Panel

Namespace: Box.Entities.Container

Description

Represents a generic container for UI elements, managing child entities and layout updates. The panel tracks a dirty state to know when its contents or layout have changed, and provides hooks for recalculating layout and rendering debug outlines.

Constructor

public Panel(params Entity[] children)

Stores the provided child entities for addition on screen entry and marks the panel dirty for initial layout.

Properties

Property	Description
bool IsDirty	Indicates whether the panel’s content or layout needs updating.

Methods

Method Signature	Description	Returns
protected override void OnEnter()	Called when the panel enters the active state; adds initial children, connects entity added/removed signals, and clears the child buffer.	void
protected override void Update()	Called each frame; if dirty, calls UpdateDirtyState() then resets dirty flag, optionally draws debug outline, and updates child entities.	void
protected virtual void UpdateDirtyState()	Hook for derived panels to recalculate layout when the panel is marked dirty.	void
new void AddChild(Entity entity)	Adds a single child entity to the panel and marks the panel (and its parents) dirty.	void
new void AddChild(params Entity[] children)	Adds multiple child entities to the panel and marks the panel (and its parents) dirty.	void
new bool RemoveChild(Entity entity)	Removes a child entity from the panel and marks the panel (and its parents) dirty.	bool
new bool RemoveChild(params Entity[] children)	Removes multiple child entities and marks dirty.	bool
new void ClearChildren()	Clears all child entities from the panel and marks dirty.	void

Examples

// Create some UI elements
var button = new Button("Play");
var label = new Label("Score: 0");

// Initialize a panel with them
var uiPanel = new Panel(button, label);

// Add to the screen (children attach on OnEnter)
mainScreen.AddEntity(uiPanel);

// Subclass to implement custom layout
public class CustomVerticalPanel : Panel
{
    protected override void CustomVerticalPanel()
    {
        float y = 10;
        foreach (var child in Children)
        {
            child.Position = new Vect2(10, y);
            y += child.Size.Y + 5;
        }
    }
}

// Use the custom panel
var verticalPanel = new CustomVerticalPanel(button, label);
mainScreen.AddEntity(verticalPanel);