Inside Macintosh: Imaging With QuickDraw /

Chapter 4 - Color QuickDraw

This chapter describes Color QuickDraw, the version of QuickDraw that provides a range of color and grayscale capabilities to your application. You should read this chapter if your application needs to use shades of gray or more colors than the eight predefined colors provided by basic QuickDraw.

Read this chapter to learn how to set up and manage a color graphics port--the sophisticated drawing environment available on Macintosh computers that support Color QuickDraw. You should also read this chapter to learn how to draw using many more colors than are available with basic QuickDraw's eight-color system.

Color QuickDraw supports all of the routines described in the previous chapters of this book. For a color graphics port, for example, you can use the ScrollRect and SetOrigin procedures, which are described in the chapter "Basic QuickDraw." Furthermore, you can use the drawing routines described in the chapter "QuickDraw Drawing" to draw with the sophisticated color and grayscale capabilities available to color graphics ports. For example, after creating an RGBColor record that describes a medium shade of green, you can use the Color QuickDraw procedure RGBForeColor to make that color the foreground color. Then, when you use the FrameRect procedure, Color QuickDraw draws the outline for your rectangle with your specified shade of green.

To prevent the choppiness that can occur when you build a complex color image onscreen, your application typically should prepare the image in an offscreen graphics world and then copy it to an onscreen color graphics port as described in the chapter "Offscreen Graphics Worlds." If you want to optimize your application's drawing for screens with different color capabilities, see the chapter "Graphics Devices."

This chapter describes color graphics ports and Color QuickDraw's routines for drawing in color. For many applications, Color QuickDraw provides a device-independent interface: draw colors in the color graphics port for a window, and Color QuickDraw automatically manages the path to the screen. If your application needs more control over its color environment, Macintosh system software provides additional graphics managers to enhance your application's color-handling abilities. These managers are described in Advanced Color Imaging on the Mac OS, which shows you how to

• manage color selection across a variety of indexed devices by using the Palette Manager
• solicit color choices from users by using the Color Picker
• match colors between the screen and other devices--such as scanners and printers--by using the ColorSync Utilities
• directly manipulate the fields of the CLUT on an indexed device--although most applications should never need to do so--by using the Color Manager

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Chapter Contents

About Color QuickDraw

RGB Colors

The Color Drawing Environment: Color Graphics Ports

Pixel Maps

Pixel Patterns

Color QuickDraw's Translation of RGB Colors to Pixel Values

Colors on Grayscale Screens

Using Color QuickDraw

Initializing Color QuickDraw

Creating Color Graphics Ports

Drawing With Different Foreground Colors

Drawing With Pixel Patterns

Copying Pixels Between Color Graphics Ports

Boolean Transfer Modes With Color Pixels

Dithering

Arithmetic Transfer Modes

Highlighting

Color QuickDraw Reference

Data Structures

Color QuickDraw Routines

Opening and Closing Color Graphics Ports

Managing a Color Graphics Pen

Changing the Background Pixel Pattern

Drawing With Color QuickDraw Colors

Determining Current Colors and Best Intermediate Colors

Calculating Color Fills

Creating, Setting, and Disposing of Pixel Maps

Creating and Disposing of Pixel Patterns

Creating and Disposing of Color Tables

Retrieving Color QuickDraw Result Codes

Customizing Color QuickDraw Operations

Reporting Data Structure Changes to QuickDraw

Application-Defined Routine

Resources

The Pixel Pattern Resource

The Color Table Resource

The Color Icon Resource

Summary of Color QuickDraw

Pascal Summary

Constants

Data Types

Color QuickDraw Routines

Application-Defined Routine

C Summary

Constants

Data Types

Color QuickDraw Functions

Application-Defined Function

Assembly-Language Summary

Data Structures

Result Codes