PHP Unconference Europe 2015

The CairoFormat class

(No version information available, might only be in SVN)

Wstęp

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

Krótki opis klasy

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

Stałe predefiniowane

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 endianess 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.

Spis treści

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