ShutDown: PROC [];         -- free memory in case the last user has left

OpenPixelBuffer: PROC [buffer: PixelArray ← NIL] RETURNS [PixelArray]; -- redirect writes for double-buffer

ClosePixelBuffer: PROC [];        -- drop pixel buffer ref

RGBtoPixel: PROC [color: RGBValue] RETURNS [PxlValue];  -- Color to device transform

PixeltoRGB: PROC [pxlValue: PxlValue] RETURNS [RGBValue];

HilitePxls: PROC [area: IntRectangle];     -- Device dependent highlighting scheme

MovePxls: PROC [source: IntRectangle, destination: IntVec];     -- move on display

StorePxls: PROC [source: IntRectangle] RETURNS [PixelArray];

LoadPxls: PROC [source: PixelArray ← NIL, destination: IntVec];

StoreScanSeg: PROC [x, y, length: CARDINAL] RETURNS [ByteSequence];

LoadScanSeg: PROC [x, y, length: CARDINAL, segment: ByteSequence];

LoadTrapezoid: PROC [top, bottom, leftTop, leftBot, rightTop, rightBot: CARDINAL, pxlValue: PxlValue];             -- Scan convert trapezoid, constant color

SetPxl: PROC [x, y: CARDINAL, pxlValue: PxlValue];

GetPxl: PROC [x, y: CARDINAL] RETURNS [PxlValue];

DrawLine: PROC [a, b: IntVec, pxlValue: PxlValue];   -- draw a fast line, constant color

END.