I'm trying to create an overlay in wpf (with darkening background), similar to the ones you can find on the web to popup images.
I would like it to be reusable in more than 1 part of the application, with diffent types of content.
this is the temporary code of the constructor of the adorner class (just to try)
private readonly Grid _grid = new Grid();
public DarkOverlayAdorner(UIElement adornedElement, Object content) :
base(adornedElement)
{
_grid.Background = new SolidColorBrush(Color.FromArgb(99, 0, 0, 0));
IsHitTestVisible = true;
var visual = content as UIElement;
if (visual != null)
_grid.Children.Add(visual);
}
In addition in the class (of course), I have the ovverrides of MeasureOverride and ArrangeOverride to give the adorner the correct size of the adorned element, GetVisualChild, and VisualChildCount...
The problem here is that the adorner is correctly shown, but no events or behaviour are applied on the adorned element. For example:
AdornerLayer layer = AdornerLayer.GetAdornerLayer(textBoxProva);
layer.Add(new DarkOverlayAdorner(textBoxProva, new Button{Content = "prova"}));
The button here is shown, but I can-t click the button and no effects on button mouseover are applied.
I still can't figure out the problem.
Ok, I've lost a lot of time trying to figure out what was the problem.
In the end I found the solution:
If you want the element added to react to events, I think that the element must be bound to the visual tree of the adorner.
The way to do it is to use a VisualCollection, intitialized to the adorner itself:
VisualCollection visualChildren;
FrameworkElement #object;
public DarkOverlayAdorner(UIElement adornedElement) :
base(adornedElement)
{
visualChildren = new VisualCollection(this);
#object = new Button {Content = "prova"};
visualChildren.Add(#object);
}
protected override Visual GetVisualChild(int index)
{
return visualChildren[index];
}
This way the events are correctly routed.
You might want to take a look at the ChildWindow control in the Extended WPF Toolkit. It is a control that pops up a Window with a modal background effect, and you can specify the content to put inside the Window.
Related
Say for example you have a stackpanel that you would like to programmatically add buttons to.
The code behind for the button generation and addition to the stackpanel is:
Button button = new Button();
button.Content = "Button";
button.HorizontalAlignment = HorizontalAlignment.Left;
button.Name = "Button" + i
stackPanel1.Children.Add(button);
My question is - Is it possible to generate the button once and have it as some kind of template that can be added to the stackpanel whenever it is needed without going through the generation code again?
In WPF each UIElement can only be the logical child of one control at any given time, see WPF Error: Specified element is already the logical child of another element. Disconnect it first, so no you can't use the same button and add it to another control later on, unless you're sure you've gotten rid of that stackpanel
But, you can do recycling. See Optimizing Performance: Controls. especially if you are willing to override MeasureOverride and ArrangeOverride of you stackpanel
I've actually written such a recycler because I had grids with many controls, and I wanted to implement some kind of virtualizing grid. These are the main methods of my class:
internal class Recycler
{
private UIElementCollection _children;
public Recycler(UIElementCollection children)
{
_children = children;
//You need this because you're not going to remove any
//UIElement from your control without calling this class
}
public void Recycle(UIElement uie)
{
//Keep this element for recycling, remove it from Children
}
public UIElement GiveMeAnElement(Type type)
{
//Return one of the elements you kept of this type, or
//if none remain create one using the default constructor
}
}
I'm trying to design a Popup which will appear on the bottom-right corner of its PlacementTarget
Let's admit that you set its PlacementTarget to a Window, well, the Popup will act as classic toaster notifications.
Given the fact that WPF is not smart enough to provide us a "corner" solution, I'm trying to implement a new control, inheriting from Popup , which will place itself at the appropriate location.
Here is my first idea: work on Loaded event to determine where should I place the Popup.
Problem? I don't want to give any fixed dimensions to the popup, which is supposed to size itself according to the text displayed.
However, I can't get the ActualWidth property when Loaded event is raised.
I can't have it either when Opened event is raised.
Here is the draft code so far:
public class ExceptionPopup : Popup
{
public ExceptionPopup()
{
InitializeComponent();
Loaded += new RoutedEventHandler(ExceptionPopup_Loaded);
}
void ExceptionPopup_Loaded(object sender, RoutedEventArgs e)
{
if (PlacementTarget != null)
{
if (PlacementTarget is FrameworkElement)
{
parentWidth = (PlacementTarget as FrameworkElement).ActualWidth;
parentHeight = (PlacementTarget as FrameworkElement).ActualHeight;
}
}
}
protected override void OnOpened(EventArgs e)
{
this.HorizontalOffset = parentWidth;
this.VerticalOffset = parentHeight;
base.OnOpened(e);
}
}
Is there any other event I could use to catch what I want here?
I'd basically like to set HorizontalOffset to parentWidth - ActualWidth/2 , same for height :)
Any idea?
Thanks!
Usually I set the PlacementTarget to either Bottom or Right, then apply a RenderTransform which shifts the Popup by the remaining value.
For example, I might use Placement=Bottom, then use a RenderTransform to shift the popup (Window.Width - Popup.Width) to the right, and Popup.Height upwards. You might not even need to re-adjust based on the Popup Height/Width becauase MSDN says that Popups are not allowed to be displayed off screen, and it will automatically adjust their placement to keep them visible
Be sure you use a RenderTransform instead of a LayoutTransform, because RenderTransforms get applied after the Popup gets Rendered, so the ActualHeight and ActualWidth will be greater than 0.
I am trying to make a nice "drag and drop zone" in WPF that is displayed in the adorner layer when something is being dragged into the main application. The problem is that I do not get any events from my adorner, even though it according to documentation should receive all input events since it is in a higher z-order.
