Resizable

Overview

Resizable is a convenience host for a row (or column) of resizable panes: the consumer declares each pane as a plain child element, exactly like a StackPanel, and NaviusResizablePanelGroup does a one-time expansion into a real Grid with star-sized ColumnDefinitions (or RowDefinitions) plus an auto-inserted, keyed-styled GridSplitter between every adjacent pair. It derives from Grid directly rather than reimplementing star-sizing and drag-resize math Grid/GridSplitter already provide.

Usage

xmlns:resizable="clr-namespace:Navius.Wpf.Ui.Resizable;assembly=Navius.Wpf.Ui"

<ResourceDictionary.MergedDictionaries>
    <ResourceDictionary Source="pack://application:,,,/Navius.Wpf.Ui;component/Themes/Resizable.xaml" />
</ResourceDictionary.MergedDictionaries>

<resizable:NaviusResizablePanelGroup Height="140">
    <Border Background="{DynamicResource Navius.Card}" BorderBrush="{DynamicResource Navius.Border}"
            BorderThickness="1" resizable:NaviusResizablePanelGroup.MinSize="80">
        <TextBlock Text="Pane 1" />
    </Border>
    <Border Background="{DynamicResource Navius.Card}" BorderBrush="{DynamicResource Navius.Border}"
            BorderThickness="1" resizable:NaviusResizablePanelGroup.MinSize="80"
            resizable:NaviusResizablePanelGroup.InitialSize="2">
        <TextBlock Text="Pane 2 (double star-weight)" />
    </Border>
    <Border Background="{DynamicResource Navius.Card}" BorderBrush="{DynamicResource Navius.Border}"
            BorderThickness="1" resizable:NaviusResizablePanelGroup.MinSize="80">
        <TextBlock Text="Pane 3" />
    </Border>
</resizable:NaviusResizablePanelGroup>

The expansion runs automatically from OnInitialized, so panes declared as XAML children are already expanded by the time the page loads; building the group in code-behind instead requires calling EnsureExpanded() after adding children.

Properties

Property	Type	Default	From	Description
Orientation	Orientation	Horizontal	NaviusResizablePanelGroup	Horizontal uses columns; Vertical uses rows.
SplitterThickness	double	9	NaviusResizablePanelGroup	Width (Horizontal) or height (Vertical) reserved for each inserted GridSplitter.
NaviusResizablePanelGroup.InitialSize (attached)	double	1	NaviusResizablePanelGroup	Set on a pane to give it a star-weight (proportional size) relative to its siblings.
NaviusResizablePanelGroup.MinSize (attached)	double	48	NaviusResizablePanelGroup	Set on a pane to give it a minimum width (Horizontal) or height (Vertical).

Methods

Method	Description
EnsureExpanded()	Runs the one-time expansion of declared children into panes plus splitters. Idempotent: a second call with the same children is a no-op. Called automatically from OnInitialized; call it directly when panes are added in code-behind after construction.

Keyboard interactions

Key	Behavior
Arrow keys (when a splitter has focus)	Native GridSplitter keyboard resize; the splitter styles in Themes/Resizable.xaml set Focusable="True" but add no keyboard handling of their own.

UIA mechanism

NaviusResizablePanelGroup ships no custom automation peer; as a Grid subclass it creates none by default and is transparent to UI Automation. The inserted dividers are stock WPF GridSplitter instances (re-skinned via Navius.Splitter.Horizontal/Navius.Splitter.Vertical styles in Themes/Resizable.xaml), carrying whatever native automation support GridSplitter provides on its own; this family’s code does not touch it. The unit suite exercises the expansion logic (ResizablePanelGroup_ExpandsPanesWithSplittersBetween, _VerticalOrientation_UsesRowDefinitions, _EnsureExpanded_IsIdempotent) against real Grid.Children/ColumnDefinitions/RowDefinitions, not automation surface.