CGBitmapContext 文档译文

A type of CGContextRef that you can use for drawing bits to memory.

CGBitmapContext是CGContextRef的一个类型，你可以使用它来将位绘制进内存中

Overview

The number of components for each pixel in a bitmap graphics context is specified by a color space, defined by a CGColorSpaceRef .The bitmap graphics context specifies whether the bitmap should contain an alpha channel, and how the bitmap is generated.

在位图绘制上下文中每个像素组成元素的个数是通过定义一个CGColorSpaceRef来指定的。CGBitmapContext说明了当前位图是否包含alpha通道，以及如何创建一个alpha通道

Creating Bitmap Context

CGBitmapContextCreate

Creates a bitmap graphics context.
CGBitmapContextCreateImage译文地址

创建一个位图绘制上下文

CGBitmapContextCreateWithData

Creates a bitmap graphics context with the specified callback function.

通过指定的回调函数来创建位图绘制上下文

CGBitmapContextCreateImage

Creates and returns a CGImage from the pixel data in a bitmap graphics context.

从像素数据中创建并返回一个CGImage对象

Getting Information About Bitmap Contexts

These functions return the values of attributes specified when a bitmap context is created.（这些函数返回创建位图上下文是指定的属性值）