Element is already the child of another element when doesnt exist? - c#

I'm trying to programatically create a button flyout, within my XAML I have:
<Page.Resources>
<Button x:Key="LaunchFlyout" Content="LAUNCH">
<Button.Flyout>
<Flyout Placement="Top">
<Grid Width="200" Height="200">
<StackPanel>
<Rectangle Fill="Red" Width="100" Height="100" />
<Rectangle Fill="Green" Width="100" Height="100" />
</StackPanel>
</Grid>
</Flyout>
</Button.Flyout>
</Button>
</Page.Resources>
Nested within grids I have:
<Grid x:Name="launchBtn_grid" Grid.Column="1">
</Grid>
And then in my code within the Page_Loaded method I have:
bool hasContainer = localSettings.Containers.ContainsKey("appStatus");
if (!hasContainer) {
Button button = (Button)this.Resources["LaunchFlyout"];
launchBtn_grid.Children.Add(button);
}
else {
Button button = new Button();
button.Content = "LAUNCH";
button.Click += launch_btn_Click;
launchBtn_grid.Children.Add(button);
}
When I debug this, it reaches the IF statement and reaches this line launchBtn_grid.Children.Add(button); and then I get this error Element is already the child of another element.
Does anyone understand why? I have already looked and they dont already exist so I don't understand why it is giving me this error. Does anyone know what I am doing wrong?

I'm not sure in what context/use case your are doing that, but it feels weird to me to have an actual control as a Resource (not a DataTemplate, Style, etc).
If you only want to have 1 button of the 2 different template, why not switch Visibility on the 2 instead of loading controls from your code behind ?
Going forward with the idea, just add both buttons in the Grid within your XAML and switch their Visibility according to the setting you read.
There is a BooleanToVisibilityConverter within the framework to help you with this.

Related

WPF Copied Button Click not firing

I'm quite new to c# wpf and have a problem.
I have used the answer from this post to duplicate a Grid control. The grid control contains a button. It looks like it is being duplicated correctly.
When the original control's button is pressed, the click event is handled which calls a method in the window's code.
When the copy of the control's button is pressed, the click event is not fired and the method is not called. This is confusing me as I want it to call that same method.
Maybe the event handling data is not being copied properly? Is there a way around this?
Both the origional grid and copied grid (containing the buttons) are children of another grid.
Edit:
This is the xaml for the origional grid which contains a button:
<Grid Name="TempTab" DockPanel.Dock="Left" HorizontalAlignment="Left" Margin="5,5,5,0">
<Rectangle Fill="Black" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Stroke ="White" Margin="0,0,-2,0">
</Rectangle>
<Grid>
<DockPanel LastChildFill="False">
<TextBlock Foreground="White" HorizontalAlignment="Left" VerticalAlignment="Bottom" Margin="3,0,3,3">Some Text</TextBlock>
<Button Width="50" BorderBrush="{x:Null}" Foreground="{x:Null}" BorderThickness="0" Margin="3,0,0,0" Click="tabdowntest">
<Button.Background>
<ImageBrush ImageSource="TopMenuBar_Close.png" Stretch="Uniform"/>
</Button.Background>
</Button>
</DockPanel>
</Grid>
</Grid>
This grid is a child of a DockPanel with name 'TabsDock'.
It is being copied with the following code:
string gridXaml = XamlWriter.Save(TempTab);
StringReader stringReader = new StringReader(gridXaml);
XmlReader xmlReader = XmlReader.Create(stringReader);
Grid newTab = (Grid)XamlReader.Load(xmlReader);
TabsDock.Children.Add(newTab);
This is the code for the 'Click' event handler which should be called when the either the origional or the copied button's are pressed. But it is only called for the origional:
private void tabdowntest(object sender, MouseButtonEventArgs e)
{
Console.WriteLine("Button Pressed");
}
The bindigs are not set, you need to set them (comment in the orig post):
To be clear, this is only half the solution (as it stood back in 08). This will cause bindings to be evaluated and the results be serialized. If you wish to preserve bindings (as the question asked) you must either add a ExpressionConverter to the Binding type at runtime (see the second part of my question for the relevant link) or see my own answer below for how to do it in 4.0.

WPF DataGridTemplateColumn.HeaderTemplate issue

Have an issue with getting access to a button that is embedded in a
DataGridTemplateColumn.HeaderTemplate. The button is created fine and can attach an event to the button. All works well, except when attempting to get access from the code behind, Ex:btnbutton.IsEnabled = false; Returns an error and said the object does not exist. I have tested this with various version of .NET up to 4.5 and get the same results, btnButton does not exist.
I have done this same with a ListView object and it works fine.
<DataGrid Name="dgTest1" ItemsSource="{Binding} AutoGenerateColumns="False"
<DataGrid.Columns>
<DataGridTemplateColumn.HeaderTemplate>
<DataTemplate>
<Grid>
<Grid.RowDefinitions>
<RowDefinition></RowDefinition>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition></ColumnDefinition>
</Grid.ColumnDefinitions>
<Button Name="btnButton" Content="One Button" WinWidth="100"></Button>
</Grid>
</DataTemplate>
</DataGridTemplateColumn.HeaderTemplate>
</DataGrid.Columns>
</DataGrid>
Code Behind: btnButton.IsEnabled = false;
Is there a way to gain access to a button in a DataGrid Template Header?
You can try something like this :
var aButton = templateName.ChildrenOfType<Button>().FirstOrDefault( b => b.Name == "btnButton" );
You can not access template control like that, you need to apply template and then find them
You need to call apply template first on DataGrid header and then
var button = dgTest1.template.findname("btnButton", dgTest1)
I believe the proper way here would be to bind your button to a property on the view model:
<Button IsEnabled="{Binding IsButtonEnabled}" Content="One Button"/>
or to a command (you can implement your own command, create a property IsEnabled in it, and return this property's value from the CanExecute() method). Let me know if you need more details here.

