[comp.sys.mac.programmer] Apple Scanner Question

chao@polya.Stanford.EDU (Chih-Chao Lam) (12/27/88)

I am having some difficulty getting the Apple Scanner to work in gray   
scale mode and would greatly appreciate any help.
              
I get an scParamErr when I call ScSetScanArea after setting the scanArea
to a 'grayscale type' scanArea and I can't understand why.  I use the 
following code to initialize the scanArea :                           
 

function SetupScanner: OSErr;
  var
    anErr: OSErr;
    bestRes: Integer;
    myStdFeatures: ScStdFeaturesRec;
    myScanAreas: ScScanAreaRec;
    fullPageArea: ScAreaRec;

begin
  anErr := ScOpen(scannerRef); 
  if anErr = noErr then begin {Fill in the standard features record.}
    anErr := ScGetStdFeatures(scannerRef, @myStdFeatures,
                              SizeOf(ScStdFeaturesRec));

    if anErr = noErr then begin
      with fullPageArea do begin
        xDpi := 75;
        yDpi := 75;
        SetRect(aRect, 0, 0, 200, 200);
        scanRect := aRect;
        contrast := 0; {And default contrast}
        composition := scGrayScale;
        bitsPerPixel := $F0;
      end;

      with myScanAreas do begin
        numAreas := 1;
        scanAreas[1] := fullPageArea;
      end;
      anErr := ScSetScanArea(scannerRef, @myScanAreas);

    end; {No error getting std features}
  end; {No error on ScOpen}
  SetupScanner := anErr;	
  writeln('the error is:',anErr);{Return any error.}
end;

Am I doing anything stupid that I'm not aware of?  
Thanks in advance,

Chih-Chao Lam
lam@sumex-aim.stanford.edu
Knowledge System Laboratory
Stanford University