Is there any way for me to do this?
You can tell when the VerticalOffset changes by adding a handler to the ScrollViewer.ScrollChanged event to your TextBox. Something like this:
<TextBox AcceptsReturn="True" ScrollViewer.ScrollChanged="TextBox_ScrollChanged" />
The TextBox uses a ScrollViewer internally, so it's ScrollChanged event will bubble up to the TextBox (where you can handle it). The event arguments include information about what changed, such as the VerticalChange (the amount that the control has scrolled vertically).
private void TextBox_ScrollChanged(object sender, ScrollChangedEventArgs e) {
System.Diagnostics.Debug.WriteLine(string.Format("************ {0}", e.VerticalChange));
}
Related
I have a textbox and several custom controls. Each of the custom controls has a "hint text" property that should appear in the textbox when that control is hovered over.
In winforms I was able to just give the custom control a textbox property and change its text property with events, however in WPF it instead makes a new textbox when I give it a property.
So how can I get the desired functionality?
Assuming your custom controls all inherit from a common base type (which I have called CustomControl as an example)...
XAML:
<TextBox x:Name=TextBox/>
<Button VerticalAlignment="Bottom" Click="ButtonBase_OnClick" MouseEnter="UIElement_OnMouseEnter" MouseLeave="UIElement_OnMouseLeave">test</Button>
Code behind:
private void UIElement_OnMouseEnter(object sender, MouseEventArgs e)
{
TextBox.Text = ((CustomControl) sender).HintText;
}
private void UIElement_OnMouseLeave(object sender, MouseEventArgs e)
{
TextBox.Text = string.Empty;
}
I have a UserControl with a number of StackPanel's. I like to hide specific panels depending on the user action. A StackPanel which is visible on startup gives me a number of working buttons. The buttons have click events in the code behind file. After collapsing the panel and then making it visible again the buttons no longer work. Here is a part of my UserControl:
<StackPanel x:Name="buttonPanel" Orientation="Horizontal">
<Button x:Name="ReMindNodeNotes" Content=""
FontFamily="Segoe UI Symbol" FontSize="14" Foreground="#FF292323"
HorizontalAlignment="Left" BorderThickness="1" Padding="0"
UseLayoutRounding="True" Click="NoteClicked" />
<Button x:Name="ReMindNodeRemove" Content=""
FontFamily="Segoe UI Symbol" FontSize="14" Foreground="#FF292323"
HorizontalAlignment="Left" BorderThickness="1" Padding="0"
UseLayoutRounding="True" Click="RemoveClicked" />
</StackPanel>
And here is the code (for now just some text):
private void NoteClicked(object sender, RoutedEventArgs e)
{
System.Diagnostics.Debug.WriteLine("NoteClicked...");
}
private void RemoveClicked(object sender, RoutedEventArgs e)
{
System.Diagnostics.Debug.WriteLine("RemoveClicked...");
}
I have been looking for a solution the last two days. No luck so far. Who can help...?
THX Peter
Follow up 1...
Here is the code for collapsing the panel:
private void MoreClicked(object sender, RoutedEventArgs e)
{
System.Diagnostics.Debug.WriteLine(this.nodeName);
this.buttonPanel.Visibility =
this.buttonPanel.Visibility ==
Visibility.Visible ? Visibility.Collapsed : Visibility.Visible;
}
It works if the buttonPanel has focus. If the focus is on another panel it does not. Furthermore, what I probably should have mentioned... is that users can create multiple instances of the user control.
THX
Follow up 2...
I continue working on a solution of course... ;-) and I found a solution, which however is not the solution I want. Let me explain.
Users can interactively create multiple instances of the user control mentioned before. When a new instance is created, that instance gets focus. Now every instance has its own set of buttons which are on a stackpanel. When the focus goes to another instance I want the panel of the previous instance to collapse. The focus should then be set to the new (or selected existing) instance.
When I do this manually, it works! When I try to achieve this through the GotFocus and LostFocus events however, it does not. Here is the code for the manual solution (which works):
private void MoreClicked(object sender, RoutedEventArgs e)
{
this.buttonPanel.Visibility =
this.buttonPanel.Visibility ==
Visibility.Visible ? Visibility.Collapsed : Visibility.Visible;
}
Here are the LostFocus and GotFocus events:
private void NodeGotFocus(object sender, RoutedEventArgs e)
{
this.buttonPanel.Visibility = Visibility.Visible;
}
private void NodeLostFocus(object sender, RoutedEventArgs e)
{
this.buttonPanel.Visibility = Visibility.Collapsed;
}
I really appreciate your help! THX again...
