C# Remove custom MouseClick EventHandler from control

Question

I am trying to add and then remove custom MouseClick event handlers to some Buttons. The controls on the window are being built at run-time. I can add my custom handler as per another answered question. localBtn.MouseClick += new MouseEventHandler((se, e) => Move_MouseClick(se, e, center, type));

I read the other questions about remove EventHandlers, but they seem to geared to the 'standard' event handler. I finally got this to compile object se=null; MouseEventArgs e=null; localBtn.MouseClick -= new MouseEventHandler((se1, e1) => Move_MouseClick( se, e, center, type)); (Where center and type are passed in parameters.) I do not know if this works or not...as I have run out of time for today....

I'm creating a grid (8x4) of buttons (maybe larger in the future), when one is clicked, the surrounding buttons 'change' into action buttons. Think of tic-tac-toe and the center button is the one clicked, all the others become 'active'. The custom handler is created with a reference to the 'center' button and then an enum indicating which of the 8 buttons then handler is for, top,left,right, topLeft, BottomRight, etc.. Once one of the 'active' buttons is pressed 'something happens' and the handlers need to be removed and the buttons will revert to their 'inactive' state. The buttons are derived from an object that has 'references' to all the other 'buttons' around it.

I read How to remove all event handlers from a control and C# removing an event handlerr.

Perhaps a better control is more suited to what I'm doing ?

[edit] I have tried the -= as shown above but that did not work. The control still had both event handlers attached. The program did not fail in anyway, so I'm not sure what the -= did? I guess nothing.

Answer 1

It sounds like you should use a user control for what you're trying to accomplish. Here is an example of how it could be done in code behind (there may be a better way for what you're doing specifically; this is just to give you a working example):

ButtonGrid.xaml:

<UserControl x:Class="WpfApplication1.ButtonGrid"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             mc:Ignorable="d" 
             d:DesignHeight="300" d:DesignWidth="300">
    <Grid x:Name="PART_Grid">
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="*" />
            <ColumnDefinition Width="*" />
            <ColumnDefinition Width="*" />
            <ColumnDefinition Width="*" />
        </Grid.ColumnDefinitions>
        <Grid.RowDefinitions>
            <RowDefinition Height="*" />
            <RowDefinition Height="*" />
            <RowDefinition Height="*" />
            <RowDefinition Height="*" />
            <RowDefinition Height="*" />
            <RowDefinition Height="*" />
            <RowDefinition Height="*" />
            <RowDefinition Height="*" />
        </Grid.RowDefinitions>
    </Grid>
</UserControl>

ButtonGrid.cs (could also make the Grid in here, since everything else is being done in here):

public partial class ButtonGrid : UserControl
    {
        private int rows, cols;
        private Button[] buttons;
        public ButtonGrid()
        {
            InitializeComponent();

            cols = 4;
            rows = 8;
            buttons = new Button[cols * rows];
            Button button;
            for (int i = 0; i < cols; i++)
            {
                for (int j = 0; j < rows; j++)
                {
                    // Make the button, set its place on the grid, set the necessary properties, give it OnClick, then add it to the grid
                    button = new Button();
                    button.SetValue(Grid.ColumnProperty, i);
                    button.SetValue(Grid.RowProperty, j);

                    button.Name = "Button" + (j + (rows * (i))).ToString();
                    button.Content = j + (rows * (i));
                    button.IsEnabled = false;

                    button.Click += OnClick;

                    buttons[j + (rows * (i))] = button;
                    PART_Grid.Children.Add(button);
                }
            }
            buttons[12].IsEnabled = true;
        }

        private void OnClick(object sender, RoutedEventArgs e)
        {
            int index;
            Button button = sender as Button;
            // Determine which button was pressed by finding the index of the button that called this from the button name
            if (button.Name.Length == 7)
            {
                index = Int32.Parse(button.Name.Substring(6, 1));
            }
            else
            {
                index = Int32.Parse(button.Name.Substring(6, 2));
            }

            // Make sure the buttons that are being affected are within bounds
            if ((index - 1) >= 0)
            {
                buttons[index - 1].IsEnabled = true;
            }

            if ((index - rows) >= 0)
            {
                buttons[index - rows].IsEnabled = true;
            }

            if ((index + 1) <= (cols * rows - 1))
            {
                buttons[index + 1].IsEnabled = true;
            }

            if ((index + rows) <= (cols * rows - 1))
            {
                buttons[index + rows].IsEnabled = true;
            }
        }
    }

I just put it in the main window with <local:ButtonGrid Width="500" Height="500" />.

And when pressed:

And you can keep clicking the buttons to see how the ones around it become enabled (or whatever you want to happen to them).

Answer 2

you can create another on mouseclick event empty and assign your button's click to that empty button,

but this time dont use += , just use =