draggable line(rectangle) in c #???

Sounds like you're on the right track.

I can't find the pen drive with my code on but from what i remember i did the following:

create a class with two points in it (start and end) and the rectangle for the hit testing, expose properties or methods to access these fields

have a generic list object that stores this class

on mouse down event create a Rectangle based on the current mouse coordinates with a width/height of 1.

iterate over the list and see whether any of the items.Rectangle property contains the rectangle you just created, if it does you have a hit.

If you have a hit you need to store the mouse position and in the mouse up event store the new position, then using these two points you can determine which way to move the line

Babycorn-Starfish,

Thanks so much for answering and getting the code for me.
I will try out your code and let you know if I can figure out from your code.
Again thanks much.

No probs, hope you can adapt it to what you want.  Post here if you've any questions about adapting it to your needs :)

Babycorn-Starfish,

I ran your code and worked fine.
Thanks so much.

Can I ask a few more questions please?
I know these are things I need to think about myself but can use help!!

1) I want that rectangle(line, width of 1) to move from left to right direction.
when I move it downward, I see length of line gets reduced, meaning it is moving downward. How can I stop that??

2) Two lines come across when I move them, how can I stop two lines to pass each other??

3) I want two lines to stay on the graph( panel or rectangle). Just stay inside of x axis..

Maybe I should create a thread..
Thanks again.

Hi again,

post the code that you have so far and i'll try and modify it for you, i'll comment it so you'll understand the changes.

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

namespace DragLineTest
{
  public partial class Form1 : Form
  {
    private List<Rectangle> rects = new List<Rectangle>();
    private int currIdx = -1;
    private Point oldPoint;
    private Point newPoint;
    private Boolean hit = false;
    private Boolean mouseDown = false;

    public Form1()
    {
      InitializeComponent();
      Rectangle rect1 = new Rectangle(1, 1, 190, 100);
      Rectangle leftBar = new Rectangle(21, 1, 1, 100);
      Rectangle rightBar = new Rectangle(170, 1, 1,100);
      rects.Add(rect1);
      rects.Add(leftBar);
      rects.Add(rightBar);
   
    }
    private void panel1_Paint(object sender, PaintEventArgs e)
    {
      e.Graphics.DrawRectangle(Pens.Black,rects[0]);
      e.Graphics.FillRectangle(Brushes.Red, rects[1]);
      e.Graphics.FillRectangle(Brushes.Red, rects[2]);
   
    }
    private void panel1_MouseDown(object sender, MouseEventArgs e)
    {
      currIdx = -1;
      for (int idx = 1; idx < rects.Count; idx++)
      {
        if (rects[idx].Contains(e.Location))
        {
          if (e.Button == MouseButtons.Left)
          {
            oldPoint = e.Location;
            currIdx = idx;
            mouseDown = true;
            hit = true;
          }
          return;
        }
      }
        hit = false;
        return;
    }
    private void panel1_MouseUp(object sender, MouseEventArgs e)
    {
      mouseDown = false;
      hit = false;
      Invalidate();
      Update();
    }
    private Point GetDifference(Point end, Point start)
    {
      return new Point(end.X - start.X, end.Y - start.Y);
    }
    private void panel1_MouseMove(object sender, MouseEventArgs e)
    {
      if (mouseDown && hit)
      {      
            newPoint = e.Location;
            Point diff = GetDifference(newPoint, oldPoint);
            Rectangle currentRect = rects[currIdx];
            currentRect.X += diff.X;
            currentRect.Y += diff.Y;
            ShowCurrectRectCoordinates(currentRect.X, currentRect.Y);
            rects[currIdx] = currentRect;
            Invalidate(true);
            Update();
            oldPoint = newPoint;      
      }
    }
    private void ShowCurrectRectCoordinates(int x, int y)
    {
      this.textBox1.Text = "x: " + x + " y: " + y;
   

    }
  }
}

Actually, this is more reliable, BUT (perhaps it's because i'm using a laptop's touch pad instead of a 'real' mouse) i found it hard to move the lines because there always seemed to be an element of up/down motion which cancels the overall line movement. Let me know how it works for you. Incidentally the IntersectsWith method i used earlier is a no go, doesn't always work :(

private const int LEFT = 0;
        private const int RIGHT = 1;

        private void panel3_MouseMove(object sender, MouseEventArgs e)
        {
            if (mouseDown && hit)
            {
                newPoint = e.Location;
                Point diff = GetDifference(newPoint, oldPoint);
                Rectangle currentRect = rects[currIdx];
                currentRect.X += diff.X;
                currentRect.Y += diff.Y;

                switch (currIdx)
                {
                    case LEFT://left most line
                        {
                            if (currentRect.X >= rects[RIGHT].X)
                            {
                                return;
                            }
                            else if(currentRect.X <= rect1.X)
                            {
                                return;
                            }    
                            break;
                        }
                    case RIGHT://right most line
                        {
                            if (currentRect.X <= rects[LEFT].X)
                            {
                                return;
                            }
                            else if (currentRect.X >= rect1.X + rect1.Width)
                            {
                                return;
                            }
                            break;
                        }
                    default:
                        {
                            break;
                        }
                }

                if (currentRect.Y <= rect1.Y)
                {
                    return;
                }
                else if (currentRect.Y + currentRect.Height >= rect1.Y + rect1.Height)
                {
                    return;
                }

                ShowCurrectRectCoordinates(currentRect.X, currentRect.Y);
                rects[currIdx] = currentRect;
                Invalidate(true);
                Update();
                oldPoint = newPoint;
            }
        }