在数据模板中，鼠标移动时更新图像源（视频缩略图）

Question

我想在MouseMove事件触发时更新Image的来源：

<DataTemplate>
...
 <Viewbox  MaxWidth="100" MaxHeight="100" >
  <Image x:Name="Vignette0" Source="{Binding Vignette}" MouseMove="Vignette0_OnMouseMove"/>
 </Viewbox>
</DataTemplate>

[2]
<Image.Style>
 <Style TargetType="Image">
  <Style.Triggers>
   <DataTrigger Binding="{Binding xxxx}" Value="true">
    <Setter Property="Source" Value="{Binding Vignette}" />
   </DataTrigger>
  </Style.Triggers>
 </Style>
</Image.Style>

其中Vignette 是具有通知更改的属性。

• 我尝试 [2] 用 style.triggers (Change image using trigger WPF MVVM) 计算出一些东西，但在我的情况下，源是动态绑定（数据模板）
• 我无法将 MouseMove 放入 xxxx 的 Binding 中
• 我也尝试使用代码隐藏做一些事情，但我无法弄清楚。

有人有想法吗？

原始 XAML 代码：

<DataGrid x:Name="DgTest" ItemsSource="{Binding Evm.RawImagesCollectionView}" AutoGenerateColumns="false"
                      SelectedItem="{Binding Evm.SelectedImage}">
                <DataGrid.GroupStyle>
                    <GroupStyle>
                        <GroupStyle.HeaderTemplate>
                            <DataTemplate>
                                <StackPanel>
                                    <TextBlock Text="{Binding Path=ParentDir}" />
                                </StackPanel>
                            </DataTemplate>
                        </GroupStyle.HeaderTemplate>
                        <GroupStyle.ContainerStyle>
                            <Style TargetType="{x:Type GroupItem}">
                                <Setter Property="Template">
                                    <Setter.Value>
                                        <ControlTemplate TargetType="{x:Type GroupItem}">
                                            <Expander>
                                                <Expander.Header>
                                                    <StackPanel Orientation="Horizontal">
                                                        <TextBlock Text="{Binding Path=ParentDir}" />
                                                        <TextBlock Text="{Binding Path=ItemCount}"/>
                                                        <TextBlock Text=" images"/>
                                                    </StackPanel>
                                                </Expander.Header>
                                                <ItemsPresenter />
                                            </Expander>
                                        </ControlTemplate>
                                    </Setter.Value>
                                </Setter>
                            </Style>
                        </GroupStyle.ContainerStyle>
                    </GroupStyle>
                </DataGrid.GroupStyle>
                <DataGrid.Columns>
                    <DataGridTextColumn Header="Name" Binding="{Binding Name}" IsReadOnly="True"/>
                    <DataGridTextColumn Header="#frames" Binding="{Binding NumberOfFrames}" IsReadOnly="True"/>
                    <DataGridTextColumn Header="#bg" Binding="{Binding NumberOfBackgrounds}" IsReadOnly="True"/>
                    <DataGridTextColumn Header="path" Binding="{Binding ParentDir}" IsReadOnly="True"/>
                    <DataGridTemplateColumn Header="action">
                        <DataGridTemplateColumn.CellTemplate>
                            <DataTemplate>
                                <StackPanel Orientation="vertical" VerticalAlignment="Center">
                                    <StackPanel Orientation="Horizontal">
                                        <Button Content="prepare" Command="{Binding DecodeCommand}" Height="24"/>
                                        <ProgressBar Minimum="0" Maximum="1.00" Value="{Binding PercentDone}" Width="40" Height="24"/>
                                    </StackPanel>
                                    <Viewbox  MaxWidth="100" MaxHeight="100" >
                                        <Image x:Name="VignetteViewBox0" Source="{Binding Vignette}" MouseMove="VignetteViewBox0_OnMouseMove">
                                            <Image.Style>
                                                <Style TargetType="Image">
                                                    <Style.Triggers>
                                                        <DataTrigger Binding="{Binding }" Value="true">
                                                            <Setter Property="Source" Value="{Binding Vignette}" />
                                                        </DataTrigger>
                                                    </Style.Triggers>
                                                </Style>
                                            </Image.Style>
                                        </Image>
                                    </Viewbox>
                                </StackPanel>
                            </DataTemplate>
                        </DataGridTemplateColumn.CellTemplate>
                    </DataGridTemplateColumn>
                </DataGrid.Columns>
            </DataGrid>

