742 lines
24 KiB
C
742 lines
24 KiB
C
/*---------------------------------------------------------------------------
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rpng - simple PNG display program rpng-x.c
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This program decodes and displays PNG images, with gamma correction and
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optionally with a user-specified background color (in case the image has
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transparency). It is very nearly the most basic PNG viewer possible.
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This version is for the X Window System (tested under Unix, but may work
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under VMS or OS/2 with a little tweaking).
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to do:
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- 8-bit support
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- use %.1023s to simplify truncation of title-bar string?
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---------------------------------------------------------------------------
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Copyright (c) 1998-1999 Greg Roelofs. All rights reserved.
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This software is provided "as is," without warranty of any kind,
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express or implied. In no event shall the author or contributors
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be held liable for any damages arising in any way from the use of
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this software.
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Permission is granted to anyone to use this software for any purpose,
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including commercial applications, and to alter it and redistribute
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it freely, subject to the following restrictions:
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1. Redistributions of source code must retain the above copyright
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notice, disclaimer, and this list of conditions.
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2. Redistributions in binary form must reproduce the above copyright
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notice, disclaimer, and this list of conditions in the documenta-
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tion and/or other materials provided with the distribution.
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3. All advertising materials mentioning features or use of this
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software must display the following acknowledgment:
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This product includes software developed by Greg Roelofs
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and contributors for the book, "PNG: The Definitive Guide,"
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published by O'Reilly and Associates.
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---------------------------------------------------------------------------*/
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#define PROGNAME "rpng-x"
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#define LONGNAME "Simple PNG Viewer for X"
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#define VERSION "1.01 of 31 March 1999"
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <time.h>
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#include <X11/Xlib.h>
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#include <X11/Xutil.h>
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#include <X11/Xos.h>
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#include <X11/keysym.h>
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/* #define DEBUG : this enables the Trace() macros */
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#include "readpng.h" /* typedefs, common macros, readpng prototypes */
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/* could just include png.h, but this macro is the only thing we need
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* (name and typedefs changed to local versions); note that side effects
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* only happen with alpha (which could easily be avoided with
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* "ush acopy = (alpha);") */
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#define alpha_composite(composite, fg, alpha, bg) { \
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ush temp = ((ush)(fg)*(ush)(alpha) + \
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(ush)(bg)*(ush)(255 - (ush)(alpha)) + (ush)128); \
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(composite) = (uch)((temp + (temp >> 8)) >> 8); \
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}
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/* local prototypes */
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static int rpng_x_create_window(void);
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static int rpng_x_display_image(void);
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static void rpng_x_cleanup(void);
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static int rpng_x_msb(ulg u32val);
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static char titlebar[1024], *window_name = titlebar;
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static char *appname = LONGNAME;
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static char *icon_name = PROGNAME;
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static char *filename;
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static FILE *infile;
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static char *bgstr;
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static uch bg_red=0, bg_green=0, bg_blue=0;
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static double display_exponent;
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static ulg image_width, image_height, image_rowbytes;
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static int image_channels;
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static uch *image_data;
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/* X-specific variables */
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static char *displayname;
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static XImage *ximage;
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static Display *display;
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static int bitmap_order;
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static int depth;
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static Visual *visual;
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static int RPixelShift, GPixelShift, BPixelShift;
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static ulg RedMask, GreenMask, BlueMask;
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static Window window;
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static GC gc;
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static Colormap colormap;
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static int have_colormap = FALSE;
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static int have_window = FALSE;
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/*
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ulg numcolors=0, pixels[256];
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ush reds[256], greens[256], blues[256];
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*/
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int main(int argc, char **argv)
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{
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#ifdef sgi
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char tmpline[80];
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#endif
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char *p;
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int rc, alen, flen;
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int error = 0;
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int have_bg = FALSE;
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double LUT_exponent; /* just the lookup table */
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double CRT_exponent = 2.2; /* just the monitor */
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double default_display_exponent; /* whole display system */
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XEvent e;
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KeySym k;
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displayname = (char *)NULL;
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filename = (char *)NULL;
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/* First set the default value for our display-system exponent, i.e.,
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* the product of the CRT exponent and the exponent corresponding to
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* the frame-buffer's lookup table (LUT), if any. This is not an
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* exhaustive list of LUT values (e.g., OpenStep has a lot of weird
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* ones), but it should cover 99% of the current possibilities. */
