The CairoFormat class

(PECL cairo >= 0.1.0)

Введение

CairoFormat enums are used to identify the memory format of the image data.

Обзор классов

CairoFormat {
/* Константы */
const integer ARGB32 = 0 ;
const integer RGB24 = 1 ;
const integer A8 = 2 ;
const integer A1 = 3 ;
/* Методы */
public static strideForWidth ( int $format , int $width ) : int
}

Предопределенные константы

CairoFormat::ARGB32

Each pixel is a 32-bit quantity, with alpha in the upper 8 bits, then red, then green, then blue. The 32-bit quantities are stored native-endian. Pre-multiplied alpha is used. (That is, 50% transparent red is 0x80800000, not 0x80ff0000.)

CairoFormat::RGB24

Each pixel is a 32-bit quantity, with the upper 8 bits unused. Red, Green, and Blue are stored in the remaining 24 bits in that order.

CairoFormat::A8

Each pixel is a 8-bit quantity holding an alpha value.

CairoFormat::A1

Each pixel is a 1-bit quantity holding an alpha value. Pixels are packed together into 32-bit quantities. The ordering of the bits matches the endianness of the platform. On a big-endian machine, the first pixel is in the uppermost bit, on a little-endian machine the first pixel is in the least-significant bit.

Содержание

  • CairoFormat::strideForWidth — Расчитывает значение "stride" для заданной ширины изображения