jpgview.cxx

#include <stdio.h>
#include <jpeglib.h>

#include <FL/Fl.H>
#include <FL/Fl_Window.H>
#include <FL/fl_ask.H>
#include <FL/fl_draw.H>
#include <FL/fl_file_chooser.H>

using namespace std;

//-------------------------------------------------------------------------

void jpeg_output_message(j_common_ptr cinfo);
int arg(int argc, char** argv, int& i);

//-------------------------------------------------------------------------

class Image_Window
:
    public Fl_Window
{
public:

    Image_Window();
    ~Image_Window();

    void fill_buffer();

    const char* get_name()
    {
        return m_name;
    }

    void set_name(const char* name)
    {
        m_name = name;
    }

private:

    void set_label();

    void draw();

    //---------------------------------------------------------------------

    const char* m_name;

    JDIMENSION m_width;
    JDIMENSION m_height;

    unsigned char* m_buffer;
};

Image_Window image_window;

//-------------------------------------------------------------------------

Image_Window::Image_Window()
:
    Fl_Window(10,10),
    m_name(0),
    m_width(10),
    m_height(10),
    m_buffer(0)
{
    box(FL_NO_BOX);
}

//-------------------------------------------------------------------------

Image_Window::~Image_Window()
{
    delete [] m_buffer;
}

//-------------------------------------------------------------------------

void
Image_Window::set_label()
{
    const char* sname = strrchr(m_name, '/');

    if (sname == 0)
    {
        sname = m_name;
    }
    else
    {
        sname += 1;
    }

    char buffer[100];

    snprintf(buffer,
             sizeof(buffer),
             "%s - (%lux%lu)",
             sname,
             (unsigned long)m_width,
             (unsigned long)m_height);

    label(buffer);
}

//-------------------------------------------------------------------------

void
Image_Window::draw()
{
    fl_draw_image(m_buffer, 0, 0, m_width, m_height);
}

//-------------------------------------------------------------------------

void
Image_Window::fill_buffer()
{
    FILE* fpin = fopen(m_name, "rb");

    if (fpin == 0)
    {
        fl_alert("Can't open file for reading");
        exit(EXIT_FAILURE);
    }

    //---------------------------------------------------------------------

    struct jpeg_decompress_struct cinfo;
    struct jpeg_error_mgr jerr;

    cinfo.err = jpeg_std_error(&jerr);
    cinfo.err->output_message = jpeg_output_message;

    jpeg_create_decompress(&cinfo);
    jpeg_stdio_src(&cinfo, fpin);
    jpeg_read_header(&cinfo, TRUE);
    cinfo.out_color_space = JCS_RGB;
    jpeg_start_decompress(&cinfo);

    m_width = cinfo.output_width;
    m_height = cinfo.output_height;

    //---------------------------------------------------------------------

    if (m_buffer)
    {
        delete [] m_buffer;
    }

    m_buffer = new unsigned char[m_width * m_height * 3];

    //---------------------------------------------------------------------

    for (JDIMENSION j = 0; j < m_height; ++j)
    {
        unsigned char* row = m_buffer + (j * 3 * m_width);
        jpeg_read_scanlines(&cinfo, &row, 1);
    }

    //---------------------------------------------------------------------

    jpeg_finish_decompress(&cinfo);
    jpeg_destroy_decompress(&cinfo);
    fclose(fpin);

    //---------------------------------------------------------------------

    set_label();
    size(m_width, m_height);

    damage(FL_DAMAGE_ALL);
}

//-------------------------------------------------------------------------

void jpeg_output_message(j_common_ptr cinfo)
{
     char buffer[JMSG_LENGTH_MAX];
     (*cinfo->err->format_message) (cinfo, buffer);
     fl_alert(buffer);
}

//-------------------------------------------------------------------------

int arg(int argc, char** argv, int& i)
{
    if (argv[i][0] == '-')
    {
        return 0;
    }

    image_window.set_name(argv[i]);
    ++i;

    return 1;
}

//-------------------------------------------------------------------------

int main(int argc, char ** argv)
{
    const char* program_name = fl_filename_name(argv[0]);

    fl_message_title(program_name);

    int i = 0;

    if (Fl::args(argc, argv, i, arg) < argc)
    {
        Fl::error("%s <file.jpg>", program_name);
    }

    const char* name = image_window.get_name();

    if (name == 0)
    {
        name = fl_file_chooser("JPEG file", "*.jpg", "");

        if (name != 0)
        {
            image_window.set_name(name);
        }
    }

    if (name == 0)
    {
        return 0;
    }

    //---------------------------------------------------------------------

    Fl::visual(FL_RGB);

    image_window.end();

    image_window.show(argc, argv);

    image_window.set_name(name);
    image_window.fill_buffer();

    //---------------------------------------------------------------------

    return Fl::run();
}