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WPF Docking Library

By , 17 Jul 2007
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Screenshot - ScrShot1.gif

Introduction

Recently, I started a project for porting a Windows Forms application to WPF. I was quite a novice in WPF, so at first I was considering using some type of Windows Forms interoperability. In particular, the WinForm application has cool docking functionalities that I wanted to port to a newer version. As I was going deeper into WPF technology, I discovered a new world that radically changed my initial ideas. In this article, I wish to share a library that implements the Windows docking feature in pure WPF without any Win32-interop.

Using the code

There are three fundamental classes: DockManager, DockableContent and DocumentContent. DockManager is a class responsible for managing the main window layout. Pane represents the window area that can be docked to a border. Each Pane contains one or more ManagedContent elements, which precisely refer to a window content element of the client code. Using this library is straightforward. DockManager is a user control that can be easily embedded into a window. For example, the following XAML code creates a DockManager in a DockPanel:

<Window x:Class="DockingDemo.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="DockingDemo" Height="500" Width="500"
    xmlns:custom="clr-namespace:DockingLibrary;assembly=DockingLibrary"
    Loaded="OnLoaded" Background="LightGray" >
    <DockPanel>
        <Menu DockPanel.Dock="Top">
                        <MenuItem Header="File">
                <MenuItem Header="New" Click="NewDocument"/>
                <MenuItem Header="Exit"  Click="ExitApplication"/>
            </MenuItem>
            <MenuItem Header="Edit"/>
            <MenuItem Header="Window">
                <MenuItem Header="Explorer" Click="ShowExplorerWindow"/>
                <MenuItem Header="Output"  Click="ShowOutputWindow"/>
                <MenuItem Header="Property" Click="ShowPropertyWindow"/>
                <MenuItem Header="ToDoList"  Click="ShowListWindow"/>
            </MenuItem>
            <MenuItem Header="?"/>
        </Menu>
        <ToolBar DockPanel.Dock="Top">
            <Button>OK</Button>
        </ToolBar>
        <custom:DockManager Name ="DockManager"/>
    </DockPanel>
</Window>

Notice that to use DockManager you have to refer an external CLR namespace, DockingLibary here. You can now add your windows to DockManager with code like this:

public partial class MainWindow : System.Windows.Window
{
    private TreeViewWindow explorerWindow = new TreeViewWindow();
    private OutputWindow outputWindow = new OutputWindow();
    private PropertyWindow propertyWindow = new PropertyWindow();
    private ListViewWindow listWindow = new ListViewWindow();

    public MainWindow()
    {
        InitializeComponent();
    }

    private void OnLoaded(object sender, EventArgs e)
    {
        //set window parent for dragging operations
        dockManager.ParentWindow = this;

        //Show PropertyWindow docked to the top border
        propertyWindow.DockManager = dockManager;
        propertyWindow.Show(Dock.Top);

        //Show ExplorerWindow docked to the right border as default
        explorerWindow.DockManager = dockManager;
        explorerWindow.Show();

        //Show ListWindow in documents pane
        listWindow.DockManager = dockManager;
        listWindow.ShowAsDocument();
    }
} 

Ib order to be dockable, a window must derive from DockableContent. Deriving from DockableContent indicates that the window content can be hosted in DockablePane. Windows are initially docked either where you set the Show member call or, by default, to the left border. The last thing to see is how to add a document window. A document window is a particular window that can't be docked to the main window border. It lives only in DocumentsPane which, as DockablePane, is a particular kind of Pane. The following code adds a document window with a unique title to DockManager:

private bool ContainsDocument(string docTitle)
{
    foreach (DockingLibrary.DocumentContent doc in DockManager.Documents)
    if (string.CompareOrdinal(doc.Title, docTitle) == 0)
    return true;
    return false;
}

private void NewDocument(object sender, EventArgs e)
{
    string title = "Document";
    int i = 1;
    while (ContainsDocument(title + i.ToString()))
    i++;

    DocumentWindow doc = new DocumentWindow();
    doc.Title = title+i.ToString();
    DockManager.AddDocumentContent(doc);
}

Points of interest

Exactly how is docking realized? I implement a simple algorithm here to manage relations between windows that are docked. DockingGrid contains code to organize Pane in a logical tree. DockManager calls DockingGrid.ArrangeLayout in order to organize the window layout. You also use DockingGrid.ChangeDock when you need to dock a Pane to a main window border. The following image shows a logical tree of panes. Don't get confused with the WPF logical tree.

