下列常量由此扩展定义，且仅在此扩展编译入 PHP 或在运行时动态载入时可用。
PRINTER_COPIES
(integer)
PRINTER_MODE
(integer)
PRINTER_TITLE
(integer)
PRINTER_DEVICENAME
(integer)
PRINTER_DRIVERVERSION
(integer)
PRINTER_OUTPUT_FILE
(integer)
PRINTER_RESOLUTION_Y
(integer)
PRINTER_RESOLUTION_X
(integer)
PRINTER_SCALE
(integer)
PRINTER_BACKGROUND_COLOR
(integer)
PRINTER_PAPER_LENGTH
(integer)
PRINTER_PAPER_WIDTH
(integer)
PRINTER_PAPER_FORMAT
(integer)
PRINTER_FORMAT_CUSTOM
(integer)
PRINTER_FORMAT_LETTER
(integer)
PRINTER_FORMAT_LEGAL
(integer)
PRINTER_FORMAT_A3
(integer)
PRINTER_FORMAT_A4
(integer)
PRINTER_FORMAT_A5
(integer)
PRINTER_FORMAT_B4
(integer)
PRINTER_FORMAT_B5
(integer)
PRINTER_FORMAT_FOLIO
(integer)
PRINTER_ORIENTATION
(integer)
PRINTER_ORIENTATION_PORTRAIT
(integer)
PRINTER_ORIENTATION_LANDSCAPE
(integer)
PRINTER_TEXT_COLOR
(integer)
PRINTER_TEXT_ALIGN
(integer)
PRINTER_TA_BASELINE
(integer)
PRINTER_TA_BOTTOM
(integer)
PRINTER_TA_TOP
(integer)
PRINTER_TA_CENTER
(integer)
PRINTER_TA_LEFT
(integer)
PRINTER_TA_RIGHT
(integer)
PRINTER_PEN_SOLID
(integer)
PRINTER_PEN_DASH
(integer)
PRINTER_PEN_DOT
(integer)
PRINTER_PEN_DASHDOT
(integer)
PRINTER_PEN_DASHDOTDOT
(integer)
PRINTER_PEN_INVISIBLE
(integer)
PRINTER_BRUSH_SOLID
(integer)
PRINTER_BRUSH_CUSTOM
(integer)
PRINTER_BRUSH_DIAGONAL
(integer)
PRINTER_BRUSH_CROSS
(integer)
PRINTER_BRUSH_DIAGCROSS
(integer)
PRINTER_BRUSH_FDIAGONAL
(integer)
PRINTER_BRUSH_HORIZONTAL
(integer)
PRINTER_BRUSH_VERTICAL
(integer)
PRINTER_FW_THIN
(integer)
PRINTER_FW_ULTRALIGHT
(integer)
PRINTER_FW_LIGHT
(integer)
PRINTER_FW_NORMAL
(integer)
PRINTER_FW_MEDIUM
(integer)
PRINTER_FW_BOLD
(integer)
PRINTER_FW_ULTRABOLD
(integer)
PRINTER_FW_HEAVY
(integer)
PRINTER_ENUM_LOCAL
(integer)
PRINTER_ENUM_NAME
(integer)
PRINTER_ENUM_DEFAULT
(integer)
PRINTER_ENUM_CONNECTIONS
(integer)
PRINTER_ENUM_NETWORK
(integer)
PRINTER_ENUM_REMOTE
(integer)