单击时更改文本块文本

本文关键字：文本 单击 | 更新日期: 2023-09-27 18:35:08

我里面有一个<Border>，我有一个<Image>和一个<Textblock>，我正在尝试向下更改鼠标左按钮上的文本块文本，因为在此单击事件中有一些更冗长的操作，文本块的文本在此操作完成之前不会更改。

我也尝试了Dispatcher.BeginInvoke()，但没有成功。

这是我的代码： 

<Border x:Name="btnReadMe" Grid.Row="0" Style="{StaticResource BorderStyle1}" MouseLeftButtonDown="btnReadMe_MouseLeftButtonDown" MouseLeftButtonUp="btnReadMe_MouseLeftButtonUp" >
    <Border.Background>
        <LinearGradientBrush StartPoint="0.5,0" EndPoint="0.5,1">
            <GradientStop Color="#46c746" Offset="0"/>
            <GradientStop Color="#129312" Offset="1"/>
        </LinearGradientBrush>
    </Border.Background>
    <Grid>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="3*"/>
            <ColumnDefinition Width="6*"/>
        </Grid.ColumnDefinitions>
        <Image Grid.Column="0" Source="/CareFamily.AtHome;component/Resources/read_message-read_it.png" Margin="5,15" >
            <Image.RenderTransform>
                <ScaleTransform ScaleX="1" ScaleY="1"/>
            </Image.RenderTransform>
        </Image>
        <StackPanel Grid.Column="1" Margin="0,10,0,10"  VerticalAlignment="Center">
            <TextBlock Name="tbReadToMe" Text="Read to Me" Style="{StaticResource TextBlockStyle1}" Margin="0,0,0,0"  />
        </StackPanel>
    </Grid>
</Border>

SpVoice voice;
private void btnReadMe_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
    if (voice == null)
        voice = new SpVoice();

    string readMessageState = tbReadToMe.Text;
    switch (readMessageState)
    {
        case "Read to Me":
            {
                tbReadToMe.Text = "Pause";
                break;
            }
        case "Pause":
            {
                tbReadToMe.Text = "Resume";
                voice.Pause();
                break;
            }
        case "Resume":
            {
                tbReadToMe.Text = "Pause";
                voice.Resume();
                break;
            }
        default:
            {
                tbReadToMe.Text = "Read to Me";
                break;
            }
    }

    if (!string.IsNullOrEmpty(Msg.Subject))
    {
        voice.Speak(Msg.Subject, SpeechVoiceSpeakFlags.SVSFDefault);
    }
    if (!string.IsNullOrEmpty(Msg.Body))
    {
        voice.Speak(Msg.Body, SpeechVoiceSpeakFlags.SVSFDefault); // Length operation
    }
}

单击时更改文本块文本

在线程上执行冗长的操作并使用

调度

以相应地更新 UI。

示例代码：

var opThread = new Thread(delegate()
{
    //your lengthy operation
    tbReadToMe.Dispatcher.Invoke(new Action(delegate
    {
        tbReadToMe.Text = "Pause";
    }));
    //your lengthy operation
    tbReadToMe.Dispatcher.Invoke(new Action(delegate
    {
        tbReadToMe.Text = "etc...";
    }));
});
opThread.Start();

Dispatcher.BeginInvoke（） 没有帮助的原因是，即使它以非常规方式运行，它仍然在 main/UI 线程上执行此操作。使用 BackgroundWorkerThread 类在后台线程上执行冗长的操作。

我做了一个小样本来演示：

窗口 1.xaml：

<Window x:Class="BackgroundWorkerExample.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="Window1" Height="300" Width="663">
<Grid>
    <TextBox PreviewMouseDown="textBox1_PreviewMouseDown" Height="38" Margin="24,34,26,0" Name="textBox1" VerticalAlignment="Top" FontSize="24">
        The quick Velociraptor jumped over the torpid tapir.
    </TextBox>
</Grid>

窗口1.xaml.cs：

using System.Windows;
using System.Windows.Input;
using System.ComponentModel;
using System.Threading;
using System.Windows.Media;
using System;
namespace BackgroundWorkerExample
{
    public partial class Window1 : Window
    {
        public Window1()
        {
            InitializeComponent();
        }

        void _asyncSpeakerThread_DoWork(object sender, DoWorkEventArgs e)
        {
            // Change color of text to Red to indicate Start of operation
            this.Dispatcher.BeginInvoke(new Action(() =>  { textBox1.Foreground = Brushes.Red; }));
            string text = e.Argument as string;
            //voice.Speak(text, SpeechVoiceSpeakFlags.SVSFDefault); // Lengthy operation 
            Thread.Sleep(1000); // Simulate lengthy operation
            // Change color of text to Black to indicate End of operation
            this.Dispatcher.BeginInvoke(new Action(() => { textBox1.Foreground = Brushes.Black; }));
        }
        private void textBox1_PreviewMouseDown(object sender, MouseButtonEventArgs e)
        {
            BackgroundWorker bw = new BackgroundWorker();
            bw.DoWork += new DoWorkEventHandler(_asyncSpeakerThread_DoWork);
            string workerArgument = textBox1.Text;
            bw.RunWorkerAsync(workerArgument);
        }
    }
}

在"冗长"操作之前使用Application.DoEvents()！

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