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How do I change the properties of a control within a list dynamically (C# Winform)?

I have a list of checkbox controls
public List<CheckBox> _checkBoxes = new List<CheckBox>();
I add a certain amount during runtime using a switch case with the properties such as location and visibility.
This all works fine, but if I want the checkboxes to disappear or become checked at some point the GUI doesn't get updated, the list is updated with the new data but just not visually.
* I ended up doing this*
I created a bunch of checkboxes on the winfrom.Created a method which you can choose which ones are visible. Then created a method to fill a list of type checkbox. Then you can search the panel for control types, once you found the control, it can be manipulated. This isn't elegant and probably isn't the best way, but i am new to custom controls and winforms.
//search panel for checkboxes
foreach (Control c in panel1.Controls)
{
if (c is CustomControls.RoundedCheckBox)
{
CustomControls.RoundedCheckBox checkBox = c as CustomControls.RoundedCheckBox;
//if it is checked add to list
if(checkBox.Checked)
{
_checkBoxes.Add(checkBox);
}
}
}

If you have something like this:
_checkBoxes.Add(new CheckBox());
_checkBoxes[0].Parent = this;
then you should be able to manipulate your checkboxes from the list:
_checkBoxes[0].Checked = false;
But, the problem may occur if you do it in some kind of loop and want to see the results immediately.
In Windows there is something called message loop. Application simply works like that (pseudocode: TL;DR)
while(true)
{
message = GetFirstMessage();
if(message != null)
{
if(message.Id == CloseApplication)
break;
DispatchMessage(message);
RemoveFirstMessage();
}
}
So, application takes message from queue, then process it. A message is everything - button click, mouse move, paint... Everything.
So when a message is dispatched it looks for the control that should receive this message and then it does some work.
So, for example if you have something like that:
foreach(var ch in _checkBoxes)
{
ch.Checked = false;
DoSomeWorkThatTakesTime();
ch.Checked = true;
}
You won't see the change, because you are "trapped" in DispatchMessage. When you set Checked, you really sending a message. But this message cannot be Dispatched right now, because you are inside the foreach loop.
So the only thing you can do here is to tell your application - now, please DO READ message queue. In WinForms it's called "DoEvents", so this will do the work:
foreach(var ch in _checkBoxes)
{
ch.Checked = false;
Application.DoEvents();
DoSomeWorkThatTakesTime();
ch.Checked = true;
Application.DoEvents();
}

Wpf rollback|stop transfer of focus and stop other events

I have a really big wpf application with many nested controls using caliburn micro and MVVM.
One control needs a check a condition before(while) the user leaves. If the check fails the focus is transfered back to the said control.
Using Finding ALL child controls WPF
I solved the problem with child control also firing the LostFocus event. And I used the Dispatcher to put the focus back to the control.
my code looks like this:
public void LostKeyboardFocus(object sender, KeyboardFocusChangedEventArgs e)
{
var parent = ParentFinder.TryFindParent<ProfileFunctionView>(e.NewFocus as FrameworkElement);
//only fire for outside controls, not child controls
if (parent == null)
{
if (!Apply())
{
var restoreFocus = (System.Threading.ThreadStart)delegate { SyntaxEditor.Focus(); };
Application.Current.Dispatcher.BeginInvoke(restoreFocus);
//stuff should happen here
}
}
}
The problem is that, if I click on a tab control somewhere above my control f.e.. The focus is set back correctly, but than the tab changes. I want to prevent the controls that are clicked outside of my control to react if the condition fails.
Is this possible? Is my approach correct?
Please excuse my confusing title, this problem is really hard to formulate or google. Any help is appreciated.

So, the first thing I would do is use the FocusManager to create a focus scope. Here is the MSDN Documentation.
https://learn.microsoft.com/en-us/dotnet/api/system.windows.input.focusmanager?view=netcore-3.1
Setting a focus scope is essentially a container of elements within the scope. So, for your example I would do something like this.
ProfileFunctionView ()
{
// This will make child controls use this as their FocusScope.
FocusManager.SetIsFocusScope ( this );
}
Next, now that we have created a FocusScope it is easy to check if the element that has focus is in scope or not.
public void LostKeyboardFocus( object sender, KeyboardFocusChangedEventArgs e )
{
if ( sender is UIElement element ) {
var scope = FocusManager.GetFocusScope ( element );
if ( scope is Window ) {
// This is the default focus scope you have actually lost focus.
RestoreFocus();
}
else if ( scope is ProfileFunctionView view )
{
// Haven't lost focus do nothing
return;
}
else
{
// Handle case where focus does not belong to either.
}
}
}
Another method and probably the more appropriate method would be to set the parent elements Focusable property to False. This will prevent the lost focus events from firing in the first place.
Edit: Adding information based on your comment.
If the events are unwanted Disable all controls out side of FocusScope.
ProfileFunctionView ()
{
// This will make child controls use this as their FocusScope.
FocusManager.SetIsFocusScope ( this );
// Better to do this during the Loaded event.
FocusManagerUtility.DisableUIOutsideOfScope ( scope: this );
}
public static class FocusScopeUtility
{
public static void DisableUIOutsideScope ( scope )
{
// Psuedo function to get the top level UIElement in the tree.
var container = GetOwningWindowOrPage ( scope );
// Psuedo function to get traversal of tree
var traversal = GetVisualTreeTraversalAsEnumerable ();
foreach ( var node in traversal )
{
var element = node as UIElement;
if ( FocusScopeUtility.IsInScope ( scope, element )
{
// This line disables the control from receiving input.
element.Enabled = false;
}
}
}
}

