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我有一个简化的WPF示例，我在一个更大的项目中遇到了一个问题。我有一个名为“UserControl1”的用户控件。数据上下文设置为self，因此我在代码隐藏中定义了依赖项属性。WPF用户控件不更新路径
在控件中我有一个ItemsControl。在ItemsSource中，我有一个CompositeCollection，它包含一个CollectionContainer和一个Line。这条线只是为了向我自己证明我正在绘画。
我也有一个叫做“GraphPen”的对象，它包含一个PathGeometry依赖项属性。用户控件的CollectionContainer包含这些GraphPens的ObservableCollection。
现在，我有一个“MainWindow”来测试用户控件。在MainWindow中，我有一个DispatchTimer，并且在该计时器的Tick事件中，我将LineSegments添加到已添加到GraphPen单一实例的PathGeometry的Figures集合的PathFigure中。
我希望看到一条对角线与现有的红线并行绘制，但没有任何显示。如果我在Tick事件处理程序的末尾放置了一个断点，我可以检查用户控件并深入了解并确定线段确实存在。由于某些原因，他们没有被渲染。我怀疑我在绑定中做了什么错误。
我会提供下面的代码。
GraphPen.cs
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Media;
namespace WpfExampleControlLibrary
{
public class GraphPen : DependencyObject
{
#region Constructor
public GraphPen()
{
PenGeometry = new PathGeometry();
}
#endregion Constructor
#region Dependency Properties
// Line Color
public static PropertyMetadata PenLineColorPropertyMetadata
= new PropertyMetadata(null);
public static DependencyProperty PenLineColorProperty
= DependencyProperty.Register(
"PenLineColor",
typeof(Brush),
typeof(GraphPen),
PenLineColorPropertyMetadata);
public Brush PenLineColor
{
get { return (Brush)GetValue(PenLineColorProperty); }
set { SetValue(PenLineColorProperty, value); }
}
// Line Thickness
public static PropertyMetadata PenLineThicknessPropertyMetadata
= new PropertyMetadata(null);
public static DependencyProperty PenLineThicknessProperty
= DependencyProperty.Register(
"PenLineThickness",
typeof(Int32),
typeof(GraphPen),
PenLineThicknessPropertyMetadata);
public Int32 PenLineThickness
{
get { return (Int32)GetValue(PenLineThicknessProperty); }
set { SetValue(PenLineThicknessProperty, value); }
}
// Pen Geometry
public static PropertyMetadata PenGeometryMetadata = new PropertyMetadata(null);
public static DependencyProperty PenGeometryProperty
= DependencyProperty.Register(
"PenGeometry",
typeof(PathGeometry),
typeof(UserControl1),
PenGeometryMetadata);
public PathGeometry PenGeometry
{
get { return (PathGeometry)GetValue(PenGeometryProperty); }
set { SetValue(PenGeometryProperty, value); }
}
#endregion Dependency Properties
}
}
UserControl1.xaml
<UserControl Name="ExampleControl"
x:Class="WpfExampleControlLibrary.UserControl1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:local="clr-namespace:WpfExampleControlLibrary"
DataContext="{Binding RelativeSource={RelativeSource Self}}"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="300">
<UserControl.Resources>
<DataTemplate DataType="{x:Type local:GraphPen}">
<Path Stroke="{Binding Path=PenLineColor}"
StrokeThickness="{Binding Path=PenLineThickness}"
Data="{Binding Path=Geometry}">
</Path>
</DataTemplate>
</UserControl.Resources>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition/>
<RowDefinition Height="40"/>
</Grid.RowDefinitions>
<ItemsControl Grid.Column="0" Grid.Row="0">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<Canvas Background="Aquamarine">
<Canvas.LayoutTransform>
<ScaleTransform ScaleX="1" ScaleY="-1" CenterX=".5" CenterY=".5"/>
</Canvas.LayoutTransform>
</Canvas>
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<ItemsControl.ItemsSource>
<CompositeCollection>
<CollectionContainer
Collection="{
Binding Source={RelativeSource Self},
Path=GraphPens,
Mode=OneWay}"/>
<Line X1="10" Y1="0" X2="200" Y2="180" Stroke="DarkRed" StrokeThickness="2"/>
</CompositeCollection>
</ItemsControl.ItemsSource>
