PHP将ARGB转换为RGBA？ [关闭]

Question

Need solution or description of: How to convert color value from ARGB to RGBA which is possible to use for css:

Examples:

ARGB color : #ff502797 convert to RGBA
RGBA result example: rgba(80,39,151,1)

thx.

Answer 1

ARGB contains 4 groups of HEX values(channels): Alpha, Red, Green, Blue.

Scheme: Exampe: #ff502797 - color in ARGB formatt Elements on positions:

0,1 - Alpa  (ff)
2,3 - Red   (50)
4,5 - Green (27)
6,7 - Blue  (97)

After this convert each channel to decimal. And putt on their places into RBGA: rgba(Red,Green,Blue,Alpha) - rgba(80,39,151,1)

Example function:

function argb2rgba($color)
    {
        $output = 'rgba(0,0,0,1)';

        if (empty($color))
            return $output;

        if ($color[0] == '#') {
            $color = substr($color, 1);
        }

        if (strlen($color) == 8) { //ARGB
            $opacity = round(hexdec($color[0].$color[1]) / 255, 2);
            $hex = array($color[2].$color[3], $color[4].$color[5], $color[6].$color[7]);
            $rgb = array_map('hexdec', $hex);
            $output = 'rgba(' . implode(",", $rgb) . ',' . $opacity . ')';
        }

        return $output;
    }