adding stackpanel as child to other stackpanel

Question

4.00/5 (1 vote)

See more:

hi,
In my user control i have main StackPanel and i want add ObservableCollection<stackpanel> az child of main StackPanel Programmatically
in CollectionChanched event. but get this error :
specified element is already the logical child of another element.Disconnect it frist
can help me to find the problem,please?

XML

<UserControl
	xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
	xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
	xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
	xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
	mc:Ignorable="d"
	x:Class="Win8Panel.LeftRightPanel"
	x:Name="UserControl"
	d:DesignWidth="150" d:DesignHeight="500">
	<UserControl.Resources>
		<Storyboard x:Key="OnMouseEnter1">
			<DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Opacity)" Storyboard.TargetName="UserControl">
				<EasingDoubleKeyFrame KeyTime="0" Value="0"/>
				<EasingDoubleKeyFrame KeyTime="0:0:0.6" Value="0.4"/>
				<EasingDoubleKeyFrame KeyTime="0:0:0.8" Value="1" />
			</DoubleAnimationUsingKeyFrames>
		</Storyboard>
		<Storyboard x:Key="OnMouseLeave1">
			<DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Opacity)" Storyboard.TargetName="UserControl">
				<EasingDoubleKeyFrame KeyTime="0:0:0.5" Value="0.4"/>
				<EasingDoubleKeyFrame KeyTime="0:0:0.7" Value="0"/>
			</DoubleAnimationUsingKeyFrames>
		</Storyboard>
	</UserControl.Resources>
	<UserControl.Triggers>
		<EventTrigger RoutedEvent="Mouse.MouseEnter">
			<BeginStoryboard x:Name="OnMouseEnter1_BeginStoryboard" Storyboard="{StaticResource OnMouseEnter1}"/>
		</EventTrigger>
		<EventTrigger RoutedEvent="Mouse.MouseLeave">
			<BeginStoryboard x:Name="OnMouseLeave1_BeginStoryboard" Storyboard="{StaticResource OnMouseLeave1}"/>
		</EventTrigger>
	</UserControl.Triggers>


    <Border Name="root">
    <StackPanel Name="ContainerStk" Orientation="Vertical" >
     
        </StackPanel>
    </Border>

</UserControl>

C#

public static readonly DependencyProperty ItemsPanelProperty = DependencyProperty.Register
     ("ItemsPanel",
     typeof(ObservableCollection<StackPanel>),
     typeof(LeftRightPanel),
     new PropertyMetadata(new ObservableCollection<StackPanel>()));
 public ObservableCollection<StackPanel> ItemsPanel
 {
     set { SetValue(ItemsPanelProperty, value); }
     get { return GetValue(ItemsPanelProperty) as ObservableCollection<StackPanel>; }
 }

C#

void ItemsPanel_CollectionChanged(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
{


    foreach (StackPanel stk in ItemsPanel)
    {
        stk.MinHeight = 100;
        stk.MinWidth = 100;
        stk.Background = Brushes.White;
        ContainerStk.Children.Add(stk);


    }
}

Posted 1-Sep-12 20:40pm

loger21

Updated 1-Sep-12 20:52pm

v3

Add a Solution

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Philip Stuyck · Answer 1 · 2012-09-01T22:12:00

Solution 1

The stackpanel already belongs to the itemspanel, you must remove it from there before you can add it to the containerstk.Children. My guess is that you get an exception at the line where you want to add it.
The error is actually quite correct.

Posted 1-Sep-12 22:12pm

Philip Stuyck

Comments

loger21 2-Sep-12 8:30am

yes.exception at the line where i want to add it.but i do not know how to remove it from itemspanel with out error.

Philip Stuyck 2-Sep-12 12:56pm

your problem is twofold. In a foreach you have to make sure the list on which you iterate on does not change. So make a copy of it with toList or toArray whatever.
Then iterate over the copy and remove the panel from the itemspanel. The remove method works because it is an observable collection. Then after removing it from the collection adding it to a different elements children should work. But if the items are already part of some controls chidren, you must remove it first. That is the point.