How to display a Button which hosts TextBlock with the style PhoneTextSubtleStyle?

I need to create a button with two lines of text:
The first one is Command Title like "Save"
The second one is a Description of the Command like "The application state will be saved"
So I have written the next xaml:
<Button Margin="0,128,0,0" Padding="10,5" HorizontalContentAlignment="Stretch" VerticalContentAlignment="Stretch">
<StackPanel Margin="0" UseLayoutRounding="False">
<TextBlock FontSize="{StaticResource PhoneFontSizeMediumLarge}" FontFamily="{StaticResource PhoneFontFamilySemiBold}">Save</TextBlock>
<TextBlock Style="{StaticResource PhoneTextSubtleStyle}" Margin="0">The application state will be saved</TextBlock>
</StackPanel>
</Button>
This code working well except a one issue. The Description line becomes invisible when the button is pushed.
I'm sure the root cause is the low contrast color of the description line. But I don't know how to fix it.
Update: I have tried to use the PhoneTextSubtleStyle style but still have the same issue.
You could retemplate the Button (using the Control.Template property) to look different so that when pushed it no longer interferes with the content.
Could you try something like this
System.Windows.Visibility.Visible;
System.Windows.Visibility.Hidden;
or
System.Windows.Visibility.Collapsed
here is a link that will show an example of how to use this inside of a StackPanel
How to: Change the Visibility Property

Why is my Button event is not occuring?

I am having an issue with my button event not occuring
Basically I have cart items that are listed in the listbox. When the delete button is clicked then the item is deleted from the list box.
I tried debugging, but it seems to not even call the method for when the button is clicked.
In my ticketscreen.xaml file I specify my button in the template:
<DataTemplate x:Key="TicketTemplate">
<StackPanel Orientation="Horizontal" HorizontalAlignment="Left" Height="50">
...
<Button Name="Remove" Width="35" Height="35"
FontFamily="Resources/#charlemagnestd-regular.otf" FontSize="24"
Click="removeCartItem" Grid.Column="5"
MouseMove="Remove_MouseMove">X</Button>
...
</StackPanel>
</DataTemplate>
My List box is the following:
<ListBox Name="TicketItems" ItemsSource="{Binding}"
ItemTemplate="{StaticResource TicketTemplate}"
Grid.Row="3" Grid.ColumnSpan="6" Background="Transparent"
BorderBrush="Transparent" IsHitTestVisible="False">
</ListBox>
My method removeCartItem is in the ticketscreen.xaml.cs:
private void removeCartItem(object sender, RoutedEventArgs e)
{
Console.WriteLine("TestingCartRemove");
}
Am I missing something obvious?
Thx in adv! :)
Edit:
There seems to be something infront of it... maybe the listbox? How do I make it so that I am not clicking the ListBox, but I can click on things within the Stackpanel, which are contents of the list box.
IsHitTestVisible="False" for the ListBox is disabling the click event for the Button. It makes all content within the ListBox invisible to hit-test as well.
Are you sure is not firing? Maybe you haven't seen the output in Visual Studio Output Window. Try to call a MessageBox.Show("Test"); instead.
You have a listbox control, which leads me to believe that this is not a console application. Therefore, Console.WriteLine() will not show you anything. Try MessageBox.Show() instead.

ControlTemplate

I am quite new to WPF and have a basic question :
Assume the following is xaml declaration in my xaml file
<ContentControl x:Name="interactionActivityContent" Loaded="interactionActivityContent_Loaded">
<shapes:BaseShape.DragThumbTemplate >
<ControlTemplate x:Name="interactionActivityTemplate">
<Grid AllowDrop="True" x:Name="GridTest" >
<Rectangle Name="Interaction" Fill="Yellow" Stroke="Green" StrokeThickness="2" IsHitTestVisible="True" AllowDrop="True"></Rectangle>
<local:DesignerCanvas x:Name="ActivitiesCanvasArea" Margin="1,1,1,1" IsHitTestVisible="True" AllowDrop="True" Background="Blue"></local:DesignerCanvas>
</Grid>
</ControlTemplate>
</shapes:BaseShape.DragThumbTemplate>
*shapes:BaseShape.DragThumbTemplate is coming from some different class.
*DesignerCanvas is my own custom canvas for which I want to set value at run time.
How can I access ActivitiesCanvasArea in my C# code from the code behind file?
Do I need to change the way xaml is declared. I need to apply DragThumbTemplate to my grid so that I can move around grid on main screen.
From http://blogs.msdn.com/b/wpfsdk/archive/2007/03/16/how-do-i-programmatically-interact-with-template-generated-elements-part-i.aspx
If you need to find a named element in the ControlTemplate of myButton1, like the Grid, you can use Template.FindName like so:
// Finding the grid generated by the ControlTemplate of the Button
Grid gridInTemplate = (Grid)myButton1.Template.FindName("grid", myButton1);

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