Table of Contents

MDI Layout Helpers and Defaults

Dock’s MDI layout commands are backed by helper methods in Dock.Model.Core.MdiLayoutHelper. These helpers update IMdiDocument.MdiBounds, MdiState, and MdiZIndex so MDI windows are repositioned consistently.

Built-in helper methods

MdiLayoutHelper exposes four static methods that operate on an IDocumentDock:

  • CascadeDocuments – Offsets windows with a cascading diagonal.
  • TileDocumentsHorizontal – Stacks windows vertically.
  • TileDocumentsVertical – Stacks windows horizontally.
  • RestoreDocuments – Sets all windows back to Normal state.

These are the methods used by the CascadeDocuments, TileDocumentsHorizontal, TileDocumentsVertical, and RestoreDocuments commands exposed on IDocumentDock implementations.

Default layout constants

MdiLayoutDefaults defines the constants used by the helper:

  • CascadeOffset
  • MinimizedHeight
  • MinimizedWidth
  • MinimizedSpacing
  • DefaultWidthRatio
  • DefaultHeightRatio
  • MinimumWidth
  • MinimumHeight

These values are constants; override layout behavior by supplying your own layout logic instead of changing the defaults.

Calling the helpers directly

You can invoke the helper methods whenever you need to enforce a layout:

using Dock.Model.Core;

MdiLayoutHelper.CascadeDocuments(documentDock);

MdiLayoutHelper relies on IDocumentDock.GetVisibleBounds to compute layout bounds, so ensure your dockables are being tracked in the visual tree when you call it.

Custom layout managers

MDI layouts in the Avalonia UI are arranged by MdiLayoutPanel. It uses ClassicMdiLayoutManager by default but can be replaced:

var mdiDocumentControl = new MdiDocumentControl
{
    LayoutManager = new MyMdiLayoutManager()
};

You can also set it in XAML:

<controls:MdiDocumentControl>
  <controls:MdiDocumentControl.LayoutManager>
    <local:MyMdiLayoutManager />
  </controls:MdiDocumentControl.LayoutManager>
</controls:MdiDocumentControl>

Your layout manager receives MdiLayoutEntry instances and is responsible for arranging each document window.

IMdiDocument.MdiBounds uses the DockRect struct to store bounds. In the Avalonia control layer, DockRect is converted to Rect as windows are arranged.

See MDI document layout for the user-facing behavior and commands.

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