C# 当ItemsSource集合中的属性更改时,如何重新绘制ItemsControl ItemsPanel?
我创建了一个自定义的WeightedUniformGrid类,在ItemsControl中用作ItemsPanel。每个网格元素都使用ItemsSource集合中对象的权重属性进行加权 但是当我在视图模型中更改权重属性时,它不会立即显示在视图中。我必须更改窗口的大小,以便使用新值绘制WeightedUniformGrid 如何使ItemsSource集合中的属性更改导致ItemsControl重新绘制?我想也许在WeightedUniformGrid中添加DependencyProperty,这将影响范围和影响度量。但我不确定我能把它绑在什么东西上 我在这里搜索了很长一段时间,有一些类似的问题(比如一个)。但我还没能使它们中的任何一个适应我的需要 MainWindow.xaml:C# 当ItemsSource集合中的属性更改时,如何重新绘制ItemsControl ItemsPanel?,c#,wpf,itemscontrol,C#,Wpf,Itemscontrol,我创建了一个自定义的WeightedUniformGrid类,在ItemsControl中用作ItemsPanel。每个网格元素都使用ItemsSource集合中对象的权重属性进行加权 但是当我在视图模型中更改权重属性时,它不会立即显示在视图中。我必须更改窗口的大小,以便使用新值绘制WeightedUniformGrid 如何使ItemsSource集合中的属性更改导致ItemsControl重新绘制?我想也许在WeightedUniformGrid中添加DependencyProperty,
<ItemsControl ItemsSource="{Binding Path=ElementGroupCollection}">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<local:WeightedUniformGrid Rows="2" />
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<ItemsControl.ItemTemplate>
<DataTemplate>
<Border BorderBrush="Black" BorderThickness="1"
RenderOptions.EdgeMode="Aliased">
<Viewbox Stretch="Uniform">
<TextBlock Text="{Binding Path=Number}" Foreground="Black" FontSize="20"
HorizontalAlignment="Center" VerticalAlignment="Center"/>
</Viewbox>
</Border>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
MainWindowVM.cs:
public class MainWindowVM
{
public MainWindowVM()
{
_elementGroupCollection = new ObservableCollection<ElementGroup>()
{
new ElementGroup(1, 60),
new ElementGroup(2, 150),
new ElementGroup(3, 90),
new ElementGroup(4, 80),
new ElementGroup(5, 60),
new ElementGroup(6, 160)
};
}
private ObservableCollection<ElementGroup> _elementGroupCollection;
public ObservableCollection<ElementGroup> ElementGroupCollection
{
get { return _elementGroupCollection; }
}
}
公共类MainWindowVM
{
公共MainWindowVM()
{
_elementGroupCollection=新的ObservableCollection()
{
新元素组(1,60),
新元素组(2150),
新元素组(3,90),
新元素组(4,80),
新元素组(5,60),
新元素组(6160)
};
}
私有可观察集合_elementGroupCollection;
公共可观测集合元素GroupCollection
{
获取{return\u elementGroupCollection;}
}
}
ElementGroup.cs:
public class ElementGroup : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
public ElementGroup(int number, double? weight)
{
Number = number;
Weight = (weight >= 0) ? weight : null;
}
public int Number { get; }
private double? _weight;
public double? Weight
{
get { return _weight; }
set { SetNotify(ref _weight, value); }
}
public void SetNotify<T>(ref T storage,
T value,
[CallerMemberName] string propertyName = null)
{
storage = value;
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}
公共类元素组:INotifyPropertyChanged
{
公共事件属性更改事件处理程序属性更改;
公共元素组(整数,双倍重量)
{
数字=数字;
权重=(权重>=0)?权重:空;
}
公共整数{get;}
私人双倍重量;
公众双倍体重
{
获取{return\u weight;}
set{SetNotify(ref_weight,value);}
}
公共无效设置通知(参考T存储、,
T值,
[CallerMemberName]字符串propertyName=null)
{
储存=价值;
PropertyChanged?.Invoke(这是新的PropertyChangedEventArgs(propertyName));
}
}
WeightedUniformGrid.cs:
public class WeightedUniformGrid : UniformGrid
{
protected override Size MeasureOverride(Size constraint)
{
var size = base.MeasureOverride(constraint);
double elementsPerRow = Math.Ceiling((double)Children.Count / Rows);
double elementHeight = size.Height / Rows;
double unweightedElementWidth = size.Width / elementsPerRow;
for (int i = 0; i < Children.Count; ++i)
{
var child = (FrameworkElement)Children[i];
var dc = child.DataContext;
int rowNumber = (int)Math.Floor(i / elementsPerRow);
double? weight = dc.GetType().GetProperty("Weight")?.GetValue(dc, null) as double?;
if (weight == null) { weight = 100; }
double weightedElementWidth = unweightedElementWidth * (double)weight / 100;
child.Measure(new Size(weightedElementWidth, elementHeight));
}
return size;
}
protected override Size ArrangeOverride(Size arrangeSize)
{
var size = base.ArrangeOverride(arrangeSize);
int elementsPerRow = (int)Math.Ceiling((double)Children.Count / Rows);
double elementHeight = size.Height / Rows;
double unweightedElementWidth = size.Width / elementsPerRow;
double[] accumulatedWidthPerRow = new double[Rows];