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#if defined(NeXT)
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LUT_exponent = 1.0 / 2.2;
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/*
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if (some_next_function_that_returns_gamma(&next_gamma))
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LUT_exponent = 1.0 / next_gamma;
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*/
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#elif defined(sgi)
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LUT_exponent = 1.0 / 1.7;
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/* there doesn't seem to be any documented function to get the
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* "gamma" value, so we do it the hard way */
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infile = fopen("/etc/config/system.glGammaVal", "r");
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if (infile) {
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double sgi_gamma;
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fgets(tmpline, 80, infile);
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fclose(infile);
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sgi_gamma = atof(tmpline);
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if (sgi_gamma > 0.0)
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LUT_exponent = 1.0 / sgi_gamma;
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}
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#elif defined(Macintosh)
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LUT_exponent = 1.8 / 2.61;
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/*
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if (some_mac_function_that_returns_gamma(&mac_gamma))
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LUT_exponent = mac_gamma / 2.61;
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*/
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#else
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LUT_exponent = 1.0; /* assume no LUT: most PCs */
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#endif
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/* the defaults above give 1.0, 1.3, 1.5 and 2.2, respectively: */
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default_display_exponent = LUT_exponent * CRT_exponent;
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/* If the user has set the SCREEN_GAMMA environment variable as suggested
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* (somewhat imprecisely) in the libpng documentation, use that; otherwise
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* use the default value we just calculated. Either way, the user may
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* override this via a command-line option. */
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if ((p = getenv("SCREEN_GAMMA")) != NULL)
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display_exponent = atof(p);
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else
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display_exponent = default_display_exponent;
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/* Now parse the command line for options and the PNG filename. */
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while (*++argv && !error) {
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if (!strcmp(*argv, "-display")) {
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if (!*++argv)
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++error;
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displayname = *argv;
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} else if (!strcmp(*argv, "-gamma")) {
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if (!*++argv)
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++error;
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display_exponent = atof(*argv);
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if (display_exponent <= 0.0)
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++error;
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} else if (!strcmp(*argv, "-bgcolor")) {
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if (!*++argv)
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++error;
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bgstr = *argv;
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if (strlen(bgstr) != 7 || bgstr[0] != '#')
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++error;
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else
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have_bg = TRUE;
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} else {
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if (**argv != '-') {
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filename = *argv;
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if (argv[1]) /* shouldn't be any more args after filename */
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++error;
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} else
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++error; /* not expecting any other options */
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}
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}
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if (!filename) {
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++error;
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} else if (!(infile = fopen(filename, "rb"))) {
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fprintf(stderr, PROGNAME ": can't open PNG file [%s]\n", filename);
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++error;
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} else {
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if ((rc = readpng_init(infile, (long *)(&image_width),
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(long *)(&image_height))) != 0) {
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switch (rc) {
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case 1:
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fprintf(stderr, PROGNAME
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": [%s] is not a PNG file: incorrect signature\n",
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filename);
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break;
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case 2:
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fprintf(stderr, PROGNAME
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": [%s] has bad IHDR (libpng longjmp)\n",
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filename);
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break;
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case 4:
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fprintf(stderr, PROGNAME ": insufficient memory\n");
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break;
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default:
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fprintf(stderr, PROGNAME
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": unknown readpng_init() error\n");
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break;
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}
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++error;
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} else {
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display = XOpenDisplay(displayname);
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if (!display) {
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readpng_cleanup(TRUE);
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fprintf(stderr, PROGNAME ": can't open X display [%s]\n",
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displayname? displayname : "default");
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++error;
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}
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}
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if (error)
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fclose(infile);
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}
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if (error) {
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fprintf(stderr, "\n%s %s: %s\n", PROGNAME, VERSION, appname);
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readpng_version_info();
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fprintf(stderr, "\n"
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"Usage: %s [-display xdpy] [-gamma exp] [-bgcolor bg] file.png\n"
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" xdpy\tname of the target X display (e.g., ``hostname:0'')\n"
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" exp \ttransfer-function exponent (``gamma'') of the display\n"
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"\t\t system in floating-point format (e.g., ``%.1f''); equal\n"
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"\t\t to the product of the lookup-table exponent (varies)\n"
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"\t\t and the CRT exponent (usually 2.2); must be positive\n"
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" bg \tdesired background color in 7-character hex RGB format\n"
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"\t\t (e.g., ``#ff7f00'' for orange: same as HTML colors);\n"
