );

Restore the window to a normal window:

AppBarFunctions.SetAppBar( this, ABEdge.None );

Here's the full code to the file - note you'll want to change the namespace on line 7 to something apropriate.

using System;
using System.Collections.Generic;
using System.Runtime.InteropServices;
using System.Windows;
using System.Windows.Interop;
using System.Windows.Threading;

namespace AppBarApplication
{    
    public enum ABEdge : int
    {
        Left = 0,
        Top,
        Right,
        Bottom,
        None
    }

    internal static class AppBarFunctions
    {
        [StructLayout(LayoutKind.Sequential)]
        private struct RECT
        {
            public int left;
            public int top;
            public int right;
            public int bottom;
        }

        [StructLayout(LayoutKind.Sequential)]
        private struct APPBARDATA
        {
            public int cbSize;
            public IntPtr hWnd;
            public int uCallbackMessage;
            public int uEdge;
            public RECT rc;
            public IntPtr lParam;
        }

        private enum ABMsg : int
        {
            ABM_NEW = 0,
            ABM_REMOVE,
            ABM_QUERYPOS,
            ABM_SETPOS,
            ABM_GETSTATE,
            ABM_GETTASKBARPOS,
            ABM_ACTIVATE,
            ABM_GETAUTOHIDEBAR,
            ABM_SETAUTOHIDEBAR,
            ABM_WINDOWPOSCHANGED,
            ABM_SETSTATE
        }
        private enum ABNotify : int
        {
            ABN_STATECHANGE = 0,
            ABN_POSCHANGED,
            ABN_FULLSCREENAPP,
            ABN_WINDOWARRANGE
        }

        [DllImport("SHELL32", CallingConvention = CallingConvention.StdCall)]
        private static extern uint SHAppBarMessage(int dwMessage, ref APPBARDATA pData);

        [DllImport("User32.dll", CharSet = CharSet.Auto)]
        private static extern int RegisterWindowMessage(string msg);

        private class RegisterInfo
        {
            public int CallbackId { get; set; }
            public bool IsRegistered { get; set; }
            public Window Window { get; set; }
            public ABEdge Edge { get; set; }
            public WindowStyle OriginalStyle { get; set; }            
            public Point OriginalPosition { get; set; }
            public Size OriginalSize { get; set; }
            public ResizeMode OriginalResizeMode { get; set; }


            public IntPtr WndProc(IntPtr hwnd, int msg, IntPtr wParam, 
                                    IntPtr lParam, ref bool handled)
            {
                if (msg == CallbackId)
                {
                    if (wParam.ToInt32() == (int)ABNotify.ABN_POSCHANGED)
                    {
                        ABSetPos(Edge, Window);
                        handled = true;
                    }
                }
                return IntPtr.Zero;
            }

        }
        private static Dictionary<Window, RegisterInfo> s_RegisteredWindowInfo 
            = new Dictionary<Window, RegisterInfo>();
        private static RegisterInfo GetRegisterInfo(Window appbarWindow)
        {
            RegisterInfo reg;
            if( s_RegisteredWindowInfo.ContainsKey(appbarWindow))
            {
                reg = s_RegisteredWindowInfo[appbarWindow];
            }
            else
            {
                reg = new RegisterInfo()
                    {
                        CallbackId = 0,
                        Window = appbarWindow,
                        IsRegistered = false,
                        Edge = ABEdge.Top,
                        OriginalStyle = appbarWindow.WindowStyle,                        
                        OriginalPosition =new Point( appbarWindow.Left, appbarWindow.Top),
                        OriginalSize = 
                            new Size( appbarWindow.ActualWidth, appbarWindow.ActualHeight),
                        OriginalResizeMode = appbarWindow.ResizeMode,
                    };
                s_RegisteredWindowInfo.Add(appbarWindow, reg);
            }
            return reg;
        }

        private static void RestoreWindow(Window appbarWindow)
        {
            RegisterInfo info = GetRegisterInfo(appbarWindow);

            appbarWindow.WindowStyle = info.OriginalStyle;            
            appbarWindow.ResizeMode = info.OriginalResizeMode;
            appbarWindow.Topmost = false;

