ImagerContextImpl.mesa
Created April 8, 1983
Last Edit By:
Plass, April 8, 1983 7:38 pm
Last Edited by: Crow, June 15, 1983 7:02 pm
DIRECTORY
ImagerBasic USING [Context, ImagingDevice, ContextRep],
Imager USING [Mark, nullMark, Inclusions, ResetTransform],
Imager8bitDisplay USING [SetUp];
Client-called Procedures
CreateContext:
PUBLIC PROC [device: ImagingDevice]
RETURNS [Context] = {
Called by the viewers package, or other utilities, to set up a context. Returns NIL if unable to create the context.
context: Context ← NEW[ContextRep];
context.device ← device;
SELECT device FROM
$CRT8 => { [ context.deviceTransform,
context.deviceClipper,
context.deviceProcs ] ← Imager8bitDisplay.SetUp[];
context.interactive ← TRUE; };
ENDCASE => ERROR; -- attempt to scrounge up procs record from somewhere
context.currentSource ← [white, [1., 1., 1.], 255, NIL];
context.currentFont ← NIL;
context.currentIntPosition ← [0, 0];
context.currentPosition ← [0., 0.];
context.viewerTransform ← [0, 0, identity, NIL];
Imager.ResetTransform[context]; -- Set client xform to identity and build composite xform
context.clipper ← context.clientClipper ← context.viewerClipper ← context.deviceClipper;
context.noClipArmed ← context.noClip ← FALSE;
RETURN [ context ];
};
DestroyContext:
PUBLIC PROC [context: Context] = {
Remove all traces of the given context, clean up VM.
};
Save:
PUBLIC PROC [context: Context, what: Imager.Inclusions]
RETURNS [Imager.Mark] = {
Note the current state of the display context, and return a mark value which can later be passed to Restore.
RETURN [ Imager.nullMark ];
};
Restore:
PUBLIC PROC [context: Context, mark: Imager.Mark ← Imager.nullMark] = {};
Restore the state of the display context to its condition prior to the call on Save that returned the given mark. Defaulting the mark means restore to the most recent Save.
Clear, Next Page, etc.
NewFrame:
PUBLIC PROC [context: Context] = {
-- who keeps the background color??
If printer or InterPress, start new page; if double-buffering, display newly completed image; otherwise clear inside context.
IF context.interactive THEN context.deviceProcs.loadPxls[NIL, [0, 0]]; -- Blt buffer to display
context.deviceProcs.loadTrapezoid[ context.clipper.yMax, context.clipper.yMin, -- clear
context.clipper.xMin, context.clipper.xMin,
context.clipper.xMax, context.clipper.xMax,
context.currentSource.pxlValue ];
};
END.