Inside Macintosh: Text /

Chapter 3 - QuickDraw Text

This chapter describes the text-handling components of QuickDraw. You can use the QuickDraw text routines to measure and draw text ranging in complexity from a single glyph to a line of justified text containing multiple languages and styles. In addition to measuring and drawing text, the QuickDraw text routines also help you to determine which characters to highlight and where to position the caret to mark the insertion point. These routines translate pixel locations into byte offsets and vice versa.

Read this chapter if you are writing an application that draws static text in a box, such as a dialog box, or draws and manipulates text of any length in one or more languages. Before you use the routines described in this chapter, read the chapter "Introduction to Text on the Macintosh" in this book. To understand the concepts and routines described in this chapter, you must be familiar with the other parts of QuickDraw described in Inside Macintosh: Imaging.

Read this chapter along with the chapter "Font Manager," in this book, because of the close relationship between QuickDraw and the Font Manager. For help in understanding the tasks involved in text layout, refer to the chapters "Text Utilities" and "Script Manager," also in this book.

This chapter explains how to set up the text-drawing environment and lay out and draw text, including how to

• draw and measure a single character, a text segment, or a line of text
• determine where to break a line of text
• determine the order in which to draw text segments for a line of text containing multiple styles and mixed directions
• eliminate trailing space characters
• distribute extra space throughout a line of text to justify it appropriately for the
  script system
• draw and measure scaled text
• identify caret positions for marking an insertion point and highlighting text

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Chapter Contents

About QuickDraw Text

Graphics Ports and Text Drawing

Font, Font Style, and Font Size

Transfer Modes

QuickDraw Text, Script Systems, and Other Managers

Text Formatting and Justification

Scaling

Carets and Highlighting

Using QuickDraw Text

Preparing to Use QuickDraw

Determining the Version and Initializing QuickDraw

Setting Up the Text-Drawing Environment

Specifying Text Characteristics

Setting the Font

Modifying the Text Style

Changing the Font Size

Changing the Width of Characters

Using Fractional Glyph Widths

Specifying the Transfer Mode

Basic Transfer Mode Operations

Arithmetic Transfer Mode Operations

The grayishTextOr Transfer Mode

Text Mask Mode

Transparent Transfer Mode

Transfer Modes and Multibit Fonts

Measuring and Drawing Single Segments of Text

Individual Glyphs

Pascal Strings

Text Segments

Measuring and Drawing Lines of Text

Determining Where to Break the Line

Determining the Display Order for Style Runs

Eliminating Trailing Spaces (for Justified Text)

Calculating the Slop Value (for Justified Text)

Allocating the Slop to Each Style Run (for Justified Text)

Drawing the Line of Text

Using Scaled Text

Drawing Carets and Highlighting

Converting an Onscreen Pixel Location to a Byte Offset

Finding a Caret Position and Drawing a Caret

Synchronizing the Caret With the Keyboard Script

Highlighting a Text Selection

Customizing QuickDraw's Text Handling

Text in QuickDraw Pictures

Fonts

Text With Multiple Style Runs

QuickDraw Text Reference

Data Structures

The Font Information Record

The Style Data Type

Routines

The slop Parameter

The styleRunPosition Parameter

The numer and denom Parameters

Setting Text Characteristics

Drawing Text

Measuring Text

Laying Out a Line of Text

Determining the Caret Position, and Selecting and Highlighting Text

Low-Level QuickDraw Text Routines

Application-Supplied Routine

Summary of QuickDraw Text

Pascal Summary

Constants

Data Types

Routines

C Summary

Constants

Types

Routines

Assembly-Language Summary

Trap Macros

Global Variables