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"\t\t used with transparent images\n"
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"\nPress Q, Esc or mouse button 1 after image is displayed to quit.\n"
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"\n", PROGNAME, default_display_exponent);
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exit(1);
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}
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/* set the title-bar string, but make sure buffer doesn't overflow */
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alen = strlen(appname);
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flen = strlen(filename);
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if (alen + flen + 3 > 1023)
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sprintf(titlebar, "%s: ...%s", appname, filename+(alen+flen+6-1023));
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else
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sprintf(titlebar, "%s: %s", appname, filename);
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/* if the user didn't specify a background color on the command line,
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* check for one in the PNG file--if not, the initialized values of 0
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* (black) will be used */
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if (have_bg) {
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unsigned r, g, b; /* this approach quiets compiler warnings */
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sscanf(bgstr+1, "%2x%2x%2x", &r, &g, &b);
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bg_red = (uch)r;
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bg_green = (uch)g;
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bg_blue = (uch)b;
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} else if (readpng_get_bgcolor(&bg_red, &bg_green, &bg_blue) > 1) {
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readpng_cleanup(TRUE);
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fprintf(stderr, PROGNAME
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": libpng error while checking for background color\n");
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exit(2);
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}
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/* do the basic X initialization stuff, make the window and fill it
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* with the background color */
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if (rpng_x_create_window())
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exit(2);
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/* decode the image, all at once */
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Trace((stderr, "calling readpng_get_image()\n"))
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image_data = readpng_get_image(display_exponent, &image_channels,
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&image_rowbytes);
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Trace((stderr, "done with readpng_get_image()\n"))
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/* done with PNG file, so clean up to minimize memory usage (but do NOT
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* nuke image_data!) */
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readpng_cleanup(FALSE);
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fclose(infile);
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if (!image_data) {
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fprintf(stderr, PROGNAME ": unable to decode PNG image\n");
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exit(3);
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}
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/* display image (composite with background if requested) */
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Trace((stderr, "calling rpng_x_display_image()\n"))
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if (rpng_x_display_image()) {
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free(image_data);
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exit(4);
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}
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Trace((stderr, "done with rpng_x_display_image()\n"))
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/* wait for the user to tell us when to quit */
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do
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XNextEvent(display, &e);
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while (!(e.type == ButtonPress && e.xbutton.button == Button1) &&
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!(e.type == KeyPress && /* v--- or 1 for shifted keys */
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((k = XLookupKeysym(&e.xkey, 0)) == XK_q || k == XK_Escape) ));
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/* OK, we're done: clean up all image and X resources and go away */
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rpng_x_cleanup();
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return 0;
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}
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static int rpng_x_create_window()
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{
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uch *xdata;
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int screen, pad;
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ulg bg_pixel = 0L;
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Window root;
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XEvent e;
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XGCValues gcvalues;
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XSetWindowAttributes attr;
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XSizeHints *size_hints;
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XTextProperty windowName, *pWindowName = &windowName;
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XTextProperty iconName, *pIconName = &iconName;
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XVisualInfo visual_info;
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XWMHints *wm_hints;
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bitmap_order = BitmapBitOrder(display);
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screen = DefaultScreen(display);
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depth = DisplayPlanes(display, screen);
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root = RootWindow(display, screen);
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/* GRR: add 8-bit support */
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if (/* depth != 8 && */ depth != 16 && depth != 24 && depth != 32) {
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fprintf(stderr,
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"screen depth %d not supported (only 16-, 24- or 32-bit TrueColor)\n",
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depth);
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return 2;
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}
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XMatchVisualInfo(display, screen, depth,
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(depth == 8)? PseudoColor : TrueColor, &visual_info);
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visual = visual_info.visual;
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RedMask = visual->red_mask;
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GreenMask = visual->green_mask;
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BlueMask = visual->blue_mask;
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/* GRR: add/check 8-bit support */
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if (depth == 8) {
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colormap = XCreateColormap(display, root, visual, AllocNone);
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if (!colormap) {
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fprintf(stderr, "XCreateColormap() failed\n");
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return 2;
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}
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have_colormap = TRUE;
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} else if (depth == 16) {
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RPixelShift = 15 - rpng_x_msb(RedMask); /* these are right-shifts */
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GPixelShift = 15 - rpng_x_msb(GreenMask);
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BPixelShift = 15 - rpng_x_msb(BlueMask);
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} else /* if (depth > 16) */ {
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RPixelShift = rpng_x_msb(RedMask) - 7; /* these are left-shifts */
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GPixelShift = rpng_x_msb(GreenMask) - 7;
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BPixelShift = rpng_x_msb(BlueMask) - 7;
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}
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/*---------------------------------------------------------------------------
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Finally, create the window.
