Adding and removing WPF UIElements at runtime
Solution 1
A very good place to use an Attached Property
.
Example:
// Create an attached property named `GroupID`
public static class UIElementExtensions
{
public static Int32 GetGroupID(DependencyObject obj)
{
return (Int32)obj.GetValue(GroupIDProperty);
}
public static void SetGroupID(DependencyObject obj, Int32 value)
{
obj.SetValue(GroupIDProperty, value);
}
// Using a DependencyProperty as the backing store for GroupID. This enables animation, styling, binding, etc...
public static readonly DependencyProperty GroupIDProperty =
DependencyProperty.RegisterAttached("GroupID", typeof(Int32), typeof(UIElementExtensions), new UIPropertyMetadata(null));
}
Usage:
public void AddChild(UIElement element, Int32 groupID)
{
UIElementExtensions.SetGroupID(element, groupID);
rootPanel.Children.Add(element);
}
public void RemoveChildrenWithGroupID(Int32 groupID)
{
var childrenToRemove = rootPanel.Children.OfType<UIElement>().
Where(c => UIElementExtensions.GetGroupID(c) == groupID);
foreach (var child in childrenToRemove)
{
rootPanel.Children.Remove(child);
}
}
Solution 2
Try drawing on a Canvas
inside your grid... that way its as easy as:
MyCanvas.Chlidren.Clear();
MyCanvas.Children.Add(new Ellipse { Canvas.Top = 3....});
Hope it helps.
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Ra.
Updated on May 12, 2022Comments
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Ra. almost 2 years
Is there a way to logically group or tag UIElements like shapes and controls added at runtime for easy removal?
For eg., I have a
Grid
with some (design-time) child elements and add Ellipses andTextBlock
s to it at runtime. When I want to draw a different set of Ellipses andTextBlock
s, I'd like to remove the original set I added. What would be an easy way to logically group these while adding them so I can just have a children.clear() or some way to identify them to remove them?It is possible to add a tag value but there is no way to retrieve or read this while iterating through children of a control because they are of type
UIElement
which does not have a tag property.Thoughts?
-
Ra. over 13 yearsbut there are design-time children in there that I do not want to clear
-
Machinarius over 13 yearsThen put those you dont want to clear in an array [using x:Name], then loop trough the canvas children, clearing anything not in the array
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Ra. over 13 yearsthis was really useful and works great for me. Thanks a lot. I have not yet been able to get the query for the remove part working because my parent element is a user control and so the type is different from a panel, but that should be straight-forward.