Since 1.5?: X11で定義されている色を Cairo::Color::RGBオブジェクトにしたものの集まりです。
cairoにはないrcairoでの拡張です。
ALICE_BLUEANTIQUE_WHITEAQUAAQUAMARINEAZUREBEIGEBISQUEBLACKBLANCHED_ALMONDBLUEBLUE_VIOLETBROWNBURLY_WOODCADET_BLUECHARTREUSECHOCOLATECORALCORNFLOWER_BLUECORNSILKCRIMSONCYANDARK_BLUEDARK_CYANDARK_GOLDENRODDARK_GRAYDARK_GREENDARK_KHAKIDARK_MAGENTADARK_OLIVE_GREENDARK_ORANGEDARK_ORCHIDDARK_REDDARK_SALMONDARK_SEA_GREENDARK_SLATE_BLUEDARK_SLATE_GRAYDARK_TURQUOISEDARK_VIOLETDEEP_PINKDEEP_SKY_BLUEDIM_GRAYDODGER_BLUEFIRE_BRICKFLORAL_WHITEFOREST_GREENFUCHSIAGAINSBOROGHOST_WHITEGOLDGOLDENRODGRAYGREENGREEN_YELLOWHONEYDEWHOT_PINKINDIAN_REDINDIGOIVORYKHAKILAVENDERLAVENDER_BLUSHLAWN_GREENLEMON_CHIFFONLIGHT_BLUELIGHT_CORALLIGHT_CYANLIGHT_GOLDENROD_YELLOWLIGHT_GREENLIGHT_GREYLIGHT_PINKLIGHT_SALMONLIGHT_SEA_GREENLIGHT_SKY_BLUELIGHT_SLATE_GRAYLIGHT_STEEL_BLUELIGHT_YELLOWLIMELIME_GREENLINENMAGENTAMAROONMEDIUM_AQUAMARINEMEDIUM_BLUEMEDIUM_ORCHIDMEDIUM_PURPLEMEDIUM_SEA_GREENMEDIUM_SLATE_BLUEMEDIUM_SPRING_GREENMEDIUM_TURQUOISEMEDIUM_VIOLET_REDMIDNIGHT_BLUEMINT_CREAMMISTY_ROSEMOCCASINNAVAJO_WHITEOLD_LACEOLIVEOLIVE_DRABORANGEORANGE_REDORCHIDPALE_GOLDENRODPALE_GREENPALE_TURQUOISEPALE_VIOLET_REDPAPAYA_WHIPPEACH_PUFFPERUPINKPLUMPOWDER_BLUEPURPLEREDROSY_BROWNROYAL_BLUESADDLE_BROWNSALMONSANDY_BROWNSEASHELLSEA_GREENSIENNASILVERSKY_BLUESLATE_BLUESLATE_GRAYSNOWSPRING_GREENSTEEL_BLUETANTEALTHISTLETOMATOTURQUOISEVIOLETWHEATWHITEWHITE_SMOKEYELLOWYELLOW_GREEN