Drawing Classes and the Coordinate System

Figure 17.1 depicts a portion of namespace System.Drawing, including several graphics classes and structures covered in this chapter. Namespaces System.Drawing and System.Drawing.Drawing2D contain the most commonly used GDI+ components.

Figure 17.1. System.Drawing namespace's classes and structures.

Class Graphics contains methods used for drawing strings, lines, rectangles and other shapes on a Control. The drawing methods of class Graphics usually require a Pen or Brush object to render a specified shape. The Pen draws shape outlines; the Brush draws solid objects.

The Color structure contains numerous static properties, which set the colors of various graphical components, plus methods that allow users to create new colors. Class Font contains properties that define unique fonts. Class FontFamily contains methods for obtaining font information.

To begin drawing in C#, we first must understand GDI+'s coordinate system (Fig. 17.2), a scheme for identifying every point on the screen. By default, the upper-left corner of a GUI component (such as a Panel or a Form) has the coordinates (0, 0). A coordinate pair has both an x-coordinate (the horizontal coordinate) and a y-coordinate (the vertical coordinate). The x-coordinate is the horizontal distance (to the right) from the upper-left corner. The y-coordinate is the vertical distance (downward) from the upperleft corner. The x-axis defines every horizontal coordinate, and the y-axis defines every vertical coordinate. Programmers position text and shapes on the screen by specifying their (x, y) coordinates. Coordinate units are measured in pixels ("picture elements"), which are the smallest units of resolution on a display monitor.

Figure 17.2. GDI+ coordinate system. Units are measured in pixels.

Portability Tip 17 1

Different display monitors have different resolutions, so the density of pixels on such monitors will vary. This might cause the sizes of graphics to appear different on different monitors.

The System.Drawing namespace provides several structures that represent sizes and locations in the coordinate system. The Point structure represents the x-y coordinates of a point on a two-dimensional plane. The Rectangle structure defines the loading width and height of a rectangular shape. The Size structure represents the width and height of a shape.

Graphics Contexts and Graphics Objects



    Introduction to Computers, the Internet and Visual C#

    Introduction to the Visual C# 2005 Express Edition IDE

    Introduction to C# Applications

    Introduction to Classes and Objects

    Control Statements: Part 1

    Control Statements: Part 2

    Methods: A Deeper Look


    Classes and Objects: A Deeper Look

    Object-Oriented Programming: Inheritance

    Polymorphism, Interfaces & Operator Overloading

    Exception Handling

    Graphical User Interface Concepts: Part 1

    Graphical User Interface Concepts: Part 2


    Strings, Characters and Regular Expressions

    Graphics and Multimedia

    Files and Streams

    Extensible Markup Language (XML)

    Database, SQL and ADO.NET

    ASP.NET 2.0, Web Forms and Web Controls

    Web Services

    Networking: Streams-Based Sockets and Datagrams

    Searching and Sorting

    Data Structures



    Appendix A. Operator Precedence Chart

    Appendix B. Number Systems

    Appendix C. Using the Visual Studio 2005 Debugger

    Appendix D. ASCII Character Set

    Appendix E. Unicode®

    Appendix F. Introduction to XHTML: Part 1

    Appendix G. Introduction to XHTML: Part 2

    Appendix H. HTML/XHTML Special Characters

    Appendix I. HTML/XHTML Colors

    Appendix J. ATM Case Study Code

    Appendix K. UML 2: Additional Diagram Types

    Appendix L. Simple Types


    Visual C# How to Program
    Visual C# 2005 How to Program (2nd Edition)
    ISBN: 0131525239
    EAN: 2147483647
    Year: 2004
    Pages: 600

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