如何设置行中断直到ActualHeight of RichEditBox？

Question

如果用户单击我的RichEditBox，那么插入指针应该出现在行的开头，而不是字符串的末尾。例如，假设RichEditBox可以包含其Height的5行，因此当用户单击第3行时，插入指针应该位于第3行的开头，而不是在第1行。很难解释我希望你能理解。

为了实现这一点，我认为默认情况下，可以将换行设置为RichEditBox的末尾。

尝试解决方案：

我使用了下面的代码来完成它，但是它没有工作。

var oldActualHeight = PATH_RICH_EDIT_BOX.ActualHeight;
while (PATH_RICH_EDIT_BOX.ActualHeight <= oldActualHeight)
{
    PATH_RICH_EDIT_BOX.Document.GetText(Windows.UI.Text.TextGetOptions.None, out string a);
    PATH_RICH_EDIT_BOX.Document.SetText(Windows.UI.Text.TextSetOptions.None, a + Environment.NewLine);
}

My RichEditBox代码在XAML中

<Page.Resources>
    <Style x:Key="RichEditBoxStyle" TargetType="RichEditBox">
        <Setter Property="MinWidth" Value="{ThemeResource TextControlThemeMinWidth}"/>
        <Setter Property="MinHeight" Value="{ThemeResource TextControlThemeMinHeight}"/>
        <Setter Property="Foreground" Value="{ThemeResource TextControlForeground}"/>
        <Setter Property="Background" Value="{ThemeResource TextControlBackground}"/>
        <Setter Property="SelectionHighlightColor" Value="{ThemeResource TextControlSelectionHighlightColor}"/>
        <Setter Property="FontFamily" Value="{ThemeResource ContentControlThemeFontFamily}"/>
        <Setter Property="FontSize" Value="{ThemeResource ControlContentThemeFontSize}"/>
        <Setter Property="ScrollViewer.HorizontalScrollMode" Value="Auto"/>
        <Setter Property="ScrollViewer.VerticalScrollMode" Value="Auto"/>
        <Setter Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Auto"/>
        <Setter Property="ScrollViewer.VerticalScrollBarVisibility" Value="Auto"/>
        <Setter Property="ScrollViewer.IsDeferredScrollingEnabled" Value="False"/>
        <Setter Property="TextWrapping" Value="Wrap"/>
        <Setter Property="Padding" Value="{ThemeResource TextControlThemePadding}"/>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="RichEditBox">
                    <Grid>
                        <Grid.RowDefinitions>
                            <RowDefinition Height="Auto"/>
                            <RowDefinition Height="*"/>
                        </Grid.RowDefinitions>
                        <ContentPresenter x:Name="HeaderContentPresenter" Grid.ColumnSpan="2" ContentTemplate="{TemplateBinding HeaderTemplate}" Content="{TemplateBinding Header}" Foreground="{ThemeResource TextControlHeaderForeground}" FontWeight="Normal" Margin="0,0,0,8" Grid.Row="0" Visibility="Collapsed" x:DeferLoadStrategy="Lazy"/>
                        <ScrollViewer x:Name="ContentElement" AutomationProperties.AccessibilityView="Raw" HorizontalScrollMode="{TemplateBinding ScrollViewer.HorizontalScrollMode}" HorizontalScrollBarVisibility="{TemplateBinding ScrollViewer.HorizontalScrollBarVisibility}" IsTabStop="False" IsHorizontalRailEnabled="{TemplateBinding ScrollViewer.IsHorizontalRailEnabled}" IsVerticalRailEnabled="{TemplateBinding ScrollViewer.IsVerticalRailEnabled}" IsDeferredScrollingEnabled="{TemplateBinding ScrollViewer.IsDeferredScrollingEnabled}" Margin="{TemplateBinding BorderThickness}" Padding="{TemplateBinding Padding}" Grid.Row="1" VerticalScrollBarVisibility="{TemplateBinding ScrollViewer.VerticalScrollBarVisibility}" VerticalScrollMode="{TemplateBinding ScrollViewer.VerticalScrollMode}" ZoomMode="Disabled" HorizontalAlignment="Stretch" VerticalAlignment="Stretch"/>
                        <ContentControl x:Name="PlaceholderTextContentPresenter" Grid.ColumnSpan="2" Content="{TemplateBinding PlaceholderText}" Foreground="{ThemeResource TextControlPlaceholderForeground}" IsHitTestVisible="False" IsTabStop="False" Margin="{TemplateBinding BorderThickness}" Padding="{TemplateBinding Padding}" Grid.Row="1"/>
                    </Grid>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</Page.Resources>

<Grid Name="MainGrid" Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
    <Grid.RowDefinitions>
        <RowDefinition Height="Auto"/>
        <RowDefinition Height="*"/>
    </Grid.RowDefinitions>
    <StackPanel Orientation="Horizontal">
        <InkToolbar TargetInkCanvas="{x:Bind PATH_INK_CANVAS}"/>
        <Button Name="ChangeButton" Content="Change" Click="ChangeButton_Click"/>
    </StackPanel>
    <ScrollViewer Grid.Row="1" HorizontalScrollBarVisibility="Visible" Visibility="Visible">
        <Grid>
            <InkCanvas Name="PATH_INK_CANVAS" Canvas.ZIndex="-1"/>
            <RichEditBox Name="PATH_RICH_EDIT_BOX" PlaceholderText="Input Text" Style="{StaticResource RichEditBoxStyle}"/>
        </Grid>
    </ScrollViewer>
</Grid>

Answer 1

目前，没有任何这样的api可以获取每一行RichEditBox。因此，如果要将光标移动到行的开头。你可以得到线的起始位置并聚焦它。

最重要的是，您应该获得RichEditBox文档的起点。

public MainPage()
{
    this.InitializeComponent();
    ITextSelection selection = PATH_RICH_EDIT_BOX.Document.Selection;
    selection.StartPosition = 0;
    selection.EndPosition = 0;
    originPoint = new Point();
    selection.GetPoint(HorizontalCharacterAlignment.Left, VerticalCharacterAlignment.Baseline, PointOptions.Start, out originPoint);  
}

对于每个行起点的点，它们都有相同的X。所以你可以根据当前光标的位置得到行的起始点。

private void ChangeButton_Click(object sender, RoutedEventArgs e)
{
    Point point = new Point();
    ITextSelection selection = PATH_RICH_EDIT_BOX.Document.Selection;

    var sta = selection.StartPosition;
    var en = selection.EndPosition;
    selection.GetPoint(HorizontalCharacterAlignment.Left, VerticalCharacterAlignment.Baseline, PointOptions.Start, out point);
    point = new Point(originPoint.X, point.Y);
    var pgformat = selection.ParagraphFormat;
    selection.SetPoint(point, PointOptions.Start, false);
    var start = selection.StartPosition;
    var end = selection.EndPosition;
    PATH_RICH_EDIT_BOX.Document.Selection.SetRange(start, end + 1);
    PATH_RICH_EDIT_BOX.Focus(FocusState.Pointer);
}

请注意，带有一个空格的前一行的结束位置与当前行的起始位置相同。所以你应该用一个长度范围来区分它们。

PATH_RICH_EDIT_BOX.Document.Selection.SetRange(start, end + 1);