I have the following scenario:
<ScrollViewer>
<Grid>
<!--many other controls-->
<DataGrid />
</Grid>
</ScrollViewer>
Now, when I bind DataGrid to large amount of data (around 10.000 rows) I am having very slow perfomance. In fact, i get OutOfmemory exception (and I have 8 GB memory)! I read somewhere that this is because ScrollViewer overrides DataGrid virtualisation (or something like that), but I don't know how to prevent that. If I remove the ScrollViewer, problem solved! The data loads in less than a second.
I want to keep the ScrollViewer (because of other controls) and have good performance. Is that possible? If not, is there any other solution-workaround?
A common workaround to these sorts of problems is to add an invisible "sizing element" in the same Row as the DataGrid, then you can bind DataGrid.Height to the ActualHeight of the sizing element. This way, your DataGrid will always consume the Height of the RowDefinition. Example
<ScrollViewer>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="*"/>
<RowDefinition Height="Auto"/>
</Grid.RowDefinitions>
<Button Content="Some Control.." />
<Rectangle Name="sizingElement"
Grid.Row="1"
Fill="Transparent"
Margin="1"/>
<DataGrid Grid.Row="1"
Height="{Binding ElementName=sizingElement,
Path=ActualHeight, FallbackValue=1}">
<!--...-->
</DataGrid>
<Button Content="Some more controls etc.." Grid.Row="2"/>
</Grid>
</ScrollViewer>
The outer ScrollViewer effectively gives the DataGrid as much space as it likes, that way its height becomes huge, showing all rows at once. Just restrict the DataGrid by explicitly setting a height on it for example.
Related
I have an Expander control, and the grid inside will have a ListBox with a Label on top of it saying 'Video Sources'. I am attempting to use Grid Row Definitions to achieve this. My issue however is that the grid rows separate everything evenly. I want the label to be directly on top of the ListBox. Removing the definitons causes the ListBox to fill up the entire grid including covering up the Label (which makes no sense to me as the label is on top).
My current code is below:
<Expander HorizontalAlignment="Left" Height="434" Header="Expander" ExpandDirection="Left" Margin="651,8,0,8">
<Grid Background="#FF252525" ShowGridLines="True">
<Grid.RowDefinitions>
<RowDefinition></RowDefinition>
<RowDefinition></RowDefinition>
<RowDefinition></RowDefinition>
</Grid.RowDefinitions>
<Label Content="Video Sources" Grid.Row="0"/>
<ListBox Grid.Row="1" d:ItemsSource="{d:SampleData}">
</ListBox>
</Grid>
</Expander>
The code produces this result. You can see there are even gaps between each control. I want the video sources label right above the listbox:
It would be nice if you could set the column name like in a ListView, however as far as I am aware that is not possible. I don't think it's worth using a ListView for something that will only have a single column, either
You have to set the rows height ; to auto (ie: minimal value) and * (ie: remaining space).
Also only two rows definition are needed.
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="auto" />
<RowDefinition Height="*" />
</Grid.RowDefinitions>
<Label Grid.Row="0"
Content="Video Sources" />
<ListBox Grid.Row="1"
ItemsSource="{d:SampleData}"
VerticalAlignement="Top" />
</Grid>
I want the ScrollViewer to do only one thing - allow me to scroll. I don't want it to allow its Content to grow. Yet it does. How to prevent that?
<ScrollViewer VerticalScrollBarVisibility="Auto" >
<Grid >
<Grid.RowDefinitions>
<RowDefinition Height="*"/>
<RowDefinition Height="Auto"/>
</Grid.RowDefinitions>
<Image Grid.Row="0" Source="a.png"/>
<Grid Grid.Row="1" Height="400"/>
</Grid>
</ScrollViewer>
If I comment out the ScrollViewer - the Image is small. If I leave the ScrollViewer - the Image grows. How to prevent that?
You would avoid stretching the Image by setting its Stretch property to None.
<Image Grid.Row="0" Stretch="None" .../>
The Grid and hence the Image element use the full width of the scrollable area. Since the default Stretch value is Uniform, the Image subsequently adjusts its height to keep its aspect ratio.
An equivalent, but simpler layout would be
<ScrollViewer VerticalScrollBarVisibility="Auto">
<StackPanel>
<Image Stretch="None" Source="a.png"/>
<Grid Height="400"/>
</StackPanel>
</ScrollViewer>
I've spent two straight days on this and still can't figure it out! Please help!
