Php 使用按位枚举EXIF闪存可读字符串

当您使用PHP从图像中提取EXIF数据时，它有一个整数Flash值

例如，16在转换为十六进制时为0x10。这意味着闪光灯已关闭，但没有启动：

0x0     = No Flash
0x1     = Fired
0x5     = Fired, Return not detected
0x7     = Fired, Return detected
0x8     = On, Did not fire
0x9     = On, Fired
0xd     = On, Return not detected
0xf     = On, Return detected
0x10    = Off, Did not fire
0x14    = Off, Did not fire, Return not detected
0x18    = Auto, Did not fire
0x19    = Auto, Fired
0x1d    = Auto, Fired, Return not detected
0x1f    = Auto, Fired, Return detected
0x20    = No flash function
0x30    = Off, No flash function
0x41    = Fired, Red-eye reduction
0x45    = Fired, Red-eye reduction, Return not detected
0x47    = Fired, Red-eye reduction, Return detected
0x49    = On, Red-eye reduction
0x4d    = On, Red-eye reduction, Return not detected
0x4f    = On, Red-eye reduction, Return detected
0x50    = Off, Red-eye reduction
0x58    = Auto, Did not fire, Red-eye reduction
0x59    = Auto, Fired, Red-eye reduction
0x5d    = Auto, Fired, Red-eye reduction, Return not detected
0x5f    = Auto, Fired, Red-eye reduction, Return detected

有没有一种方法可以在PHP中使用按位枚举，以便返回可读字符串

例如，值为25（0x19）看起来可能与此类似，并且似乎有效：

$fired = 0x01;
$auto = 0x18;

$flashValue = dechex(25); // 0x19

$parts = [];
if ($flashValue & $fired)
{
    $parts[] = 'Fired';
}
if ($flashValue & $auto)
{
    $parts[] = 'Auto';
}

$string = implode(', ', $parts); // "Fired, Auto"

这似乎是可行的，但像我的原始示例这样的示例似乎无法运行

$flashValue = dechex(25); // 0x19

不要使用dechex。它返回一个字符串；您尝试使用的位运算符对数字进行运算。25是一个非常好的数字——事实上你没有用十六进制写它并不重要

您必须处理的一个复杂问题是，auto是一个奇怪的标志组合：0x08为off，0x10为on，并且将0x10+0x08=0x18组合在一起会提供auto。你需要小心处理这些