(PECL imagick 2, PECL imagick 3)
Imagick::getImageIndex — Gets the index of the current active image
此函数在 Imagick 3.4.4 中被 废弃，强烈建议不要应用此函数。
Returns the index of the current active image within the Imagick object. This method has been deprecated. See Imagick::getIteratorIndex().
此函数没有参数。
Returns an integer containing the index of the image in the stack.
错误时抛出 ImagickException。