What I want to do seems relatively simple. I have a window with a grid in it. There are three rows: one "Auto", one set to fill remaining space, and one set to "Auto" with a max height. Here is the xaml:
<Grid Name="theGrid" >
<Grid.RowDefinitions>
<RowDefinition Height="Auto"></RowDefinition>
<RowDefinition Height="*"></RowDefinition>
<RowDefinition Height="Auto" MaxHeight="300"></RowDefinition>
</Grid.RowDefinitions>
<ContentControl Grid.Row="0" Content="{Binding fixedLabel}"></ContentControl>
<ContentControl Grid.Row="1" Content="{Binding bigLabel}"></ContentControl>
<ContentControl Grid.Row="2" Content="{Binding gridWithStackPanel}"></ContentControl>
</Grid>
The first two rows just have a simple label in them. The third row is itself made up of a grid. It is a simple grid with two rows, one allowed to fill the remaining space, and one marked "Auto". Here is the xaml for that grid:
<Grid Name="theGrid" Style="{StaticResource BasePGOGridStyle}">
<Grid.RowDefinitions>
<RowDefinition Height="1*"></RowDefinition>
<RowDefinition Height="Auto"></RowDefinition>
</Grid.RowDefinitions>
<ContentControl Grid.Row="0" Content="{Binding stackPanel}"></ContentControl>
<ContentControl Grid.Row="1" Content="{Binding simpleLabel}"></ContentControl>
</Grid>
The desired behavior is simple: the second grid would have a stackpanel as its top item, with a simple label on the bottom. However, if the stackpanel has a lot of items, it just blows out the label on the bottom. Despite being set to "Auto", WPF doesn't seem to reserve the space for the 'simpleLabel'.
What seems to be happening is that WPF tells the second grid "Hey, you are marked down as 'Auto' in your parent grid, so take up as much space as you need". So, the second grid lays itself out as though it has lots of space, showing all of the items in the stackpanel. Then, WPF seems to say, "Wait a sec, there's a maxHeight value for your parent row, so you need to clip yourself". What ends up happening is that the 'simpleLabel' then gets cut out of the layout.
That's my best guess for what's happening, but maybe there is something else going on. I've done extensive research and can't find a solution to the problem. Am I really the only person ever putting a grid within a grid that has a MaxHeight? It seems like a basic part of WPF functionality.
Please let me know if you have any ideas!
Ok, I finally figured out a solution! You have to forget about using maxHeight in the grid row and just place the maxHeight value on the item that you are binding to. This seems to fix the problem completely.
I have a WPF usercontrol that I want to load with dynamic content in code using a FlowDocument: textblocks, bulleted lists, etc. Content is loaded as expected. And the box sizes looks fine in designer, but in runtime the FlowDocument insists on clipping the result and only show part of the width.
My assumption was that the Viewbox would fill the grid cell and the inner FlowDocument to fill up all available space.
I tried to set the PageWidth/PageHeigth of the FlowDocument in code but with no result.
Any help appreciated.
<Grid x:Name="grdDisplay">
<Grid.RowDefinitions>
<RowDefinition Height="22*"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<Viewbox x:Name="viewboxContent" Grid.Row="0" Grid.Column="0" Grid.ColumnSpan="2" HorizontalAlignment="Left" VerticalAlignment="Top" StretchDirection="DownOnly">
<FlowDocumentScrollViewer VerticalScrollBarVisibility="Hidden" HorizontalScrollBarVisibility="Hidden">
<FlowDocument x:Name="flowDocument">
</FlowDocument>
</FlowDocumentScrollViewer>
</Viewbox>
<Viewbox Grid.Row="1" Grid.Column="0" VerticalAlignment="Bottom" HorizontalAlignment="Left" StretchDirection="DownOnly">
<TextBlock x:Name="txtBottom" />
</Viewbox>
</Grid>
I finally got it to work!!
The problem lies in the fact that Viewbox scaling is based on the design time size of the child object. Even if the actual size of the internal child objects are bigger, they will still report their design time size also to the ActualWidth and ActualHeight properties. This is kind of confusing.
The workaround is to create the whole content including the FlowDocumentScrollViewer and its FlowDocument in runtime. They will then be based on the current available space and will fill the content as expected.
In my case the purpose was to make a simple markdown parser that will generate dynamic layout. This is now implemented and working fine :)
I would like the ScrollViewer of the page to be displayed when all the information cannot be shown on the screen (i.e. resize the window)
However, the ListBox here doesn't get a scroll and it gets sketch till the bottom of the page unless i set it to have a MaxSize. Is there a way to give priority to the ListBox to display its ScrollViewer before the one I have made?
what i have right now
http://i.imgur.com/bEJcz.png
what i would like to achieve, but i used a MaxHeight for the ListBox here.