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---------------------------------------------------------------------------*/
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attr.backing_store = Always;
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attr.event_mask = ExposureMask | KeyPressMask | ButtonPressMask;
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window = XCreateWindow(display, root, 0, 0, image_width, image_height,
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0, depth, InputOutput, visual, CWBackingStore | CWEventMask, &attr);
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if (window == None) {
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fprintf(stderr, "XCreateWindow() failed\n");
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return 2;
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} else
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have_window = TRUE;
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if (depth == 8)
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XSetWindowColormap(display, window, colormap);
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if (!XStringListToTextProperty(&window_name, 1, pWindowName))
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pWindowName = NULL;
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if (!XStringListToTextProperty(&icon_name, 1, pIconName))
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pIconName = NULL;
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/* OK if either hints allocation fails; XSetWMProperties() allows NULLs */
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if ((size_hints = XAllocSizeHints()) != NULL) {
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/* window will not be resizable */
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size_hints->flags = PMinSize | PMaxSize;
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size_hints->min_width = size_hints->max_width = image_width;
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size_hints->min_height = size_hints->max_height = image_height;
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}
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if ((wm_hints = XAllocWMHints()) != NULL) {
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wm_hints->initial_state = NormalState;
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wm_hints->input = True;
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/* wm_hints->icon_pixmap = icon_pixmap; */
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wm_hints->flags = StateHint | InputHint /* | IconPixmapHint */ ;
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}
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XSetWMProperties(display, window, pWindowName, pIconName, NULL, 0,
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size_hints, wm_hints, NULL);
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XMapWindow(display, window);
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gc = XCreateGC(display, window, 0, &gcvalues);
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/*---------------------------------------------------------------------------
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Fill window with the specified background color.
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---------------------------------------------------------------------------*/
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if (depth == 24 || depth == 32) {
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bg_pixel = ((ulg)bg_red << RPixelShift) |
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((ulg)bg_green << GPixelShift) |
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((ulg)bg_blue << BPixelShift);
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} else if (depth == 16) {
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bg_pixel = ((((ulg)bg_red << 8) >> RPixelShift) & RedMask) |
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((((ulg)bg_green << 8) >> GPixelShift) & GreenMask) |
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((((ulg)bg_blue << 8) >> BPixelShift) & BlueMask);
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} else /* depth == 8 */ {
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/* GRR: add 8-bit support */
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}
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XSetForeground(display, gc, bg_pixel);
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XFillRectangle(display, window, gc, 0, 0, image_width, image_height);
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/*---------------------------------------------------------------------------
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Wait for first Expose event to do any drawing, then flush.
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---------------------------------------------------------------------------*/
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do
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XNextEvent(display, &e);
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while (e.type != Expose || e.xexpose.count);
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XFlush(display);
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/*---------------------------------------------------------------------------
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Allocate memory for the X- and display-specific version of the image.