            Rect rect = new Rect(info.OriginalPosition.X, info.OriginalPosition.Y, 
                info.OriginalSize.Width, info.OriginalSize.Height);
            appbarWindow.Dispatcher.BeginInvoke(DispatcherPriority.ApplicationIdle,
                    new ResizeDelegate(DoResize), appbarWindow, rect);

        }

        public static void SetAppBar(Window appbarWindow, ABEdge edge)
        {
            RegisterInfo info = GetRegisterInfo(appbarWindow);
            info.Edge = edge;

            APPBARDATA abd = new APPBARDATA();
            abd.cbSize = Marshal.SizeOf(abd);
            abd.hWnd = new WindowInteropHelper(appbarWindow).Handle;

            if( edge == ABEdge.None)
            {
                if( info.IsRegistered)
                {
                    SHAppBarMessage((int)ABMsg.ABM_REMOVE, ref abd);
                    info.IsRegistered = false;
                }
                RestoreWindow(appbarWindow);
                return;
            }

            if (!info.IsRegistered)
            {
                info.IsRegistered = true; 
                info.CallbackId = RegisterWindowMessage("AppBarMessage");
                abd.uCallbackMessage = info.CallbackId;

                uint ret = SHAppBarMessage((int)ABMsg.ABM_NEW, ref abd);

                HwndSource source = HwndSource.FromHwnd(abd.hWnd);
                source.AddHook(new HwndSourceHook(info.WndProc));
            }

            appbarWindow.WindowStyle = WindowStyle.None;            
            appbarWindow.ResizeMode = ResizeMode.NoResize;
            appbarWindow.Topmost = true;

            ABSetPos(info.Edge, appbarWindow);                
        }

        private delegate void ResizeDelegate(Window appbarWindow, Rect rect);
        private static void DoResize(Window appbarWindow, Rect rect)
        {
            appbarWindow.Width = rect.Width;
            appbarWindow.Height = rect.Height;
            appbarWindow.Top = rect.Top;
            appbarWindow.Left = rect.Left;
        }



        private static void ABSetPos(ABEdge edge, Window appbarWindow)
        {
            APPBARDATA barData = new APPBARDATA();
            barData.cbSize = Marshal.SizeOf(barData);
            barData.hWnd = new WindowInteropHelper(appbarWindow).Handle;
            barData.uEdge = (int)edge;

            if (barData.uEdge == (int)ABEdge.Left || barData.uEdge == (int)ABEdge.Right)
            {
                barData.rc.top = 0;
                barData.rc.bottom = (int)SystemParameters.PrimaryScreenHeight;
                if (barData.uEdge == (int)ABEdge.Left)
                {
                    barData.rc.left = 0;
                    barData.rc.right = (int)Math.Round(appbarWindow.ActualWidth);
                }
                else
                {
                    barData.rc.right = (int)SystemParameters.PrimaryScreenWidth;
                    barData.rc.left = barData.rc.right - (int)Math.Round(appbarWindow.ActualWidth);
                }
            }
            else
            {
                barData.rc.left = 0;
                barData.rc.right = (int)SystemParameters.PrimaryScreenWidth;
                if (barData.uEdge == (int)ABEdge.Top)
                {
                    barData.rc.top = 0;
                    barData.rc.bottom = (int)Math.Round(appbarWindow.ActualHeight);
                }
                else
                {
                    barData.rc.bottom = (int)SystemParameters.PrimaryScreenHeight;
                    barData.rc.top = barData.rc.bottom - (int)Math.Round(appbarWindow.ActualHeight);
                }
            }

            SHAppBarMessage((int)ABMsg.ABM_QUERYPOS, ref barData);
            SHAppBarMessage((int)ABMsg.ABM_SETPOS, ref barData);

            Rect rect = new Rect((double)barData.rc.left, (double)barData.rc.top, 
                (double)(barData.rc.right - barData.rc.left), (double)(barData.rc.bottom - barData.rc.top));
            //This is done async, because WPF will send a resize after a new appbar is added.  
            //if we size right away, WPFs resize comes last and overrides us.
            appbarWindow.Dispatcher.BeginInvoke(DispatcherPriority.ApplicationIdle, 
                new ResizeDelegate(DoResize), appbarWindow, rect);
        }
    }
}

