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      1 /*---------------------------------------------------------------------------
      2 
      3    rpng - simple PNG display program                               rpng-x.c
      4 
      5    This program decodes and displays PNG images, with gamma correction and
      6    optionally with a user-specified background color (in case the image has
      7    transparency).  It is very nearly the most basic PNG viewer possible.
      8    This version is for the X Window System (tested by author under Unix and
      9    by Martin Zinser under OpenVMS; may work under OS/2 with some tweaking).
     10 
     11    to do:
     12     - 8-bit (colormapped) X support
     13     - use %.1023s to simplify truncation of title-bar string?
     14 
     15   ---------------------------------------------------------------------------
     16 
     17    Changelog:
     18     - 1.01:  initial public release
     19     - 1.02:  modified to allow abbreviated options; fixed long/ulong mis-
     20               match; switched to png_jmpbuf() macro
     21     - 1.10:  added support for non-default visuals; fixed X pixel-conversion
     22     - 1.11:  added extra set of parentheses to png_jmpbuf() macro; fixed
     23               command-line parsing bug
     24     - 1.12:  fixed some small X memory leaks (thanks to Franois Petitjean)
     25     - 1.13:  fixed XFreeGC() crash bug (thanks to Patrick Welche)
     26     - 1.14:  added support for X resources (thanks to Gerhard Niklasch)
     27     - 2.00:  dual-licensed (added GNU GPL)
     28     - 2.01:  fixed improper display of usage screen on PNG error(s)
     29     - 2.02:  Added "void(argc);" statement to quiet pedantic compiler warnings
     30              about unused variable (GR-P)
     31 
     32   ---------------------------------------------------------------------------
     33 
     34       Copyright (c) 1998-2008 Greg Roelofs.  All rights reserved.
     35 
     36       This software is provided "as is," without warranty of any kind,
     37       express or implied.  In no event shall the author or contributors
     38       be held liable for any damages arising in any way from the use of
     39       this software.
     40 
     41       The contents of this file are DUAL-LICENSED.  You may modify and/or
     42       redistribute this software according to the terms of one of the
     43       following two licenses (at your option):
     44 
     45 
     46       LICENSE 1 ("BSD-like with advertising clause"):
     47 
     48       Permission is granted to anyone to use this software for any purpose,
     49       including commercial applications, and to alter it and redistribute
     50       it freely, subject to the following restrictions:
     51 
     52       1. Redistributions of source code must retain the above copyright
     53          notice, disclaimer, and this list of conditions.
     54       2. Redistributions in binary form must reproduce the above copyright
     55          notice, disclaimer, and this list of conditions in the documenta-
     56          tion and/or other materials provided with the distribution.
     57       3. All advertising materials mentioning features or use of this
     58          software must display the following acknowledgment:
     59 
     60             This product includes software developed by Greg Roelofs
     61             and contributors for the book, "PNG: The Definitive Guide,"
     62             published by O'Reilly and Associates.
     63 
     64 
     65       LICENSE 2 (GNU GPL v2 or later):
     66 
     67       This program is free software; you can redistribute it and/or modify
     68       it under the terms of the GNU General Public License as published by
     69       the Free Software Foundation; either version 2 of the License, or
     70       (at your option) any later version.
     71 
     72       This program is distributed in the hope that it will be useful,
     73       but WITHOUT ANY WARRANTY; without even the implied warranty of
     74       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     75       GNU General Public License for more details.
     76 
     77       You should have received a copy of the GNU General Public License
     78       along with this program; if not, write to the Free Software Foundation,
     79       Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
     80 
     81   ---------------------------------------------------------------------------*/
     82 
     83 #define PROGNAME  "rpng-x"
     84 #define LONGNAME  "Simple PNG Viewer for X"
     85 #define VERSION   "2.02 of 15 June 2014"
     86 #define RESNAME   "rpng"        /* our X resource application name */
     87 #define RESCLASS  "Rpng"        /* our X resource class name */
     88 
     89 #include <stdio.h>
     90 #include <stdlib.h>
     91 #include <string.h>
     92 #include <time.h>
     93 #include <X11/Xlib.h>
     94 #include <X11/Xutil.h>
     95 #include <X11/Xos.h>
     96 #include <X11/keysym.h>
     97 
     98 /* #define DEBUG  :  this enables the Trace() macros */
     99 
    100 #include "readpng.h"   /* typedefs, common macros, readpng prototypes */
    101 
    102 
    103 /* could just include png.h, but this macro is the only thing we need
    104  * (name and typedefs changed to local versions); note that side effects
    105  * only happen with alpha (which could easily be avoided with
    106  * "ush acopy = (alpha);") */
    107 
    108 #define alpha_composite(composite, fg, alpha, bg) {               \
    109     ush temp = ((ush)(fg)*(ush)(alpha) +                          \
