How to draw and move shapes using mouse in C#

Question

I'm new to programming in C# and wanted to ask for a little bit of help. I'm currently trying to move a color-filled rectangle that I draw on a Windows Application form with my left mouse button, and I'm trying to drag-and-drop it to another location using my right mouse button. Currently I've managed to draw the rectangle, but the right click is dragging the entire form along.

Here's my code:

public partial class Form1 : Form
{
    private Point MouseDownLocation;

    public Form1()
    {
        InitializeComponent();
        this.DoubleBuffered = true;
    }
    Rectangle rec = new Rectangle(0, 0, 0, 0);

    protected override void OnPaint(PaintEventArgs e)
    {   
        e.Graphics.FillRectangle(Brushes.DeepSkyBlue, rec);
    }


    protected override void OnMouseDown(MouseEventArgs e)
    {
        if (e.Button == MouseButtons.Left) 
        {
            rec = new Rectangle(e.X, e.Y, 0, 0);
            Invalidate();

        }
        if (e.Button == MouseButtons.Right)
        {
            MouseDownLocation = e.Location;
        }
    }
    protected override void OnMouseMove(MouseEventArgs e)
    {             

        if (e.Button == MouseButtons.Left)
        {
            rec.Width = e.X - rec.X;
            rec.Height = e.Y - rec.Y;
            Invalidate();
        }

        if (e.Button == MouseButtons.Right)
        {
            this.Left = e.X + this.Left - MouseDownLocation.X;
            this.Top = e.Y + this.Top - MouseDownLocation.Y;

        }
    }

}

I only need to drag-and-drop the rectangles with right mouse button.

EDIT: Thanks to you all i got my answer very fast and here's the code that works:

public partial class Form1 : Form
{
    private Point MouseDownLocation;

    public Form1()
    {
        InitializeComponent();
        this.DoubleBuffered = true;            
    }

    Rectangle rec = new Rectangle(0, 0, 0, 0);

    protected override void OnPaint(PaintEventArgs e)
    {
        e.Graphics.FillRectangle(Brushes.DeepSkyBlue, rec);
        //Generates the shape            
    }

    protected override void OnMouseDown(MouseEventArgs e)
    {
        if (e.Button == MouseButtons.Left)
        //can also use this one:
        //if (e.Button == System.Windows.Forms.MouseButtons.Left)
        {
            rec = new Rectangle(e.X, e.Y, 0, 0);
            Invalidate();

        }
        if (e.Button == MouseButtons.Right)
        {
            MouseDownLocation = e.Location;
        }
    }
    protected override void OnMouseMove(MouseEventArgs e)
    {
        if (e.Button == MouseButtons.Left)
        {
            rec.Width = e.X - rec.X;
            rec.Height = e.Y - rec.Y;
            this.Invalidate();
        }

        if (e.Button == MouseButtons.Right)
        {
            rec.Location = new Point((e.X - MouseDownLocation.X) + rec.Left, (e.Y - MouseDownLocation.Y) + rec.Top);
            MouseDownLocation = e.Location;
            this.Invalidate();
        }
    }

}

score 2 · Accepted Answer · answered Apr 12 '13 at 22:45

This seems to work

    protected override void OnMouseMove(MouseEventArgs e)
    {


        if (e.Button == MouseButtons.Left)
        {
            rec.Width = e.X - rec.X;
            rec.Height = e.Y - rec.Y;
            this.Invalidate();
        }

        if (e.Button == MouseButtons.Right)
        {
            rec.Location = new Point((e.X-MouseDownLocation.X) + rec.Left, (e.Y-MouseDownLocation.Y) + rec.Top);
            MouseDownLocation = e.Location;
            this.Invalidate();
        }
    }

Elior · Answer 2 · 2013-04-12T23:47:56.370

2

try this one : Notice that I add timer to the form in this method you don't need to call Invalidate on mouse event the timertick is calling to the Refresh() so the form will paint himself in each tick..

public partial class Form1 : Form
{
   private Point MouseDownLocation;

   public Form1()
   {
      InitializeComponent();
      this.DoubleBuffered = true;
      timer1.Start(); // add timer to the form
   }
   Rectangle rec = new Rectangle(0, 0, 0, 0);

   protected override void OnPaint(PaintEventArgs e)
   {
       e.Graphics.FillRectangle(Brushes.DeepSkyBlue, rec);
   }

   private void timer1_Tick(object sender, EventArgs e)
   {
       Refresh();
   }


  protected override void OnMouseMove(MouseEventArgs e)
  {
      if (e.Button == MouseButtons.Left)
      {
         rec.Width = e.X - rec.X;
         rec.Height = e.Y - rec.Y;
      }
      else if (e.Button == MouseButtons.Right)
      {
        rec.X = e.X - MouseDownLocation.X;
        rec.Y = e.Y - MouseDownLocation.Y;
      }
  }

   protected override void OnMouseUp(object sender, MouseEventArgs e)
   {
       if (e.Button == MouseButtons.Right)
          MouseDownLocation = e.Location;
   }
 }

edited Apr 12 '13 at 23:47

answered Apr 12 '13 at 22:55

Elior

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As im new to this i haven't used timer yet. Seems logical to add that. But how do you define the Timer1 in this case? – User_T Apr 12 '13 at 23:10
On WinForms go to the design view and drag timer control to your form after that you'll see it below, to add the timerTick method just double click on it, you can start the timer when the form is load or on the form c'tor, using timer.Start() or timer.Enabled = true when you want to stop the timer you can use timer.Stop() or timer.Enabled = false – Elior Apr 12 '13 at 23:14
I've done all that now and the program starts, but it isn't drawing anything – User_T Apr 12 '13 at 23:22
it doesn't draw anything at start because the initial rectangle's width and height are 0 , you need to press the left button and move the mouse to change the width and height of the rectangle and the it'll draw the rectangle – Elior Apr 12 '13 at 23:38

How to draw and move shapes using mouse in C#

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