BerndKraemer

BerndKraemer

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Recent Comments

  • WPF Tutorial - Using An ItemsPanel
    02/25/2009 - 12:12

    I have used the same technique (supplying a WrapPanel or a UniformGrid for displaying a number of images in a ListBox), with the possibility to set the number of visible rows and columns in the ScrollViewer inside the ListBox.
    My question is: how can I scroll in discrete steps, i.e. per whole item instead of the smooth scrolling that I get by default? (I also changed the setting of the scroll wheel in the Windows configuration to scroll 1 line at a time. For the normal VirtualStackPanel this works fine, but I need multiple columns of images).

    Some code snippets from my experiment. I edited the generic.xaml for my own special ListBox.

    <Setter Property="Template">
       <Setter.Value>
          <ControlTemplate
            TargetType="{x:Type MyListBox}">
             <Border x:Name="Bd">
                <ScrollViewer
                  CanContentScroll="True"
                  VerticalContentAlignment="Top"
                  HorizontalContentAlignment="Left"
                  HorizontalScrollBarVisibility ="Disabled">
                   <ItemsPresenter
                     VerticalAlignment="Top"
                     HorizontalAlignment="Stretch"
                     Width="Auto"/>
                   </ScrollViewer>
               </Border>
           </ControlTemplate>
       </Setter.Value>
    </Setter>

    And in C# I created the UniformGrid to fit an exact number of visible rows and columns of images inside the scrollviewer of the listbox:

    // Create a matrix layout for the total number of images
    FrameworkElementFactory uGrid =
        new FrameworkElementFactory(typeof(UniformGrid));
    uGrid.SetValue(UniformGrid.ColumnsProperty, totalCols);
    uGrid.SetValue(UniformGrid.RowsProperty, totalRows);

    // show only a submatrix of images in the listbox
    double width = this.ActualWidth * totalCols / visibleCols;
    double height = this.ActualHeight * totalRows / visibleRows;
    uGrid.SetValue(UniformGrid.WidthProperty, width);
    uGrid.SetValue(UniformGrid.HeightProperty, height);

    this.ItemsPanel = new ItemsPanelTemplate(uGrid);

    How can I scroll the images row by row and column by column? Or maybe there are more convenient ways to do this... Thanks in advance for your answer! - Bernd -

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