</ItemsControl>
<TextBox x:Name="debug" Grid.Column="0" Grid.Row="1" Text="{Binding Path=DebugText}"/>
</Grid>
</UserControl>
UserControl1.xaml.cs
namespace WpfExampleControlLibrary
{
/// <summary>
/// Interaction logic for UserControl1.xaml
/// </summary>
public partial class UserControl1 : UserControl
{
public UserControl1()
{
InitializeComponent();
GraphPens = new ObservableCollection<GraphPen>();
}
#region Dependency Properties
// Pens
public static PropertyMetadata GraphPenMetadata = new PropertyMetadata(null);
public static DependencyProperty GraphPensProperty
= DependencyProperty.Register(
"GraphPens",
typeof(ObservableCollection<GraphPen>),
typeof(UserControl1),
GraphPenMetadata);
public ObservableCollection<GraphPen> GraphPens
{
get { return (ObservableCollection<GraphPen>)GetValue(GraphPensProperty); }
set { SetValue(GraphPensProperty, value); }
}
// Debug Text
public static PropertyMetadata DebugTextMetadata = new PropertyMetadata(null);
public static DependencyProperty DebugTextProperty
= DependencyProperty.Register(
"DebugText",
typeof(string),
typeof(UserControl1),
DebugTextMetadata);
public string DebugText
{
get { return (string)GetValue(DebugTextProperty); }
set { SetValue(DebugTextProperty, value); }
}
#endregion Dependency Properties
}
}
MainWindow.xaml
<Window x:Class="POC_WPF_UserControlExample.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:Exmpl="clr-namespace:WpfExampleControlLibrary;assembly=WpfExampleControlLibrary"
xmlns:local="clr-namespace:POC_WPF_UserControlExample"
mc:Ignorable="d"
Title="MainWindow" Height="550" Width="550">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="100"/>
<ColumnDefinition />
<ColumnDefinition Width="100"/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="100" />
<RowDefinition />
<RowDefinition Height="100" />
</Grid.RowDefinitions>
<Exmpl:UserControl1 Grid.Column="1" Grid.Row="1" x:Name="myExample"/>
</Grid>
</Window>
MainWindow.xaml.cs
namespace POC_WPF_UserControlExample
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
private DispatcherTimer _timer = null;
private GraphPen _graphPen0 = null;
private Int32 _pos = 0;
private PathFigure _pathFigure = null;
public MainWindow()
{
InitializeComponent();
_graphPen0 = new GraphPen();
_graphPen0.PenLineColor = Brushes.DarkGoldenrod;
_graphPen0.PenLineThickness = 2;
myExample.GraphPens.Add(_graphPen0);
_timer = new DispatcherTimer();
_timer.Tick += Timer_Tick;
_timer.Interval = new TimeSpan(0, 0, 0, 0, 100);
_timer.Start();
}
private void Timer_Tick(object sender, EventArgs e)
{
_pos++;
Point penPoint0 = new Point(_pos, _pos + 20);
if (_graphPen0.PenGeometry.Figures.Count == 0)
{
_pathFigure = new PathFigure();
_graphPen0.PenGeometry.Figures.Add(_pathFigure);
_pathFigure.StartPoint = penPoint0;
}
else
{
LineSegment segment = new LineSegment(penPoint0, false);
_pathFigure.Segments.Add(segment);
}
myExample.DebugText = _pos.ToString();
}
}
}
屏幕截图
你尝试更换GraphPen，而不是改变现有的？ –
埃德，感谢您的快速回复。刚刚尝试过，但没有喜悦。我很高兴那不是答案。在这个大项目中，我将有数十支笔每10毫秒更新一次线。我会讨厌每次重新创建笔的开销。我会认为ObservableCollection会为我处理这个问题。 – dtaylor
当您向其中添加或删除项目时，ObservableCollection会引发事件。它不知道它包含的项目的属性是怎么回事。这里的关键是['_graphPen0.PenGeometry.Figures.Add（_pathFigure）;']（https://msdn.microsoft.com/en-us/library/system.windows.media.pathfigurecollection（v = vs.110 ）.aspx）和['_pathFigure.Segments.Add（segment）;']（https://msdn.microsoft.com/en-us/library/system.windows.media.pathsegmentcollection（v = vs.110））。 ASPX）。我不认为这些藏品中的任何一个在您更改其内容时都会举办任何活动。 –