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Diffstat (limited to 'editor/pnmshear.c')
| -rw-r--r-- | editor/pnmshear.c | 227 |
1 files changed, 227 insertions, 0 deletions
diff --git a/editor/pnmshear.c b/editor/pnmshear.c new file mode 100644 index 00000000..1b2d36a8 --- /dev/null +++ b/editor/pnmshear.c @@ -0,0 +1,227 @@ +/* pnmshear.c - read a portable anymap and shear it by some angle +** +** Copyright (C) 1989, 1991 by Jef Poskanzer. +** +** Permission to use, copy, modify, and distribute this software and its +** documentation for any purpose and without fee is hereby granted, provided +** that the above copyright notice appear in all copies and that both that +** copyright notice and this permission notice appear in supporting +** documentation. This software is provided "as is" without express or +** implied warranty. +*/ + +#define _XOPEN_SOURCE /* get M_PI in math.h */ + +#include <math.h> +#include <string.h> + +#include "pnm.h" +#include "shhopt.h" + +#define SCALE 4096 +#define HALFSCALE 2048 + +struct cmdline_info { + /* All the information the user supplied in the command line, + in a form easy for the program to use. + */ + const char * input_filespec; /* Filespec of input file */ + double angle; /* requested shear angle, in radians */ + unsigned int noantialias; /* -noantialias option */ +}; + + + +static void +parse_command_line(int argc, char ** argv, + struct cmdline_info *cmdlineP) { + + optStruct3 opt; + unsigned int option_def_index = 0; + optEntry *option_def = malloc(100*sizeof(optEntry)); + + OPTENT3(0, "noantialias", OPT_FLAG, NULL, &cmdlineP->noantialias, 0); + + opt.opt_table = option_def; + opt.short_allowed = FALSE; + opt.allowNegNum = TRUE; + + optParseOptions3(&argc, argv, opt, sizeof(opt), 0); + + if (argc-1 < 1) + pm_error("Need an argument: the shear angle.\n"); + else { + char *endptr; + cmdlineP->angle = strtod(argv[1], &endptr) * M_PI / 180; + if (*endptr != '\0' || strlen(argv[1]) == 0) + pm_error("Angle argument is not a valid floating point number: " + "'%s'", argv[1]); + if (argc-1 < 2) + cmdlineP->input_filespec = "-"; + else { + cmdlineP->input_filespec = argv[2]; + if (argc-1 > 2) + pm_error("too many arguments (%d). " + "The only arguments are shear angle and filespec.", + argc-1); + } + } +} + + +static void +makeNewXel(xel * const outputXelP, xel const curXel, xel const prevXel, + double const fracnew0, double const omfracnew0, int const format) { +/*---------------------------------------------------------------------------- + Create an output xel as *outputXel, which is part curXel and part + prevXel, the part given by the fractions omfracnew0 and fracnew0, + respectively. These fraction values are the numerator of a fraction + whose denominator is SCALE. + + The format of the pixel is 'format'. +-----------------------------------------------------------------------------*/ + + switch ( PNM_FORMAT_TYPE(format) ) { + case PPM_TYPE: + PPM_ASSIGN( *outputXelP, + ( fracnew0 * PPM_GETR(prevXel) + + omfracnew0 * PPM_GETR(curXel) + + HALFSCALE ) / SCALE, + ( fracnew0 * PPM_GETG(prevXel) + + omfracnew0 * PPM_GETG(curXel) + + HALFSCALE ) / SCALE, + ( fracnew0 * PPM_GETB(prevXel) + + omfracnew0 * PPM_GETB(curXel) + + HALFSCALE ) / SCALE ); + break; + + default: + PNM_ASSIGN1( *outputXelP, + ( fracnew0 * PNM_GET1(prevXel) + + omfracnew0 * PNM_GET1(curXel) + + HALFSCALE ) / SCALE ); + break; + } +} + + +static void +shear_row(xel * const xelrow, int const cols, + xel * const newxelrow, int const newcols, + double const shearCols, + int const format, xel const bgxel, bool const antialias) { +/*---------------------------------------------------------------------------- + Shear the row 'xelrow' by 'shearCols' columns, and return the result as + 'newxelrow'. They are 'cols' and 'newcols' columns wide, respectively. + + Fill in the part of the output row that doesn't contain image data with + 'bgxel'. + + Use antialiasing iff 'antialias'. + + The format of the input xels (which implies something about the + output xels too) is 'format'. +-----------------------------------------------------------------------------*/ + int const intShearCols = (int) shearCols; + + if ( antialias ) { + const long fracnew0 = ( shearCols - intShearCols ) * SCALE; + const long omfracnew0 = SCALE - fracnew0; + + int col; + xel prevXel; + + for ( col = 0; col < newcols; ++col ) + newxelrow[col] = bgxel; + + prevXel = bgxel; + for ( col = 0; col < cols; ++col){ + makeNewXel(&newxelrow[intShearCols + col], + xelrow[col], prevXel, fracnew0, omfracnew0, + format); + prevXel = xelrow[col]; + } + if ( fracnew0 > 0 ) + /* Need to add a column for what's left over */ + makeNewXel(&newxelrow[intShearCols + cols], + bgxel, prevXel, fracnew0, omfracnew0, format); + } else { + int col; + for ( col = 0; col < intShearCols; ++col ) + newxelrow[col] = bgxel; + for ( col = 0; col < cols; ++col ) + newxelrow[intShearCols+col] = xelrow[col]; + for ( col = intShearCols + cols; col < newcols; ++col ) + newxelrow[col] = bgxel; + } +} + + + +int +main(int argc, char * argv[]) { + FILE* ifp; + xel* xelrow; + xel* newxelrow; + xel bgxel; + int rows, cols, format; + int newformat, newcols; + int row; + xelval maxval, newmaxval; + double shearfac; + + struct cmdline_info cmdline; + + pnm_init( &argc, argv ); + + parse_command_line( argc, argv, &cmdline ); + + ifp = pm_openr( cmdline.input_filespec ); + + pnm_readpnminit( ifp, &cols, &rows, &maxval, &format ); + xelrow = pnm_allocrow( cols ); + + /* Promote PBM files to PGM. */ + if ( !cmdline.noantialias && PNM_FORMAT_TYPE(format) == PBM_TYPE ) { + newformat = PGM_TYPE; + newmaxval = PGM_MAXMAXVAL; + pm_message( "promoting from PBM to PGM - " + "use -noantialias to avoid this" ); + } else { + newformat = format; + newmaxval = maxval; + } + + shearfac = tan( cmdline.angle ); + if ( shearfac < 0.0 ) + shearfac = -shearfac; + + newcols = rows * shearfac + cols + 0.999999; + + pnm_writepnminit( stdout, newcols, rows, newmaxval, newformat, 0 ); + newxelrow = pnm_allocrow( newcols ); + + bgxel = pnm_backgroundxelrow( xelrow, cols, newmaxval, format ); + + for ( row = 0; row < rows; ++row ) { + double shearCols; + + pnm_readpnmrow( ifp, xelrow, cols, newmaxval, format ); + + if ( cmdline.angle > 0.0 ) + shearCols = row * shearfac; + else + shearCols = ( rows - row ) * shearfac; + + shear_row(xelrow, cols, newxelrow, newcols, + shearCols, format, bgxel, !cmdline.noantialias); + + pnm_writepnmrow( stdout, newxelrow, newcols, newmaxval, newformat, 0 ); + } + + pm_close( ifp ); + pm_close( stdout ); + + exit( 0 ); +} + |