WPF RichTextBox滚动条自动滚动实例、文本自动滚动实例

说明：
1.后台代码添加测试 数据

2.使用 richTextBox.ScrollToVerticalOffset()方法，滚动竖直方向滚动条位置

3.使用定时器DispatcherTimer，修改页面显示数据

4.自己计算处理，已经滚动的高度位置

Xaml代码：

<Grid>
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="205*"/>
        <ColumnDefinition Width="87*"/>
    </Grid.ColumnDefinitions>
    <Button x:Name="button" Content="开始播放"
            HorizontalAlignment="Left" Margin="2,36,0,0" VerticalAlignment="Top" Width="75" Grid.Column="1" Height="29" Click="button_Click"/>
    <RichTextBox x:Name="richTextBox" 
                    HorizontalAlignment="Left" Height="209" Margin="10,36,0,0" VerticalAlignment="Top" Width="170">
    </RichTextBox>
</Grid>

后台添加测试数据代码：

public text4()
{
    InitializeComponent();

    richTextBox.Document = doc;
    richTextBox.FontSize = 20;
    //添加内容
    appendLine(null, "从你的全世界路过");
    appendLine("one", "海上生明月");
    appendLine(null, "从你的全世界路过");
    appendLine(null, "天涯共此时");
    appendLine("two", "张三丰");
    appendLine(null, "从你的全世界路过");
    appendLine(null, "鲁迅先生");
    appendLine(null,null);
}
FlowDocument doc = new FlowDocument();
private void appendLine(string name, string line)
{
    Paragraph p = new Paragraph();
    if (string.IsNullOrEmpty(name) == false)
        doc.RegisterName(name, p);
    Run r = new Run(line);
    p.TextAlignment = TextAlignment.Center;
    p.Inlines.Add(r);
    doc.Blocks.Add(p);
}

定时器显示控制代码：

int pIndex = 0;
double curTop = 0;
private void button_Click(object sender, RoutedEventArgs e)
{
    //定时控制内容显示和滚动条位置
    DispatcherTimer _timer = new DispatcherTimer();
    _timer.Interval = TimeSpan.FromSeconds(1);
    _timer.Tick += (st, et) =>
    {
        //获取指定行的内容
        BlockCollection col = richTextBox.Document.Blocks;
        int index = 0;
        TextElement prev = null;
        foreach (TextElement item in col)
        {
            //修改当前行的样式
            if (index == pIndex)
            {
                AlterStyle(item, prev);
            }
            index++;
            prev = item;
        }
        pIndex++;
    };
    _timer.Start();
}
private void AlterStyle(TextElement item, TextElement prev)
{
    //当前行
    Paragraph cP = item as Paragraph;
    cP.Foreground = Brushes.Red;
    TextRange range = new TextRange(cP.ContentStart, cP.ContentEnd);
    //滚动位置控制
    if (pIndex > 0 && range.Text.Length > 0)
    {
        //上一行，样式回调
        if (prev != null)
        {
            prev.Foreground = Brushes.Black;
        }
        curTop += range.Text.Length > 7 ? 40 : 20;
        curTop += 20;
        richTextBox.ScrollToVerticalOffset(curTop);
    }
}

运行结果：