Explorer Layout

Windows Explorer-style hierarchical tree layout with left-to-right expansion

Overview

The TTreeExplorerAlignChild class provides the classic Windows Explorer tree layout, where child nodes are positioned to the right of their parent nodes, creating a familiar hierarchical structure.

This is the default child manager for TeeTree components.

Class Reference

TTreeExplorerAlignChild

Base class for Explorer-style layouts. Positions children to the right of parent nodes with vertical stacking.

Properties

HorizMargin · Integer · default: "19"

Horizontal spacing between parent and child nodes in pixels.

VertMargin · Integer · default: "1"

Vertical spacing between sibling nodes in pixels.

CrossMargin · Integer · default: "5"

Horizontal margin for the cross-box (expand/collapse control) in pixels.

TopPos · Integer · default: "2"

Default top position for root nodes in pixels.

Layout Behavior

The Explorer layout algorithm:

1. Root nodes - Positioned vertically at the left edge of the tree
2. Child nodes - Indented horizontally to the right of their parent
3. Siblings - Stacked vertically with VertMargin spacing
4. Connections - Drawn as angled lines from parent to children

Visual Description

Root
├── Child 1
│   ├── Grandchild 1.1
│   └── Grandchild 1.2
└── Child 2
    └── Grandchild 2.1

Usage

Setting Explorer Layout

// Default - Explorer layout is already active
Tree1.GlobalFormat.ChildManager; // TTreeExplorerAlignChild instance

Customizing Margins

with TTreeExplorerAlignChild(Tree1.GlobalFormat.ChildManager) do
begin
  HorizMargin := 30;  // Wider horizontal spacing
  VertMargin := 5;    // More vertical spacing between siblings
  CrossMargin := 8;   // Adjust cross-box position
end;

Creating a Basic Tree

var
  Root, Child1, Child2: TTreeNodeShape;
begin
  // Create root node
  Root := Tree1.AddRoot('Project');
  Root.Expanded := True;
  
  // Add children - they automatically use Explorer layout
  Child1 := Root.AddChild('Source Files');
  Child2 := Root.AddChild('Documentation');
  
  // Add grandchildren
  Child1.AddChild('Unit1.pas');
  Child1.AddChild('Unit2.pas');
  
  Child1.Expanded := True;
end;

Right-Aligned Explorer

TTreeExplorerAlignRight

A variant that positions children to the left of parents, creating a right-to-left explorer layout.

uses TreeChildManagers;

// Switch to right-aligned explorer
Tree1.GlobalFormat.ChildManager.Free;
Tree1.GlobalFormat.ChildManager := TTreeExplorerAlignRight.Create;

Visual Description (Right-Aligned)

              Root
        Child 1 ├──
 Grandchild 1.1 │   ├──
 Grandchild 1.2 │   └──
        Child 2 └──
 Grandchild 2.1     └──

Connection Drawing

The Explorer layout draws connections with:

• From point - Right edge of parent node
• To point - Left edge of child node
• Style - Angled connector lines with horizontal and vertical segments
• Auto-positioning - Connections update automatically when nodes move

Common Use Cases

File Systems

Perfect for displaying hierarchical folder structures and file explorers.

Organization Charts

Display company hierarchies with departments and employees.

XML/JSON Viewers

Show nested data structures with expandable nodes.

Decision Trees

Create decision flowcharts with sequential branching.

Related Classes

• Horizontal Layout - Top-to-bottom expansion
• Vertical Layout - Left-to-right with centered children
• Circular Layout - Radial arrangement
• Custom Layout - Create your own layout algorithm