How to get StackPanel s children to fill maximum space downward

Question

I simply want flowing text on the left  and a help box on the right   The help box should extend all the way to the bottom   If you take out the outer StackPanel below it works great   But for reasons of layout  I m inserting UserControls dynamically  I need to have the wrapping StackPanel   How do I get the GroupBox to extend down to the bottom of the StackPanel  as you can see I ve tried    VerticalAlignment  Stretch  VerticalContentAlignment  Stretch   Height  Auto    XAML    lt Window x Class  TestDynamic033 Test3      xmlns  http   schemas microsoft com winfx 2006 xaml presentation      xmlns x  http   schemas microsoft com winfx 2006 xaml      Title  Test3  Height  300  Width  600  gt       lt StackPanel          VerticalAlignment  Stretch           Height  Auto  gt            lt DockPanel              HorizontalAlignment  Stretch               VerticalAlignment  Stretch               Height  Auto               Margin  10  gt                lt GroupBox                  DockPanel Dock  Right                   Header  Help                   Width  100                   Background  Beige                   VerticalAlignment  Stretch                   VerticalContentAlignment  Stretch                   Height  Auto  gt                   lt TextBlock Text  This is the help that is available on the news screen   TextWrapping  Wrap    gt               lt  GroupBox gt                lt StackPanel DockPanel Dock  Left  Margin  10  Width  Auto  HorizontalAlignment  Stretch  gt                   lt TextBlock Text  Here is the news that should wrap around   TextWrapping  Wrap   gt               lt  StackPanel gt            lt  DockPanel gt       lt  StackPanel gt   lt  Window gt    Answer   Thanks Mark  using DockPanel instead of StackPanel cleared it up  In general  I find myself using DockPanel more and more now for WPF layouting  here s the fixed XAML    lt Window x Class  TestDynamic033 Test3      xmlns  http   schemas microsoft com winfx 2006 xaml presentation      xmlns x  http   schemas microsoft com winfx 2006 xaml      Title  Test3  Height  300  Width  600  MinWidth  500  MinHeight  200  gt       lt DockPanel          VerticalAlignment  Stretch           Height  Auto  gt            lt DockPanel              HorizontalAlignment  Stretch               VerticalAlignment  Stretch               Height  Auto               MinWidth  400              Margin  10  gt                lt GroupBox                  DockPanel Dock  Right                   Header  Help                   Width  100                   VerticalAlignment  Stretch                   VerticalContentAlignment  Stretch                   Height  Auto  gt                   lt Border CornerRadius  3  Background  Beige  gt                       lt TextBlock Text  This is the help that is available on the news screen   TextWrapping  Wrap                    Padding  5   gt                   lt  Border gt               lt  GroupBox gt                lt StackPanel DockPanel Dock  Left  Margin  10  Width  Auto  HorizontalAlignment  Stretch  gt                   lt TextBlock Text  Here is the news that should wrap around   TextWrapping  Wrap   gt               lt  StackPanel gt            lt  DockPanel gt       lt  DockPanel gt   lt  Window gt

User · Answer

The reason that this is happening is because the stack panel measures every child element with positive infinity as the constraint for the axis that it is stacking elements along. The child controls have to return how big they want to be (positive infinity is not a valid return from the MeasureOverride in either axis) so they return the smallest size where everything will fit. They have no way of knowing how much space they really have to fill.

If your view doesn’t need to have a scrolling feature and the answer above doesn't suit your needs, I would suggest implement your own panel. You can probably derive straight from StackPanel and then all you will need to do is change the ArrangeOverride method so that it divides the remaining space up between its child elements (giving them each the same amount of extra space). Elements should render fine if they are given more space than they wanted, but if you give them less you will start to see glitches.

If you want to be able to scroll the whole thing then I am afraid things will be quite a bit more difficult, because the ScrollViewer gives you an infinite amount of space to work with which will put you in the same position as the child elements were originally. In this situation you might want to create a new property on your new panel which lets you specify the viewport size, you should be able to bind this to the ScrollViewer’s size. Ideally you would implement IScrollInfo, but that starts to get complicated if you are going to implement all of it properly.

