Graphics - conceptual question

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• GF

  Gary Fritz17y agoPosted May 24, 2009, 9:59 AM

  I think I've got an answer.  I wasn't thinking in the event-based model.  Instead of launching the game from main(), I'm now creating a private instance of the game logic class (BoardClass) in the UI code (BoardGraphics).  That lets the UI access the game logic as needed.
  
• GF

  Gary Fritz17y agoPosted May 21, 2009, 12:51 PM

  Hummm.  I suspect my organization is all wrong.  Here is a rough outline of what I'm doing so far:
  
  namespace Game;
    static class Global {
      public static BoardClass Game;  // I actually use get/put accessors
    }
  
    static class Program {
      static void main() {
        Global.Game = new BoardClass();  // creates and populates gameboard
        Application.Run(new BoardGraphics());  // displays board
      }
  
      partial class BoardGraphics : Form {  // I renamed the default Form1 to BoardGraphics
        public BoardGraphics()
          {
              this.Paint += new PaintEventHandler(DrawBoard);
          }
        public void DrawBoard(object sender, PaintEventArgs e) {
          Graphics g = e.Graphics;
          // draw the game board using the g Graphics object,
          // accessing the BoardClass instance via Global.Game
        }
      }
  
    public class BoardClass {
      // define public data structures for board and board squares
      // define logic for the game
      }
    }
  
  ...so among other problems:
  
  * I had to cheat and use a global var to initialize the board from main() so I could also access the board from BoardGraphics (so BoardGraphics knew what to display).  Maybe I should define BoardClass methods to retrieve game board info, and use those methods to access the board status from BoardGraphics, but I still need a way to access the BoardClass instance so I can invoke it from other classes.  What's the/a right way to do that?  Should I define the BoardClass instance as a local in main() and then pass it to anything that needs it?  But what if the Paint method needs to call the BoardClass logic -- I can't pass an instance to that Paint event handler?
  
  * The graphics apparently has to be in a separate class -- the partial class created in the Form Designer.  That causes some difficulties when the BoardClass (which has all the game logic) has trouble accessing the BoardGraphics class (which has the graphics objects).  I suspect I will run into similar problems when I add user interaction (Click events, etc).  Again, I suspect I need to reorganize so there's no need for the classes to dig into each other.  I'm just not sure how yet.
  
  * Other than the form itself, I'm not sure I used any controls.  I just use the Graphics object in the BoardGraphics.DrawBoard method to call DrawLine, DrawPolygon, and DrawImage.  Which, since DrawBoard gets invoked by the form Paint method, draws on the form.  Which is an instance of BoardGraphics but since it's created by the framework, I'm not even sure where the form instance is.  I only know how to access it as "this" in BoardGraphics methods.  How do I access it from other classes?  Or should I design it so only BoardGraphics methods need to access the form?
  
  * Even though BoardGraphics is the renamed Form1 created by Visual Studio, it doesn't seem to be accepting property changes.  I went into Form1.cs [Design] and changed the Text and Size attributes, but it still creates the form with the default size and no text in the title bar.
  
  So...  still confused......  :-)
  
  Thanks!!
  Gary
• 

  Mahesh Chand17y agoPosted May 20, 2009, 8:34 PM

  You can create and use a Graphics object even without the OnPaint event. You can use CreateGraphics method of a control (say form, button, or any other control, say each rectangle of your chess board if rectangle being a control) and whatever you do with this Graphics object, it will affect that area only.