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---------------------------------------------------------------------------*/
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if (depth == 24 || depth == 32) {
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xdata = (uch *)malloc(4*image_width*image_height);
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pad = 32;
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} else if (depth == 16) {
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xdata = (uch *)malloc(2*image_width*image_height);
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pad = 16;
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} else /* depth == 8 */ {
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xdata = (uch *)malloc(image_width*image_height);
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pad = 8;
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}
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|
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if (!xdata) {
|
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fprintf(stderr, PROGNAME ": unable to allocate image memory\n");
|
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return 4;
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}
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|
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ximage = XCreateImage(display, visual, depth, ZPixmap, 0,
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(char *)xdata, image_width, image_height, pad, 0);
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|
|
if (!ximage) {
|
|
fprintf(stderr, PROGNAME ": XCreateImage() failed\n");
|
|
free(xdata);
|
|
return 3;
|
|
}
|
|
|
|
/* to avoid testing the bitmap_order every pixel (or doubling the size of
|
|
* the drawing routine with a giant if-test), we arbitrarily set the byte
|
|
* order to MSBFirst and let Xlib worry about inverting things on little-
|
|
* endian machines (like Linux/x86, old VAXen, etc.)--this is not the most
|
|
* efficient approach (the giant if-test would be better), but in the
|
|
* interest of clarity, we take the easy way out... */
|
|
|
|
ximage->byte_order = MSBFirst;
|
|
|
|
return 0;
|
|
|
|
} /* end function rpng_x_create_window() */
|
|
|
|
|
|
|
|
|
|
|
|
static int rpng_x_display_image()
|
|
{
|
|
uch *src;
|
|
char *dest;
|
|
uch r, g, b, a;
|
|
int ximage_rowbytes = ximage->bytes_per_line;
|
|
ulg i, row, lastrow = 0;
|
|
ulg pixel;
|
|
|
|
|
|
Trace((stderr, "beginning display loop (image_channels == %d)\n",
|
|
image_channels))
|
|
Trace((stderr, "(width = %ld, rowbytes = %ld, ximage_rowbytes = %d)\n",
|
|
image_width, image_rowbytes, ximage_rowbytes))
|
|
|
|
if (depth == 24 || depth == 32) {
|
|
ulg red, green, blue;
|
|
|
|
for (lastrow = row = 0; row < image_height; ++row) {
|
|
src = image_data + row*image_rowbytes;
|
|
dest = ximage->data + row*ximage_rowbytes;
|
|
if (image_channels == 3) {
|
|
for (i = image_width; i > 0; --i) {
|
|
red = *src++;
|
|
green = *src++;
|
|
blue = *src++;
|
|
pixel = (red << RPixelShift) |
|
|
(green << GPixelShift) |
|
|
(blue << BPixelShift);
|
|
/* recall that we set ximage->byte_order = MSBFirst above */
|
|
*dest++ = ((uch *)&pixel)[3];
|
|
*dest++ = ((uch *)&pixel)[2];
|
|
*dest++ = ((uch *)&pixel)[1];
|
|
*dest++ = ((uch *)&pixel)[0];
|
|
}
|
|
} else /* if (image_channels == 4) */ {
|
|
for (i = image_width; i > 0; --i) {
|
|
r = *src++;
|
|
g = *src++;
|
|
b = *src++;
|
|
a = *src++;
|
|
if (a == 255) {
|
|
red = r;
|
|
green = g;
|
|
blue = b;
|
|
} else if (a == 0) {
|
|
red = bg_red;
|
|
green = bg_green;
|
|
blue = bg_blue;
|
|
} else {
|
|
/* this macro (from png.h) composites the foreground
