NKDPostnetBarcode.m

// -----------------------------------------------------------------------------------
//  NKDPostnetBarcode.m
// -----------------------------------------------------------------------------------
//  Created by Jeff LaMarche on Sun May 05 2002.
//  �2002 Naked Software. All rights reserved.
// -----------------------------------------------------------------------------------
// THIS	SOURCE CODE IS PROVIDED AS-IS WITH NO WARRANTY OF ANY KIND
// -----------------------------------------------------------------------------------
// You may use and redistribute this source code without limitation
// -----------------------------------------------------------------------------------
#import "NKDPostnetBarcode.h"


@implementation NKDPostnetBarcode
// -----------------------------------------------------------------------------------
-(id)initWithContent: (NSString *)inContent
       printsCaption: (BOOL)inPrints
// -----------------------------------------------------------------------------------
{

    if (self = [super init])
    {
        if (!inContent)
        {
            [self release];
            return nil;
        }
        [self setContent:inContent];

        [self setBarWidth:.015*kScreenResolution];
        [self setPrintsCaption:inPrints];

        // Postnet has a mandatory check digit
        [self generateChecksum];
        
        // .125 inch bar height is about the middle of the allowed values
        [self setHeight:.125*kScreenResolution];

        // Calculate width based on number of bars needed to encode this content
        [self calculateWidth];

        

    }
    return self;
}
// -----------------------------------------------------------------------------------
-(BOOL)printsCaption
// -----------------------------------------------------------------------------------
{
    // PostNet barcodes NEVER,EVER use a caption
    return NO;
}
// -----------------------------------------------------------------------------------
-(NSString *)initiator
// -----------------------------------------------------------------------------------
{
    return @"100";
}
// -----------------------------------------------------------------------------------
-(NSString *)terminator
// -----------------------------------------------------------------------------------
{
    return @"1";
}
// -----------------------------------------------------------------------------------
-(NSString *)_encodeChar:(char)inChar
// -----------------------------------------------------------------------------------
{
    // Each postnet character takes up 5 bars
    return @"100100100100100";
}
// -----------------------------------------------------------------------------------
-(float)barTop:(int)index
// -----------------------------------------------------------------------------------
{
    int		digit, bar;
    
    // Postnet works by varying the height of the bars - there are two heights, tall
    // and short. The terminator and initiator bars are always single tall bars

    // Look for and deal with terminator and initiator first
    if (index == 0)
        return TALL_BAR * kScreenResolution;

    if (index >= ([[self completeBarcode] length] - 1))
        return TALL_BAR * kScreenResolution;

    // Now, figure out which digit we're encoding, and which bar of that digit
    digit = (int)((index-3) / 15);
    bar = (index - (digit * 15)) / 3;
    return [self _heightForDigit:digit andBar:bar] * kScreenResolution;
}
// -----------------------------------------------------------------------------------
-(float)_heightForDigit:(int)index
                andBar:(int)bar
// -----------------------------------------------------------------------------------
{
    char *	barcode = (char *) [content cStringUsingEncoding:NSStringEncodingConversionAllowLossy];
    char	check;

    check = (index >= strlen(barcode)) ? checkDigit : barcode[index];
    switch (check)
    {
       case '1':
           switch (bar)
           {
               case 4:
               case 5:
                   return TALL_BAR;
               default:
                   return SHORT_BAR;
           }
       case '2':
           switch (bar)
           {
               case 3:
               case 5:
                   return TALL_BAR;
               default:
                   return SHORT_BAR;
           }
       case '3':
           switch (bar)
           {
               case 3:
               case 4:
                   return TALL_BAR;
               default:
                   return SHORT_BAR;
           }
       case '4':
           switch (bar)
           {
               case 2:
               case 5:
                   return TALL_BAR;
               default:
                   return SHORT_BAR;
               
           }
       case '5':
           switch (bar)
           {
               case 2:
               case 4:
                   return TALL_BAR;
               default:
                   return SHORT_BAR;
               
            }
       case '6':
           switch (bar)
           {
               case 2:
               case 3:
                   return TALL_BAR;
               default:
                   return SHORT_BAR;
           }
       case '7':
           switch (bar)
           {
               case 1:
               case 5:
                   return TALL_BAR;
               default:
                   return SHORT_BAR;
           }
       case '8':
           switch (bar)
           {
               case 1:
               case 4:
                   return TALL_BAR;
               default:
                   return SHORT_BAR;
           }
       case '9':
           switch (bar)
           {
               case 1:
               case 3:
                   return TALL_BAR;
               default:
                   return SHORT_BAR;
           }
       case '0':
           switch (bar)
           {
               case 1:
               case 2:
                   return TALL_BAR;
               default:
                   return SHORT_BAR;
           }
    }
    return 0;
}
// -----------------------------------------------------------------------------------
-(void)generateChecksum
// -----------------------------------------------------------------------------------
{
    char *	code = (char *)[[self content] cStringUsingEncoding:NSStringEncodingConversionAllowLossy];
    int		i, sum=0;

    for (i = 0; i < strlen(code); i++)
        sum += code[i] - '0';

    [self setCheckDigit: (sum%10 == 0) ? '0': (10-(sum%10)) + '0'];
    
}
// Method contributed by Nik Sands <Nik.Sands@utas.edu.au>
// -----------------------------------------------------------------------------------
-(BOOL) isContentValid
// -----------------------------------------------------------------------------------
{

    return ( [[[self content] stringByTrimmingCharactersInSet:[NSCharacterSet decimalDigitCharacterSet]] isEqualToString:@""]
	    && ( [[self content] length] == 5
	      || [[self content] length] == 9
      	  || [[self content] length] == 11 ));
}
@end