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我在DispatcherTimer占用太多资源时遇到了麻烦。我希望有人能帮帮忙。

我正在使用 XAML 在屏幕上显示项目列表。列表的每一行都有一个用于修改该行信息的按钮。后面的代码需要判断列表的哪一行被点击了。这是正在分解的代码的神奇部分：

int row_index = DataGridRow.GetRowContainingElement(sender as FrameworkElement).GetIndex();

有时时间 row_index 设置正确，有时它返回 -1。为什么它不总是返回正确的索引？更令我沮丧的是，我可以使用调试器在 DataGridRow 结构中看到正确的索引。正确的索引在那里，但GetIndex()有时仍返回 -1。

接口代码：

<Window x:Class="WhyNoButtonClick.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="WhyNoButtonClick" Height="265" Width="306">
    <Grid Margin="0,0,0,1">
        <StackPanel Height="192" VerticalAlignment="Top">
            <DataGrid x:Name="dg_driver_list" AutoGenerateColumns="False" Height="186">
                <DataGrid.Columns>
                    <DataGridTemplateColumn Header="Name">
                        <DataGridTemplateColumn.CellTemplate>
                            <DataTemplate>
                                <Label x:Name="col_driver_name" Content="{Binding Name}" TextBlock.LineStackingStrategy="BlockLineHeight" TextBlock.LineHeight="5" FontSize="12"/>
                            </DataTemplate>
                        </DataGridTemplateColumn.CellTemplate>
                    </DataGridTemplateColumn>
                    <DataGridTemplateColumn Header="Time remaining">
                        <DataGridTemplateColumn.CellTemplate>
                            <DataTemplate>
                                <Label x:Name="col_driver_time_remain" Content="{Binding TimeRemain}" TextBlock.LineStackingStrategy="BlockLineHeight" TextBlock.LineHeight="5" FontSize="12"/>
                            </DataTemplate>
                        </DataGridTemplateColumn.CellTemplate>
                    </DataGridTemplateColumn>
                    <DataGridTemplateColumn Header="Action button">
                        <DataGridTemplateColumn.CellTemplate>
                            <DataTemplate>
                                <Button x:Name="btn_driver_hit" PreviewMouseDown="btn_driver_hit_Click" Content="Hit" Height="20" TextBlock.LineStackingStrategy="BlockLineHeight" TextBlock.LineHeight="5" FontSize="12"/>
                            </DataTemplate>
                        </DataGridTemplateColumn.CellTemplate>
                    </DataGridTemplateColumn>
                </DataGrid.Columns>
            </DataGrid>
        </StackPanel>
        <StackPanel Margin="105,192,105,10">
            <Button x:Name="btn_pause_active" Content="Start/Pause" ToolTip="Start/Pause stopwatches for all active drivers" Height="22" Click="btn_start_pause_active_Click"/>
        </StackPanel>
    </Grid>
</Window>

代码隐藏：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Windows;
using System.Windows.Controls;
using System.Diagnostics;
using System.Windows.Threading;
using System.Windows.Media;

namespace WhyNoButtonClick
{
    public partial class MainWindow : Window
    {
        // ### Modify this to increase or decrease the chances of getting the correct index.
        TimeSpan screen_refresh_delay = new TimeSpan(0, 0, 0, 0, 025);

        DispatcherTimer update_timer_dispatch = new DispatcherTimer(DispatcherPriority.Normal);
        List<Stopwatch> driver_hit_timer_watches = new List<Stopwatch>();
        List<Participant> driver_list = new List<Participant>();
        SolidColorBrush color_red = new SolidColorBrush(Color.FromRgb(255, 0, 0));  // Red
        SolidColorBrush color_black = new SolidColorBrush(Color.FromRgb(0, 0, 0));  // Black

        TimeSpan hit_timer = new TimeSpan(0, 0, 60);
        TimeSpan time_almost_up = new TimeSpan(0, 0, 0, 59);
        TimeSpan time_remaining = new TimeSpan(0, 0, 0);

        public MainWindow()
        {
            InitializeComponent();

