更新ObservableCollecttion对象属性已更改 [英] Update ObservableCollecttion on objects property changed
本文介绍了更新ObservableCollecttion对象属性已更改的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我有一个代表项目的类。它包含一个ObservableCollection，每个Layer都有一个ObservableCollection。元素是一个抽象类。有一个TextElement和ImageElement类继承自Element。
我的问题是当我更改集合中的元素时，UI永远不会被更新。我在我的所有属性上使用INotifyPropertyChanged，并且我收集了CollectionChanged的集合，但仍然没有去。 ObservableCollection的CollectionChanged事件从未受到其中一个元素的更新的打击。
这是我原来有的代码：
void Elements_CollectionChanged（
object sender，
System.Collections.Specialized.NotifyCollectionChangedEventArgs e）
{this.NotifyChange（Elements ）;
这是绑定：
<！ - 工作区 - >
< ScrollViewer Grid.Column =1VerticalScrollBarVisibility =AutoHorizontalScrollBarVisibility =AutoMargin =5DataContext ={Binding Project}>
< Canvas x：Name =CanvasBackground =LightGrayWidth ={Binding Path = CanvasWidth}Height ={Binding Path = CanvasHeight}>
< ItemsControl ItemsSource ={Binding Path = Layers，Mode = OneWay，UpdateSourceTrigger = PropertyChanged}>
< ItemsControl.ItemsPanel>
< ItemsPanelTemplate>
< Canvas />
< / ItemsPanelTemplate>
< /ItemsControl.ItemsPanel>
< ItemsControl.ItemTemplate>
< DataTemplate>
< ItemsControl ItemsSource ={Binding Path = Elements，Mode = OneWay}>
< ItemsControl.ItemsPanel>
< ItemsPanelTemplate>
< Canvas Background ={Binding Path = BackgroundColor}
Visibility ={Binding Path = Visible，Converter = {StaticResource BoolConverter}}
Opacity ={Binding Path = Opacity
Width ={Binding ElementName = Canvas，Path = DataContext.CanvasWidth}
Height ={Binding ElementName = Canvas，Path = DataContext.CanvasHeight}>
< / Canvas>
< / ItemsPanelTemplate>
< /ItemsControl.ItemsPanel>
< ItemsControl.ItemTemplate>
< DataTemplate>
< Canvas>
< ContentControl Content ={Binding Converter = {StaticResource ElementConverter}}
Canvas.Top ={Binding Path = Top，Mode = TwoWay}
Canvas.Left ={ Binding Path = Left，Mode = TwoWay
Opacity ={Binding Path = Opacity}
MouseLeftButtonDown =ContentControl_MouseLeftButtonDown>
< interactiveivity：Interaction.Behaviors>
<行为：DragInCanvasBehavior />
< / interactivity：Interaction.Behaviors>
< / ContentControl>
< / Canvas>
< / DataTemplate>
< /ItemsControl.ItemTemplate>
< / ItemsControl>
< / DataTemplate>
< /ItemsControl.ItemTemplate>
< / ItemsControl>
< / Canvas>
< / ScrollViewer>
这是我的转换器：
public class LayerElementToFrameworkElementConverter：IValueConverter
{
public object Convert（object value，Type targetType，object parameter，System.Globalization.CultureInfo culture）
{
元素元素=值作为元素;
if（element is ImageEditor.Client.BLL.TextElement）
{
ImageEditor.Client.BLL.TextElement txt = element as ImageEditor.Client.BLL.TextElement;
返回CreateTextBlock（txt）;
}
else if（element is ImageElement）
{
ImageElement imgEle = element as ImageElement;
返回CreateImage（imgEle）;
}
else
返回null;
}
public object ConvertBack（object value，Type targetType，object parameter，System.Globalization.CultureInfo culture）
{
FrameworkElement frameworkElement = Value as FrameworkElement;
if（frameworkElement is TextBlock）
{
TextBlock txtBlock = value as TextBlock;
return CreateTextElement（txtBlock）;
}
else if（frameworkElement为Image）
{
图像img = value as Image;
return CreateImageElement（img）;
}
else
返回null;
}
private TextBlock CreateTextBlock（TextElement textElement）
{
TextBlock text = new TextBlock（）;
text.Text = textElement.Text;
text.Cursor = Cursors.Hand;
text.SetValue（Canvas.ZIndexProperty，textElement.Order）;
ColorHexToBrushConverter converter = new ColorHexToBrushConverter（）;
SolidColorBrush画笔=（SolidColorBrush）converter.Convert（textElement.Color，null，null，null）;
text.Foreground = brush;