属性Vignette：

public BitmapImage Vignette
{
    get
    {
        if (NumberOfFrames > 0)
        {
            var files = Directory.GetFiles(Filedir, "out*");
            if (files.Length >= 5)
                VignetteNumber = VignetteNumber != 5 ? 5 : _rgen.Next(0, files.Length);
            else
                VignetteNumber = _rgen.Next(0, files.Length);
            var filepath = files[VignetteNumber];
            var buffer = new BitmapImage();
            using (Stream imageStreamSource = new FileStream(filepath,
                FileMode.Open, FileAccess.Read, FileShare.Read))
            {
                buffer.BeginInit();
                buffer.CacheOption = BitmapCacheOption.OnLoad;
                buffer.StreamSource = imageStreamSource;
                buffer.EndInit();
            }
            return buffer;
        }
        return null;
    }
}

Answer 1

这是您尝试实现的功能的工作示例。 确保更改视图模型中的常量以引用您有一些 BMP 进行测试的目录。
祝你有美好的一天:)

MainWindow.xaml

<Window x:Class="WpfApplication13.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:local="clr-namespace:WpfApplication13"
        mc:Ignorable="d"
        Title="MainWindow" Height="350" Width="525" d:DataContext="{d:DesignInstance local:VmMainWindow, IsDesignTimeCreatable=True}">
    <Grid>
        <DataGrid x:Name="dataGrid" ItemsSource="{Binding Items}" AutoGenerateColumns="false">
            <DataGrid.Columns>
                <DataGridTextColumn Header="Name" Binding="{Binding Name}" IsReadOnly="True" Width="150"/>
                <DataGridTemplateColumn Header="BMP" Width="150" IsReadOnly="False">
                    <DataGridTemplateColumn.CellTemplate>
                        <DataTemplate DataType="local:VmItemInGrid">
                            <Viewbox  MaxWidth="100" MaxHeight="100">
                                <Image Source="{Binding BMP}" MouseEnter="Image_MouseEnter" />
                            </Viewbox>
                        </DataTemplate>
                    </DataGridTemplateColumn.CellTemplate>
                </DataGridTemplateColumn>
            </DataGrid.Columns>
        </DataGrid>
    </Grid>
</Window>

MainWindow.xaml.cs（代码隐藏）

using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;

namespace WpfApplication13
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            DataContext = new VmMainWindow();
        }

        private void Image_MouseEnter(object sender, MouseEventArgs e)
        {
            ((VmItemInGrid)((Image)sender).DataContext).GetNextFile();
        }
    }
}

视图模型部件

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.IO;
using System.Windows.Media.Imaging;

namespace WpfApplication13
{
    public class VmMainWindow : INotifyPropertyChanged
    {
        public event PropertyChangedEventHandler PropertyChanged;

        public List<VmItemInGrid> Items { get; }

        public VmMainWindow()
        {
            Items = new List<VmItemInGrid>
            {
                new VmItemInGrid {Name = "Item1"},
                new VmItemInGrid {Name = "Item2"},
                new VmItemInGrid {Name = "Item3"}
            };
        }
    }

    public class VmItemInGrid : INotifyPropertyChanged
    {
        private const string generalBmpPath = @"C:\Users\Gil\Pictures\TestBMPs\";

        public event PropertyChangedEventHandler PropertyChanged;

        private string filepath;

        public VmItemInGrid()
        {
            GetNextFile();
        }

        public string Name { get; set; }

        public BitmapImage BMP
        {
            get
            {
                var buffer = new BitmapImage();
                using (Stream imageStreamSource = new FileStream(filepath,
                    FileMode.Open, FileAccess.Read, FileShare.Read))
                {
                    buffer.BeginInit();
                    buffer.CacheOption = BitmapCacheOption.OnLoad;
                    buffer.StreamSource = imageStreamSource;
                    buffer.EndInit();
                }
                return buffer;
            }
        }

        public void GetNextFile()
        {
            var allFiles = Directory.GetFiles(generalBmpPath, "*.bmp");
            var random = new Random();
            var index = random.Next(allFiles.Length);
            filepath = allFiles[index];
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(BMP)));
        }
    }
}