            Label driver_name_01 = new Label();
            Label driver_time_remain_01 = new Label();
            driver_name_01.Content = "adam (1)";

            Label driver_name_02 = new Label();
            Label driver_time_remain_02 = new Label();
            driver_name_02.Content = "ben (2)";

            Label driver_name_03 = new Label();
            Label driver_time_remain_03 = new Label();
            driver_name_03.Content = "chad (3)";

            driver_list.Add(new Participant(0, driver_name_01, driver_time_remain_01));
            driver_list.Add(new Participant(1, driver_name_02, driver_time_remain_02));
            driver_list.Add(new Participant(2, driver_name_03, driver_time_remain_03));

            for (Int16 driver_index = 0; driver_index < driver_list.Count; driver_index++)
            {
                driver_hit_timer_watches.Add(new Stopwatch());
                driver_hit_timer_watches[driver_index].Stop();
                driver_hit_timer_watches[driver_index].Reset();
            }

            dg_driver_list.ItemsSource = driver_list;

            update_timer_dispatch.Interval = screen_refresh_delay;
            update_timer_dispatch.Tick += new EventHandler(update_timer_dispatch_tick);
            update_timer_dispatch.Start();
        }

        void update_timer_dispatch_tick(object sender, EventArgs e)
        {
            for (Int16 driver_index = 0; driver_index < driver_hit_timer_watches.Count; driver_index++)
            {
                time_remaining = hit_timer - driver_hit_timer_watches[driver_index].Elapsed;

                if (time_remaining.CompareTo(time_almost_up) < 0)
                {
                    driver_list[driver_index].Name.Foreground = color_black;
                    driver_list[driver_index].TimeRemain.Foreground = color_black;
                }

                driver_list[driver_index].TimeRemain.Content = String.Format("{0:0}:{1:00}.{2:0}", time_remaining.Minutes.ToString(), time_remaining.Seconds.ToString(), (time_remaining.Milliseconds / 100).ToString());
            }

            dg_driver_list.Items.Refresh();
        }

        private void btn_driver_hit_Click(object sender, RoutedEventArgs e)
        {
            int row_index = DataGridRow.GetRowContainingElement(sender as FrameworkElement).GetIndex();
            if (row_index > -1)
            {
                driver_list[row_index].Name.Foreground = color_red;
                driver_list[row_index].TimeRemain.Foreground = color_red;
                if (driver_hit_timer_watches[row_index].IsRunning)
                {
                    driver_hit_timer_watches[row_index].Restart();
                }
                else
                {
                    driver_hit_timer_watches[row_index].Reset();
                }
            }
            else
            {
                // I need to know what row to modify but don't have an index!
                // ### Debug - Breakpoint here.
                DataGridRow myrow = DataGridRow.GetRowContainingElement(sender as FrameworkElement);
                int myindex = myrow.GetIndex();
            }
        }

        private void btn_start_pause_active_Click(object sender, RoutedEventArgs e)
        {
            for (Int16 driver_index = 0; driver_index < driver_hit_timer_watches.Count; driver_index++)
            {
                if (driver_hit_timer_watches[driver_index].IsRunning)
                {
                    driver_hit_timer_watches[driver_index].Stop();
                }
                else
                {
                    driver_hit_timer_watches[driver_index].Start();
                }
            }
        }
    }

    public class Participant
    {
        public Int16 Index { get; set; }
        public Label Name { get; set; }
        public Label TimeRemain { get; set; }

        public Participant(Int16 index, Label name, Label timeRemain)
        {
            this.Index = index;
            this.Name = name;
            this.TimeRemain = timeRemain;
        }
    }
}

有任何想法吗？

注意：在代码中搜索“###”（三重磅）以查看我放置断点的位置。

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1 回答 1

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我想我明白了。我在 btn_driver_hit_Click 中使用了它：

DataGridRow dgr_test = DataGridRow.GetRowContainingElement(sender as FrameworkElement);
Participant one_participant = (Participant)dgr_test.Item;
int row_index = one_participant.Index;
if (row_index > -1)

从列表中获取参与者并使用该索引。

于 2014-01-15T04:57:41.793 回答