C＃如何在mutliple类中访问相同的变量

Question

I'm working on my third C# program and I'm having a hard time. I don't get how I can access a variable in multiple classes :

This is a slider to control the size of the shape I'm drawing

    public void trackBar1_Scroll(object sender, EventArgs e)
    {
        int slider = (int)trackBar1.Value ;

    }




    public void DrawCar ()
    {
        drawArea = drawingArea.CreateGraphics();
        Pen blackpen = new Pen(Color.Orange);
        drawArea.DrawLine(blackpen, slider , 10, 500, 500);
        drawArea.DrawArc(Pens.Orange, new Rectangle( 10 , 10, 100, 100), 50, 100);
    }

I need to access the "slider" value to control the size of the car.

Answer 1

If you want to access it in the same class, but multiple methods, you can make that as a member variable of the class.

public class YourClass
{
  private int sliderValue=0;
  public void MethodA()
  {
   sliderValue=12;
  }
  public void MethodB()
  {
    var localValue=sliderValue+10;
  }
}

If you want the value across multiple classes, you might consider creating a singleton class and add the properties you want to that.

Answer 2

Add a property to your class that contains trackBar1 like this:

public int Slider { get { return this.trackBar1.Value; } }

Then you can access the slider value outside on the class where the trackBar1 is defined from instances of that class.

Answer 3

the best thing you can achieve to get access is this way or start using mvvm pattern and defining properties, that will make things lot easier:

   public static int slider;  

    public void trackBar1_Scroll(object sender, EventArgs e)
        {
          slider  = (int)trackBar1.Value ;
        }
        public void DrawCar ()
        {
            drawArea = drawingArea.CreateGraphics();
            Pen blackpen = new Pen(Color.Orange);
            drawArea.DrawLine(blackpen, slider , 10, 500, 500);
            drawArea.DrawArc(Pens.Orange, new Rectangle( 10 , 10, 100, 100), 50, 100);
        }