I have an Ellipse and a TextBlock that I want to be Centred relative to each other - ie the TextBlock shows in the Centre of the Ellipse no matter the content eg. its says 88 (like a Bingo Ball) and the Ellipse is the Ball itself - and the number shows in the centre of this ball.
How to I accomplish this in Silverlight, where the sizes are not fixed, as if possible I want the Ellipse and TextBlock to be the relative size of their parent - which I cannot seem to do in Silverlight either.
Related to this problem is I cannot find the code behind equivelent for "LimeGreen" the colour, which can be set in XAML but not in Code, where only a few Colours are available the in the Color class?
The style of layout desired is provided by the Grid control. However I suspect you would also want the text to scale with the size of the ellipse, this can be acheived with the Silverlight Toolkit Viewbox control:-
<Grid>
<Ellipse Fill="Blue" />
<controlstk:Viewbox>
<TextBlock Text="88" Margin="2" />
</controlstk:Viewbox>
</Grid>
BTW, LimeGreen is #FF32CD32.
Related
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 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.
The common question about positioning an element inside a Canvas is "How to position the center of element (instead of the top left corner)".
WPF: Resizing a circle, keeping the center point instead of TopLeft?
WPF Center Ellipse at X, Y
WPF element positioning on a Canvas
Several solutions are presented, but they all have drawbacks.
The easiest solution is to accommodate the element size during while setting the Canvas.Left and Canvas.Top properties programmatically. This works, but only once. This solution doesn't support bindings and it will break when the element size is changed. You also cannot set the Canvas.Left or Canvas.Top using
Another set of solutions involve translate transformations utilizing either RenderTransform or Margin. These solutions require binding some property to the -0.5 * Width or -0.5 * Height. Such binding requires creating a custom ValueConverter and is impossible to create using only XAML.
So, is there a simple way to position an element inside canvas so that its Canvas.Left and Canvas.Top correspond to the element's center and both size and position properties can be bound to some other properties?
XAML and bindings seem very powerful, but sometimes there are simple problems that require very complex solutions. In my bindings library creating such binding would be as easy as writing element.Center = position or element.TopLeft = position - element.Size / 2, but don't let me get carried away.
I've found a very simple solution which uses only XAML and supports binding both size and position properties of the element. It seems that when the WPF control with alignment set too Stretch or Center is placed inside the canvas, the element "gravitates" towards centering as the (Canvas.Left, Canvas.Top) point (the state that we desire), but is stopped by the "angle plate" placed at the same (Canvas.Left, Canvas.Top) point. How do I know about this "gravitation"? It's evident when you ease the block by setting the Margin of the element to a negative value. Setting the negative margin allows the element to move towards its center goal. The element moves until the Margin reaches (-Height / 2, -Width / 2) so that the element becomes perfectly centered at the (Canvas.Left, Canvas.Top) point. Further changes don't cause any movement since the element is already perfectly positioned.
Solution: set Margin="-1000000".
So in the following code the ellipses are both centered at the (200, 200) point. The first ellipse has Left and Top properties corresponding to the ellipse center allowing to easily bind them with some other objects' properties.
<Canvas>
<Ellipse Width="100" Height="100" Canvas.Left="200" Canvas.Top="200" Opacity="0.5" Fill="Red" Margin="-100000" />
<Ellipse Width="100" Height="100" Canvas.Left="150" Canvas.Top="150" Opacity="0.5" Fill="Blue" />
</Canvas>
The bad thing is this solution only work in WPF. Silverlight and WinRT don't have the described behavior.
Even simpler, at least for Shapes, would be to use a Path with an appropriate Geometry:
<Canvas>
<Path Canvas.Left="200" Canvas.Top="200" Fill="Red" Opacity="0.5">
<Path.Data>
<EllipseGeometry RadiusX="50" RadiusY="50"/>
</Path.Data>
</Path>
</Canvas>
I solved this by putting the canvas into the bottom-right cell of a 2x2 grid. That makes the 0,0 coordinate the center of the grid, and then you can do all your drawing relative to that.