Screenshot - DockingLibTree.jpg

Each node is a group of either two Panes or a Pane and a child. To arrange the layout, DockingGrid creates a WPF grid for each group with two columns or two rows, depending on split orientation. I hope the image is self-explanatory. Anyway, feel free to ask for more details if you are interested.

From version 0.1, the library supports floating windows, as you can see in VS. A floating window is an instance of the FloatingWindow class. It' s a very particular window because it needs to "float" between two windows. One is the parent window, MainWindow in this case, which is usually the main application window. The other is a transparent window owned by FloatingWindow itself, which is shown during dragging operations.

Screenshot - ScrShot2.gif

As you can see in the previous image, FloatingWindow supports useful switching options through a context menu on the title bar. In WinForms, controlling a non-client window area means overriding WndProc and managing relevant messages like WM_NCMOUSEMOVE.

In WPF, we have no access to messages posted to a window. This is because everything is controlled by the WPF engine that draws window content, fires keyboard and mouse events and does a lot of other things. The only way I know of to intercept messages is to install HwndSourceHook with a delegate to our functions. The following code shows how to manage a WM_NCLBUTTONDOWN message:

protected void OnLoaded(object sender, EventArgs e)
{
    WindowInteropHelper helper = new WindowInteropHelper(this);
    _hwndSource = HwndSource.FromHwnd(helper.Handle);
    _hwndSource.AddHook(new HwndSourceHook(this.HookHandler));
}

private IntPtr HookHandler(
    IntPtr hwnd,
    int msg,
    IntPtr wParam,
    IntPtr lParam,
    ref bool handled
    )
{
    handled = false;

    switch(msg)
    {
        case WM_NCLBUTTONDOWN:
        if (HostedPane.State == PaneState.DockableWindow && 
            wParam.ToInt32() == HTCAPTION)
        {
            short x = (short)((lParam.ToInt32() & 0xFFFF));
            short y = (short)((lParam.ToInt32() >> 16));

            HostedPane.ReferencedPane.DockManager.Drag(
                this, new Point(x, y), new Point(x - Left, y - Top));

            handled = true;}
            break;
        }
    }
}

Although the delegate signature looks like a window procedure signature, it's not the same thing. You can, however, handle every message, even WM_PAINT.

History

  • 13/05/07 -- First preliminary release
  • 17/05/07 -- Update
  • 11/06/07 -- Version 0.1: Floating window, many improvements and bug fixes
  • 16/07/07 -- Version 0.1.1: Some annoying bug fixes

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

About the Author

adospace.NET
Systems Engineer
Italy Italy
I bought my first computer in Nov 1991, 21th and I started programming with QBasic under MSDOS.
Today my main interest is developping application with .NET 3.5.
Visit YouDev.net for tutorials on AvalonDock, download WPF controls, samples and code.

Comments and Discussions

 
GeneralRe: Crash when run demo PinmemberJohn Willcox2-Apr-08 3:02 
GeneralRe: Crash when run demo PinmemberJohn Willcox2-Apr-08 3:09 
GeneralDocking library for .NET 2.0 or .NET 1.0 Pinmemberchinkuanyeh21-Mar-08 8:37 
GeneralRe: Docking library for .NET 2.0 or .NET 1.0 Pinmemberadospace.NET24-Mar-08 23:42 
GeneralShowAsFloating PinmemberDerek Bartram11-Mar-08 13:42 
GeneralRe: ShowAsFloating Pinmemberadospace.NET12-Mar-08 3:10 
GeneralDockableContent Size PinmemberDerek Bartram11-Mar-08 8:25 
GeneralThe image is too wide PinmemberDerek Bartram8-Mar-08 3:25 
GeneralRe: The image is too wide Pinmemberadospace.NET9-Mar-08 23:22 
GeneralRe: The image is too wide PinmemberDerek Bartram10-Mar-08 0:48 
QuestionSave layout and docking?? Pinmemberarbrunda25-Jan-08 2:09 
GeneralRe: Save layout and docking?? PinmemberSreekar198125-Jan-08 2:28 
GeneralRe: Save layout and docking?? Pinmemberadospace.NET27-Jan-08 21:32 
QuestionHow to find the active Window of the DockManager Pinmembersimon.roderus6-Nov-07 1:53 
Hello,
 
thanks for your great work.
It works fine on my project, but I have a small question that I wasn't able to solve yet.
 
