understanding-wpf-content-model

# WPF Content Model Patterns

WPF controls are classified into 4 main models based on how they contain content.

## 1. Content Model Hierarchy

```
Control
├── ContentControl          (Single Content)
│   ├── Button
│   ├── Label
│   ├── CheckBox
│   ├── RadioButton
│   ├── ToolTip
│   ├── ScrollViewer
│   ├── UserControl
│   ├── Window
│   └── HeaderedContentControl  (Content + Header)
│       ├── Expander
│       ├── GroupBox
│       └── TabItem
│
└── ItemsControl            (Multiple Items)
    ├── ListBox
    ├── ComboBox
    ├── ListView
    ├── TreeView
    ├── Menu
    ├── TabControl
    └── HeaderedItemsControl    (Items + Header)
        ├── MenuItem
        ├── TreeViewItem
        └── ToolBar
```

---

## 2. ContentControl

### 2.1 Characteristics

- **Single Content property**: Holds only one child element
- **Content type**: object (allows all types)
- **ContentTemplate**: Specifies how Content is rendered

### 2.2 Basic Usage

```xml
<!-- String content -->
<Button Content="Click Me"/>

<!-- Complex content -->
<Button>
    <StackPanel Orientation="Horizontal">
        <Image Source="/icon.png" Width="16"/>
        <TextBlock Text="Save" Margin="5,0,0,0"/>
    </StackPanel>
</Button>
```

### 2.3 Using ContentTemplate

```xml
<Button Content="Download">
    <Button.ContentTemplate>
        <DataTemplate>
            <StackPanel Orientation="Horizontal">
                <Path Data="M12,2L12,14L8,10L12,14L16,10L12,14"
                      Fill="White" Width="16"/>
                <TextBlock Text="{Binding}" Margin="5,0,0,0"/>
            </StackPanel>
        </DataTemplate>
    </Button.ContentTemplate>
</Button>
```

### 2.4 Creating ContentControl-Derived Controls

```csharp
namespace MyApp.Controls;

using System.Windows;
using System.Windows.Controls;

/// <summary>
/// Card control that displays single content
/// </summary>
public sealed class CardControl : ContentControl
{
    static CardControl()
    {
        DefaultStyleKeyProperty.OverrideMe