for (int i = 0; i < Children.Count; ++i)
{
var child = (FrameworkElement)Children[i];
var dc = child.DataContext;
int rowNumber = i / elementsPerRow;
double? weight = dc.GetType().GetProperty("Weight")?.GetValue(dc, null) as double?;
if (weight == null) { weight = 100; }
double weightedElementWidth = unweightedElementWidth * (double)weight / 100;
child.Arrange(new Rect(new Point(accumulatedWidthPerRow[rowNumber], rowNumber * elementHeight),
new Point(accumulatedWidthPerRow[rowNumber] + weightedElementWidth, (rowNumber + 1) * elementHeight)));
accumulatedWidthPerRow[rowNumber] += weightedElementWidth;
}
return size;
}
}
公共类WeightedUniformGrid:UniformGrid
{
受保护的覆盖尺寸测量覆盖(尺寸约束)
{
变量大小=基本度量超越(约束);
double elementsPerRow=Math.天花((双)Children.Count/行);
双元素高度=大小。高度/行;
双重未加权元素宽度=大小。宽度/元素如箭头所示;
for(int i=0;i
您的WeightedUniformGrid不能直接访问其子元素的DataContext中的Weight属性。此外,这是一种不好的做法,它无法正常工作,因为当视图模型项的权重发生变化时,没有强制布局传递的机制
应该有一个绑定到权重的附加属性。附加属性的FrameworkPropertyMetadataOptions
将强制布局传递
public class WeightedUniformGrid : UniformGrid
{
public static readonly DependencyProperty WeightProperty =
DependencyProperty.RegisterAttached(
"Weight", typeof(double), typeof(WeightedUniformGrid),
new FrameworkPropertyMetadata(double.NaN,
FrameworkPropertyMetadataOptions.AffectsParentMeasure |
FrameworkPropertyMetadataOptions.AffectsParentArrange));
public static double GetWeight(UIElement element)
{
return (double)element.GetValue(WeightProperty);
}
public static void SetWeight(UIElement element, double value)
{
element.SetValue(WeightProperty, value);
}
protected override Size MeasureOverride(Size constraint)
{
var size = base.MeasureOverride(constraint);
double elementsPerRow = Math.Ceiling((double)Children.Count / Rows);
double elementHeight = size.Height / Rows;
double unweightedElementWidth = size.Width / elementsPerRow;
for (int i = 0; i < Children.Count; ++i)
{
var child = Children[i];
int rowNumber = (int)Math.Floor(i / elementsPerRow);
// get attached property value
double weight = GetWeight(child);
if (double.IsNaN(weight)) { weight = 100; }
double weightedElementWidth = unweightedElementWidth * weight / 100;
child.Measure(new Size(weightedElementWidth, elementHeight));
}
return size;
}
protected override Size ArrangeOverride(Size arrangeSize)
{
var size = base.ArrangeOverride(arrangeSize);
int elementsPerRow = (int)Math.Ceiling((double)Children.Count / Rows);
double elementHeight = size.Height / Rows;
double unweightedElementWidth = size.Width / elementsPerRow;
double[] accumulatedWidthPerRow = new double[Rows];
for (int i = 0; i < Children.Count; ++i)
{
var child = Children[i];
int rowNumber = i / elementsPerRow;
// get attached property value
double weight = GetWeight(child);
if (double.IsNaN(weight)) { weight = 100; }
double weightedElementWidth = unweightedElementWidth * (double)weight / 100;
child.Arrange(new Rect(new Point(accumulatedWidthPerRow[rowNumber], rowNumber * elementHeight),
new Point(accumulatedWidthPerRow[rowNumber] + weightedElementWidth, (rowNumber + 1) * elementHeight)));
accumulatedWidthPerRow[rowNumber] += weightedElementWidth;
}
return size;
}
}
公共类WeightedUniformGrid:UniformGrid
{
公共静态只读DependencyProperty WeightProperty=
DependencyProperty.RegisterAttached(
“重量”、类型(双)和类型(重量),
新的FrameworkPropertyMetadata(double.NaN,
FrameworkPropertyMetadataOptions.AffectsParentMeasure|
FrameworkPropertyMetadataOptions.AffectsParentArrange));
公共静态双GetWeight(UIElement)
{
return(double)元素.GetValue(WeightProperty);
}
公共静态无效设置重量(UIElement,双值)
{
元素设置值(WeightProperty,value);
}
受保护的覆盖尺寸测量覆盖(尺寸约束)
{
变量大小=基本度量超越(约束);
double elementsPerRow=Math.天花((双)Children.Count/行);
双元素高度=大小。高度/行;
阴沉的
<ItemsControl ItemsSource="{Binding Path=ElementGroupCollection}">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<local:WeightedUniformGrid Rows="2" />
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<ItemsControl.ItemContainerStyle>
<Style TargetType="ContentPresenter">
<Setter Property="local:WeightedUniformGrid.Weight" Value="{Binding Weight}"/>
</Style>
</ItemsControl.ItemContainerStyle>
...
</ItemsControl>