Question

I’m trying to create a drawing on a Windows Form that will simulate what I was trying to do with a ProgressBar used as a health bar. I didn’t like the ProgressBar because it would animate a fill at the start when I set the Value equal to the Maximum.

This is my method

private void Battlefield_Paint(object sender, PaintEventArgs e)
  {
      using (SolidBrush blackBrush = new SolidBrush(Color.Black))
      using (SolidBrush redBrush = new SolidBrush(Color.Red))
      using (Graphics formGraphics = this.CreateGraphics())
      {
          formGraphics.FillRectangle(blackBrush, new Rectangle(12, 12, 76, 23));
          formGraphics.FillRectangle(redBrush, new Rectangle(14, 14, 72*(p1.CurrentHealth/p1.MaxHealth), 19));
          int result = 72 * (p1.CurrentHealth / p1.MaxHealth);
          Console.WriteLine(result);
      }
  }

I have a timer redrawing the form every 50ms.

I am having a problem where the red rectangle inside the black rectangle will draw fine at first, but once my character takes damage, and CurrentHealth is less than MaxHealth, the result of 72*(p1.CurrentHealth/p1.MaxHealth) comes back as 0, and the rectangle doesn’t even show up on the screen, as I think it’s being drawn with 0 width…

I don’t know what is going wrong with this calculation that would make it return 0. I’ve ran it thru the debugger a bunch and the values going in look correct, 30 and 30 for both at first, then something like 28, 30 the next time thru, and I get a value of 0…

Answer 1

I suppose that CurrentHealth and MaxHealth are integers and that you are doing integer division, when you divide 6 with 10 you get 0, instead of 0.6

You should try this:

private void Battlefield_Paint(object sender, PaintEventArgs e)
  {
      using (SolidBrush blackBrush = new SolidBrush(Color.Black))
      using (SolidBrush redBrush = new SolidBrush(Color.Red))
      {
          e.Graphics.FillRectangle(blackBrush, new Rectangle(12, 12, 76, 23));
          e.Graphics.FillRectangle(redBrush, new Rectangle(14, 14, (int)(72.0*((double)p1.CurrentHealth/(double)p1.MaxHealth)), 19));
          int result = (int)(72.0*((double)p1.CurrentHealth/(double)p1.MaxHealth));
          Console.WriteLine(result);
      }
  }

Also you should use e.Graphics instead of making new Graphics object every time.