C# Dynamic form (reflection) - linking controls

Sorry for the poor quality of the title. I couldn't think of a better way to phrase this.
For a project I'm currently working on with a few friends, I got myself in the situation where I have created a dynamic form (with reflection) which I now want to validate.
Example (ignore the black box, it contains old form elements which are now irrelevant and i didn't want to confuse you guys):
As you may have guessed already, it is an application for creating a mysql database.
Which is where I get to my problem(s). I want to disable checkboxes if others are checked.
For example: If I check "PrimaryKey" I want to disable the checkbox "Null".
Changing from unsigned to signed changes the numericupdown minimum and maximum etc.
But with reflection and all, I find it difficult to know exactly which checkbox to disable.
I was hoping you guys would have some suggestions.
I have been thinking about this for a while and a few thoughts have come to mind. Maybe these are better solutions than the current one.
Thought 1: I create UserControls for every datatype. Pro's: no problems with reflection and easy identifying of every control in the UserControl for validation. Con's: Copy-Pasting, Lots of UserControls, with a lot of the same controls.
Thought 2: Doing something with the description tags for every property of the classes. Creating rules in the description that allow me to link the checkboxes together. Here I'll only have to copy the rules to every class property and then it should be ok.
I had been thinking of other solutions but I failed to remember them.
I hope you guys can give me a few good pointers/suggestions.
[Edit]
Maybe my code can explain a bit more.
My code:
PropertyInfo[] properties = DataTypes.DataTypes.GetTypeFromString(modelElement.DataType.ToString()).GetType().GetProperties();
foreach (PropertyInfo prop in properties)
{
if (prop.Name != "Label" && prop.Name != "Project" && prop.Name != "Panel")
{
var value = prop.GetValue(modelElement.DataType, null);
if (value != null)
{
tableLayoutPanel1.Controls.Add(new Label { Text = prop.Name, Anchor = AnchorStyles.Left, AutoSize = true });
switch (value.GetType().ToString())
{
case "System.Int32":
NumericUpDown numericUpDown = new NumericUpDown();
numericUpDown.Text = value.ToString();
numericUpDown.Dock = DockStyle.None;
tableLayoutPanel1.Controls.Add(numericUpDown);
break;
case "System.Boolean":
CheckBox checkBox = new CheckBox();
checkBox.Dock = DockStyle.None;
// checkbox will become huge if not for these changes
checkBox.AutoSize = false;
checkBox.Size = new Size(16, 16);
if (value.Equals(true))
{
checkBox.CheckState = CheckState.Checked;
}
tableLayoutPanel1.Controls.Add(checkBox);
break;
default:
MessageBox.Show(#"The following type has not been implemented yet: " + value.GetType());
break;
}
}
}
}

Here is a mockup from my comments:
// The ViewModel is responsible for handling the actual visual layout of the form.
public class ViewModel {
// Fire this when your ViewModel changes
public event EventHandler WindowUpdated;
public Boolean IsIsNullCheckBoxVisible { get; private set; }
// This method would contain the actual logic for handling window changes.
public void CalculateFormLayout() {
Boolean someLogic = true;
// If the logic is true, set the isNullCheckbox to true
if (someLogic) {
IsIsNullCheckBoxVisible = true;
}
// Inform the UI to update
UpdateVisual();
}
// This fires the 'WindowUpdated' event.
public void UpdateVisual() {
if (WindowUpdated != null) {
WindowUpdated(this, new EventArgs());
}
}
}
public class TheUI : Form {
// Attach to the viewModel;
ViewModel myViewModel = new ViewModel();
CheckBox isNullCheckBox = new CheckBox();
public TheUI() {
this.myViewModel.WindowUpdated += myViewModel_WindowUpdated;
}
void myViewModel_WindowUpdated(object sender, EventArgs e) {
// Update the view here.
// Notie that all we do in the UI is to update the visual based on the
// results from the ViewModel;
this.isNullCheckBox.Visible = myViewModel.IsIsNullCheckBoxVisible;
}
}
The basic idea here is that you ensure that the UI does as little as possible. It's role should just be to update. Update what? That's for the ViewModel class to decide. We perform all of the updating logic in the ViewModel class, and then when the updating computations are done, we call the UpdateVisual() event, which tells the UI that it needs to represent itself. When the WindowUpdated Event occurs, the UI just responds by displaying the configuration set up by the ViewModel.
This may seem like a lot of work to set up initially, but once in place it will save you tons and tons of time down the road. Let me know if you have any questions.

