在插入点将“ FontWeightProperty”设置为BOLD

Question

I use to make decoration toggle button for my rich text box in wpf my XAML code for button is :

<ToggleButton x:Name="TbtnBold" HorizontalAlignment="Right" Height="24" Margin="0,84,318,0" VerticalAlignment="Top" Width="24" Click="ToggleButton_Click">
        <Image RenderOptions.BitmapScalingMode="Fant" Source="Pics/Icons/bold.png" Width="15" Height="15"/>
        </ToggleButton>

and I wrote this code in VS for "ToggleButton_Click" event :

if (TbtnBold.IsChecked == true)
            {
                if (richTxtBoxQ.Selection.GetPropertyValue(Run.FontWeightProperty) is FontWeight && ((FontWeight)richTxtBoxQ.Selection.GetPropertyValue(Run.FontWeightProperty)) == FontWeights.Normal)
                    richTxtBoxQ.Selection.ApplyPropertyValue(Run.FontWeightProperty, FontWeights.Bold);
                else
                    richTxtBoxQ.Selection.ApplyPropertyValue(Run.FontWeightProperty, FontWeights.Normal); 
            if (TbtnBold.IsChecked == false)                                                      
            {
                if (richTxtBoxQ.Selection.GetPropertyValue(Run.FontWeightProperty) is FontWeight && ((FontWeight)richTxtBoxQ.Selection.GetPropertyValue(Run.FontWeightProperty)) == FontWeights.Bold)
                    richTxtBoxQ.Selection.ApplyPropertyValue(Run.FontWeightProperty, FontWeights.Normal);
                else
                    richTxtBoxQ.Selection.ApplyPropertyValue(Run.FontWeightProperty, FontWeights.Bold);
            }

and this for when user click somewhere in the rich text box the toggle button change according to what is the clicked text font weight is :

private void richTxtBoxQ_SelectionChanged(object sender, RoutedEventArgs e)
    {
        if (richTxtBoxQ.Selection.GetPropertyValue(Run.FontWeightProperty) is FontWeight && ((FontWeight)richTxtBoxQ.Selection.GetPropertyValue(Run.FontWeightProperty)) == FontWeights.Normal)
        {
            TbtnBold.IsChecked = false;
        }
        else
        {
            TbtnBold.IsChecked = true;
        }
    }

all the thing work fine you can bold selection text and insertion point at the end of line BUT when you change the carter position to the middle of the text and change toggle button to make insertion bold all the text get bold and vice versa. I search for long time but no answer can help me to make the insertion point font weight bold without changing other text.THX for your helps

Answer 1

Its not changing the entire text just the work that has caret and I think that is how it is intended to work.

if you check for if(richTxtBoxQ.Selection.IsEmpty) before applying the text decoration you can get rid of the issue.