I have am making a map editor for a game which has a user control that has an image. Inside that control I attached the MouseWheel event to it, but I've noticed two issues that I hope to have a better understanding of why it behaves the way it does and how to properly implement it.
For one the event only seems to fire when the mouse is hovering over it instead of when the control is in focus. If possible I would like to switch that and be able to fire the event no matter where the mouse is as long as that control is in focus and the second issue is that checking the delta when the number is positive works fine, but when I get a number back when it's negative I get a value of 0xfffffffd or something in that range. How would I go about differentiating the difference between a positive balue and a negative value if I always get something positive?
Thanks in advance for the help.
If you want to fire MouseWheel event for focused element try:
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
this.MouseWheel += OnMouseWheel;
}
IInputElement focusedElement;
private void OnMouseWheel(object sender, MouseWheelEventArgs e)
{
if (focusedElement is TextBox)
{
var tbx = focusedElement as TextBox;
//do something
}
}
protected override void OnPreviewLostKeyboardFocus(KeyboardFocusChangedEventArgs e)
{
focusedElement = e.NewFocus;
}
}
Related
I have multiple children of the same WinForms form, each with its own handler for a keyboard event. For a minimal example (C#):
public Form1() {
InitializeComponent();
c1 = new Control();
c2 = new Control();
c1.KeyPress += c1_KeyPress;
c2.KeyPress += c2_KeyPress;
Controls.Add(c1);
Controls.Add(c2);
}
void c1_KeyPress(object sender, KeyPressEventArgs e) {
Text += " c1";
e.Handled = true;
}
void c2_KeyPress(object sender, KeyPressEventArgs e) {
Text += " c2";
e.Handled = true;
}
When the event fires, it always gets handled by whichever child was originally added to the form first. Reordering the children with c2.BringToFront() or Controls.SetChildIndex(c2, 0) doesn't change the priority. Reordering the constructions or the delegate assignments doesn't change anything either. Calling c2.Focus() doesn't either. Changing the order of the Add calls is the only thing that seems to affect it.
(By contrast, for mouse events the priority gets resolved in an expected way: the topmost control under the pointer hotspot gets dibs on the event, and "topmost" is a clear concept I can control using BringToFront and friends.)
In my real case, c1 is a simple custom control derived from WinForms.UserControl, and c2 is a CefSharp.WinForms.ChromiumWebBrowser. There the keyboard events are caught by c2 no matter what I do.
What decides this priority of handlers? How can I change it?
There is no "priority", keyboard events are raised on the control that has the focus. Intuitively simple to understand, entering text in a TextBox requires selecting it first. A very significant flaw in the posted snippet is that you cannot tell which one has the focus. Although the Control class is usable as-is, in practice you almost always need to derive your own class from it to give it desirable behavior.
Add a new class to your project and paste the code shown below. Replace new Control() with new MyControl(). Now you can tell.
using System;
using System.Windows.Forms;
class MyControl : Control {
protected override void OnEnter(EventArgs e) {
this.Invalidate();
base.OnEnter(e);
}
protected override void OnLeave(EventArgs e) {
this.Invalidate();
base.OnLeave(e);
}
protected override void OnPaint(PaintEventArgs e) {
if (this.Focused) {
ControlPaint.DrawFocusRectangle(e.Graphics, this.DisplayRectangle);
}
base.OnPaint(e);
}
}
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'm building a Windows Presentation Foundation control with Microsoft Blend.
When I leave my control by pressing the left-mouse-button, the MouseLeave-Event is not raised. Why not?
This is intended behaviour: When you are doing mousedown on a control and leaving the control, the control STILL retains its "capture" on the mouse, meaning the control won't fire the MouseLeave-Event. The Mouse-Leave Event instead will be fired, once the Mousebutton is released outside of the control.
To avoid this, you can simple tell your control NOT to capture the mouse at all:
private void ControlMouseDown(System.Object sender, System.Windows.Forms.MouseEventArgs e)
{
Control control = (Control) sender;
control.Capture = false; //release capture.
