I hope this isn't a duplicate but I can't find any documentation or examples on how to actually use ScrollToVerticalOffset(). I'm using it in a Windows Phone 8 app, but I think it will still apply to WP7 and Silverlight (although, feel free to correct me if I'm wrong).
So here is my basic set up (pseudo-code from memory):
<phone.PivotItem>
<ScrollViewer>
<Grid Height="1500">
<Grid.RowDefinitions>
<!-- about 20 rows, all auto-height -->
</Grid.RowDefinitions>
<Border Grid.Row="0">
<TextBox x:Name="txt1" />
</Border>
<Border Grid.Row="1">
<TextBox x:Name="txt2" />
</Border>
<!-- ...... -->
<Border Grid.Row="19">
<TextBox x:Name="txt20" />
</Border>
</Grid>
</ScrollViewer>
</phone.PivotItem>
So as you can see, I've got a ScrollViewer within a PivotItem, and inside is a Grid. In the Grid there are about 20 TextBoxs, each within a Border. I am dynamically setting focus to one of these TextBoxs when this page loads, so anytime I set focus to TextBox #6-20 (roughly) - I have to manually scroll down to see it. I want to auto-scroll my ScrollViewer so that whichever TextBox has focus, it will be centered for the user to see.
The documentation for ScrollToVerticalOffset() says:
Scrolls the content that is within the ScrollViewer to the specified
vertical offset position.
And that it accepts a type of System.Double.
What I don't understand is A) the value I'm supposed to pass, and B) how I could even get that value? Is it supposed to be a number between 0 and the height of my Grid (1500)? If so, how could I determine the position of any given TextBox so I can scroll to it?
If there are any straightforward examples, please feel free to link out to them. I'm not sure if the content within the ScrollViewer matters when calling this method, but in case it does I wanted to show exactly how I'm using it.
Many thanks in advance!
You can see any UIElement's position relative to another UIElement using the UIElement.TransformToVisual call.
First, get the transform between the TextBox and ScrollViewer.
GeneralTransform transform = textBox.TransformToVisual(scrollViewer);
Then, figure out what point (0,0) of the TextBox is relative to the ScrollViewer. Meaning, the TextBox origin (0,0) is located at what ScrollViewer position.
Point textBoxPosition = transform.Transform(new Point(0, 0));
Now that you know the Y position of the TextBox relative to the ScrollViewer, scroll to that Y offset.
scrollViewer.ScrollToVerticalOffset(textBoxPosition.Y);
Good luck!
This is a very old post, but the meaning of VerticalOffset varies.
Most of the solutions I have seen assume VeritcalOffset is in pixels. This is not always the case.
From: https://learn.microsoft.com/en-us/dotnet/api/system.windows.controls.scrollviewer.extentheight
If CanContentScroll is true, the values of the ExtentHeight, ScrollableHeight,
ViewportHeight, and VerticalOffset properties are number of items. If
CanContentScroll is false, the values of these properties are Device Independent Pixels.
Related
I am trying to set up an element within a WPF application, but cannot get the TextTrimming on the TextBlocks to work properly. This is within a ScrollViewer. I am currently using a DockPanel as the inner container.
I have searched quite a bit, but found no questions addressing this issue.
The XAML for the container:
<Grid>
<ScrollViewer>
<DockPanel Name="listedCharacters" LastChildFill="False"></DockPanel>
</ScrollViewer>
</Grid>
The XAML for the child elements (added by code):
<UserControl …>
<Grid DockPanel.Dock="Top" HorizontalAlignment="Stretch">
<TextBlock Text="{Binding FullName}" TextTrimming="CharacterEllipsis" />
</Grid>
</UserControl>
The first problem is that whether I use the DockPanel or a StackPanel, as the inner container, the child element's width appears to be dictated by its content (the TextBlocks) rather than constrained by the parent ScrollViewer.
The effect I want is for the ellipsis to truncate each TextBlock's content when the Window's grid column (not shown in code) is narrower than the bound text. Basically, a list that scrolls vertically when needed, and trims horizontally (which I thought would have been sufficiently common that the answer would be out there; alas, no).
I believe I need to use my own UserControl for this, as there is a lot more going on than shown her; right-click menus on the item in the list, etc.
The secondary issue, iff the optimal panel to use is the DockPanel, how to apply the DockPanel.Dock="Top" through code (C#) when the elements are dynamically added? Again, I cannot find anything that appears to explain this. (I know it is probably in the wrong place in the sample code above.)
How can canvas in wpf be autosized? I have a canvas in scrollviewer and I will add several buttons and lines in this canvas in code behind. since I don't know the position of the buttons, I have to hard code a very large number for the width and height of the canvas or if I add too many buttons, it can only show part of them.
I try to set the Width and Height to Auto but it doesn't work.
