I'm working in WPF to create a ListView component. The items in the list are based on another user control that reacts to MouseLeftDown events. The List also reacts to SelectionChanged events.
Right now, if I mouse down on any item on the list and move the cursor, the other items I pass along react to the SelectionChanged event (which is expected since the selection is changing as per the Mouse Down event in List view). I need to be able to disable this reaction when its down through a drag-to-scroll behavior, but to keep it active when the user selects an item on the list.
Does anyone have any ideas how this can be achieved?
Thanks everyone,
RK
I believe one of the ways that could help you is to implement your own handlers of MouseUp and MouseDown events of your items to select item on MouseUp instead of MouseDown. You could start from a sample like this:
public class MyListView : ListView
{
protected override DependencyObject GetContainerForItemOverride()
{
return new MyListViewItem();
}
}
public class MyListViewItem : ListViewItem
{
protected override void OnMouseLeftButtonDown(MouseButtonEventArgs e)
{
return;
}
protected override void OnMouseLeftButtonUp(MouseButtonEventArgs e)
{
base.OnMouseLeftButtonDown(e);
}
}
Related
I am using a ListView in a Windows Store App.
Whenever I start swiping(using simulator tap mode) over the list view all the items move together as illustrated in the picture.
How can I disable this manipulation event?
To your ListView, add:
ScrollViewer.VerticalScrollBarVisibility="Disabled" ScrollViewer.VerticalScrollMode="Disabled"
If that is not enough (this sometimes does not work with MouseWheel events, in that the events still tend to be caught in the ListView and also tends to happen if the list inside of the ScrollViewer is particularly large, I've found), then you need to create a custom control to specifically ignore the event, such as this for PointerWheelChanged.
public class CustomListView : ListView
{
protected override void OnApplyTemplate()
{
base.OnApplyTemplate();
var sv = this.GetTemplateChild("ScrollViewer") as UIElement;
if (sv != null)
sv.AddHandler(UIElement.PointerWheelChangedEvent, new PointerEventHandler(OnPointerWheelChanged), true);
}
private void OnPointerWheelChanged(object sender, PointerRoutedEventArgs e)
{
e.Handled = false;
}
}
This will disable mouse wheel scrolling inside of your ListView. You'll have to change your XAML reference to the ListView from <ListView> to <namespace:ListView> where namespace is the namespace you've created your ListView in.
I'm writing some code to detect toggling of selections in a WindForms ListBox with MultiSelect turned on. Since SelectedIndexChanged only lets me see what is selected after the click, I was looking for a way to detect what was selected before the ListBox was clicked. I implemented the MouseDown event and I can get exactly what I want, but an unfortunate side effect is that I have killed the SelectedIndexChanged event. It will not fire.
Is this known behavior? Are there any thoughts about getting to the selection list before the click?
Thanks.
Edited to include code snippets as requested.
Designer generated events:
this.lbPhysicianClinic.SelectedIndexChanged += new System.EventHandler( this.lbPhysicianClinic_SelectedIndexChanged );
this.lbPhysicianClinic.MouseDown += new System.Windows.Forms.MouseEventHandler( this.lbPhysicianClinic_MouseDown );
Code snippet showing MouseDown event:
private void lbPhysicianClinic_MouseDown( object sender, MouseEventArgs e )
{
List<Clinic_List_ByPhysicianResult> Selected = this.PhysicianGetSelectedClinics( this.lbPhysicianClinic.SelectedIndices );
}
Code snippet showing SelectedIndexChanged event:
private void lbPhysicianClinic_SelectedIndexChanged( object sender, EventArgs e )
{
try
{
if ( this.FormInitComplete && this.RefreshUIComplete )
{
List<Clinic_List_ByPhysicianResult> Selected = this.PhysicianGetSelectedClinics( this.lbPhysicianClinic.SelectedIndices );
Clinic_List_ByPhysicianResult DroppedClinic = new Clinic_List_ByPhysicianResult();
I set a breakpoint in each event and if the MouseDown event is there, the SelectedIndexChanged event never fires. It only fires when the MouseDown event is gone.
Hopefully this clarifies things.
The ListBox changes its selection before it raises the MouseDown or SelectedIndexChanged events.