Thanks for your sample morincer. The problem however is a little more complex. Let me try to explain the solution which I found after some more research. Maybe other developers can benefit from it as well.
I added the GotFocus and LostFocus events to my userconctrol. If I click somewhere inside the usercontrol the focus changes every time. Strange as these events are only defined on the usercontrol itself and not it's children. I have several buttons and a textbox inside the usercontrol and when I for example click on one of the buttons of the usercontrol that has focus the LostFocus and GotFocus events are fired for usercontrol anyway.
The most important event for me in this case is the LostFocus event. When the usercontrol looses focus - for example to another control - I want the button panel to disappear. Since the LostFocus event fires every time a object inside the usercontrol is touched, I cannot distinguish between the situation in which I want to hide and show the buttons.
I got a little closer to a solution by changing the LostFocus event as follows:
private void LostFocus(object sender, RoutedEventArgs e)
{
Object fo = FocusManager.GetFocusedElement();
if (fo.GetType().ToString().Contains("TextBox") ||
fo.GetType().ToString().Contains("ScrollViewer"))
{
this.buttonPanel.Visibility = Visibility.Collapsed;
}
}
This covers most of the situations. When the cursor is positioned in the TextBox the button panel is closed. The button panel is also closed when the user clicks on the background. This seems to be a ScrollViewer (found through debugging the code). Can anyone explain this...?
The situation which is not covered however, is when a user clicks on another usercontrol. It does of course when the user clicks on the TextBox (see the code) but not when the user clicks on a button. I tried to compare sender and FocusManager.GetFocusedElement(). Problem is that the sender returns the usercontrol (which is what I am looking for) but the FocusManager.GetFocusedElement() returns the button that was pressed. Now I could ask for it's parent which is a border then ask for the borders parent which is a stack panel and so on until I arrive at the usercontrol. A code behind file however was introduced with the idea to split design and logic while this solution would tie them together again. If I would change the XAML I would have to change the logic as well. Doesn't seem to be the right solution to me.
I found a solotion by giving every usercontrol a unique name in the constructor. I then give all the buttons unique names as well (I don't use them in my code anyway) starting with the name of the usercontrol. This then gives me the possibility to compare names at runtime and determine whether the focus has changed to another instance of the usercontrol. Here is the code:
private void NodeLostFocus(object sender, RoutedEventArgs e)
{
Object fo = FocusManager.GetFocusedElement();
if (fo.GetType().ToString().Contains("ScrollViewer"))
{
this.buttonPanel.Visibility = Visibility.Collapsed;
}
else if (fo.GetType().ToString().Contains("TextBox"))
{
if (!((TextBox)fo).Name.Contains(this.nodeName))
{
this.buttonPanel.Visibility = Visibility.Collapsed;
}
}
else if (fo.GetType().ToString().Contains("Button"))
{
if (!((Button)fo).Name.Contains(this.nodeName))
{
this.buttonPanel.Visibility = Visibility.Collapsed;
}
}
}
Now this works! But…I don't like the solution. I am depending on names instead of a good architecture. Does anyone hove an idea how to compare the actual sender with the usercontrol that is the parent of the button pressed (FocusManager.GetFocusedElement())? Or any other solution that relies on good programming?
THX again
In my main window, I have a child control(user control) which contains a text box . How can I handle the textchange event of the text box of child control in main(parent) window.
Please provide me some example with code as I am new to routing of events.
You should just be able to hook the event from the parent control. But since your parent control doesn't have a TextChanged event of its own, you'll need to use attached-property syntax:
<Window ...
TextBox.TextChanged="ChildTextBoxChanged">
and in your codebehind:
private void ChildTextBoxChanged(object sender, TextChangedEventArgs args)
{
...
}
You don't have to put the TextBox.TextChanged= on the Window specifically -- just any control that's a parent of the TextBox, i.e., any control that's a parent of your UserControl. The event will bubble up to each parent in turn, all the way up to the top-level Window, and can get handled anywhere along the way.
(Note that if anyone hooks the event and sets e.Handled = true, the event won't bubble past that point. Useful to know if you have handlers at multiple levels.)
this also helped me. I will have a event in the container of the child control and define the event in the code behind file. The event will handle all the text changed events for all the children.