Here's some my markup:
<ScrollViewer HorizontalAlignment="Stretch" VerticalScrollBarVisibility="Auto" Name="scrollViewer1" VerticalAlignment="Stretch" >
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="Auto"/>
</Grid.RowDefinitions>
<ComboBox Grid.Row="0" Width="120" HorizontalAlignment="Left"></ComboBox>
<ListBox HorizontalAlignment="Left" Name="listBox" Width="120" Grid.Row="1" <!--MaxHeight="500"--> />
</Grid>
</ScrollViewer>
I know this question is old, but I had exactly the same problem and came up with a bit of a hack as a fix but its better than having the question unsolved.
Much of what I've read states that using things like StackPanel is bad in this case because the panel grows to fit the elements it holds. Normally this works fine because you can stick the StackPanel into a Grid and set the MinHeight and MaxHeight of the column/row and lock the controls in place. As soon as the ScrollView is added this kind of goes to hell. The answer above describes the problem well, but lacks a solution.
I tried many different types of Panels instead of a StackPanel but they all yield the same result. I decided that since my ListBox sits inside of a Grid, I needed to bind the MaxHeight of that grid location to some other value in the control to keep the ListBox from growing. The problem with this is that there is no element that you can bind straight to and get the exact height your looking for.
Enter the hack:
My height was just a tiny bit too big creating a weird always offscreen ListBox (in fact 36 pixels too large, which was the height of the label above the ListBox). So I implemented the IValueConverter:
class HeightToAdjustedHeightConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
var height = (double) value - 33d;
return height < 360d ? 360d : height;
//360 being the minimum height allowed for the listbox
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
return null;
}
}
All I did after that was include it as a converter for the binding on MaxHeight (Note you need to name your usercontrol and bind to its x:Name):
<Grid Grid.Column="0"
Grid.Row="1"
VerticalAlignment="Top"
ClipToBounds="True"
MaxHeight="{Binding ElementName=AdHocUserControl, Path=ActualHeight, Converter={StaticResource HeightToAdjustedHeightConverter}}">
The only other alternative I can think of is to extend one of the panels and try to play with its growth behavior. I admit this is a hack, but it will work.
Try this
<ScrollViewer HorizontalAlignment="Stretch" VerticalScrollBarVisibility="Auto" Name="scrollViewer1" VerticalAlignment="Stretch" >
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<ComboBox Grid.Row="0" Width="120" HorizontalAlignment="Left" ></ComboBox>
<ListBox HorizontalAlignment="Left" Name="listBox" Width="120" VerticalAllignment = "Top" Grid.Row="1"/>
</Grid>
</ScrollViewer>
Or you can also try this
<Grid >
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<ComboBox Grid.Row="0" Width="120" HorizontalAlignment="Left" ></ComboBox>
<ListBox HorizontalAlignment="Left" Name="listBox" VerticalAlignment= "Top" Width="120" Grid.Row="1" ScrollViewer.VerticalScrollBarVisibility="Auto"/>
</Grid>
You have a logical inconsistency in your definitions.
The requirement as you put it: "I would like the scrollviewer of the page to be displayed when all the information cannot be shown on the screen [without using MaxHeight]" - a question arises: "How do you determine that 'all the information cannot be shown on the screen'?" or "At what point the ListBox should stop growing and show the scroll bar?".
From a WPF\Silverlight layout management logic, it does exactly what you want - when the sum of height of list box plus the height of the combo box is greater than the ViewportHeight of the scroll viewer - you get a scroll bar. That is possible only when you allow the ListBox to grow to it's desired size without scroll bars.
Dont set the MaxHeight on the ListBox, just use the star '*' notation in your RowDefinitions to get the relative sizing between your 2 controls correct.
Another solution:
<ScrollViewer HorizontalAlignment="Stretch" VerticalScrollBarVisibility="Auto" Name="scrollViewer1" VerticalAlignment="Stretch" >
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<ComboBox Grid.Row="0" Width="120" HorizontalAlignment="Left"></ComboBox>
<ScrollViewer x:Name="scrollViewer" Grid.Row="1" ScrollViewer.VerticalScrollBarVisibility="Disabled" >
<ListBox HorizontalAlignment="Left" Name="listBox" Width="120" Grid.Row="1" MaxHeight="{Binding ActualHeight, ElementName=scrollViewer}" ScrollViewer.VerticalScrollBarVisibility="Auto"/>
</ScrollViewer>
</Grid>