Event handlers and mouse click

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I'm having a trouble figuring out how to manage the handlers.
Problem is i have 5 picture box and they have shared handlers for example when I hover over them they get BorderStyle.Fixed3D if mouse leaves then BorderStyle.None occurs that works fine. But here is the problem.. I need to left click the mouse to keep the picturebox Stuck in BorderStyle.Fixed3D but I think it doesn't work because of the MouseLeave event any suggestion how to fix that ?

What I have tried:

private void SetEvents() //Initilize events
        {
            teningur1.MouseHover += PictureBoxes_MouseHover;
            teningur2.MouseHover += PictureBoxes_MouseHover;
            teningur3.MouseHover += PictureBoxes_MouseHover;
            teningur4.MouseHover += PictureBoxes_MouseHover;
            teningur5.MouseHover += PictureBoxes_MouseHover;

            teningur1.MouseLeave += PictureBoxes_MouseLeave;
            teningur2.MouseLeave += PictureBoxes_MouseLeave;
            teningur3.MouseLeave += PictureBoxes_MouseLeave;
            teningur4.MouseLeave += PictureBoxes_MouseLeave;
            teningur5.MouseLeave += PictureBoxes_MouseLeave;

            teningur1.MouseClick += PictureBoxes_MouseClick;
            teningur2.MouseClick += PictureBoxes_MouseClick;
            teningur3.MouseClick += PictureBoxes_MouseClick;
            teningur4.MouseClick += PictureBoxes_MouseClick;
            teningur5.MouseClick += PictureBoxes_MouseClick;
        }


        private void PictureBoxes_MouseClick(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                ((PictureBox)sender).BorderStyle = BorderStyle.Fixed3D;
                
            }
            
        }


        //Event handlers
        static private void PictureBoxes_MouseHover(object sender, EventArgs e)
        {
            ((PictureBox)sender).BorderStyle = BorderStyle.Fixed3D;
        }

        static private void PictureBoxes_MouseLeave(object sender, EventArgs e)
        {
            ((PictureBox)sender).BorderStyle = BorderStyle.None;
        }

Posted 5-Feb-18 5:02am

ThisandThatorWhat

Updated 5-Feb-18 5:55am

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OriginalGriff · Answer 1 · 2018-02-05T05:19:00

Solution 1

Every control has a Tag property: you can use it to hold any object.
Set the Tag property of all your pictureboxes to BorderStyle.None
Then in your Hover method:

C#

PictureBox p = sender as PictureBox;
if (p != null)
    {
    p.BorderStyle = BorderStyle.Fixed3D;
    }

In your Leave hander:

C#

PictureBox p = sender as PictureBox;
if (p != null)
    {
    p.BorderStyle = (BorderStyle) p.Tag;
    }

And your Click handler:

C#

PictureBox p = sender as PictureBox;
if (p != null)
    {
    p.BorderStyle = BorderStyle.Fixed3D;
    p.Tag = p.BorderStyle;
    }

Posted 5-Feb-18 5:19am

OriginalGriff

Comments

ThisandThatorWhat 5-Feb-18 11:30am

NullReferenceException was unhandled

An unhandled exception of type 'System.NullReferenceException' occurred

Additional information: Object reference not set to an instance of an object.

This happens when I hover over the picturebox.

I dont understand this p.Tag

static private void PictureBoxes_MouseLeave(object sender, EventArgs e)
{
PictureBox p = sender as PictureBox;
if (p != null)
{
p.BorderStyle = (BorderStyle)p.Tag;<---- here is the error
}
}

OriginalGriff 5-Feb-18 11:37am

That's because you ignored the first instruction:
"Set the Tag property of all your pictureboxes to BorderStyle.None"

ThisandThatorWhat 6-Feb-18 17:15pm

I think I got it but it says
Additional information: Specified cast is not valid. System.InvalidCastException'

PictureBox p = sender as PictureBox;

if (p != null)
{
p.BorderStyle = (BorderStyle)p.Tag;
}

ThisandThatorWhat 6-Feb-18 17:20pm

I have all the PictureBoxes tags set to BorderStyle.None
But I still get a error InvalidCastException Specified cast is not valid.

OriginalGriff 7-Feb-18 4:43am

Use the debugger to look at exactly what you have in the Tag when the exception occurs - I don't think it is what you expect, because when I do it here, it works. I suspect that you are setting the tag value in the wrong place, but I can't see your code to be sure.

ThisandThatorWhat 6-Feb-18 17:23pm

this.pictureBox.Tag = "BorderStyle.None";

User 7407470 · Answer 2 · 2018-02-05T05:55:00

OriginalGriff's solution is very good, but maybe this one's more convenient and easier to understand for you:

When you click on a PictureBox the border is already set to Fixed3D because of the MouseHover event (btw. better is to use MouseEnter).
So if you want to permanently keep this type of border you can just unsubscribe from the MouseLeave event (you can restore the border mechanism with the right mouse button):

C#

private void PictureBoxes_MouseClick(object sender, MouseEventArgs e)
{
    PictureBox pBox = sender as PictureBox;

    if (e.Button == MouseButtons.Left)
    {
        pBox.MouseLeave -= PictureBoxes_MouseLeave;                
    }
    else if (e.Button == MouseButtons.Right)
    {
        pBox.MouseLeave -= PictureBoxes_MouseLeave; // prevent double subscription
        pBox.MouseLeave += PictureBoxes_MouseLeave;
    }
}