返回文字;
}
private TextElement CreateTextElement（TextBlock textBlock）
{
TextElement textElement = new TextElement（）;
textElement.Text = textBlock.Text;
textElement.Top =（double）textBlock.GetValue（Canvas.TopProperty）;
textElement.Left =（double）textBlock.GetValue（Canvas.LeftProperty）;
textElement.Order =（int）textBlock.GetValue（Canvas.ZIndexProperty）;
ColorHexToBrushConverter converter = new ColorHexToBrushConverter（）;
textElement.Color =（string）converter.ConvertBack（textBlock.Foreground，null，null，null）;
return textElement;
}
private Image CreateImage（ImageElement imageElement）
{
Image img = new Image（）;
img.Width = imageElement.Width;
img.Height = imageElement.Height;
img.Source = imageElement.Source;
img.Opacity = imageElement.Opacity;
img.Cursor = Cursors.Hand;
img.SetValue（Canvas.ZIndexProperty，imageElement.Order）;
img.SetValue（Canvas.TopProperty，imageElement.Top）;
img.SetValue（Canvas.LeftProperty，imageElement.Left）;
return img;
}
private ImageElement CreateImageElement（Image image）
{
ImageElement imageElement = new ImageElement（）;
imageElement.Width = image.Width;
imageElement.Height = image.Height;
imageElement.Source =（BitmapImage）image.Source;
imageElement.Order =（int）image.GetValue（Canvas.ZIndexProperty）;
return imageElement;
}
}
这是包含收藏的类： p>
public class Layer：BaseBLL
{
private int numberOfElements;
#region属性
public int Order
{
get {return this.GetValue< int>（Order）; }
set {this.SetValue< int>（Order，value）; }
}
public string BackgroundColor
{
get {return this.GetValue< string>（BackgroundColor）; }
set {this.SetValue< string>（BackgroundColor，value）; }
}
public double Opacity
{
get {return this.GetValue< double>（Opacity）; }
set {this.SetValue< double>（Opacity，value）; }
}
public bool可见
{
get {return this.GetValue< bool>（Visible）; }
set {this.SetValue< bool>（Visible，value）; }
}
public ObservableCollection< Element>元素{get;组; }
public Element SelectedElement
{
get {return this.GetValue< Element>（SelectedElement）; }
set {this.SetValue< Element>（SelectedElement，value）;
}
#endregion
#region命令
public ICommand AddTextElementCommand {get;组; }
public ICommand AddImageElementCommand {get;组; }
public ICommand DeleteElementCommand {get;组; }
public ICommand SetSelectedElementCommand {get;组;
#endregion
#region方法
public Layer（）
：this（Untitled，0，#ffffff，1，true，new ObservableCollection< ;元素>（））
{
}
public Layer（string name，int order，string backgroundColor，double opacity，bool visible，ObservableCollection< Element>元素）
：base（name）
{
this.Order = order;
this.BackgroundColor = backgroundColor;
this.Opacity = opacity;
this.Visible = visible;
this.Elements = elements;
this.Elements.CollectionChanged + = new System.Collections.Specialized.NotifyCollectionChangedEventHandler（Elements_CollectionChanged）;
this.AddTextElementCommand = new DelegateCommand（AddTextElement，CanAddTextElement）;
this.AddImageElementCommand = new DelegateCommand（AddImageElement，CanAddImageElement）;
this.DeleteElementCommand = new DelegateCommand（DeleteElement，CanDeleteElement）;
}
private void Elements_CollectionChanged（object sender，System.Collections.Specialized.NotifyCollectionChangedEventArgs e）
{
foreach（e.NewItems中的元素元素）
element.PropertyChanged + = new System.ComponentModel.PropertyChangedEventHandler（element_PropertyChanged）;
}
void element_PropertyChanged（object sender，System.ComponentModel.PropertyChangedEventArgs e）
{
this.NotifyChange（Elements）;
}
private bool CanAddTextElement（object param）{return true;
private void AddTextElement（object param）
{
TextElement text = new TextElement（）;
text.Order = this.numberOfElements;
