Boundaries for mouseenter event?

Question

0.00/5 (No votes)

See more:

I have a class named Resistor. Yes, its about electronics. But I am experimenting, still. Inside it, in a Paint event,I add a image of a rezistor.png and some e.Graphics.FillRectangle colors and text.
In this class, I add "public event EventHandler MouseEnter;"
And from Form1 I can call it fine:
resistorx1.MouseEnter += new EventHandler(resistorx1_MouseEnter);

void resistorx1_MouseEnter(object sender, EventArgs e)
{
resistorx1.text1 = "gugu";
}
But noting is happening after I run with my mouse over it. No text changing!

I suppose some boundaries must be set to be able to "feel" when the mouse is inside ? How can I do that? - an example would help immensely - thank you.

What I have tried:

a lot of work ___________________

Posted 9-Dec-18 15:05pm

_Q12_

Updated 9-Dec-18 19:59pm

v2

Add a Solution

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

OriginalGriff · Answer 1 · 2018-12-09T19:59:00

Solution 1

You can't just add an event and expect it to be automatically hooked up - if you want to respond to system events then the class needs to be one that knows about system events: a UserControl.

I quickly constructed one, and it works. Add a new UserControl, Call it "Resistor" and set it's CS code to this:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Drawing;
using System.Data;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace GeneralTesting
    {
    public partial class Resistor : UserControl
        {
        public Resistor()
            {
            InitializeComponent();
            Text = "100R";
            }

        private void Resistor_Paint(object sender, PaintEventArgs e)
            {
            e.Graphics.FillRectangle(Brushes.Pink, e.ClipRectangle);
            e.Graphics.DrawString(Text, Font, Brushes.Black, e.ClipRectangle);
            }

        private void Resistor_MouseEnter(object sender, EventArgs e)
            {
            Text = "Hello";
            Invalidate();
            }

        private void Resistor_MouseLeave(object sender, EventArgs e)
            {
            Text = "100R";
            Invalidate();
            }

        }
    }

Drop one on my form in design mode, and run the app. when the mouse enters, it changes text, when the mouse leaves, it goes back.

Posted 9-Dec-18 19:59pm

OriginalGriff

Comments

_Q12_ 10-Dec-18 3:07am

Thank you mister OriginalGriff ! You give the best answer !
But... I want something special this time(if possible). I want to maintain it as a class only! (not transform it into UserControl). Why, you ask me? Different motifs. The essential one is to keep transparency after the control drawing (no background). That's the whole reason why I Paint my items in a class and refer to that paint, outside in my Form1. I understand I must make the whole event mechanism from scratch, but it is what it is, so I will do it this way. My question is How? It's a hard way to do it, but it's the only way my poor soul will be happy with the results.
Thank you !

OriginalGriff 10-Dec-18 3:27am

You can't. Classes are not "displayable items" in themselves, they do not - and cannot, because of the way Windows works - recieve or respond to Windows actions, including but not limited to mouse operations. Only items which are derived from the Control class (which includes the Form class) can be displayed, and can receive mouse actions.

To do what you want with a "standard class" would mean a huge amount of work in the "containing form": handling the mouse move for the container, working out that it's over an area your class is "in" and translating the messages and raising the events.
It's a huge investment, most of which is duplicating code which is already in .NET! Not to mention which but it's also a massive OOPs failure, because it breaks the independence of your new class in that the form becomes responsible for knowing where it is and drawing it!
And when you have a circuit diagram containing 40 resistors, 60 caps, a dozen IC's, uncounted diodes, and a few inductors your form has to be responsible for all of them.

Do it "the proper way" and they all become responsible for themselves, and the container becomes responsible for the links between them - which is a lot more of an accurate mapping to a real-world PCB and it's components!

Trust me on this: you are setting yourself up for a huge input of effort to get what you could have got with a single line of code ... :laugh:

_Q12_ 10-Dec-18 7:38am

edited:
I am testing your code now.
i dont think I actually tried this method that you present here... intriguing. Though I run over similar ones many times(in my searches).

_Q12_ 12-Dec-18 22:11pm

InitializeComponent(); does not work!
Error 1 The name 'InitializeComponent' does not exist in the current context.

OriginalGriff 13-Dec-18 3:38am

Let me guess ... You added ": UserControl" to the end of your existing class definition?

You don't create a UserControl like that, any more than adding ": Form" to a class will turn it into a working Form. Or if you like, adding a Ferrari logo to a bicycle will make it a race car! Controls have Designer.cs files which construct the control, in the same way the Forms do (and for the same reason, Forms are Controls!).

Add a new UserControl to your project, and copy your code into it.

_Q12_ 13-Dec-18 5:51am

thank you for your reply. I made a new control as you suggested. But how i get rid of the background of the control and paint directly on Form1 through Paint event of the control?
Is this an impossible task?

here is my working code since yours didn't did anything !
But even with my code, I paint on the background of the control and not directly on Form1 as I originally intend.

public partial class ResistorXA : UserControl
{
public ResistorXA()
{
InitializeComponent();
Text = "100R";
this.Paint += new PaintEventHandler(ResistorXA_Paint);
this.MouseEnter += new EventHandler(ResistorXA_MouseEnter);
this.MouseLeave += new EventHandler(ResistorXA_MouseLeave);
}

void ResistorXA_Paint(object sender, PaintEventArgs e)
{
e.Graphics.FillRectangle(Brushes.Pink, 2, 2, 30, 30);
e.Graphics.DrawString(Text, new Font("arial", 8f), Brushes.Black, 0, 0);
}

void ResistorXA_MouseEnter(object sender, EventArgs e)
{
Text = "Hello";
Invalidate();
}
void ResistorXA_MouseLeave(object sender, EventArgs e)
{
Text = "100R";
Invalidate();
}