}
Now the MouseLeave Event will be fired even when moving out while a button is pressed.
If you need the Capture INSIDE the Control, you need to put in more effort:
Start tracking the mouseposition manually, when the mousekey is pressed
Compare the position with the Top, Left and Size Attributes of the control in question.
Decide whether you need to stop the control capturing your mouse or not.
public partial class Form1 : Form
{
private Point point;
private Boolean myCapture = false;
public Form1()
{
InitializeComponent();
}
private void button1_MouseDown(object sender, MouseEventArgs e)
{
myCapture = true;
}
private void button1_MouseMove(object sender, MouseEventArgs e)
{
if (myCapture)
{
point = Cursor.Position;
if (!(point.X > button1.Left && point.X < button1.Left + button1.Size.Width && point.Y > button1.Top && point.Y < button1.Top + button1.Size.Height))
{
button1.Capture = false; //this will release the capture and trigger the MouseLeave event immediately.
myCapture = false;
}
}
}
private void button1_MouseLeave(object sender, EventArgs e)
{
MessageBox.Show("Mouse leaving");
}
}
of course you need to stop the own tracking ( myCapture=false;) on MouseUp. Forgot that one :)
When I don't get mouse events I expect I typically use Snoop to help me understand what is happening.
Here are a couple of links:
1- Snoop (a WPF utility)
2- CodePlex project for Snoop
And for completeness and historical reasons (not the bounty - it doesn't make sense having two duplicate questions - you should probably move it into one if not too late)...
I made a thorough solution using global mouse hook here (approach 2)
WPF: mouse leave event doesn't trigger with mouse down
And simplified its use - you can use it by binding to commands in your view-model - e.g.
my:Hooks.EnterCommand="{Binding EnterCommand}"
my:Hooks.LeaveCommand="{Binding LeaveCommand}"
my:Hooks.MouseMoveCommand="{Binding MoveCommand}"
...more details in there
Old question but I came across the same problem with a Button (MouseLeave does not fire while MouseDown because MouseDown Captures the Mouse...)
This is how I solved it anyway:
element.GotMouseCapture += element_MouseCaptured;
static void element_MouseCaptured(object sender, MouseEventArgs e)
{
FrameworkElement element = (FrameworkElement)sender;
element.ReleaseMouseCapture();
}
Hope that helps someone looking for a quick fix :P
I have a UserControl in my WPF application.
I want to call a click event and do some things when the user clicked the UserControl.
The problem is- the UserControl doesn't have a click event.
I searched on the web and found that you can use the MouseLeftButtonUp event.
I tried it- but it doesn't respond to my clicks.
You didn't write what you are trying to do but if you need a click event maybe you are writing some kind of button (the Button class is actually "something you can click" with the visual representation in a control template you can replace)
If you need a button with complex content inside - put your user control inside a button
If you need a button that doesn't look like a button write a custom control template for button
If you need a button with extra functionality subclass button, add the extra data/behavior in code and put the display XAML in a style.
I think for your needs PreviewMouseLeftButtonUp(Down) event is more suitable. Then you need to handle ClickCount for counting amount of clicks and then raise your own event, on which other controls will know, that your control is clicked. There are much more methods on handling click event. You should look at this msdn article and this
UPDATE to handle both Click and DoubleClick
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
_myCustomUserControl.MouseLeftButtonUp += new MouseButtonEventHandler(_myCustomUserControl_MouseLeftButtonUp);
_myCustomUserControl.MouseDoubleClick += new MouseButtonEventHandler(_myCustomUserControl_MouseDoubleClick);
}
bool _doubleClicked;
void _myCustomUserControl_MouseDoubleClick(object sender, MouseButtonEventArgs e)
{
_textBlock.Text = "Mouse left button clicked twice";
_doubleClicked = true;
e.Handled = true;
}
void _myCustomUserControl_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
{
if (_doubleClicked)
{
_doubleClicked = false;
return;
}
_textBlock.Text = "Mouse left button clicked once";
e.Handled = true;
}
}
To test this example name your control as _myCustomUserControl and add a TextBlock named _textBlock to your MainWindow.xaml
Why not just use MouseDown?