Try relating the event of one checkbox to disable the other; something like this:
private void primaryKeyBox_AfterCheck(object sender, EventArgs e)
{
nullBox.Enabled = false;
}
This is a very simple example and would have to be changed a bit, but for what I think you're asking it should work. You would also have to add to an event for the boxes being unchecked. You would also need logic to only get data from certain checkboxes based on the ones that are and are not checked.
For all the other things, such as changing the numbers based on the dropdown, change them based on events as well.

For WinForms I would use data binding.
Create an object and implement INotifyPropertyChanged and work with that object.
Then, If you have an object instance aObj:
To bind the last name property to a textbox on the form do this:
Private WithEvents txtLastNameBinding As Binding
txtLastNameBinding = New Binding("Text", aObj, "LastName", True, DataSourceUpdateMode.OnValidation, "")
txtLastName.DataBindings.Add(txtLastNameBinding)
Take a look here for more info.
INotifyPropertyChanged

c# wpf overlapping controls not receiving mouse events

I am building a canvas control. This root canvas has several overlapping children (canvas as well). This is done so each child can handle its own drawing and I can then compose the final result with any combination of children to get the desired behavior.
This is working very well as far as rendering is concerned. This does not work so well with mouse events however. The way mouse events works are as follow (using previewmousemove as an example):
1- If root canvas is under mouse, fire event
2- Check all children, if one is under mouse, fire event and stop
As such, only the first child I add will receive the mouse move event. The event is not propagated to all children because they overlap.
To overcome this, I attempted the following:
1- Override mouse events in the root canvas
2- For every event, find all children that want to handle the event using VisualTreeHelper.HitTest
3- For all children that returned a valid hit test result (ie: under mouse and willing to handle the event (IsHitTestVisible == true)), ???
This is where I am stuck, I somehow need to send the mouse event to all children, and stop the normal flow of the event to make sure the first child doesn't receive it twice (via handled = true in the event).
By using RaiseEvent with the same event passed on the children, things seem to work but somehow it raises the event on the parent (root canvas) as well. To bypass this I needed to create a copy of the event and set force set the source though it appears to be more of a hack than a solution. Is there a proper way to do what I am trying to do? Code example follows.
public class CustomCanvas : Canvas
{
private List<object> m_HitTestResults = new List<object>();
public new event MouseEventHandler MouseMove;
public CustomCanvas()
{
base.PreviewMouseMove += new MouseEventHandler(CustomCanvas_MouseMove);
}
private void CustomCanvas_MouseMove(object sender, MouseEventArgs e)
{
// Hack here, why is the event raised on the parent as well???
if (e.OriginalSource == this)
{
return;
}
Point pt = e.GetPosition((UIElement)sender);
m_HitTestResults.Clear();
VisualTreeHelper.HitTest(this,
new HitTestFilterCallback(OnHitTest),
new HitTestResultCallback(OnHitTest),
new PointHitTestParameters(pt));
MouseEventArgs tmpe = new MouseEventArgs(e.MouseDevice, e.Timestamp, e.StylusDevice);
tmpe.RoutedEvent = e.RoutedEvent;
tmpe.Source = this;
foreach (object hit in m_HitTestResults)
{
UIElement element = hit as UIElement;
if (element != null)
{
// This somehow raises the event on us as well as the element here, why???
element.RaiseEvent(tmpe);
}
}
var handlers = MouseMove;
if (handlers != null)
{
handlers(sender, e);
}
e.Handled = true;
}
private HitTestFilterBehavior OnHitTest(DependencyObject o)
{
UIElement element = o as UIElement;
if (element == this)
{
return HitTestFilterBehavior.ContinueSkipSelf;
}
else if (element != null && element.IsHitTestVisible && element != this)
{
return HitTestFilterBehavior.Continue;
}
return HitTestFilterBehavior.ContinueSkipSelfAndChildren;
}
private HitTestResultBehavior OnHitTest(HitTestResult result)
{
// Add the hit test result to the list that will be processed after the enumeration.
m_HitTestResults.Add(result.VisualHit);
// Set the behavior to return visuals at all z-order levels.
return HitTestResultBehavior.Continue;
}

I think you should use the preview events because those are RoutingStrategy.Tunnel from Window to the most high control in Z-Order, and normal events are RoutingStrategy.Bubble.
In this RoutedEvents there are a property Handle when it's true the system will stop to traverse the visual tree because someone used this event.