<Grid>
<ScrollViewer HorizontalScrollBarVisibility="Visible" VerticalScrollBarVisibility="Visible">
<Canvas Width="Auto" Height="Auto" Name="cv1"></Canvas>
</ScrollViewer>
</Grid>
The Canvas element is the only element that can not be automatically resized, because has no inherent layout characteristics. If you want the Control to be resized as child elements come in, you could use something deriving from Grid.
Try a UniformGrid instead of your Canvas ans fill it with the elements you want. It allows you to just add elements without any layout constraints that are handled by the UniformGrid. otherwise if you use a simple Grid, you will have to define a Position for your element by setting the Margin property of each child element.
Hope this helps.
I'm trying to implement a certain layout.
I have two elements that I want to stack vertically (I need them to follow each other closely). I am currently trying to achieve it using a Stackpanel.
The problem is that I want the first element to have a limited width and the other to use all the width available in the StackPanel. Ideally, I would like that the first element have a width equals to the width of four columns from the grid that contains the StackPanel, here is my code.
<Grid>
<!-- Colums and Rows definition go here -->
<StackPanel Grid.Column="0" Grid.ColumnSpan="4" Grid.Row="3" Grid.RowSpan="8">
//The first element
<Viewbox Name="viewbox_choix" Margin="160,0,0,0" HorizontalAlignment="Left" VerticalAlignment="Top" Grid.Column="0" Grid.ColumnSpan="4" Grid.Row="3" Grid.RowSpan="4">
//The second element
<StackPanel Grid.Column="0" Grid.ColumnSpan="5">
<Border></Border>
etc...
</StackPanel>
</StackPanel>
</Grid>
The grid attributes are referring to the parent grid of the stackpanel. But the Grid.Column and Grid.ColumnSpans seem to have no effect when I try to use them inside the StackPanel.
The problem of that code is that the first element also uses all the width of the StackPanel but that isn't what I want...
Can anybody help me ? I precise that I'm still learning WPF and I don't really know how bindings work...
In WPF, a StackPanel does not work like a Grid. There is no maximum width... it will happily let content disappear out of its right side. If you want automatic resizing, just replace the StackPanels with `Grid
UPDATE >>>
In the Grid class, there is an attached property called IsSharedSizeScope. Add this to the parent Grid and set it to true. Then in your RowDefinitions, you can add SharedSizeGroup properties to the columns that you require.
These examples may help you:
Grid's SharedSizeGroup and * sizing (SO post)
Grid.IsSharedSizeScope Attached Property (MSDN)
You may need to experiment a bit, but you should be able to get the desired effect using these properties.
I have the following structure in my WPF application. (Using Prism and Regions)
Window---->
UserControl---->
DockPanel------>
Grid(2X2)------>Row0Col0--
Grid (2X1)------>
ItemsControl------>
UserControl(injected into ItemsControl with Prism)----->
DockPanel----->
DataGrid.(60 rows, 10 columns)
The behavior that I expect is that the DataGrid will size itself to fit the size of the grid cell and display both scrollbars because it is too big to fit. But it doesnt. It remains its maximum size and cuts out of the edges of the grid cell. All cells of both grids have no size specifications (Auto Sized). When I explicitly specify datagrid's height and width, I see the scrollbars, but of course I don't want to do that.
Please help!.
Thanks
I have saved the screenshots at the following link.
http://s1199.photobucket.com/albums/aa467/vikasgoyalgzs/
You say: "All cells of both grids have no size specifications (Auto Sized)" - this is where the problem is. When the grid cell is auto sized the grid gives the content in that cell as much space as it wants (doesn't matter if it fits in the window or not). To fix it you have to put your DataGrid into a star-sized cell.
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<Border Grid.Row="0">
<!-- Content that will take as much space as it wants -->
</Border>
<Border Grid.Row="1">
<!-- Content that will take all the remaining space -->
</Border>
</Grid>
UPDATE: Based on the screenshots you provided...
First, get rid of the DockPanel in the top level control. DockPanel gives its child all the space it asks for. If it is not a "fill" child (LastChildFill="True"). Use grid instead of DockPanel (i.e. at the top level a grid with two rows - one auto-sized for the menu and the second star-size for the rest of the stuff, the in that star-size row put another grid for you items controls, etc.).
Remember, whenever you put the content either in an auto-size cell in a grid or in a DockPanel with dock type different than Fill, the content will take as much space as it required without showing a scroll bar (it will go beyond the window).
UPDATE 2: Looking at the new screenshots (see comments to this post)...
OK, I think I see the problem. The thing is that ItemsControl uses StackPanel to display its children, but StackPanel also gives its children all the space they want (your DataGrid thinks that it has enough space to render itself without scroll bars).