|
|
* and background values and puts the result into the
|
|
* first argument */
|
|
alpha_composite(red, r, a, bg_red);
|
|
alpha_composite(green, g, a, bg_green);
|
|
alpha_composite(blue, b, a, bg_blue);
|
|
}
|
|
pixel = (red << RPixelShift) |
|
|
(green << GPixelShift) |
|
|
(blue << BPixelShift);
|
|
/* recall that we set ximage->byte_order = MSBFirst above */
|
|
*dest++ = ((uch *)&pixel)[3];
|
|
*dest++ = ((uch *)&pixel)[2];
|
|
*dest++ = ((uch *)&pixel)[1];
|
|
*dest++ = ((uch *)&pixel)[0];
|
|
}
|
|
}
|
|
/* display after every 16 lines */
|
|
if (((row+1) & 0xf) == 0) {
|
|
XPutImage(display, window, gc, ximage, 0, lastrow, 0, lastrow,
|
|
image_width, 16);
|
|
XFlush(display);
|
|
lastrow = row + 1;
|
|
}
|
|
}
|
|
|
|
} else if (depth == 16) {
|
|
ush red, green, blue;
|
|
|
|
for (lastrow = row = 0; row < image_height; ++row) {
|
|
src = image_data + row*image_rowbytes;
|
|
dest = ximage->data + row*ximage_rowbytes;
|
|
if (image_channels == 3) {
|
|
for (i = image_width; i > 0; --i) {
|
|
red = ((ush)(*src) << 8);
|
|
++src;
|
|
green = ((ush)(*src) << 8);
|
|
++src;
|
|
blue = ((ush)(*src) << 8);
|
|
++src;
|
|
pixel = ((red >> RPixelShift) & RedMask) |
|
|
((green >> GPixelShift) & GreenMask) |
|
|
((blue >> BPixelShift) & BlueMask);
|
|
/* recall that we set ximage->byte_order = MSBFirst above */
|
|
*dest++ = ((uch *)&pixel)[1];
|
|
*dest++ = ((uch *)&pixel)[0];
|
|
}
|
|
} else /* if (image_channels == 4) */ {
|
|
for (i = image_width; i > 0; --i) {
|
|
r = *src++;
|
|
g = *src++;
|
|
b = *src++;
|
|
a = *src++;
|
|
if (a == 255) {
|
|
red = ((ush)r << 8);
|
|
green = ((ush)g << 8);
|
|
blue = ((ush)b << 8);
|
|
} else if (a == 0) {
|
|
red = ((ush)bg_red << 8);
|
|
green = ((ush)bg_green << 8);
|
|
blue = ((ush)bg_blue << 8);
|
|
} else {
|
|
/* this macro (from png.h) composites the foreground
|
|
* and background values and puts the result back into
|
|
* the first argument (== fg byte here: safe) */
|
|
alpha_composite(r, r, a, bg_red);
|
|
alpha_composite(g, g, a, bg_green);
|
|
alpha_composite(b, b, a, bg_blue);
|
|
red = ((ush)r << 8);
|
|
green = ((ush)g << 8);
|
|
blue = ((ush)b << 8);
|
|
}
|
|
pixel = ((red >> RPixelShift) & RedMask) |
|
|
((green >> GPixelShift) & GreenMask) |
|
|
((blue >> BPixelShift) & BlueMask);
|
|
/* recall that we set ximage->byte_order = MSBFirst above */
|
|
*dest++ = ((uch *)&pixel)[1];
|
|
*dest++ = ((uch *)&pixel)[0];
|
|
}
|
|
}
|
|
/* display after every 16 lines */
|
|
if (((row+1) & 0xf) == 0) {
|
|
XPutImage(display, window, gc, ximage, 0, lastrow, 0, lastrow,
|
|
image_width, 16);
|
|
XFlush(display);
|
|
lastrow = row + 1;
|
|
}
|
|
}
|
|
|
|
} else /* depth == 8 */ {
|
|
|
|
/* GRR: add 8-bit support */
|
|
|
|
}
|
|
|
|
Trace((stderr, "calling final XPutImage()\n"))
|
|
if (lastrow < image_height) {
|
|
XPutImage(display, window, gc, ximage, 0, lastrow, 0, lastrow,
|
|
image_width, image_height-lastrow);
|
|
XFlush(display);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
|
|
|
|
static void rpng_x_cleanup()
|
|
{
|
|
if (image_data) {
|
|
free(image_data);
|
|
image_data = NULL;
|
|
}
|
|
|
|
if (ximage) {
|
|
if (ximage->data) {
|
|
free(ximage->data); /* we allocated it, so we free it */
|
|
ximage->data = (char *)NULL; /* instead of XDestroyImage() */
|
|
}
|
|
XDestroyImage(ximage);
|
|
ximage = NULL;
|
|
}
|
|
|
|
XFreeGC(display, gc);
|
|
|
|
if (have_window)
|
|
XDestroyWindow(display, window);
|
|
|
|
if (have_colormap)
|
|
XFreeColormap(display, colormap);
|
|
}
|
|
|
|
|
|
|
|
|
|
|
|
static int rpng_x_msb(ulg u32val)
|
|
{
|
|
int i;
|
|
|
|
for (i = 31; i >= 0; --i) {
|
|
if (u32val & 0x80000000L)
|
|
break;
|
|
u32val <<= 1;
|
|
}
|
|
return i;
|
|
}
|