Answer 2

Sorry for my English... Here is the Philip Rieck's solution with some corrects. It correctly works with Taskbar position and size changes.

using System;
using System.Collections.Generic;
using System.Runtime.InteropServices;
using System.Windows;
using System.Windows.Interop;
using System.Windows.Threading;

namespace wpf_appbar
{
    public enum ABEdge : int
    {
        Left,
        Top,
        Right,
        Bottom,
        None
    }

    internal static class AppBarFunctions
    {
        [StructLayout(LayoutKind.Sequential)]
        private struct RECT
        {
            public int Left;
            public int Top;
            public int Right;
            public int Bottom;
            public RECT(Rect r)
            {
                Left = (int)r.Left;
                Right = (int)r.Right;
                Top = (int)r.Top;
                Bottom = (int)r.Bottom;
            }
            public static bool operator ==(RECT r1, RECT r2)
            {
                return r1.Bottom == r2.Bottom && r1.Left == r2.Left && r1.Right == r2.Right && r1.Top == r2.Top;
            }
            public static bool operator !=(RECT r1, RECT r2)
            {
                return !(r1 == r2);
            }
            public override bool Equals(object obj)
            {
                return base.Equals(obj);
            }
            public override int GetHashCode()
            {
                return base.GetHashCode();
            }
        }

        [StructLayout(LayoutKind.Sequential)]
        private struct APPBARDATA
        {
            public int cbSize;
            public IntPtr hWnd;
            public int uCallbackMessage;
            public int uEdge;
            public RECT rc;
            public IntPtr lParam;
        }

        private enum ABMsg : int
        {
            ABM_NEW = 0,
            ABM_REMOVE,
            ABM_QUERYPOS,
            ABM_SETPOS,
            ABM_GETSTATE,
            ABM_GETTASKBARPOS,
            ABM_ACTIVATE,
            ABM_GETAUTOHIDEBAR,
            ABM_SETAUTOHIDEBAR,
            ABM_WINDOWPOSCHANGED,
            ABM_SETSTATE
        }
        private enum ABNotify : int
        {
            ABN_STATECHANGE = 0,
            ABN_POSCHANGED,
            ABN_FULLSCREENAPP,
            ABN_WINDOWARRANGE
        }

        private enum TaskBarPosition : int
        {
            Left,
            Top,
            Right,
            Bottom
        }

        [StructLayout(LayoutKind.Sequential)]
        class TaskBar
        {
            public TaskBarPosition Position;
            public TaskBarPosition PreviousPosition;
            public RECT Rectangle;
            public RECT PreviousRectangle;
            public int Width;
            public int PreviousWidth;
            public int Height;
            public int PreviousHeight;
            public TaskBar()
            {
                Refresh();
            }
            public void Refresh()
            {
                APPBARDATA msgData = new APPBARDATA();
                msgData.cbSize = Marshal.SizeOf(msgData);
                SHAppBarMessage((int)ABMsg.ABM_GETTASKBARPOS, ref msgData);
                PreviousPosition = Position;
                PreviousRectangle = Rectangle;
                PreviousHeight = Height;
                PreviousWidth = Width;
                Rectangle = msgData.rc;
                Width = Rectangle.Right - Rectangle.Left;
                Height = Rectangle.Bottom - Rectangle.Top;
                int h = (int)SystemParameters.PrimaryScreenHeight;
                int w = (int)SystemParameters.PrimaryScreenWidth;
                if (Rectangle.Bottom == h && Rectangle.Top != 0) Position = TaskBarPosition.Bottom;
                else if (Rectangle.Top == 0 && Rectangle.Bottom != h) Position = TaskBarPosition.Top;
                else if (Rectangle.Right == w && Rectangle.Left != 0) Position = TaskBarPosition.Right;
                else if (Rectangle.Left == 0 && Rectangle.Right != w) Position = TaskBarPosition.Left;
            }
        }

        [DllImport("SHELL32", CallingConvention = CallingConvention.StdCall)]
        private static extern uint SHAppBarMessage(int dwMessage, ref APPBARDATA pData);