this.Elements.Add（text）;
numberOfElements ++;
this.SelectedElement = text;
}
private bool CanAddImageElement（object param）{return true;
private void AddImageElement（object param）
{
var dialog = new OpenFileDialog（）
{
Filter =图像文件（* .bmp; *。 ; *。gif; *。png;）| * .bmp; *。jpg; *。gif; *。png;，
Multiselect = false
};
bool？ userClickedOK = dialog.ShowDialog（）;
if（userClickedOK == true）
{
string fileName = dialog.File.Name;
FileStream stream = dialog.File.OpenRead（）;
var imageSource = new BitmapImage（）;
使用（FileStream fileStream = stream）
{
imageSource.SetSource（fileStream）;
byte [] data = new byte [fileStream.Length];
fileStream.Read（data，0，data.Length）;
fileStream.Flush（）;
fileStream.Close（）;
}
ImageElement img = new ImageElement（）;
img.Name = fileName;
img.Order = this.numberOfElements;
img.Source = imageSource;
img.Height = imageSource.PixelHeight;
img.Width = imageSource.PixelWidth;
this.Elements.Add（img）;
this.numberOfElements ++;
this.SelectedElement = img;
}
}
private bool CanDeleteElement（object param）
{
if（this.SelectedElement！= null）
return true;
else
返回false;
}
private void DeleteElement（object param）
{
throw new NotImplementedException（）;
}
#endregion
}
这是代码元素之一：
public class TextElement：Element
{
public string Text
{
get {return this.GetValue< string>（Text）; }
set {this.SetValue< string>（Text，value）; }
}
public int FontSize
{
get {return this.GetValue< int>（FontSize）; }
set {this.SetValue< int>（FontSize，value）; }
}
public bool Bold
{
get {return this.GetValue< bool>（Bold）; }
set {this.SetValue< bool>（Bold，value）;
}
public bool Italic
{
get {return this.GetValue< bool>（Italic）; }
set {this.SetValue< bool>（Italic，value）; }
}
public string Color
{
get {return this.GetValue< string>（Color）; }
set {this.SetValue< string>（Color，value）;
}
public FontFamily Font
{
get {return this.GetValue< FontFamily>（Font）; }
set {this.SetValue< FontFamily>（Font，value）;
}
public TextElement（）
：this（Untitled，1,5,5,10，0,0，New text，12，false， false，#aaaaaa，新的FontFamily（Arial）
{
}
public TextElement（string name，double opacity，double top，double left，double rotateAngle ，double centerX，double centerY，
string text，int fontSize，bool bold，bool italic，string color，FontFamily font）
：base（name，opacity，top，left，rotateAngle，centerX，centerY）
{
this.Text = text;
this.FontSize = fontSize;
this.Bold = bold;
this.Italic = italic;
this.Color = color;
this.Font = font;
}
}
如果有人可以帮助我会非常感激。 / p>
解决方案
您是否从SetValue内部触发PropertyChanged事件？
否则，您应该为Element的每个属性执行。
public string Text
{
get {return this.GetValue< string>（Text）; }
set {this.SetValue< string>（Text，value）; this.InvokePropertyChanged（Text）;
}
private void InvokePropertyChanged（string propertyName）
{
if（this.PropertyChanged！= null）
this.PropertyChanged（this，new PropertyChangedEventArgs（propertyName））;
}
Hopefully someone can help me out with this. I am creating a Silverlight app which is used for editing images. A user has a project which contain layers which contain elements. (Elements are text and image elements).
I have a class which represents the project. It contains an ObservableCollection and each Layer has an ObservableCollection. Element is an abstract class. There is a TextElement and ImageElement class which inherit from Element.
My problem is the UI never gets updated when I change an element inside the collection. I am using INotifyPropertyChanged on all my properties and I am catching CollectionChanged on the collections but still no go. The CollectionChanged event for ObservableCollection never gets hit on an update of one of its elements.
