08 Text Processing

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Working With Text

ISE 108: Introduction to Programming

SUNY at Stony Brook

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Text and StringsGoal: display information besidesshapes and images

We can do this now with print!"andprintln!"

Problem: that output only appears atthe bottom of the sketchpad, where

its hard to read

Solution: find a way to add text to theprogram window

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Fonts and TextBefore we can display any text, weneed to tell Processing what font to

useAfon!is a combination of:

a typeface !ex. Times New Roman"

a style !ex. bold or italic"

a point size !ex. 48 point"

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Fonts and

ProcessingUse the PFonttype to represent a font

Processing needs to work with a special

font format

We can convert fonts to this format!.vlw"either before or while we run theprogram

If we create the font first, we need tostore it in the sketchs data folder

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.vlw Font CreationUse the Tools menu in Processing

Choose Create font... from the menu

Select a font and size from the list

Creating a font beforehand allows youto work with fonts that the user maynot have installed

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Loading FontsTo use a pre#existing .vlw font in aProcessing sketch, use loadFont()

loadFont()takes the name of thefont file as its argument

loadFont()returns a PFontobject

PFont font =

loadFont("FFScala-32.vlw");

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Creating Fonts at

Run-timeTo create a font while your sketch isrunning, use createFont()

createFont()requires the font name,the point size, and a boolean !indicatingwhether the font should be smoothed"

PFont f =

createFont(Courier, 24, true);

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Font Creation

PitfallsProblem: you can only create a fonton the fly if the user has it installed

Solutions:

1.store an original copy of the file !in .ttf

or .otf"format in the data folder

2.use PFont.list()to get a list offonts installed on the users computer

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Using FontsThe textFont()command tellsProcessing what font to draw with

This is like fill()or stroke()fordrawings

textFont()takes a PFontas input

Processing will use that font until youcall textFont()again to change it

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Displaying TextUse the text()command to actuallydisplay text on the screen

text()uses the font set by textFont()

text()takes three arguments:

A String!character sequence"to print

the x and y coordinates where the textshould be displayed

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// Load the font to use (24-point Courier,

// with anti-aliasing turned on)

PFont f = createFont(Courier, 24, true);

// Tell Processing to use this font

// from now on

setFont(f);

// Display text starting at (25, 50)

text(Hello, world!, 25, 50);

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Aligning TextProcessing lets you change where textis positioned

textAlign()takes a constant as itsinput:

Possible values: LEFT, RIGHT, CENTER

Call textAlign()befor"text()

Ex. textAlign(CENTER);

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Strings and ThingsThe text()command takes a Stringas its first argument

A Stringholds a sequence of characters

Stringis one of the most frequentlyused data types in Processing !and Java"

Stringhas a number of useful helpermethods

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String MethodsString() creates a new String

String s = new String(Hello!);

Shorthand: String s = Hello!;

This shorthand onlyworks for String!

length() returns the total number ofcharacters in the String

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String Adjustmentstrim() returns a new String

with no leading or trailing whitespace

toLowerCase()/toUpperCase() return a new copyof the Stringin

lower/uppercase

All three methods leave the original

Stringunchanged

Java strings are immutable

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Extracting Data

From StringsThe positions in a Stringare

numbered from 0 to (length - 1)

charAt() returns the character at

a given position (index)

indexOf(str) returns the first

index at which stroccurs in the string(or -1 if it isnt there)

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Extracting Data

From Strings, contdsubstring(start, end) returns a

new Stringcontaining the characters

from position startup to (but notincluding) end

You can also call substring()with

exactly one argument

In this case, it returns everything fromthe specified index through the end

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String EqualityWhat makes two Strings equal?Do they have the same length? Thesame case? The same characters?

According to Processing,

abcdef == abcdef

is false!they areno!the same".

What gives?

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Objects & Primitives

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Remember the difference between primitive

(built-in) types and objectsPrimitive variables hold an actual value

Object variables (references) only hold theaddress of an object!

This causes problems when we try tocompare two objects

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Processing is

ShallowProcessing performs shallow comparisonsby default (using the == operator)

A shallow comparison looks at the valueimmediately associated with a variable

This is okay for primitive types

For objects, this means that we compare

their memory addresses, not their contents!

Objects are only equal if they live at thesame memory address

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String EqualityStringhas methods to test equality

based on content, not memory location

equals() returns trueif twoStrings have the same sequence of

characters

Usage: firstString.equals(secondString)

equals()requires both strings to haveidentical capitalization

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Comparing StringscompareTo() compares two strings

for their relative lexicographical ordering

case, then alphabetical, then by length

Usage: firstString.compareTo(secondString)

This method returns an integer value

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Result Positive 0 Negative

Meaning first > second first == second first < second

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Dont Be So

Sensitive!Problem: equals()and compareTo()are case#sensitive

Sometimes, we only want to compare twoStrings by length and/or characters

Processing has two more methods for thissituation:

equalsIgnoreCase()

compareToIgnoreCase()

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08 Text Processing