通过数据绑定更改列表框项的背景颜色属性
本文关键字:背景 颜色 属性 列表 数据绑定 | 更新日期: 2023-09-27 18:36:05
我正在尝试制作ListBox,它根据一些变化的数据更新其内容。XAML 如下所示
StackPanel Orientation="Vertical">
<ListBox x:Name="listWatch" >
<ListBox.ItemTemplate>
<DataTemplate>
<Grid ShowGridLines="True">
<Grid Grid.Column="0" Background="{Binding Path=Color">
<TextBlock Text="{ Binding Path=LTP}" Padding="2 2 2 2"/>
</Grid>
</Grid>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
<Button x:Name="btn" Click="btn_Click" Content="Button" />
我用于表单数据结构的类如下
public class WatchRow : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
string _color;
decimal _lTP;
public WatchRow(decimal LTP,string color)
{
this.LTP = LTP;
this.Color = color;
}
public string Color
{
get { return _color; }
set{
_color = value;
OnPropertyChanged(_color);
}
}
public decimal LTP
{
get { return _lTP; }
set
{
_lTP = value;
OnPropertyChanged(_lTP.ToString());
}
}
protected void OnPropertyChanged(string info)
{
PropertyChangedEventHandler handler = PropertyChanged;
if (handler != null)
{
handler(this, new PropertyChangedEventArgs(info));
}
}
}
public class Watch:ObservableCollection<WatchRow>
{
public Watch():base()
{
}
}
文件背后的代码就像
Watch watch = new Watch();
private void PhoneApplicationPage_Loaded_1(object sender, RoutedEventArgs e)
{
watch.Add(new WatchRow(132, "black"));
watch.Add(new WatchRow(123, "red"));
listWatch.ItemsSource = watch;
watch[0].Color = "green";
}
private void btn_Click(object sender, RoutedEventArgs e)
{
watch[0].Color = "green";
}
我的问题是我无法通过设置 color 属性(watch[0] 来更改列表框项的颜色。颜色="绿色";)btn_Click,如代码所示。但是相同的代码在PhoneApplicationPage_Loaded_1中有效。我不知道我错了什么。有什么想法吗?
我相信
问题是您使用PropertyChanged的方式略有变化。调用 OnPropertyChanged 时,请传递要更改的属性的名称,而不是值。例如:
public string Color
{
get { return _color; }
set{
_color = value;
OnPropertyChanged(_color);
}
}
应该是:
public string Color
{
get { return _color; }
set{
_color = value;
OnPropertyChanged("Color");
}
}
另外,我不确定这是否一定是一个问题,但这就是我一直创建 OnPropertyChanged 函数的方式:
而不是:
protected void OnPropertyChanged(string info)
{
PropertyChangedEventHandler handler = PropertyChanged;
if (handler != null)
{
handler(this, new PropertyChangedEventArgs(info));
}
}
尝试:
private void OnPropertyChanged(String info)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(info));
}
}
此外,正如Magnus Johansson所提到的,定义一个画笔,并绑定颜色,而不是一个字符串。所以 Color 属性将是(有关此的更多详细信息,请参阅他的解释):
private Color _color;
public Color Color
{
get { return _color; }
set{
_color = value;
OnPropertyChanged("Color");
}
}
使用 Mvvm 可以解决您的问题:我已经测试了这段代码,它可以工作。您需要将代码拆分为三个单独的文件,如下所示:
视图模型
public class WatchViewModel
{
public ObservableCollection<WatchRow> WatchRows { get; set; }
public void GetWatchRows()
{
WatchRows= new ObservableCollection<WatchRow>();
}
public void AddWatchRow(int value, string color)
{
var item=new WatchRow(value, color);
WatchRows.Add(item);
}
}
模型
public class WatchRow : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
string _color;
decimal _lTP;
public WatchRow(decimal LTP, string color)
{
this.LTP = LTP;
this.Color = color;
}
public string Color
{
get { return _color; }
set
{
_color = value;
OnPropertyChanged(_color);
}
}
public decimal LTP
{
get { return _lTP; }
set
{
_lTP = value;
OnPropertyChanged(_lTP.ToString());
}
}
protected void OnPropertyChanged(string info)
{
PropertyChangedEventHandler handler = PropertyChanged;
if (handler != null)
{
handler(this, new PropertyChangedEventArgs(info));
}
}
}
和视图(xaml 页面的代码隐藏)
public partial class MainPage : PhoneApplicationPage
{
private WatchViewModel watch;
public MainPage()
{
InitializeComponent();
watch = new WatchViewModel();
watch.GetWatchRows();
watch.AddWatchRow(132, "green");
watch.AddWatchRow(123, "red");
base.DataContext = watch;
listWatch.ItemsSource = watch.WatchRows;
}
private void btn_Click(object sender, RoutedEventArgs e)
{
watch.AddWatchRow(132, "pink");
watch.AddWatchRow(113, "yellow");
}
}