User · Answer

It sounds like you want a StackPanel where the final element uses up all the remaining space  But why not use a DockPanel  Decorate the other elements in the DockPanel with DockPanel Dock  Top   and then your help control can fill the remaining space   XAML    lt DockPanel Width  200  Height  200  Background  PowderBlue  gt       lt TextBlock DockPanel Dock  Top  gt Something lt  TextBlock gt       lt TextBlock DockPanel Dock  Top  gt Something else lt  TextBlock gt       lt DockPanel         HorizontalAlignment  Stretch           VerticalAlignment  Stretch           Height  Auto           Margin  10  gt          lt GroupBox          DockPanel Dock  Right           Header  Help           Width  100           Background  Beige           VerticalAlignment  Stretch           VerticalContentAlignment  Stretch           Height  Auto  gt           lt TextBlock Text  This is the help that is available on the news screen                       TextWrapping  Wrap    gt        lt  GroupBox gt          lt StackPanel DockPanel Dock  Left  Margin  10              Width  Auto  HorizontalAlignment  Stretch  gt             lt TextBlock Text  Here is the news that should wrap around                         TextWrapping  Wrap   gt         lt  StackPanel gt       lt  DockPanel gt   lt  DockPanel gt    If you are on a platform without DockPanel available  e g  WindowsStore   you can create the same effect with a grid  Here s the above example accomplished using grids instead    lt Grid Width  200  Height  200  Background  PowderBlue  gt       lt Grid RowDefinitions gt           lt RowDefinition Height  Auto   gt           lt RowDefinition Height      gt       lt  Grid RowDefinitions gt       lt StackPanel Grid Row  0  gt           lt TextBlock gt Something lt  TextBlock gt           lt TextBlock gt Something else lt  TextBlock gt       lt  StackPanel gt       lt Grid Height  Auto  Grid Row  1  Margin  10  gt           lt Grid ColumnDefinitions gt               lt ColumnDefinition Width      gt               lt ColumnDefinition Width  100   gt           lt  Grid ColumnDefinitions gt           lt GroupBox             Width  100              Height  Auto              Grid Column  1              Background  Beige              Header  Help  gt               lt TextBlock Text  This is the help that is available on the news screen                  TextWrapping  Wrap   gt           lt  GroupBox gt           lt StackPanel Width  Auto  Margin  10  DockPanel Dock  Left  gt               lt TextBlock Text  Here is the news that should wrap around                  TextWrapping  Wrap   gt           lt  StackPanel gt       lt  Grid gt   lt  Grid gt

User · Answer

You can use SpicyTaco AutoGrid - a modified version of StackPanel    lt st StackPanel Orientation  Horizontal  MarginBetweenChildren  10  Margin  10  gt      lt Button Content  Info  HorizontalAlignment  Left  st StackPanel Fill  Fill   gt      lt Button Content  Cancel   gt      lt Button Content  Save   gt   lt  st StackPanel gt    First button will be fill   You can install it via NuGet   Install-Package SpicyTaco AutoGrid   I recommend taking a look at SpicyTaco AutoGrid  It s very useful for forms in WPF instead of DockPanel   StackPanel and Grid and solve problem with stretching very easy and gracefully  Just look at readme on GitHub    lt st AutoGrid Columns  160    ChildMargin  3  gt       lt Label Content  Name    gt       lt TextBox  gt        lt Label Content  E-Mail    gt       lt TextBox  gt        lt Label Content  Comment    gt       lt TextBox  gt   lt  st AutoGrid gt

User · Answer

An alternative method is to use a Grid with one column and n rows   Set all the rows heights to Auto  and the bottom-most row height to 1    I prefer this method because I ve found Grids have better layout performance than DockPanels  StackPanels  and WrapPanels   But unless you re using them in an ItemTemplate  where the layout is being performed for a large number of items   you ll probably never notice

[wpf] How to get StackPanel's children to fill maximum space downward?

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