I am using many Windows as tabbed Documents in a DockManager.
Is there a way to use the DockManager to get a reference to the "active window"?
(That means to the window that was selected at the tab navigation)
 
Thanks,
- Simon
AnswerRe: How to find the active Window of the DockManager Pinmemberadospace.NET6-Nov-07 6:14 
QuestionRe: How to find the active Window of the DockManager Pinmembersimon.roderus7-Nov-07 2:26 
QuestionDo you have a version that compiles in Beta 2? PinmemberDaveKolb28-Oct-07 17:54 
GeneralRestrictions on use Pinmembermwalsma17-Oct-07 10:17 
GeneralRe: Restrictions on use Pinmemberadospace.NET21-Oct-07 22:43 
QuestionRe: Restrictions on use PinmemberTGT27-Feb-08 4:59 
QuestionHow can we use this library in Acropolis Pinmembersachinhadoltikar16-Oct-07 19:47 
AnswerRe: How can we use this library in Acropolis Pinmemberadospace.NET16-Oct-07 23:10 
GeneralWindow not showing after closing PinmemberRajeshKumarRV30-Aug-07 18:46 
GeneralWindows Disapear PinmemberMiddleTommy29-Aug-07 8:53 
GeneralRe: Windows Disapear Pinmemberadospace.NET31-Aug-07 4:28 
GeneralRe: Windows Disapear PinmemberDerek Bartram12-Apr-08 14:33 
GeneralTitle updating Pinmemberlntramper22-Jul-07 21:04 
GeneralRe: Title updating Pinmemberadospace.NET23-Jul-07 4:48 
GeneralDocking a Floating Pane inside aother pane by default. Pinmembermani8520-Jul-07 2:03 
GeneralRe: Docking a Floating Pane inside aother pane by default. Pinmemberadospace.NET20-Jul-07 2:18 
GeneralRe: Docking a Floating Pane inside aother pane by default. Pinmembermani8522-Jul-07 21:20 
GeneralRe: Docking a Floating Pane inside aother pane by default. Pinmembermani8524-Jul-07 20:34 
GeneralRe: Docking a Floating Pane inside aother pane by default. Pinmemberazamat1-Jun-08 4:39 
GeneralWinforms controls is drawn on top of flyout autohidden windows. PinmemberMartin Webrant19-Jul-07 2:45 
GeneralRe: Winforms controls is drawn on top of flyout autohidden windows. Pinmemberadospace.NET10-Aug-07 0:37 
Generalframes hosting PinmemberZajda8211-Jul-07 22:50 
GeneralRe: frames hosting Pinmemberadospace.NET16-Jul-07 8:39 
NewsNew version (0.1.8) Pinmemberadospace.NET28-Jun-07 10:07 
QuestionRe: New version (0.1.8) Pinmemberpurohitrohit7-Jul-07 4:07 
AnswerRe: New version (0.1.8) Pinmemberadospace.NET8-Jul-07 5:16 
QuestionCan we use Systems.Windows.Controls.Page? Pinmemberdarreny28-Jun-07 0:43 
AnswerRe: Can we use Systems.Windows.Controls.Page? Pinmemberadospace.NET28-Jun-07 10:02 
GeneralRe: Can we use Systems.Windows.Controls.Page? PinmemberZajda8211-Jul-07 21:59 
Questionabout dispose Pinmemberduckle18-Jun-07 5:24 
AnswerRe: about dispose Pinmemberadospace.NET18-Jun-07 5:29 
QuestionExtremely well done....question on sub-zones tho Pinmemberkfarley21515-Jun-07 10:35 
AnswerRe: Extremely well done....question on sub-zones tho [modified] Pinmemberadospace.NET16-Jun-07 8:28 
GeneralExcellent work PinmemberLogicalGenetics11-Jun-07 6:58 
GeneralRe: Excellent work Pinmemberadospace.NET11-Jun-07 11:45 
GeneralRe: Excellent work PinmemberLogicalGenetics11-Jun-07 22:47 

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