This solution worked for me Center text at a given point on a WPF Canvas. He uses a MultiBinding and a custom Converter to adjust the margin on his element. Brilliant!
I am starting to learn SL...
I am trying to make a MediaElement of size X, and on the bottom of the movie frame some subtitles that will run.
I was unable to understand if I need absolute position or something else.
Please advice
thanks
If you need to us it as a subtitle you just need to put your TextBlock under the MediaElement on your Grid and need to give VerticalAllignment property as bottom on XAML. And it will be over it. Like this;
<Grid>
<MediaElement/>
<TextBlock VerticalAllignment="Bottom"/>
</Grid>
You may refer Grid Layout as relative positioning if you're new to silverlight. And can give a margin to your textblock or anything you want just take a look at the intellisense (if using VS) and you'll understand, if you're using expression blend it'll be a lot easier with UI.
If you want to use absolute positioning you'll need to use Canvas instead of Grid Layout, its the same and you can change anything to canvas with nearly no problem. In canvas, you need to use left and right properties instead of allignments. Like this;
<Canvas>
<MediaElement/>
<TextBlock Canvas.Left="0" Canvas.Top="400"/>
</Canvas>
Another option is stackpanel its not really suitable for LayoutRoot, but its pretty nice for controls. So if you want your subtitles to stay under your movie you should use StackPanel like this;
<StackPanel Orientation="Vertical">
<MediaElement/>
<TextBlock/>
</StackPanel>
So to sum up;
-If you want your subtitles to be on top of your movie use grid like the first example,
-If you have a fixed size and you want to place your subtitles anywhere you want use Canvas,
-And if you want to put your subtitles under your movie use StackPanel.
-My personal choice would be grid. =)
For more information you may check this article it seems like a nice one!
http://weblogs.asp.net/scottgu/pages/silverlight-tutorial-part-2-using-layout-management.aspx
Happy coding!!
The TextBlock will overlay (within a Grid layout) the MediaElement simply because it is declared after the MediaElement. VerticalAlignment="Bottom" will place it at the bottom of the Grid. You might want to set the Grid's width and height (instead of the MediaElement) that of the size of the video. The MediaElement will auto size to stretch the full size of the grid.
<Grid x:Name="LayoutRoot" Width="480" Height="320">
<MediaElement/>
<TextBlock TextWrapping="Wrap" VerticalAlignment="Bottom"/>
</Grid>
How to relative scale size of User Control like image (in image editor).
Example (100%):
(source: stegnar.com)
Scaled down UC (70%):
(source: stegnar.com)
Well I achieve this in picture editor, but I would like in WPF. :) I need this to adjust my application to different screen resolution, while nothing hiding (no scrollbars).
You could try the ViewBox control that scales up/down its content so that it fills the available space.
<Window x:Class="WpfApplication1.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:WpfApplication1"
Title="Window1">
<Grid>
<Viewbox StretchDirection="Both" Stretch="Uniform">
<local:UserControl1 Height="600" Width="600"/>
</Viewbox>
</Grid>
you can place the whole container into a ViewBox
<Viewbox StretchDirection="Both" Stretch="Uniform">
<Grid>...</Grid>
</Viewbox>
you don't have to place each single textblock in it!
Use of Viewbox (as said by Milan Nankov) is a great idea. One thing that I must warn you is that it also zooms in or out other visual aspects as well.
For example, a Textbox with dimension 200 X 1000 is very different from a Textbox with dimension 20 X 100 zoomed in 10x.
WPF provides many layouting options which can change dimension of the controls according to the size of the container. But it doesn't change the size of the text. Viewbox overcomes this issue, but it introduces another issue. Check the image below which shows the same textbox in a viewbox before and after zooming.
One trick which could be used is to place every textblock in a viewbox. But I guess that would be an overkill, and I seriously don't having any backing for this trick. Please do check for yourself and reply whether it's practical or not.
Another trick could be to bind the control's height to the font size. We would be needing a converter in that case. Please refer to this reply.. Resize font in TextBox in Grid