drag n drop behavior in c#

Question

hello all im creating a game where user can drag and drop pictureboxes.I managed to do it but i dont like how it behaves when you drag n drop a picturebox. With this code

private void myPictureBox_MouseDown(object sender, MouseEventArgs e)
    {
        isDragging = true;
        currentX = e.X;
        currentY = e.Y;
    }

    private  void myPictureBox_MouseMove(object sender, MouseEventArgs e)
    {
        Control control = (Control)sender;
        if (isDragging)
        {
           control.Top = control.Top + (e.Y - currentY);
           control.Left = control.Left +(e.X - currentX); 
        }
    }

    private void myPictureBox_MouseUp(object sender, MouseEventArgs e)
    {
        isDragging = false;
    }

it behaves like this (video 1) So i put a .update() to it

private void myPictureBox_MouseDown(object sender, MouseEventArgs e)
    {
        isDragging = true;
        currentX = e.X;
        currentY = e.Y;
    }

    private  void myPictureBox_MouseMove(object sender, MouseEventArgs e)
    {
        Control control = (Control)sender;
        if (isDragging)
        {
           control.Top = control.Top + (e.Y - currentY);
           control.Left = control.Left +(e.X - currentX);
           control.update();
        }
    }

    private void myPictureBox_MouseUp(object sender, MouseEventArgs e)
    {
        isDragging = false;
    }

But because its in the if loop its behave like this (video 2) .Do you have any suggestion? thanks in advance.

The form's background image is very slow to paint so you see the ghost of pixels that were not yet overdrawn. General advice [is here](http://stackoverflow.com/a/2613272/17034). — Hans Passant, Mar 25 '15 at 10:56

score 0 · Answer 1 · answered Mar 25 '15 at 10:58

Try setting double buffering for all pictureboxes and the control they are on

SetStyle(ControlStyles.AllPaintingInWmPaint, true);
SetStyle(ControlStyles.OptimizedDoubleBuffer, true);

If that doesnt work you need to do the drawing yourself (isnt hard) to make use of the double buffer setting.

score 0 · Answer 2 · answered Mar 25 '15 at 11:28

I tried to reproduce the stuff that you're experiencing.

When the picture box have a form with a background, the same effect as your video occurs. When the picuter box have a picture box as the background, it runs a little bit better. However, I can't make the control background transparent.

The solution to draw your own control could work.

My suggestion is, if you were really into creating a game. Using already successfull game engine such as Unity, XNA could increase your productivity.

drag n drop behavior in c#

2 Answers2