why Mouse Events doesn't work?

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why Mouse Events doesn't work in this application!!!
when the mouse down event is bone on the picturebox , no reaction is done

using System.Drawing;
using System.Windows.Forms;


namespace test
{
    public partial class Form1 : Form
    {

        bool _selecting;
        Rectangle _selection;
        //---------------------------------------------------------------------
        public Form1()
        {
            InitializeComponent();
        }
        //---------------------------------------------------------------------
        private void Form1_Load(object sender, System.EventArgs e)
        {

        }
        //---------------------------------------------------------------------
        private void pictureBox1_MouseDown(object sender,MouseEventArgs e)
        {
            // Starting point of the selection:
            if (e.Button == MouseButtons.Left)
            {
                _selecting = true;
                _selection = new Rectangle(new Point(e.X, e.Y), new Size());
               
            }
        }
        //---------------------------------------------------------------------
        private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
        {
            // Update the actual size of the selection:
            if (_selecting)
            {
                _selection.Width = e.X - _selection.X;
                _selection.Height = e.Y - _selection.Y;

                // Redraw the picturebox:
                pictureBox1.Refresh();
            }
        }
        //---------------------------------------------------------------------
        private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left && _selecting)
            {


                _selecting = false;
            }
        }
        //---------------------------------------------------------------------
        private void pictureBox1_Paint(object sender, PaintEventArgs e)
        {
            if (_selecting)
            {
                // Draw a rectangle displaying the current selection
                Pen pen = Pens.GreenYellow;
                e.Graphics.DrawRectangle(pen, _selection);
            }
        }
        //---------------------------------------------------------------------

    }
}

Posted 17-Dec-11 8:57am

elgammal

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2 solutions

Solution 3

In addition to the problem pointed out by Mika:

Your question is no more that the indication of the fact you are not using debugger, it looks like. If you want to develop anything seriously, you need to have elementary skills of using the debugger whenever you have a problem, and at lease before asking a question like that. Also, do you understand that methods like pictureBox1_MouseUp are not events? Only the name suggests that the purpose of the method was related to using them as event handlers. Besides, such names violate (good) Microsoft naming conventions. Yes, they are generated by Microsoft Designer, so what? Who told you you are supposed to keep them? You need to renamed everything to some semantic names. Even better, avoid names at all. All you need is anonymous methods:

C#

this.pictureBox1.MouseMove += (sender, eventArgs) => { /* ... */ }

//and this syntax can work even for C# v.2, where lambda was not yet introduced:
this.pictureBox1.MouseUp += delegate(object sender, MouseEventArgs eventArgs)  { /* ... */ }

Now, more important problem:

The whole idea of using the class PictureBox for any interactive behavior you are trying to achieve is completely pointless. Even though this is possible, the PictureBox functionality does not add anything useful, but only creates unwanted hassles and eats up resources and extra development time. Instead, you need to use a custom control based on System.Windows.Forms.Control.

I explain this and what to do in my past solution: How do I clear a panel from old drawing[^].

—SA

Posted 17-Dec-11 14:53pm

Sergey Alexandrovich Kryukov

Comments

Wendelius 18-Dec-11 2:35am

That's very true, 5'd

Sergey Alexandrovich Kryukov 18-Dec-11 11:57am

Thank you, Mika.
--SA

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Wendelius · Accepted Answer · 2011-12-17T09:13:00

Are you sure you have wired the events. Do you have in your For1.designer.cs the following lines:

C#

this.pictureBox1.Paint += new System.Windows.Forms.PaintEventHandler(this.pictureBox1_Paint);
this.pictureBox1.MouseDown += new System.Windows.Forms.MouseEventHandler(this.pictureBox1_MouseDown);
this.pictureBox1.MouseMove += new System.Windows.Forms.MouseEventHandler(this.pictureBox1_MouseMove);
this.pictureBox1.MouseUp += new System.Windows.Forms.MouseEventHandler(this.pictureBox1_MouseUp);