How do I get the width available for the children of a scroll viewer in XAML? Thanks.
There's no direct way of doing this that I know of, since WPF automatically passes the available space in to the child controls' Measure() function so that they size to fit the available space.
Note that, by default, it passes in infinity for the vertical direction, since content can scroll forever vertically. You can change the visibility of the scroll bars in both the vertical and horizontal direction to affect whether infinity is passed vertically, horizontally, or both.
The best way of figuring out how wide the child controls actually have to layout in pure XAML would be to create an empty control - for instance, an empty grid - and then bind to its ActualWidth property:
<ScrollViewer>
<StackPanel>
<Grid x:Name="MeasureGrid"/>
<TextBox Text="{Binding ElementName=MeasureGrid, Path=ActualWidth}"/>
</StackPanel>
</ScrollViewer>
Aside from displaying the width that is actually available to controls, I don't see any other use for this information in XAML, though - all of the other scenarios I can think of can use this information implicitly. Can you give us more information on what you are trying to accomplish?
Related
In my xaml, I have some object made by me. I put them in row and, if the window is too little for all, I go in a new line.
The problem is when the window is so little that, also in a new line, the elements can't be all shown. The solution is simple: scroll bar!! But, if I set the Vertical/HorizontalScrollBarVisibility to auto, it doesn't go to a newline anymore.
This is my xaml:
<ScrollViewer CanContentScroll="True" VerticalScrollBarVisibility="Disabled" HorizontalScrollBarVisibility="Disabled" >
<ItemsControl Name="ItemGroups" ItemsSource="{Binding NotifyItemUI}" />
</ScrollViewer>
and this is a screenshot what I need as my goal:
For example, if I resize my area vertically, and I have 3 rows of objects, in this way I can't see the third row if the window becames too little. In this case, I'd like to see a vertical scrollbar to scroll it.
Same thing horizontally: if I have too many elements for one single row, I have to scroll it horizontally.
What you describe looks like a WrapPanel, but the way you write about it suggests it is a custom control, so we cannot see what your ItemsControl is doing for layout.
However, ScrollViewer can have tricky interaction with a Panel. If the Panel measures to infinity, it will always consider itself big enough, and never tell the ScrollViewer it is out of room. The result is that the ScrollViewerdoes no know the scrollbar is needed. If this is your problem, then setting the Width and Height properties, or maxima as #Sheridan said, ought to fix it.
I am trying to load an image within a canvas such that, if the size of image overflows the canvas, the scroll bars should get activated (MS Paint style)
<Window>
<ScrollViewer>
<Canvas ScrollViewer.HorizontalScrollBarVisibility="Visible"
ScrollViewer.VerticalScrollBarVisibility="Visible">
<Image Source="SampleImage.jpg" />
</Canvas>
</ScrollViewer>
</Window>
Now as Canvas is stretched to Window's size, scroll-bars won't appear as Canvas is not actually overflowing out of the Window.
Secondly, as the Image is much bigger than the Canvas, it is getting clipped at the bounds of Canvas, so ScrollViewer doesn't think that its content: Canvas is actually overflowing.
It happens a lot of time with StackPanels too, that even though the bound data has tens of rows, but still the scrollbars don't get activated. Sometimes scrollviewers appear as mystery to me.
So, what should be the basic logic kept in mind when using ScrollViewer control.
Thank you.
Edit: Just edited the question title, so that whosoever has problem with canvas can get this question easily in search.
From MSDN:
Canvas is the only panel element that has no inherent layout characteristics. A Canvas has default Height and Width properties of zero, unless it is the child of an element that automatically sizes its child elements. Child elements of a Canvas are never resized, they are just positioned at their designated coordinates. This provides flexibility for situations in which inherent sizing constraints or alignment are not needed or wanted. For cases in which you want child content to be automatically resized and aligned, it is usually best to use a Grid element.
Hovever, you can set Canvas Height and Width explicitely:
<ScrollViewer Height="100" Width="200">
<Canvas Height="400" Width="400">
//Content here
</Canvas>
</ScrollViewer>
Maybe one of these two Links might help you:
Silverlight Canvas on Scrollviewer not triggering
ScrollBars are not visible after changing positions of controls inside a Canvas
I want to create resizable window wich will initially autosize to its content.
If the size of the window reaches some limits autosizing is disabled and growing controls are either clipped or shown with scrollbars.
Autosizing also must be off when user resizes the window.
The real task is to create convinient resizable dialog window with text control.
When it contains not much and not few text lines it is reasonable to initially autosize the dialog. The amount of text increases and dialog becomes larger. Sure it must have some size constraints.
P.S. I think it's quite a frequent task to define the layout where the guiding role of the sizing during measure pass of the layout conditionaly swithces from children to parent and back.
Share you ideas or existing solutions. May be I'm missing something.
Thank you.
Update 1
Let me explain the algorithm:
1) Window is shown (let's imagine all data/content is already set).