To fix that you need to put your items controls inside an ScrollViewer like this:
<ScrollViewer VerticalScrollBarVisibility="Auto"
HorizontalScrollBarVisibility="Auto">
<ItemsControl ... />
</ScrollViewer>
The UserControl I'm trying to work with is essentially laid out like so:
<Grid>
<Grid.RowDefinitions>
<Row Height="*"/>
<Row Height="*"/>
</Grid.RowDefinitions>
<wpftoolkit:DataGrid x:Name="PrimaryGrid"/> <!-- ~10 rows -->
<Border>
<Grid>
<Grid.RowDefinitions>
<Row Height="*"/>
<Row Height="*"/>
</Grid.RowDefinitions>
<wpftoolkit:DataGrid x:Name="SecondaryGrid"/> <!-- ~2 rows -->
<wpftoolkit:DataGrid x:Name="OtherGrid"/> <!-- ~50 rows -->
</Grid>
</Border>
</Grid>
This UserControl is then placed in my Window as the last member of a Grid, the only one with Height="*". I'm having problems with the way the DataGrids are sized.
If I set VerticalAlignment of the UserControl to Stretch in the Window, then PrimaryGrid gets 1/2 height of the UserControl, and each of the two inside the Border get 1/4. They are sized like this regardless of the number of rows each have, leaving OtherGrid with too little vertical space and the others with non-row whitespace inside the scrollview.
If I set VerticalAlignment to Top, the grids seem to size pretty well to their contents, except there is an inexplicable whitespace being left at the bottom of the UserControl. I used Snoop and the RowDefinition for the UserControl has the proper ActualHeight, but the UserControl only uses a portion of it - 80% or so.
I don't really mind whether I fix the Stretch case (How do I make the DataGrid not stretch larger than its number of rows?) or the Top case (How do I make the UserControl use all the space it has available to it?)
Summary: Use Stretch for the UserControl, but Auto (instead of *) for the row heights inside your UserControl.
Explanation: "Auto" means: as much space as needed (which is what you want), whereas "*" means: a proportional share of all available space (resulting in the 1/2, 1/4, 1/4-distribution).
Since you want the UserControl to use all available space, Stretch is the correct option (it means exactly that). Set one of the row heights inside the UserControl back to "*", if you want this row to take up the remaining available space.
This is a common problem where what you really want is 2 completely different layout behaviors: Auto sizing when there's room for all three, * sizing when there isn't. Some quick fixes you can try out with limitations:
Auto sizing (as already mentioned)
DockPanel with each set to Dock=Top - this will have a similar effect to VerticalAlignment=Top but the last DataGrid (only 1) will stretch out to fill the remaining space. Also bad if the first or second take up more space than exists because they'll push the others out.
Set MinHeight/MaxHeight in combination with one of the other 2 changes on your DataGrids to keep them from getting out of control. This gives up some of the auto-layout flexibility in exchange for making sure everything shows up.
Beyond those you can try something more complex like creating a custom Panel (or find one that someone else made already), or creating a MultiValueConverter that can calculate appropriate Height (or MinHeight, MaxHeight) settings for each DG or Row based on the height of the UC and each of the DGs.
Well, here's what I ended up with. It does what I want from a layout point of view, mostly. A bit more code behind than I'd like, but oh well.
In my DataContextChanged event handler:
//for each grid
_reportObserver = new PropertyObserver<ItemCollection>(PrimaryGrid.Items)
.RegisterHandler(c => c.Count, c => UpdateMaxHeight(PrimaryGrid));
UpdateMaxHeight(PrimaryGrid);
PropertyObserver is from http://joshsmithonwpf.wordpress.com/2009/07/11/one-way-to-avoid-messy-propertychanged-event-handling/
//Lots of ugly hard-coding
private void UpdateMaxHeight(DataGrid grid)
{
double header_height = grid.ColumnHeaderHeight;
if (double.IsNaN(header_height))
header_height = 22;
double margin_height = grid.Margin.Bottom + grid.Margin.Top;
grid.MaxHeight = header_height + margin_height + grid.Items.Count * (grid.RowHeight+2);
UpdateLayout(); //this is key for changes to number of items at runtime
}
Even after setting the DataGrid's MaxHeight, things were still ugly, so I had to set the max height on the RowDefinition's too. But that still wasn't right, causing the margin_height addition above.
<RowDefinition Height="*" MaxHeight="{Binding ElementName=PrimaryGrid, Path=MaxHeight}"/>
At some point, I'll take into account my optionally visible row details in my ugly max height code.
As far as Top vs Stretch, I ended up for other reasons having the usercontrol in a ListView. Everything sizes nicely now.
Thanks again for looking at my problem.
Just wanted to follow up on this problem. Over time, the solution I provided above just did not meet users expectations. I've now changed to a scheme like this:
<ScrollViewer VerticalScrollBarVisibility="Auto">
<Grid>
<!-- row definitions -->
<KentBoogart's Resizer ResizeDirection="South">
<DataGrid/>
</kb:Resizer>
<kb:Resizer ResizeDirection="South">
<DataGrid/>
</kb:Resizer>
</Grid>
</ScrollViewer>
In another place where I've used this idiom, I've set the Resizer to have a MaxHeight bound to the ScrollViewer's ActualHeight to keep it from going out of control. This design can be a little confusing with the overall scrollbar, plus scrollbars in the DataGrid, but with good borders and margins, it's not too bad.