WPF ScrollViewer problem

3
votes

I am trying to use a simple ScrollViewer in my program, but I'm having a problem.

If I enclose everything in my program in a ScrollViewer, it works fine:

<Window x:Class="WpfTest.MainWindow"         
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow"
        Name="PrimaryWindow">
    <ScrollViewer>
        <StackPanel>
            <Menu Height="21" VerticalAlignment="Top">
                <MenuItem Header="File"/>
                <MenuItem Header="Edit"/>
            </Menu>
            <StackPanel>
                <TextBlock Text="1"/>
                <TextBlock Text="2"/>
                <TextBlock Text="3"/>
                <TextBlock Text="4"/>
                <TextBlock Text="5"/>
                <TextBlock Text="6"/>
                <TextBlock Text="7"/>
                <TextBlock Text="8"/>
                <TextBlock Text="9"/>
                <TextBlock Text="10"/>
            </StackPanel>
        </StackPanel>
    </ScrollViewer>
</Window>

However, the since the menu is part of the ScrollViewer, the menu scrolls off the screen when the user scrolls down. So I put the ScrollViewer only around the controls under the menu:

<Window x:Class="WpfTest.MainWindow"         
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow"
        Name="PrimaryWindow">
    <StackPanel>
        <Menu Height="21" VerticalAlignment="Top">
            <MenuItem Header="File"/>
            <MenuItem Header="Edit"/>
        </Menu>
        <ScrollViewer>
            <StackPanel>
                <TextBlock Text="1"/>
                <TextBlock Text="2"/>
                <TextBlock Text="3"/>
                <TextBlock Text="4"/>
                <TextBlock Text="5"/>
                <TextBlock Text="6"/>
                <TextBlock Text="7"/>
                <TextBlock Text="8"/>
                <TextBlock Text="9"/>
                <TextBlock Text="10"/>
            </StackPanel>
        </ScrollViewer>
    </StackPanel>
</Window>

But this time, the ScrollViewer doesn't work! i.e. even if I resize my window to be smaller than the height required by the labels, the scrollbar does not get activated.

What am I doing wrong?

3
c#wpfscrollviewer

3 Answers

7
votes

The problem is caused by your root StackPanel, the StackPanel is not constraining the vertical height of the ScrollViewer.

Try using the DockPanel to position the Menu instead:

<Window x:Class="WpfApplication1.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="Window1" Height="300" Width="300">
<DockPanel>
    <Menu DockPanel.Dock="Top" Height="21" VerticalAlignment="Top">
        <MenuItem Header="File"/>
        <MenuItem Header="Edit"/>
    </Menu>
    <ScrollViewer>
        <StackPanel>
            <TextBlock Text="1"/>
            <TextBlock Text="2"/>
            <TextBlock Text="3"/>
            <TextBlock Text="4"/>
            <TextBlock Text="5"/>
            <TextBlock Text="6"/>
            <TextBlock Text="7"/>
            <TextBlock Text="8"/>
            <TextBlock Text="9"/>
            <TextBlock Text="10"/>
        </StackPanel>
    </ScrollViewer>
</DockPanel>

1
votes

ScrollViewer will appear its Bars, only when Height or Width of the Ancestor element changed. So, your Ancestor is StackPanel, and it is not changing the size while you resizing the window.

1
votes

Never use a StackPanel with a ScrollViewer inside it, because the StackPanel is as big as its content wants to be ! So the ScrollViewer thinks it has always enough place !

The scrollViewer must be outside of everything