Put the event in the User Control and simply do this:
private void MyControl_MouseDown(object sender, MouseButtonEventArgs e)
{
if (e.ChangedButton == MouseButton.Left)
{
MessageBox.Show("Clicked!");
}
}
I'd like the main menu in my WPF app to behave like the main menu in IE8:
it's not visible when the app starts
pressing and releasing Alt makes it visible
pressing and releasing Alt again makes it invisible again
repeat until bored
How can I do this? Does it have to be code?
Added in response to answers submitted, because I'm still having trouble:
My Shell code-behind now looks like this:
public partial class Shell : Window
{
public static readonly DependencyProperty IsMainMenuVisibleProperty;
static Shell()
{
FrameworkPropertyMetadata metadata = new FrameworkPropertyMetadata();
metadata.DefaultValue = false;
IsMainMenuVisibleProperty = DependencyProperty.Register(
"IsMainMenuVisible", typeof(bool), typeof(Shell), metadata);
}
public Shell()
{
InitializeComponent();
this.PreviewKeyUp += new KeyEventHandler(Shell_PreviewKeyUp);
}
void Shell_PreviewKeyUp(object sender, KeyEventArgs e)
{
if (e.SystemKey == Key.LeftAlt || e.SystemKey == Key.RightAlt)
{
if (IsMainMenuVisible == true)
IsMainMenuVisible = false;
else
IsMainMenuVisible = true;
}
}
public bool IsMainMenuVisible
{
get { return (bool)GetValue(IsMainMenuVisibleProperty); }
set { SetValue(IsMainMenuVisibleProperty, value); }
}
}
You can use the PreviewKeyDown event on the window. To detect the Alt key you will need to check the SystemKey property of the KeyEventArgs, as opposed to the Key property which you normally use for most other keys.
You can use this event to set a bool value which has been declared as a DependencyProperty in the windows code behind.
The menu's Visibility property can then be bound to this property using the BooleanToVisibilityConverter.
<Menu
Visibility={Binding Path=IsMenuVisibile,
RelativeSource={RelativeSource AncestorType=Window},
Converter={StaticResource BooleanToVisibilityConverter}}
/>
I just came across this problem myself. I tried hooking into the PreviewKeyDown event, but found it to be unreliable. Instead I found the InputManager class where you can hook into the EnterMenuMode from managed code. The manager exposes two events, for enter and exit. The trick is to not collapse the menu, but set it's container height to zero when it is to be hidden. To show it, simply clear the local value and it will take its previous height.
From my TopMenu user control:
public TopMenu()
{
InitializeComponent();
InputManager.Current.EnterMenuMode += OnEnterMenuMode;
InputManager.Current.LeaveMenuMode += OnLeaveMenuMode;
Height = 0;
}
private void OnLeaveMenuMode(object sender, System.EventArgs e)
{
Height = 0;
}
private void OnEnterMenuMode(object sender, System.EventArgs e)
{
ClearValue(HeightProperty);
}
I'd try looking into handling the PreviewKeyDown event on your window. I'm not sure if pressing Alt triggers this event or not, but if it does, then I'd toggle a bool which is bound to the visibility of the main menu of the window.
If PreviewKeyDown doesn't work, I'm not sure what else to try. You could look into getting at the actual Windows messages sent to your window, but that could get messy very quickly.
It would be better to use GetKeyboardState with VK_MENU to handle both left and right Alt, to mimic the behavior of IE / Windows Explorer (Vista+) you'll need to track the previously focused element to store focus, on a VK_MENU press whilst the focused element is within your main menu. You also want to be doing this work on PreviewKeyUp (not down).
See my answer to the following thread:
How to make WPF MenuBar visibile when ALT-key is pressed?
There I describe how to solve your problem with the class InputManager (from namespace System.Windows.Input).
You can register the classes events EnterMenuMode and LeaveMenuMode.