WPF为什么我的Line对象没有改变位置?

时间:2017-12-08 15:23:47

标签: c# wpf xaml ivalueconverter valueconverter

我想在图形中显示两条水平线。线的位置取决于一些数据。 因此我创建了一个ValueConverter(基本上是int的两倍)。问题是,线总是显示在相同的位置。

我必须关注XAML:

    <Window
            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:local="clr-namespace:CGM_Auswertung"
            xmlns:chartingToolkit="clr-namespace:System.Windows.Controls.DataVisualization.Charting;assembly=System.Windows.Controls.DataVisualization.Toolkit" x:Class="CGM_Auswertung.MainWindow"
            mc:Ignorable="d"
            Title="MainWindow" Height="780" Width="1300" Loaded="Window_Loaded">
        <Window.Resources>
            <local:DoubleToPositionConverter x:Key="DtPConverter"/>
        </Window.Resources>
        <Grid Name="MainGrid">
            <StackPanel Margin="10" Orientation="Vertical">
                <Button Name="OpenFile" Content="Öffnen" Height="30" Margin="550,0" Click="OpenFile_Click"/>
                <Grid x:Name="drawGrid" >
                    <TextBox Height="30" Width="40" HorizontalAlignment="Left" VerticalAlignment="Top" Text="{Binding OptMinimum}"/>
                    <Frame x:Name="drawFrame" HorizontalAlignment="Left" Height="420" Margin="40,10,10,50" VerticalAlignment="Top" Width="1210" BorderBrush="Black" BorderThickness="3">
                        <Frame.Content>
                            <Grid Name="contentGrid" Background="Transparent" >
                                <Line x:Name="MinLine" Stroke="Red" StrokeThickness="2" StrokeDashArray="2,2" X1="0" X2="1200" Y1="{Binding OptMinimum, Converter={StaticResource DtPConverter}}" Y2="{Binding OptMinimum, Converter={StaticResource DtPConverter}}"/>
                                <Line x:Name="MaxLine" Stroke="Red" StrokeThickness="2" StrokeDashArray="2,2" X1="0" X2="1200" Y1="{Binding OptMaximum, Converter={StaticResource DtPConverter}}" Y2="{Binding OptMaximum, Converter={StaticResource DtPConverter}}"/>
                                <Grid Name="vertLineGrid" MouseMove="tempLineGrid_MouseMove" Background="Transparent" HorizontalAlignment="Center" VerticalAlignment="Center" Height="394" Width="1183" MouseUp="ReleaseSelectedItem"/>
                            </Grid>
                        </Frame.Content>
...

这是转换器:

namespace CGM_Auswertung
{
    public class ViewModelBase : INotifyPropertyChanged
    {
        public event PropertyChangedEventHandler PropertyChanged;

        public void OnPropertyChanged(PropertyChangedEventArgs e)
        {
            PropertyChanged?.Invoke(this, e);
        }
    }

    public class ViewModel : ViewModelBase
    {
        ...

        private double _optMinimum;
        public double OptMinimum
        {
            get { return _optMinimum; }
            set
            {
                _optMinimum = value;
                OnPropertyChanged(new PropertyChangedEventArgs("OptMinimum"));
            }
        }

        private double _optMaximum;
        public double OptMaximum
        {
            get { return _optMaximum; }
            set
            {
                _optMaximum = value;
                OnPropertyChanged(new PropertyChangedEventArgs("OptMaximum"));
            }
        }


    }

    public class DoubleToPositionConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            return (int)(Math.Abs(400 - (double)value * 20));
        }

        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            return (double)(Math.Abs((double)value / 20 - 400 / 20));
        }
    }
}

我也在转换器之前尝试过这个:

[ValueConversion(typeof(double),typeof(int))]

但它没有改变任何东西 这是我的计划的开始:

namespace CGM_Auswertung
{
    /// <summary>
    /// Interaktionslogik für MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {

        private List<CGM_Measurement> completeMeasures = new List<CGM_Measurement>();       
        private ViewModel mvm = new ViewModel() { MinimalValue = 0, MaximalValue=0, ActualValue=0};
        private UIElement selectedItem = null;

        public MainWindow()
        {
            mvm.FirstDay = mvm.LastDay = DateTime.Today;
            mvm.OverviewText = "Switch to day view";
            mvm.Visual = Visibility.Visible;
            mvm.VisualInverse = Visibility.Collapsed;
            mvm.OptMinimum = 2.0;
            mvm.OptMaximum = 3.0;

            InitializeComponent();

            MainGrid.DataContext = mvm;

        }

我猜问题是在xaml中的某个地方,因为当我在转换器中设置断点时,转换永远不会被调用。

我想因为转换非常简单,我可以在viewmodel中使用另一个属性。但由于我还在学习WPF,我想用一个值转换器来做。

感谢您的帮助。

1 个答案:

答案 0 :(得分:2)

Frame不继承父容器的DataContext(在this SO post中解释)。因此contentGrid缺少其绑定的来源。因此,绑定不会被解析,并且不会调用转换器。尝试使用ContentControl替换Frame或完全删除它