Sams Teach Yourself C# in 24 Hours

By James Foxall and Wendy Haro-Chun

• Table of Contents
  • Copyright
  • About the Authors
  • Acknowledgments
  • Tell Us What You Think!
  • Introduction
  • Audience and Organization
  • Conventions Used in This Book
  • Onward and Upward!
  • Part I. The Visual Studio Environment
  • Hour 1. A C# Programming Tour
  • Hour 2. Navigating C#
  • Hour 3. Understanding Objects and Collections
  • Hour 4. Understanding Events
  • Part II. Building a User Interface
  • Hour 5. Building FormsPart I
  • Hour 6. Building FormsPart II
  • Hour 7. Working with the Traditional Controls
  • Hour 8. Advanced Controls
  • Hour 9. Adding Menus and Toolbars to Forms
  • Hour 10. Drawing and Printing
    • Understanding the Graphics Object
    • Working with Pens
    • Using System Colors
    • Working with Rectangles
    • Drawing Shapes
    • Drawing Text
    • Persisting Graphics on a Form
    • Build a Graphics Project Example
    • Summary
    • Q&A
    • Workshop
  • Part III. Making Things HappenProgramming!
  • Hour 11. Creating and Calling Methods
  • Hour 12. Using Constants, Data Types, Variables, and Arrays
  • Hour 13. Performing Arithmetic, String Manipulation, and Date/Time Adjustments
  • Hour 14. Making Decisions in C# Code
  • Hour 15. Looping for Efficiency
  • Hour 16. Debugging Your Code
  • Hour 17. Designing Objects Using Classes
  • Hour 18. Interacting with Users
  • Part IV. Working with Data
  • Hour 19. Performing File Operations
  • Hour 20. Controlling Other Applications Using Automation
  • Hour 21. Working with a Database
  • Part V. Deploying Solutions and Beyond
  • Hour 22. Deploying a Solution
  • Hour 23. Introduction to Web Development
  • Hour 24. The 10,000-Foot View
  • Appendix A. Answers to Quizzes/Exercises

Working with Rectangles

Before learning how to draw shapes, you need to understand the concept of a rectangle as it relates to C# programming. A rectangle isn't necessarily used to draw a rectangle (although it can be). Rather, a rectangle is a structure used to hold bounding coordinates used to draw a shape. Obviously, a square or rectangle can fit within a rectangle. However, so can circles and ellipses. Figure 10.3 illustrates how most shapes can be bound by a rectangle.

Figure 10.3 Rectangles are used to define the bounds of most shapes.

To draw most shapes, you must have a rectangle. The rectangle you pass to a drawing method is used as a bounding rectangle; the proper shape (circle, ellipse, and so on) is always drawn. Creating a rectangle is easy. First, you set the dimensions of a variable as Rectangle and then you set the X, Y, Width, and Height properties of the object variable. The X, Y value is the coordinate of the upper-left corner of the rectangle. For example, the following code creates a rectangle that has its upper-left corner at coordinate 0,0, has a width of 100, and a height of 50:

Rectangle rectBounding = new Rectangle();
rectBounding.X = 0;
rectBounding.Y = 0;
rectBounding.Width = 100;
rectBounding.Height = 50;

The Rectangle object enables you to send the X, Y, Height, and Width values as part of its initialize construct. Using this technique, you could create the same rectangle with only a single line of code:

Rectangle rectBounding = new Rectangle(0,0,100,50);

You can do a number of things with a rectangle after it's defined. Perhaps the most useful is the capability to enlarge or shrink the rectangle with a single statement. You enlarge or shrink a rectangle using the Inflate() method. The most common syntax of Inflate() is the following:

   object.Inflate(changeinwidth, 
   changeinheight);

When called this way, the rectangle width is enlarged (the left side of the rectangle remains in place) and the height is enlarged (the top of the rectangle stays in place). To leave the size of the height or width unchanged, pass 0 as the appropriate argument. To shrink a dimension, specify a negative number.

If you're going to do much with drawing, you'll use a lot of Rectangle objects, and I strongly suggest that you learn as much about them as you can.

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