Corona SDK 语言与 API 参考指南

5星 · 超过95%的资源需积分: 9 27 浏览量更新于2024-07-28 1 收藏 1.77MB PDF 举报

"Corona SDK 的语言和 API 参考文档" Corona SDK 是一个用于开发2D游戏和应用的开源软件开发工具包。这个平台基于 Lua 语言，提供了一个简单的、高效的框架，使得开发者能够快速地创建跨平台的应用程序，尤其是在移动设备上，如iOS和Android。"Language and API Reference"是Corona SDK的核心参考资料，它为开发者提供了详细的编程指南和API接口说明。在Lua语言方面，Corona SDK支持基础的 Lua 语法，包括变量、表（Lua中的动态数组和关联数组）、函数、控制结构（如if语句、循环）以及错误处理。Lua语言的轻量级特性使得代码易于编写和理解，同时它的脚本特性允许开发者在运行时修改应用的行为。 API参考部分，Corona SDK 提供了一套丰富的库，涵盖了图形绘制、物理引擎、音频播放、用户输入处理、网络通信、本地存储等多方面的功能。例如，Display对象API允许开发者创建、定位和操作2D图形，包括图像、文本、形状等；Physics API 提供了Box2D物理引擎的接口，支持碰撞检测和物体动态行为的模拟；Sound和Music API则帮助开发者实现音频的播放和管理。此外，Corona SDK 还支持事件驱动的编程模型，这使得响应用户交互和系统事件变得简单。例如，触摸事件处理允许开发者创建互动式界面，而timer事件可以用于实现计时器功能或动画效果。在使用Corona SDK时，开发者需要注意版权问题，文档中提到，未经Ansca Inc.的书面许可，不得复制或以任何形式分发此文档。但个人用户可以为了个人学习和使用目的存储文档并在个人电脑上打印副本，只要包含Ansca的版权通知。 "Language and API Reference"为Corona SDK的使用者提供了全面的技术支持，无论你是初学者还是经验丰富的开发者，都能从中找到必要的信息来开发高质量的跨平台应用程序。尽管文档可能在印刷时尽力确保准确性，但开发者仍需自行检查并适应不断更新的技术环境。

Local

Local variables are declared using the local statement:

x = 1! ! ! ! ! ! ! -- global variable

local y = 10! ! ! ! ! -- local variable

Unlike global variables, local variables are visible only in the block where they are declared. The

scope of the local variable begins after the declaration and ends at the end of the block.

a = 10

local i = 1

while i <= 10 do

local a = i*i!! ! ! -- different variable 'a' local to while block

print( a )!! ! ! ! --> 1, 4, 9, 16, 25, ...

i = i + 1

end

print( a )! ! ! ! ! --> 10 (the global 'a')

Table elds (properties)

Table elds are just the elements of the table themselves. You index into the array to assign the

values to a eld. When the index is a string, the eld is known as a property (see also

Properties):

t = { foo="hello" }!! ! -- create table with a single property "foo"

print( t.foo )! ! ! ! --> "hello"

t.foo = "bye"!! ! ! ! -- assign a new value to property "foo"

print( t.foo )! ! ! ! --> "bye"

t.bar = 10! ! ! ! ! --> create a new property bar

print( t.bar )! ! ! ! --> 10

print( t["bar"] )! ! ! --> 10

Expressions

Arithmetic Operators

Lua supports the usual arithmetic operators: the binary + (addition), - (subtraction), *

(multiplication), / (division), % (modulo), and ^ (exponentiation); and unary - (negation). If the

operands are numbers, or strings that can be converted to numbers (see Conversions between

string and number), then all operations have the usual meaning. Exponentiation works for any

exponent. For instance, x^(-0.5) computes the inverse of the square root of x. Modulo is

dened as

a % b == a - math.floor(a/b)*b

That is, it is the remainder of a division that rounds the quotient towards minus innity.

Relational Operators

The relational operators in Lua are

== ~= < > <= >=

These operators always result in false or true.

Equality (==) rst compares the type of its operands. If the types are diﬀerent, then the result is

false. Otherwise, the values of the operands are compared. Numbers and strings are compared

in the usual way. Objects (tables and functions) are compared by reference: two objects are

considered equal only if they are the same object. Every time you create a new object (a table

or function), this new object is diﬀerent from any previously existing object.

The conversion rules of strings and numbers do not apply to equality comparisons. Thus,

"0"==0 evaluates to false, and t[0] and t["0"] denote diﬀerent entries in a table.

The operator ~= is exactly the negation of equality (==).

Logical Operators

The logical operators in Lua are and, or, and not. All logical operators consider both false and

nil as false and anything else as true.

The negation operator not always returns false or true. The conjunction operator and returns

its rst argument if this value is false or nil; otherwise, and returns its second argument. The

disjunction operator or returns its rst argument if this value is diﬀerent from nil and false;

otherwise, or returns its second argument. Both and and or use short-cut evaluation; that is,

the second operand is evaluated only if necessary. Here are some examples:

10 or 20 --> 10

10 or error() --> 10

nil or "a" --> "a"

nil and 10 --> nil

false and error() --> false

false and nil --> false

false or nil --> nil

10 and 20 --> 20

Concatenation

The string concatenation operator in Lua is denoted by two dots ('..'). If both operands are

strings or numbers, then they are converted to strings.

Length Operator

The length operator is denoted by the unary operator #. The length of a string is its number of

bytes (that is, the usual meaning of string length when each character is one byte).

The length of a table t is dened to be any integer index n such that t[n] is not nil and t[n+1] is

nil; moreover, if t[1] is nil, n can be zero. For a regular array, with non-nil values from 1 to a

given n, its length is exactly that n, the index of its last value. If the array has "holes" (that is, nil

values between other non-nil values), then #t can be any of the indices that directly precedes a

nil value (that is, it may consider any such nil value as the end of the array).

Precedence

Operator precedence in Lua follows the table below, from lower to higher priority:

and

< > <= >= ~= ==

+ -

* / %

not # - (unary)

As usual, you can use parentheses to change the precedences of an expression. The

concatenation ('..') and exponentiation ('^') operators are right associative. All other binary

operators are left associative.

Properties

Many Corona API’s return objects. You are free to manipulate the documented properties of

these objects just like you would on a table. You can even add your own properties provided

you do not prex any of your custom properties with an underscore (“_”). Ansca reserves the

right to use any property name that begins with an underscore.

Like most languages, all properties can be accessed via the dot (“.”) operator. It's really just a

convenient way to index into a table. In other words, we can access property foo of a table t

using the dot operator (t.foo) or index into it using a string (t["foo"]); the result is the

same.

Functions

Because functions can be variables, a table can store them as properties. This creates allows for

very exible uses of a table. It can be used to logically group a family functions into a table, e.g.

the math library. It can also be used to make a table have object methods (instance methods).

剩余67页未读，继续阅读

zx_pwd

粉丝: 0
资源: 3

Corona SDK 语言与 API 参考指南

corona sdk API手册

[Corona] 开发经典命令行程序 (Corona 实现) 第2版 (英文版)

corona renderer 的真实使用方法

图论中corona product

win10开机corona的黑框闪一下

用lua代码写按钮点击事件，点击按钮，判断软件是否后台运行，如果后台运行则暂时停止软件的后台运行，否则则恢复软件的后台运行

用lua代码写按钮点击事件，点击按钮，判断软件是否后台运行，如果后台运行则暂时停止软件的后台运行，否则则恢复软件的后台运行，不要love库，生成纯lua代码

dataframe对象的切片

游戏开发使用什么语言

最新资源