Don't move the Labels outside a PictureBox

Question

I am creating an application in which I can move the Labels that are on a PictureBox.
The problem is that I want these to only Labels move

Answer 1

The PictureBox control is not a container, you can't directly put another control inside it, as you would do with a Panel, a GroupBox or other controls that implement IContainerControl.
You could parent the Label (in this case), setting the Label Parent to a PictureBox handle. The Label.Bounds will then reflect the parent Bounds.
However it's not necessary: you can just calculate the position of the Label in relation to the control that contains both (Label(s) and PictureBox):

You can restrict the movements of other Label controls subscribing to the MovableLabel_MouseDown/MouseUp/MouseMove events.

An example:

bool ThisLabelCanMove;
Point LabelMousePosition = Point.Empty;

private void MovableLabel_MouseDown(object sender, MouseEventArgs e)
{
    if (e.Button == MouseButtons.Left)
    {
        LabelMousePosition = e.Location;
        ThisLabelCanMove = true;
    }
}

private void MovableLabel_MouseUp(object sender, MouseEventArgs e)
{
    ThisLabelCanMove = false;
}

private void MovableLabel_MouseMove(object sender, MouseEventArgs e)
{
    if (ThisLabelCanMove)
    {
        Label label = sender as Label;

        Point LabelNewLocation = new Point(label.Left + (e.Location.X - LabelMousePosition.X),
                                           label.Top + (e.Location.Y - LabelMousePosition.Y));
        LabelNewLocation.X = (LabelNewLocation.X < pictureBox1.Left) ? pictureBox1.Left : LabelNewLocation.X;
        LabelNewLocation.Y = (LabelNewLocation.Y < pictureBox1.Top) ? pictureBox1.Top : LabelNewLocation.Y;
        LabelNewLocation.X = (LabelNewLocation.X + label.Width > pictureBox1.Right) ? label.Left : LabelNewLocation.X;
        LabelNewLocation.Y = (LabelNewLocation.Y + label.Height > pictureBox1.Bottom) ? label.Top : LabelNewLocation.Y;
        label.Location = LabelNewLocation;
    }
}

Answer 2

you need to track two things: 1. is the mouse press or not - bool IsMouseDown = false; 2. the start location of the label- Point StartPoint;

// mouse is not down
private void label1_MouseUp(object sender, MouseEventArgs e)
{
    IsMouseDown = false;
}


 //mouse is down and set the starting postion
 private void label1_MouseDown(object sender, MouseEventArgs e)
 {   
     //if left mouse button was pressed
     if (e.Button == System.Windows.Forms.MouseButtons.Left)
     {
         IsMouseDown = true;
         label1.BringToFront();
         StartPoint = e.Location;
      }
   }


    //check the label is withing the borders of the picture box
    private void label1_MouseMove(object sender, MouseEventArgs e)
    {
        if (IsMouseDown)
        {
            int left = e.X + label1.Left - StartPoint.X;
            int right = e.X + label1.Right - StartPoint.X;
            int top = e.Y + label1.Top - StartPoint.Y;
            int bottom = e.Y + label1.Bottom - StartPoint.Y;
            if (left > pictureBox1.Left && top > pictureBox1.Top && pictureBox1.Bottom >= bottom && pictureBox1.Right >= right)
            {
                label1.Left = left;
                label1.Top = top;
            }
        }
    }