PPM.cpp

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/* Author: Ioan Sucan */
 
#include "ompl/util/PPM.h"
#include "ompl/util/Exception.h"
#include <cstdio>
 
void ompl::PPM::loadFile(const char *filename)
{
    FILE *fp = fopen(filename, "r");
    if (fp == nullptr)
        throw Exception("Unable to load '" + std::string(filename) + "'");
    struct AutoClose
    {
        AutoClose(FILE *f) : f_(f)
        {
        }
        ~AutoClose()
        {
            fclose(f_);
        }
        FILE *f_;
    };
    AutoClose _(fp);  // close fp when this variable goes out of scope.
 
    char p6[2] = {0};
    if (fscanf(fp, "%c", &p6[0]) != 1 || fscanf(fp, "%c", &p6[1]) != 1 || p6[0] != 'P' || p6[1] != '6')
        throw Exception("Invalid format for file '" + std::string(filename) +
                        "'. PPM is expected to start with the "
                        "characters 'P6'.");
    int nc = fgetc(fp);
    while ((char)nc != '#' && ((char)nc > '9' || (char)nc < '0'))
        nc = fgetc(fp);
    if ((char)nc == '#')
        while ((char)nc != '\n')
            nc = fgetc(fp);
    else
        ungetc(nc, fp);
    if (fscanf(fp, "%d", &width_) != 1 || fscanf(fp, "%d", &height_) != 1)
        throw Exception("Unable to parse width and height for '" + std::string(filename) + "'");
    if (width_ <= 0 || height_ <= 0)
        throw Exception("Invalid image dimensions for '" + std::string(filename) + "'");
    if (fscanf(fp, "%d", &nc) != 1 || nc != 255 /* RGB component color marker*/)
        throw Exception("Invalid RGB component for '" + std::string(filename) + "'");
    fgetc(fp);
    nc = width_ * height_ * 3;
    pixels_.resize(width_ * height_);
    if ((int)fread(&pixels_[0], sizeof(unsigned char), nc, fp) != nc)
        throw Exception("Unable to load image data from '" + std::string(filename) + "'");
}
 
void ompl::PPM::saveFile(const char *filename)
{
    if (pixels_.size() != width_ * height_)
        throw Exception("Number of pixels is " + std::to_string(pixels_.size()) +
                        " but the set width and height require " + std::to_string(width_ * height_) + " pixels.");
    FILE *fp;
    fp = fopen(filename, "wb");
    if (fp == nullptr)
        throw Exception("Unable to open '" + std::string(filename) + "' for writing");
    fprintf(fp, "P6\n");
    fprintf(fp, "%d %d\n", width_, height_);
    fprintf(fp, "%d\n", 255);  // RGB marker
    fwrite(&pixels_[0], 3 * width_, height_, fp);
    fclose(fp);
}