        [DllImport("User32.dll", CharSet = CharSet.Auto)]
        private static extern int RegisterWindowMessage(string msg);

        private class RegisterInfo
        {
            public int CallbackId { get; set; }
            public bool IsRegistered { get; set; }
            public Window Window { get; set; }
            public ABEdge Edge { get; set; }
            public ABEdge PreviousEdge { get; set; }
            public WindowStyle OriginalStyle { get; set; }
            public Point OriginalPosition { get; set; }
            public Size OriginalSize { get; set; }
            public ResizeMode OriginalResizeMode { get; set; }


            public IntPtr WndProc(IntPtr hwnd, int msg, IntPtr wParam,
                                    IntPtr lParam, ref bool handled)
            {
                if (msg == CallbackId)
                {
                    if (wParam.ToInt32() == (int)ABNotify.ABN_POSCHANGED)
                    {
                        PreviousEdge = Edge;
                        ABSetPos(Edge, PreviousEdge, Window);
                        handled = true;
                    }
                }
                return IntPtr.Zero;
            }

        }
        private static Dictionary<Window, RegisterInfo> s_RegisteredWindowInfo
            = new Dictionary<Window, RegisterInfo>();
        private static RegisterInfo GetRegisterInfo(Window appbarWindow)
        {
            RegisterInfo reg;
            if (s_RegisteredWindowInfo.ContainsKey(appbarWindow))
            {
                reg = s_RegisteredWindowInfo[appbarWindow];
            }
            else
            {
                reg = new RegisterInfo()
                {
                    CallbackId = 0,
                    Window = appbarWindow,
                    IsRegistered = false,
                    Edge = ABEdge.None,
                    PreviousEdge = ABEdge.None,
                    OriginalStyle = appbarWindow.WindowStyle,
                    OriginalPosition = new Point(appbarWindow.Left, appbarWindow.Top),
                    OriginalSize =
                        new Size(appbarWindow.ActualWidth, appbarWindow.ActualHeight),
                    OriginalResizeMode = appbarWindow.ResizeMode,
                };
                s_RegisteredWindowInfo.Add(appbarWindow, reg);
            }
            return reg;
        }

        private static void RestoreWindow(Window appbarWindow)
        {
            RegisterInfo info = GetRegisterInfo(appbarWindow);

            appbarWindow.WindowStyle = info.OriginalStyle;
            appbarWindow.ResizeMode = info.OriginalResizeMode;
            appbarWindow.Topmost = false;

            Rect rect = new Rect(info.OriginalPosition.X, info.OriginalPosition.Y,
                info.OriginalSize.Width, info.OriginalSize.Height);
            appbarWindow.Dispatcher.BeginInvoke(DispatcherPriority.ApplicationIdle,
                    new ResizeDelegate(DoResize), appbarWindow, rect);

        }


        public static void SetAppBar(Window appbarWindow, ABEdge edge)
        {
            RegisterInfo info = GetRegisterInfo(appbarWindow);
            info.Edge = edge;

            APPBARDATA abd = new APPBARDATA();
            abd.cbSize = Marshal.SizeOf(abd);
            abd.hWnd = new WindowInteropHelper(appbarWindow).Handle;

            if (edge == ABEdge.None)
            {
                if (info.IsRegistered)
                {
                    SHAppBarMessage((int)ABMsg.ABM_REMOVE, ref abd);
                    info.IsRegistered = false;
                }
                RestoreWindow(appbarWindow);
                info.PreviousEdge = info.Edge;
                return;
            }

            if (!info.IsRegistered)
            {
                info.IsRegistered = true;
                info.CallbackId = RegisterWindowMessage("AppBarMessage");
                abd.uCallbackMessage = info.CallbackId;

                uint ret = SHAppBarMessage((int)ABMsg.ABM_NEW, ref abd);

                HwndSource source = HwndSource.FromHwnd(abd.hWnd);
                source.AddHook(new HwndSourceHook(info.WndProc));
            }

            appbarWindow.WindowStyle = WindowStyle.None;
            appbarWindow.ResizeMode = ResizeMode.NoResize;
            appbarWindow.Topmost = true;

