自定义选择器控件在设置 ItemsSource 后不更新？

Question

我已经根据 Selector 原语在 C# 中的 WPF 中组合了一个自定义控件：

public class PadControl : Selector
{
    private const int padWidth = 28;
    private const int padHeight = 18;
    private const int padGap = 5;

    private double _width;
    private double _height;

    static PadControl()
    {
        DefaultStyleKeyProperty.OverrideMetadata(typeof(PadControl), new FrameworkPropertyMetadata(typeof(PadControl), 
            FrameworkPropertyMetadataOptions.AffectsMeasure | FrameworkPropertyMetadataOptions.AffectsRender));
    }

    public PadControl()
    {
        
    }

    protected override Size MeasureOverride(Size constraint)
    {
        _width = constraint.Width;
        _height = constraint.Height;

        return base.MeasureOverride(constraint);
    }

    protected override void OnRender(DrawingContext dc)
    {
        base.OnRender(dc);

        var numHorz = _width / (padWidth + padGap);
        var numVert = Math.Min(_height / (padHeight + padGap), 16);

        var pen = new Pen(Brushes.Black, 1.0);
        var brush = new SolidColorBrush(Color.FromRgb(192, 192, 192));

        for(int bar = 0; bar < numHorz; bar++)
        {
            for(int track = 0; track < numVert; track++)
            {
                var rect = GetPadRect(bar, track);
                dc.DrawRectangle(brush, pen, rect);
            }
        }

        if (Items == null)
            return;

        brush = new SolidColorBrush(Colors.LightYellow);
        var typeface = new Typeface("Tahoma");
        foreach(PadViewModel item in Items)
        {
            var rect = GetPadRect(item.Bar, item.Track);
            dc.DrawRectangle(brush, pen, rect);

            var formatted = new FormattedText(item.Text, CultureInfo.CurrentCulture, FlowDirection.LeftToRight, typeface, 12, Brushes.Black, 1.0)
            {
                MaxTextWidth = padWidth,
                TextAlignment = TextAlignment.Center
            };

            dc.DrawText(formatted, GetPadPoint(item.Bar, item.Track));
        }
    }

    private Rect GetPadRect(int bar, int track)
    {
        var rect = new Rect(bar * (padWidth + padGap) + padGap, track * (padHeight + padGap) + padGap, padWidth, padHeight);
        return rect;
    }

    private Point GetPadPoint(int bar, int track)
    {
        var point = new Point(bar * (padWidth + padGap) + padGap, track * (padHeight + padGap) + padGap);
        return point;
    }
}

这会按照我的意愿进行绘制，但在我调整控件大小之前它不会绘制项目。

当控件第一次呈现时，它不会呈现任何项目，因为它是空的。项目是用这个间接填充的：

<controls:PadControl Grid.Column="0" Grid.Row="0" ItemsSource="{Binding Pads}"/>

问题是，在设置 ItemsSource 后我没有看到更新。所以问题是，我如何附加事件处理程序来捕获它？我是将它附加到 Items 还是附加到 ItemsSource？

Answer 1

答案是覆盖 OnItemsSourceChanged，如 Keith Stein 在上面的评论中所述。

自定义选择器控件在设置 ItemsSource 后不更新？

Custom Selector control does not update after ItemsSource has been set?

c#

wpf

controls

selector