To debug my problem I created a really simple example where I have a user control with only a button in it. This user control is displayed in the adorner layer, but I cannot click the button. Why? What have I done wrong?
My adorner class is constructed like this:
public ShellOverlayAdorner(UIElement element, AdornerLayer adornerLayer)
:base(element)
{
_adornerLayer = adornerLayer;
_overlayView = new AdornedElement();
_overlayView.AllowDrop = true;
_adornerLayer.Add(this);
}
and is created in the main window by
private void Window_Loaded(object sender, RoutedEventArgs e)
{
adornerLayer = AdornerLayer.GetAdornerLayer(MyTopGridWithButtonInIt);
ShellOverlayAdorner shell = new ShellOverlayAdorner(MyTopGridWithButtonInIt, adornerLayer);
}
I do not get any events at all from my control, i.e. no mouse clicks, mouse over, button clicks. I cannot even click the button in the adorner layer. What have I done wrong?
I don't know if you already tried that:
If you want the element added to react to events, I think that the element must be bound to the visual tree of the adorner.
The way to do it is to use a VisualCollection, intitialized to the adorner itself, or at least, this way it seems to be working:
VisualCollection visualChildren;
FrameworkElement #object;
public CustomAdorner(UIElement adornedElement) :
base(adornedElement)
{
visualChildren = new VisualCollection(this);
#object = new Button {Content = "prova"};
visualChildren.Add(#object);
}
protected override Visual GetVisualChild(int index)
{
return visualChildren[index];
}
This way the events are correctly routed.
I just had the same issue. Following the advice from MSDN sorted it for me:
Adorners receive input events just
like any other FrameworkElement.
Because an adorner always has a higher
z-order than the element it adorns,
the adorner receives input events
(such as Drop or MouseMove) that may
be intended for the underlying adorned
element. An adorner can listen for
certain input events and pass these on
to the underlying adorned element by
re-raising the event.
To enable pass-through hit testing of
elements under an adorner, set the hit
test IsHitTestVisible property to
false on the adorner.
i.e In the adorner itself, make sure IsHitTestVisible = false
I'm using WPF in WinForms with ElementHost. When the form loads, there is a flash of black background where the ElementHost is about to load. This looks kind of bad. Any suggestions on how to get rid of this?
Hide the element (Visibility = Hidden) until the WinForms control is fully loaded...
I know this has already been answered and the question is old but none of the presented answers worked for myself and after a long time of troubleshooting the issue. I finally found an easier answer.
If you build a class extending from Element Host and in the initial constructor. You can set a Load Event for the Host Container. The Host Container is the panel that the Element Hosts Child is being displayed on top of. From there, just set the Host Containers background color to being of the Element Hosts Parents background color.
Like this
using System.Windows;
using System.Windows.Forms;
using System.Windows.Media;
public class MyElementHost : ElementHost
{
public MyElementHost()
{
this.HostContainer.Loaded += new RoutedEventHandler(HostPanelLoad);
}
public void HostPanelLoad(object sender, RoutedEventArgs e)
{
System.Drawing.Color parentColor = this.Parent.BackColor;
this.HostContainer.Background = new SolidColorBrush(Color.FromArgb(parentColor.A, parentColor.R, parentColor.G, parentColor.B));
}
}
you need first show control with empty bounds first time to avoid black flickering
if (!_control.Created && _control.BackColor != Color.Transparent)
{
_control.Bounds = Rectangle.Empty;
_control.Show();
}
// set control bounds and show it
Rectangle bounds = GetBounds(context, rect);
if (_control.Bounds != bounds)
_control.Bounds = bounds;
if (!_control.Visible)
_control.Show();
I have a WPF user control that contains a DataGrid. I'm binding an ObservableCollection of view models to it. Each view model has another collection of view models that I'm using to bind another DataGrid to. So the effect is a DataGrid with a nested DataGrid contained in the row details template.
Normally the binding is quite quick, but sometimes when there's a lot of data it can hang the UI while the binding/drawing is taking place.
Is there a way where I can either show a loading animation or progress bar while the binding/drawing is in progress?
There's probably a more formal, or at least simpler solution, but you could use a modal popup window that is shown in a worker thread and is closed asynchronously when your is grid done loading:
Window waitWindow = new Window { Height = 100, Width = 200, WindowStartupLocation = WindowStartupLocation.CenterScreen, WindowStyle = WindowStyle.None };
waitWindow.Content = new TextBlock { Text = "Please Wait", FontSize = 30, FontWeight = FontWeights.Bold, HorizontalAlignment = HorizontalAlignment.Center, VerticalAlignment = VerticalAlignment.Center };
BackgroundWorker worker = new BackgroundWorker();
worker.DoWork += delegate
{
Dispatcher.BeginInvoke(new Action(delegate { waitWindow.ShowDialog(); }));
DataLoader dataLoader = new DataLoader(); // I made this class up
dataLoader.DataLoaded += delegate
{
Dispatcher.BeginInvoke(new Action(delegate() { waitWindow.Close(); }));
};
dataLoader.LoadData();
};
worker.RunWorkerAsync();
You can replace the TextBlock with something pretty like a loading bar, and you could make the code re-usable by parameterizing the object that handles the loading of the grid(s) and passing it in to a commonly used method.
I hope that works for you.
I had the same problem and this is how I solved it.
I discovered that DataGrid will only start creating controls when it displays the grid. In my case this was the time consuming process. After some tracing I found that creating the controls happens during measuring !
My solution is to override MeasureOverride and put the wait cursor around the base class call. I encapsulated my wait cursor setting in a class. So the code looks like this.
protected override Size MeasureOverride(Size availableSize)
{
using (new DisposableWaitCursor(this))
{
return base.MeasureOverride(availableSize);
}
}