This is the code I had originally had:
void Elements_CollectionChanged(
object sender,
System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
{ this.NotifyChange("Elements"); }
This is the binding:
<!-- Workspace -->
<ScrollViewer Grid.Column="1" VerticalScrollBarVisibility="Auto" HorizontalScrollBarVisibility="Auto" Margin="5" DataContext="{Binding Project}">
<Canvas x:Name="Canvas" Background="LightGray" Width="{Binding Path=CanvasWidth}" Height="{Binding Path=CanvasHeight}">
<ItemsControl ItemsSource="{Binding Path=Layers, Mode=OneWay, UpdateSourceTrigger=PropertyChanged}">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<Canvas />
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<ItemsControl.ItemTemplate>
<DataTemplate>
<ItemsControl ItemsSource="{Binding Path=Elements, Mode=OneWay}">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<Canvas Background="{Binding Path=BackgroundColor}"
Visibility="{Binding Path=Visible, Converter={StaticResource BoolConverter}}"
Opacity="{Binding Path=Opacity}"
Width="{Binding ElementName=Canvas, Path=DataContext.CanvasWidth}"
Height="{Binding ElementName=Canvas, Path=DataContext.CanvasHeight}">
</Canvas>
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<ItemsControl.ItemTemplate>
<DataTemplate>
<Canvas>
<ContentControl Content="{Binding Converter={StaticResource ElementConverter}}"
Canvas.Top="{Binding Path=Top, Mode=TwoWay}"
Canvas.Left="{Binding Path=Left, Mode=TwoWay}"
Opacity="{Binding Path=Opacity}"
MouseLeftButtonDown="ContentControl_MouseLeftButtonDown">
<interactivity:Interaction.Behaviors>
<behaviors:DragInCanvasBehavior />
</interactivity:Interaction.Behaviors>
</ContentControl>
</Canvas>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
</Canvas>
</ScrollViewer>
This is my converter:
public class LayerElementToFrameworkElementConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
Element element = value as Element;
if (element is ImageEditor.Client.BLL.TextElement)
{
ImageEditor.Client.BLL.TextElement txt = element as ImageEditor.Client.BLL.TextElement;
return CreateTextBlock(txt);
}
else if (element is ImageElement)
{
ImageElement imgEle = element as ImageElement;
return CreateImage(imgEle);
}
else
return null;
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
FrameworkElement frameworkElement = value as FrameworkElement;
if (frameworkElement is TextBlock)
{
TextBlock txtBlock = value as TextBlock;
return CreateTextElement(txtBlock);
}
else if (frameworkElement is Image)
{
Image img = value as Image;
return CreateImageElement(img);
}
else
return null;
}
private TextBlock CreateTextBlock(TextElement textElement)
{
TextBlock text = new TextBlock();
text.Text = textElement.Text;
text.Cursor = Cursors.Hand;
text.SetValue(Canvas.ZIndexProperty, textElement.Order);
ColorHexToBrushConverter converter = new ColorHexToBrushConverter();
SolidColorBrush brush = (SolidColorBrush)converter.Convert(textElement.Color, null, null, null);
text.Foreground = brush;
return text;
}
private TextElement CreateTextElement(TextBlock textBlock)
{
TextElement textElement = new TextElement();
textElement.Text = textBlock.Text;
textElement.Top = (double)textBlock.GetValue(Canvas.TopProperty);
textElement.Left = (double)textBlock.GetValue(Canvas.LeftProperty);
textElement.Order = (int)textBlock.GetValue(Canvas.ZIndexProperty);
ColorHexToBrushConverter converter = new ColorHexToBrushConverter();
textElement.Color = (string)converter.ConvertBack(textBlock.Foreground, null, null, null);
return textElement;
}
private Image CreateImage(ImageElement imageElement)
{
Image img = new Image();
img.Width = imageElement.Width;
img.Height = imageElement.Height;
img.Source = imageElement.Source;
img.Opacity = imageElement.Opacity;
img.Cursor = Cursors.Hand;
img.SetValue(Canvas.ZIndexProperty, imageElement.Order);
img.SetValue(Canvas.TopProperty, imageElement.Top);
img.SetValue(Canvas.LeftProperty, imageElement.Left);
return img;
}
private ImageElement CreateImageElement(Image image)
{
ImageElement imageElement = new ImageElement();
imageElement.Width = image.Width;
imageElement.Height = image.Height;
imageElement.Source = (BitmapImage)image.Source;
imageElement.Order = (int)image.GetValue(Canvas.ZIndexProperty);
return imageElement;
}
}
This is the class which contains to collection:
public class Layer : BaseBLL
{
private int numberOfElements;
#region Properties
public int Order
{
get { return this.GetValue<int>("Order"); }
set { this.SetValue<int>("Order", value); }
}
public string BackgroundColor
{
get { return this.GetValue<string>("BackgroundColor"); }
set { this.SetValue<string>("BackgroundColor", value); }
}
public double Opacity
{
get { return this.GetValue<double>("Opacity"); }
set { this.SetValue<double>("Opacity", value); }
}
public bool Visible
{
get { return this.GetValue<bool>("Visible"); }
set { this.SetValue<bool>("Visible", value); }