I found your code example interesting so I gave it a try... but I had to make a small modification for it to work properly in my stuff.
I had to change the 2nd "if" in the HitTestFilter method as follow:
if (element == null || element.IsHitTestVisible)
As you can see I removed the useless "element != this" at the end (you already tested that condition in the 1st "if") and I added "element == null" at the beginning.
Why? Because at some point during the filtering the parameter type was System.Windows.Media.ContainerVisual which doesn't inherit from UIElement and so element would be set to null and ContinueSkipSelfAndChildren would be returned. But I don't want to skip the children because my Canvas is contained inside its "Children" collection and UIElements I want to hittest with are contained in Canvas.

Just as #GuerreroTook said, you should solve this by using WPF's RoutedEvents (more information here.

Tooltips for CheckedListBox items?

Is there a straighforward way to set additional text to appear in a tooltip when a user's mouse is held over an item in a CheckedListBox?
What I would expect to be able to do in code is:
uiChkLstTables.DisplayOnHoverMember = "DisplayOnHoverProperty"; //Property contains extended details
Can anyone point me in the right direction to do this? I've already found a couple of articles that involve detecting which item the mouse is currently over and creating a new tooltip instance, but this sounds a little too contrived to be the best way.
Thanks in advance.

Add a Tooltip object to your form and then add an event handler for the CheckedListBox.MouseHover that calls a method ShowToolTip();
Add MouseMove event of your CheckedListBox which has the following code:
//Make ttIndex a global integer variable to store index of item currently showing tooltip.
//Check if current location is different from item having tooltip, if so call method
if (ttIndex != checkedListBox1.IndexFromPoint(e.Location))
ShowToolTip();
Then create the ShowToolTip method:
private void ShowToolTip()
{
ttIndex = checkedListBox1.IndexFromPoint(checkedListBox1.PointToClient(MousePosition));
if (ttIndex > -1)
{
Point p = PointToClient(MousePosition);
toolTip1.ToolTipTitle = "Tooltip Title";
toolTip1.SetToolTip(checkedListBox1, checkedListBox1.Items[ttIndex].ToString());
}
}

Alternately, you could use a ListView with checkboxes instead. This control has
builtin support for tooltips.

Contrived or not; that's what there is...
I'm not aware of an easier way than you have already described (although I'd probably re-use a tooltip instance, rather than creating new all the time). If you have articles that show this, then use them - or use a 3rd party control that supports this natively (none leap to mind).

I would like to expand upon Fermin's answer in order to perhaps make his wonderful solution slightly more clear.
In the form that you're working in (likely in the .Designer.cs file), you need to add a MouseMove event handler to your CheckedListBox (Fermin originally suggested a MouseHover event handler, but this did not work for me).
this.checkedListBox.MouseMove += new System.Windows.Forms.MouseEventHandler(this.showCheckBoxToolTip);
Next, add two class attributes to your form, a ToolTip object and an integer to keep track of the last checkbox whose tool tip was shown
private ToolTip toolTip1;
private int toolTipIndex;
Finally, you need to implement the showCheckBoxToolTip() method. This method is very similar to Fermin's answer, except that I combined the event callback method with the ShowToolTip() method. Also, notice that one of the method parameters is a MouseEventArgs. This is because the MouseMove attribute requires a MouseEventHandler, which then supplies MouseEventArgs.
private void showCheckBoxToolTip(object sender, MouseEventArgs e)
{
if (toolTipIndex != this.checkedListBox.IndexFromPoint(e.Location))
{
toolTipIndex = checkedListBox.IndexFromPoint(checkedListBox.PointToClient(MousePosition));
if (toolTipIndex > -1)
{
toolTip1.SetToolTip(checkedListBox, checkedListBox.Items[toolTipIndex].ToString());
}
}
}

Run through your ListItems in your checkbox list of items and set the appropriate text as the item 'title' attribute, and it will display on hover...
foreach (ListItem item in checkBoxList.Items)
{
//Find your item here...maybe a switch statement or
//a bunch of if()'s
if(item.Value.ToString() == "item 1")
{
item.Attributes["title"] = "This tooltip will display when I hover over item 1 now, thats it!!!";
}
if(item.Value.ToString() == "item 2")
{
item.Attributes["title"] = "This tooltip will display when I hover over item 2 now, thats it!!!";
}
}