What you need to do is capture the underlying Win32 message and raise an event yourself. You can subclass ListBox to do this.
class MyListBox : ListBox
{
private const int WM_LBUTTONDOWN = 0x201;
public event EventHandler PreSelect;
protected override void WndProc(ref Message m)
{
switch (m.Msg)
{
case WM_LBUTTONDOWN:
OnPreSelect();
break;
}
base.WndProc(ref m);
}
protected void OnPreSelect()
{
if(null!=PreSelect)
PreSelect(this, new EventArgs());
}
}
You can use the MyListBox class, and add a handler for the PreSelect event like so:
this.lbPhysicianClinic.PreSelect +=
new EventHandler(this.lbPhysicianClinic_PreSelect);
Inside the event handler you can access the selected indices before the listbox has changed them.
I have 2 controls on a form. One numericUpDown (from the Silverlight Toolkit) and a simple Rectangle.
On the MouseLeftButtonDown of the Rectangle I popup a MessageBox with the numericUpDown value.
If I use the arrows to change the value of the numericUpDown, everyting is fine. But if I edit the value manually (with the keyboard) and immediately click on the Rectangle it shows the previous value of the numericUpDown. If I click a sencond time on the rectangle it will show the new value.
The numericUpDown.ValueChanged event is raised after the Rectangle.MouseLeftButtonDown event.
Is that a Silverlight bug? Anybody knows a workaround for that?
(btw I cannot change my Rectangle controls or events)
As workaround I propose you to create your own control like:
public class MyNumericUpDown : NumericUpDown
{
private TextBox _textBox;
public void Sync()
{
ApplyValue(_textBox.Text);
}
public override void OnApplyTemplate()
{
base.OnApplyTemplate();
_textBox = (TextBox)GetTemplateChild("Text");
}
}
Now you can use method Sync to syncronize display text with control Value property. You can call method from XAML declaratively or in code behind. In your case:
private void Rectangle_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
myNumericUpDown.Sync();
MessageBox.Show(myNumericUpDown.Value.ToString());
}
I have a button inside my UserControl. I have three instances of this UserControl on the same page.
How can I expose the click event of the button inside such that I can assign different events for each instance of my UserControl.
I think this is similar to concept behind exposing DependencyProperty but I don't understand how to do it for events.
Thanks.
I normally add an event of the same name (and same parameters) to the user control and subscribe to the child control's original event, so I can pass the event on:
public partial class ClickEventControl : UserControl
{
public event EventHandler<RoutedEventArgs> Click;
public ClickEventControl()
{
InitializeComponent();
}
private void aButton_Click(object sender, RoutedEventArgs e)
{
if (Click != null)
{
Click(sender, e);
}
}
}
I would also be interested if there is a more general way of doing it.
For a very specific reason I want to select ListViewItems on mouse button up, not actually on mouse button down. I want this behaviour to be embedded in the control. Is it possible to achieve this? can anyone give hint?
Yes it's definitely possible using attached properties. Define an attached property called SelectOnMouseUp and when it's set to true, hook to your ItemsContainerGenerator events to discover when a new item container is added. Then when you get an event for a new item container, hook into its PreviewMouseDown and ignore it (set e.Handled to true), and hook into its MouseUp event and perform the selection (set IsSelected to true).
Aviad P.'s answer is a good one and a clever use of attached properties, but I tend to use a different technique most of the time:
Subclass ListViewItem.
Override OnMouseLeftButtonDown and OnMouseRightButton to do nothing.
Override OnMouseLeftButtonUp / OnMouseRightButtonUp to call base.OnMouseLeftButtonDown / base.OnMouseRightButtonDown.
Subclass ListView.
Override GetContainerForItemOverride() to return your ListViewItem override
This seems easier to me than subscribing to ItemContainer events and adding handlers dynamically.
This is what it looks like:
public class MouseUpListViewItem : ListViewItem
{
protected override void OnMouseLeftButtonDown(MouseButtonEventArgs e) {}
protected override void OnMouseRightButtonDown(MouseButtonEventArgs e) {}
protected override void OnMouseLeftButtonUp(MouseButtonEventArgs e)
{
base.OnMouseLeftButtonDown(e);
}
protected override void OnMouseRightButtonUp(MouseButtonEventArgs e)
{
base.OnMouseRightButtonDown(e);
}
}
public class MouseUpListView : ListView
{
protected override DependencyObject GetContainerForItemOverride()
{
return new MouseUpListViewItem();
}
}
I like this technique because there is less code involved.