            ABSetPos(info.Edge, info.PreviousEdge, appbarWindow);
        }

        private delegate void ResizeDelegate(Window appbarWindow, Rect rect);
        private static void DoResize(Window appbarWindow, Rect rect)
        {
            appbarWindow.Width = rect.Width;
            appbarWindow.Height = rect.Height;
            appbarWindow.Top = rect.Top;
            appbarWindow.Left = rect.Left;
        }

        static TaskBar tb = new TaskBar();

        private static void ABSetPos(ABEdge edge, ABEdge prevEdge, Window appbarWindow)
        {
            APPBARDATA barData = new APPBARDATA();
            barData.cbSize = Marshal.SizeOf(barData);
            barData.hWnd = new WindowInteropHelper(appbarWindow).Handle;
            barData.uEdge = (int)edge;
            RECT wa = new RECT(SystemParameters.WorkArea);
            tb.Refresh();
            switch (edge)
            {
                case ABEdge.Top:
                    barData.rc.Left = wa.Left - (prevEdge == ABEdge.Left ? (int)Math.Round(appbarWindow.ActualWidth) : 0);
                    barData.rc.Right = wa.Right + (prevEdge == ABEdge.Right ? (int)Math.Round(appbarWindow.ActualWidth) : 0);
                    barData.rc.Top = wa.Top - (prevEdge == ABEdge.Top ? (int)Math.Round(appbarWindow.ActualHeight) : 0) - ((tb.Position != TaskBarPosition.Top && tb.PreviousPosition == TaskBarPosition.Top) ? tb.Height : 0) + ((tb.Position == TaskBarPosition.Top && tb.PreviousPosition != TaskBarPosition.Top) ? tb.Height : 0);
                    barData.rc.Bottom = barData.rc.Top + (int)Math.Round(appbarWindow.ActualHeight);
                    break;
                case ABEdge.Bottom:
                    barData.rc.Left = wa.Left - (prevEdge == ABEdge.Left ? (int)Math.Round(appbarWindow.ActualWidth) : 0);
                    barData.rc.Right = wa.Right + (prevEdge == ABEdge.Right ? (int)Math.Round(appbarWindow.ActualWidth) : 0);
                    barData.rc.Bottom = wa.Bottom + (prevEdge == ABEdge.Bottom ? (int)Math.Round(appbarWindow.ActualHeight) : 0) - 1 + ((tb.Position != TaskBarPosition.Bottom && tb.PreviousPosition == TaskBarPosition.Bottom) ? tb.Height : 0) - ((tb.Position == TaskBarPosition.Bottom && tb.PreviousPosition != TaskBarPosition.Bottom) ? tb.Height : 0);
                    barData.rc.Top = barData.rc.Bottom - (int)Math.Round(appbarWindow.ActualHeight);
                    break;
            }

            SHAppBarMessage((int)ABMsg.ABM_QUERYPOS, ref barData);
            switch (barData.uEdge)
            {
                case (int)ABEdge.Bottom:
                    if (tb.Position == TaskBarPosition.Bottom && tb.PreviousPosition == tb.Position)
                    {
                        barData.rc.Top += (tb.PreviousHeight - tb.Height);
                        barData.rc.Bottom = barData.rc.Top + (int)appbarWindow.ActualHeight;
                    }
                    break;
                case (int)ABEdge.Top:
                    if (tb.Position == TaskBarPosition.Top && tb.PreviousPosition == tb.Position)
                    {
                        if (tb.PreviousHeight - tb.Height > 0) barData.rc.Top -= (tb.PreviousHeight - tb.Height);
                        barData.rc.Bottom = barData.rc.Top + (int)appbarWindow.ActualHeight;
                    }
                    break;
            }
            SHAppBarMessage((int)ABMsg.ABM_SETPOS, ref barData);

            Rect rect = new Rect((double)barData.rc.Left, (double)barData.rc.Top, (double)(barData.rc.Right - barData.rc.Left), (double)(barData.rc.Bottom - barData.rc.Top));
            appbarWindow.Dispatcher.BeginInvoke(new ResizeDelegate(DoResize), DispatcherPriority.ApplicationIdle, appbarWindow, rect);
        }
    }
}

The same code you can write for the Left and Right edges. Good job, Philip Rieck, thank you!