UWP：RichEditBox的高度計算錯誤

Question

我需要根據其內容計算RichEditBox的確切高度。 為此，我使用以下方法，在任何情況下都可以，但是在文本為一行時卻可以！

    public static double GetElemHeight(FrameworkElement elem, double? actualWidth = null)
    {
        if (elem == null)
            return 0;

        // take note of the existing height, if any, since we have to re-establish it later:
        double currentH = elem.Height;
        if (!double.IsNaN(currentH))
            elem.Height = double.NaN;
        double totalW = (actualWidth ?? elem.Width) + elem.Margin.Left + elem.Margin.Right;

        // Measure() only works as expected in this context if the Height is NaN:
        elem.Measure(new Size(totalW, Double.PositiveInfinity));
        Size size = elem.DesiredSize;
        elem.Height = currentH; //re-establish the correct height
        return size.Height - elem.Margin.Top - elem.Margin.Bottom;
    }

基本上，對於RichEditBox中編寫的任何文本，該方法都會返回元素的正確高度。 但是，當我的文本僅覆蓋一行時，結果總是高度幾乎是正確結果的兩倍。

請在此處找到可重現該問題的MVC： https : //github.com/cghersi/UWPExamples/tree/master/SizeOfTextBox

關於我在做什么錯的任何線索嗎？

Answer 1

RichEditBox的默認高度為32px，這意味着當您的實際高度小於32時，它仍顯示32。在樣式上，控制內容的高度為Border，因此應更改Border的MinHeight。 另外，您可以轉到generic.xaml獲得RichEditBox的樣式。

<Page.Resources>
        <Style TargetType="RichEditBox">
            ......
            <Setter Property="SelectionFlyout" Value="{StaticResource TextControlCommandBarSelectionFlyout}"/>
            <Setter Property="Template">
                <Setter.Value>
                    <ControlTemplate TargetType="RichEditBox">
                        <Grid>
                            <Grid.RowDefinitions>
                                <RowDefinition Height="Auto"/>
                                <RowDefinition Height="*"/>
                                <RowDefinition Height="Auto"/>
                            </Grid.RowDefinitions>
                            <VisualStateManager.VisualStateGroups>
                                ......
                            </VisualStateManager.VisualStateGroups>
                            ......
                            <Border x:Name="BorderElement" Background="{TemplateBinding Background}" BorderThickness="{TemplateBinding BorderThickness}" BorderBrush="{TemplateBinding BorderBrush}" CornerRadius="{TemplateBinding CornerRadius}" MinHeight="0" MinWidth="{ThemeResource TextControlThemeMinWidth}" Grid.RowSpan="1" Grid.Row="1"/>
                            ......
                        </Grid>
                    </ControlTemplate>
                </Setter.Value>
            </Setter>
        </Style>
    </Page.Resources>