2) Its size is adjusted as if window's properties were:
MaxHeight = ...
MaxWidth = ...
SizeToContent = "WidthAndHeight"
3) User tries to resize the window. And he can do it. Inner controls change accordingly their size.
This behavior is equivalent to the properties set:
MaxWidth= "{x:Ststic Double.PositiveInfinity}"
MaxHeight = "{x:Ststic Double.PositiveInfinity}"
SizeToContent = "Manual"
ResizeMode = "CanResizeWithGrip"
Yes, you can do it with XAML only using animations/triggers but it's a little tricky.
Just hook into TextBlock Loaded event(xaml only) and change SizeToContent=manual && MaxWidth&MaxHeight=PosInfinity inside EventTrigger using animation.
Many of WPF's panels automatically resize based on their children. I'd recommend looking through this article to get an idea of what kind of layout panels are available in WPF: WPF Layouts: A Visual Quick Start
But to answer your question, place all your controls you want automatically sized in a panel that automatically stretches its children, such as a Grid or a DockPanel, and set the MaxHeight and MaxWidth properties of the panel to prevent it from growing past a certain height/width.
<Grid MaxHeight="100" MaxWidth="200">
<!-- Place your content here -->
</Grid>
Depending on the default behavior of the parent control containing your panel, you may need to set the HorizontalAlignment and VerticalAlignment to something other than Stretch too.
<Grid>
<Grid MaxHeight="100" MaxWidth="200" HorizontalAlignment="Left" VerticalAlignment="Top">
<!-- Place your content here -->
</Grid>
</Grid>
If you want a ScrollBar instead of clipping the content, add a ScrollViewer inside the Grid
In my Silverlight 4 application I need to create a user control with an irregular shape. The "main display" of the UC is a standard rectangle but I need to have tabs (simple text blocks, where the user can click) that are outside of the main display rectangle.
Is this possible with Silverlight 4? If so, how?
Thanks in advance.
You can position elements of a control outside its normal layout in a number of ways. You could use Canvas but if most of the control is standard Grid rectangle then you can use a Grid. The trick is to use negative Margins.
<Grid x:Name="LayoutRoot">
<Border Margin="0 -22 0 0">
<TextBlock Text="I appear above the UserControl layout" />
</Border>
</Grid>
Note that if the Usercontrol is being used as the Visual root then this won't work because the Silverlight plugin will not render beyound its client rectangle.
It is, you can have transparent background behind the tabs which can let clicks through, effectively behaving as if the shape was different. The UserControl will still have a rectangular shape including the tabs, unless you wrap then into a Popup and float out of the UC with some offset.
Technically, you can have elements outside the UserControl's rectangle if you use a Canvas for your LayoutRoot instead of a Grid. Elements in a Canvas aren't clipped to the canvas size. I wouldn't recommend this, however, because you won't be able to use Margin to size and align your controls inside it. It would be better to have all child controls inside a Grid LayoutRoot.
Which brings us to the question of irregularity. If you want to 'see through' parts of the control and be able to click through them (i.e. click objects underneath it), all you need to do is keep the UserControl's and the LayoutRoot's Background to null or just not set it at all. Wherever there is a lack of any background, clicks will go through. Note that if you set the background to Transparent it will make the control behave as a rectangle (as if it's filled with solid color) with respect to mouse input.
Another thing is if you want to see HTML controls under the see-through parts of your app. Then, you'll have to use windowless mode, but that's another can of worms.
How do I make a Canvas stretch fully horizontally with variable width? This is the parent Canvas, so it has no parents, only children.
XAML Source: it displays in blend
http://resopollution.com/xaml.txt
Use a Grid as the top level element in your UI - it'll stretch to fill its container. Then put a Canvas with HorizontalAlignment="Stretch" inside the Grid and it'll behave the way you want.
<Grid xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
<Canvas Background="Blue"/>
</Grid>
That worked for me. The key is your top level UI element. While a Grid fills all available space by default, Canvases take up only as much room as their contents demand.
I'm guessing you've tried
canvas.HorizontalAlignment = HorizontalAlignment.Stretch
If this doesn't work, then what you could do is bind the Width and Height properties of the canvas to the ActualWidth and ActualHeight properties of the containing window.
You could use a dock panel to get it to fill the available width. The last item in a dock panel list of controls is automatically stretched to fill the remaining space.
<DockPanel>
<Canvas />
</DockPanel>
The canvas should do this automatically, unless you are manually setting the height and/or width. What kind of control are you trying to place the canvas on? Can you post your code?
The problem is that you're specifying the Height and Width. Without these properties, the control may appear to vanish in the designer, but it should size appropriately when you insert the canvas into another control.
If I recall correctly, the next version of WPF will have 'DesignWidth' and 'DesignHeight' properties that allow you to show the control in the designer with a given size without effecting it's measurement when inserted into other controls.