}
public ObservableCollection<Element> Elements { get; set; }
public Element SelectedElement
{
get { return this.GetValue<Element>("SelectedElement"); }
set { this.SetValue<Element>("SelectedElement", value); }
}
#endregion
#region Commands
public ICommand AddTextElementCommand { get; set; }
public ICommand AddImageElementCommand { get; set; }
public ICommand DeleteElementCommand { get; set; }
public ICommand SetSelectedElementCommand { get; set; }
#endregion
#region Methods
public Layer()
:this("Untitled", 0, "#ffffff", 1, true, new ObservableCollection<Element>())
{
}
public Layer(string name, int order, string backgroundColor, double opacity, bool visible, ObservableCollection<Element> elements)
: base(name)
{
this.Order = order;
this.BackgroundColor = backgroundColor;
this.Opacity = opacity;
this.Visible = visible;
this.Elements = elements;
this.Elements.CollectionChanged += new System.Collections.Specialized.NotifyCollectionChangedEventHandler(Elements_CollectionChanged);
this.AddTextElementCommand = new DelegateCommand(AddTextElement, CanAddTextElement);
this.AddImageElementCommand = new DelegateCommand(AddImageElement, CanAddImageElement);
this.DeleteElementCommand = new DelegateCommand(DeleteElement, CanDeleteElement);
}
private void Elements_CollectionChanged(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
{
foreach (Element element in e.NewItems)
element.PropertyChanged += new System.ComponentModel.PropertyChangedEventHandler(element_PropertyChanged);
}
void element_PropertyChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e)
{
this.NotifyChange("Elements");
}
private bool CanAddTextElement(object param) { return true; }
private void AddTextElement(object param)
{
TextElement text = new TextElement();
text.Order = this.numberOfElements;
this.Elements.Add(text);
numberOfElements++;
this.SelectedElement = text;
}
private bool CanAddImageElement(object param) { return true; }
private void AddImageElement(object param)
{
var dialog = new OpenFileDialog()
{
Filter = "Image Files (*.bmp;*.jpg;*.gif;*.png;)|*.bmp;*.jpg;*.gif;*.png;",
Multiselect = false
};
bool? userClickedOK = dialog.ShowDialog();
if (userClickedOK == true)
{
string fileName = dialog.File.Name;
FileStream stream = dialog.File.OpenRead();
var imageSource = new BitmapImage();
using (FileStream fileStream = stream)
{
imageSource.SetSource(fileStream);
byte[] data = new byte[fileStream.Length];
fileStream.Read(data, 0, data.Length);
fileStream.Flush();
fileStream.Close();
}
ImageElement img = new ImageElement();
img.Name = fileName;
img.Order = this.numberOfElements;
img.Source = imageSource;
img.Height = imageSource.PixelHeight;
img.Width = imageSource.PixelWidth;
this.Elements.Add(img);
this.numberOfElements++;
this.SelectedElement = img;
}
}
private bool CanDeleteElement(object param)
{
if (this.SelectedElement != null)
return true;
else
return false;
}
private void DeleteElement(object param)
{
throw new NotImplementedException();
}
#endregion
}
This is the code for the one of the Elements:
public class TextElement : Element
{
public string Text
{
get { return this.GetValue<string>("Text"); }
set { this.SetValue<string>("Text", value); }
}
public int FontSize
{
get { return this.GetValue<int>("FontSize"); }
set { this.SetValue<int>("FontSize", value); }
}
public bool Bold
{
get { return this.GetValue<bool>("Bold"); }
set { this.SetValue<bool>("Bold", value); }
}
public bool Italic
{
get { return this.GetValue<bool>("Italic"); }
set { this.SetValue<bool>("Italic", value); }
}
public string Color
{
get { return this.GetValue<string>("Color"); }
set { this.SetValue<string>("Color", value); }
}
public FontFamily Font
{
get { return this.GetValue<FontFamily>("Font"); }
set { this.SetValue<FontFamily>("Font", value); }
}
public TextElement()
: this("Untitled", 1, 5, 5, 0, 0, 0, "New text", 12, false, false, "#aaaaaa", new FontFamily("Arial"))
{
}
public TextElement(string name, double opacity, double top, double left, double rotateAngle, double centerX, double centerY,
string text, int fontSize, bool bold, bool italic, string color, FontFamily font)
: base(name, opacity, top, left, rotateAngle, centerX, centerY)
{
this.Text = text;
this.FontSize = fontSize;
this.Bold = bold;
this.Italic = italic;
this.Color = color;
this.Font = font;
}
}
If anyone can help I would be very grateful.
解决方案
Do you fire the PropertyChanged event from inside SetValue? Otherwise, you should do it for each property of Element.
public string Text
{
get { return this.GetValue<string>("Text"); }
set { this.SetValue<string>("Text", value); this.InvokePropertyChanged("Text"); }
}
private void InvokePropertyChanged( string propertyName )
{
if( this.PropertyChanged != null )
this.PropertyChanged( this, new PropertyChangedEventArgs( propertyName ) );
}
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