<StackPanel TextBoxBase.TextChanged="test_TextChanged" Name="test">
<userControl/>
</StackPanel>
Create a event in your childcontrol -
public event TextChangedEventHandler TextChanged;
now add a handler for TextChanged event of TextBox in childcontrol -
private void TextBox_TextChanged(object sender, TextChangedEventArgs args)
{
if (TextChanged != null)
{
TextChanged.Invoke(this, args);
}
}
also update XAML for this handler -
<TextBox ... TextChanged="TextBox_TextChanged" ... />
Now, you have created a event in your childcontrol that fires when the Textbox's textchanged fires.
Now you only to add a handler for this event in mainwindow -
private void ChildControl_TextChanged(object sender, TextChangedEventArgs args)
{
//TODO: Add your further code here.
}
I have a ListBox with an ItemTemplate that contains a control that interacts with the mouse. This interfers with the selection functionality of the ListBox, i.e. clicking a control does not select the item. This is because ListBoxItem sets the Handled property of the mouse event to true in OnMouseLeftButtonDown. I tried the following
protected override void OnMouseLeftButtonDown(MouseButtonEventArgs e) {
base.OnMouseLeftButtonDown(e);
e.Handled = false;
}
but the ListBoxItem “takes over” the mouse and prevents the control from doing its own interaction. Then I had another idea
protected override void OnMouseLeftButtonDown(MouseButtonEventArgs e) {
base.OnMouseLeftButtonDown(e);
((ListBoxItem)VisualTreeHelper.GetParent(VisualTreeHelper.GetParent(VisualTreeHelper.GetParent(this)))).IsSelected = true;
}
which actually works, but feels more like an ugly kludge than an elegant solution. Are there any better solutions that don't rely on the exact contents of the visual tree?
I've found a way that is less of a kludge:
protected override void OnMouseLeftButtonDown(MouseButtonEventArgs e) {
base.OnMouseLeftButtonDown(e);
Selector.SetIsSelected(this, true);
}
For this to have any effect, the control in the ListBox' ItemTemplate needs the following XAML attribute:
Selector.IsSelected="{Binding IsSelected, Mode=OneWayToSource, RelativeSource={RelativeSource AncestorType={x:Type ListBoxItem}}}"
It raises two new questions:
Would it be better to define my own dependency property rather than finding an attached one that isn't currently in use?
Is there a way to achieve something similar in markup only?
I believe the MouseLeftButtonDown is a tunnelling event: you could try using PreviewMouseLeftButtonDown, doing your processing there, then ensuring e.Handled = false; as you tried already - that should do the trick!
Hope that helps.
Here is one simple solution, but unfortunately handler can be attached only in code, not in markup.
Event handler can be added by using handledEventsToo signature of AddHandler method:
myListBox.AddHandler(UIElement.MouseDownEvent,
new MouseButtonEventHandler(ListBox_MouseDown), true);
Third parameter above is handledEventsToo which ensures that this handler will be invoked no matter if it is already marked as Handled (which ListBoxItem does in ListBox).
See Marking Routed Events as Handled, and Class Handling for explanation.
See How to Attach to MouseDown Event on ListBox for example.
When trying to use a Slider control I'd like to listen to the MouseLeftButtonDown and MouseLeftButtonUp. I have handlers set up for both events. The MouseLeftButtonUp works as expected. MouseLeftButtonDown is not raised at all.
Any ideas why?
I've done a bit of googling and it seems that the WPF doesn't fire either. One of the solutions (in this post) was to use the Preview version of the events which is something silverlight doesn't support.
Is there any simple solution to this that I'm not seeing?
Thanks
J
It happens because Slider handles mouse down/up events. Internally its implemented as two RepeatButtons and a thumb in the middle. When you click on left or right side of the slider your mouse events are handled by RepeatButtons, and you don't get them.
If you still want to handle handled event you can use AddHandler() method. Here is Silverlight example:
XAML
<Slider Width="100"
VerticalAlignment="Top"
Minimum="0"
Maximum="100"
Name="sl" />
C#
public partial class MainPage : UserControl
{
public MainPage()
{
InitializeComponent();
sl.AddHandler(MouseLeftButtonDownEvent, new MouseButtonEventHandler(Slider_MouseLeftButtonDown), true);
sl.AddHandler(MouseLeftButtonUpEvent, new MouseButtonEventHandler(Slider_MouseLeftButtonUp), true);
}
private void Slider_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
{
}
private void Slider_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
}
}
In WPF situation is almost same (small differences in names).