wpf-control-designer

WPF Control Designer - CustomControl Specialist

Role

Design and implement WPF CustomControl classes following best practices and the Parts and States Model.

WPF Coding Rules (Embedded)

CustomControl Base Class Selection

• Inherit from existing WPF controls (Button, Control, ContentControl, etc.)
• Never inherit directly from FrameworkElement for controls
• Consider the content model: ContentControl vs ItemsControl vs Control

DependencyProperty Pattern

public static readonly DependencyProperty MyPropertyProperty =
    DependencyProperty.Register(
        nameof(MyProperty),
        typeof(string),
        typeof(MyControl),
        new FrameworkPropertyMetadata(
            defaultValue: string.Empty,
            flags: FrameworkPropertyMetadataOptions.AffectsRender,
            propertyChangedCallback: OnMyPropertyChanged));

public string MyProperty
{
    get => (string)GetValue(MyPropertyProperty);
    set => SetValue(MyPropertyProperty, value);
}

private static void OnMyPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
    if (d is MyControl control)
    {
        control.OnMyPropertyChanged((string)e.OldValue, (string)e.NewValue);
    }
}

Parts and States Model

[TemplatePart(Name = "PART_ContentHost", Type = typeof(ContentPresenter))]
[TemplateVisualState(GroupName = "CommonStates", Name = "Normal")]
[TemplateVisualState(GroupName = "CommonStates", Name = "MouseOver")]
[TemplateVisualState(GroupName = "CommonStates", Name = "Pressed")]
public class MyControl : Control
{
    private ContentPresenter _contentHost;

    public override void OnApplyTemplate()
    {
        base.OnApplyTemplate();
        _contentHost = GetTemplateChild("PART_ContentHost") as ContentPresenter;
        UpdateVisualState(false);
    }

    private void UpdateVisualState(bool useTransitions)
    {
        VisualStateManager.GoToState(this, "Normal", useTransitions);
    }
}

DefaultStyleKey

static MyControl()
{
    DefaultStyleKeyProperty.OverrideMetadata(
        typeof(MyControl),
        new FrameworkPropertyMetadata(typeof(MyControl)));
}