    110                 (ush)(bg)*(ush)(255 - (ush)(alpha)) + (ush)128);  \
    111     (composite) = (uch)((temp + (temp >> 8)) >> 8);               \
    112 }
    113 
    114 
    115 /* local prototypes */
    116 static int  rpng_x_create_window(void);
    117 static int  rpng_x_display_image(void);
    118 static void rpng_x_cleanup(void);
    119 static int  rpng_x_msb(ulg u32val);
    120 
    121 
    122 static char titlebar[1024], *window_name = titlebar;
    123 static char *appname = LONGNAME;
    124 static char *icon_name = PROGNAME;
    125 static char *res_name = RESNAME;
    126 static char *res_class = RESCLASS;
    127 static char *filename;
    128 static FILE *infile;
    129 
    130 static char *bgstr;
    131 static uch bg_red=0, bg_green=0, bg_blue=0;
    132 
    133 static double display_exponent;
    134 
    135 static ulg image_width, image_height, image_rowbytes;
    136 static int image_channels;
    137 static uch *image_data;
    138 
    139 /* X-specific variables */
    140 static char *displayname;
    141 static XImage *ximage;
    142 static Display *display;
    143 static int depth;
    144 static Visual *visual;
    145 static XVisualInfo *visual_list;
    146 static int RShift, GShift, BShift;
    147 static ulg RMask, GMask, BMask;
    148 static Window window;
    149 static GC gc;
    150 static Colormap colormap;
    151 
    152 static int have_nondefault_visual = FALSE;
    153 static int have_colormap = FALSE;
    154 static int have_window = FALSE;
    155 static int have_gc = FALSE;
    156 /*
    157 ulg numcolors=0, pixels[256];
    158 ush reds[256], greens[256], blues[256];
    159  */
    160 
    161 
    162 
    163 
    164 int main(int argc, char **argv)
    165 {
    166 #ifdef sgi
    167     char tmpline[80];
    168 #endif
    169     char *p;
    170     int rc, alen, flen;
    171     int error = 0;
    172     int have_bg = FALSE;
    173     double LUT_exponent;               /* just the lookup table */
    174     double CRT_exponent = 2.2;         /* just the monitor */
    175     double default_display_exponent;   /* whole display system */
    176     XEvent e;
    177     KeySym k;
    178 
    179 
    180     displayname = (char *)NULL;
    181     filename = (char *)NULL;
    182 
    183 
    184     /* First set the default value for our display-system exponent, i.e.,
    185      * the product of the CRT exponent and the exponent corresponding to
    186      * the frame-buffer's lookup table (LUT), if any.  This is not an
    187      * exhaustive list of LUT values (e.g., OpenStep has a lot of weird
    188      * ones), but it should cover 99% of the current possibilities. */
    189 
    190 #if defined(NeXT)
    191     LUT_exponent = 1.0 / 2.2;
    192     /*
    193     if (some_next_function_that_returns_gamma(&next_gamma))
    194         LUT_exponent = 1.0 / next_gamma;
    195      */
    196 #elif defined(sgi)
    197     LUT_exponent = 1.0 / 1.7;
    198     /* there doesn't seem to be any documented function to get the
    199      * "gamma" value, so we do it the hard way */
    200     infile = fopen("/etc/config/system.glGammaVal", "r");
    201     if (infile) {
    202         double sgi_gamma;
    203 
    204         fgets(tmpline, 80, infile);
    205         fclose(infile);
    206         sgi_gamma = atof(tmpline);
    207         if (sgi_gamma > 0.0)
    208             LUT_exponent = 1.0 / sgi_gamma;
    209     }
    210 #elif defined(Macintosh)
    211     LUT_exponent = 1.8 / 2.61;
    212     /*
    213     if (some_mac_function_that_returns_gamma(&mac_gamma))
    214         LUT_exponent = mac_gamma / 2.61;
    215      */
    216 #else
    217     LUT_exponent = 1.0;   /* assume no LUT:  most PCs */
    218 #endif
    219 
    220     /* the defaults above give 1.0, 1.3, 1.5 and 2.2, respectively: */
    221     default_display_exponent = LUT_exponent * CRT_exponent;
    222 
    223 
    224     /* If the user has set the SCREEN_GAMMA environment variable as suggested
    225      * (somewhat imprecisely) in the libpng documentation, use that; otherwise
    226      * use the default value we just calculated.  Either way, the user may
    227      * override this via a command-line option. */
    228 
    229     if ((p = getenv("SCREEN_GAMMA")) != NULL)
    230         display_exponent = atof(p);
    231     else
    232         display_exponent = default_display_exponent;
    233 
    234 
    235     /* Now parse the command line for options and the PNG filename. */
    236 
    237     while (*++argv && !error) {
    238         if (!strncmp(*argv, "-display", 2)) {
    239             if (!*++argv)
    240                 ++error;
    241             else
    242                 displayname = *argv;
    243         } else if (!strncmp(*argv, "-gamma", 2)) {
    244             if (!*++argv)
    245                 ++error;
    246             else {
    247                 display_exponent = atof(*argv);
    248                 if (display_exponent <= 0.0)
    249                     ++error;
    250             }
    251         } else if (!strncmp(*argv, "-bgcolor", 2)) {
    252             if (!*++argv)
    253                 ++error;
    254             else {
    255                 bgstr = *argv;
    256                 if (strlen(bgstr) != 7 || bgstr[0] != '#')
    257                     ++error;
    258                 else
    259                     have_bg = TRUE;
    260             }
    261         } else {
    262             if (**argv != '-') {
    263                 filename = *argv;
    264                 if (argv[1])   /* shouldn't be any more args after filename */
    265                     ++error;
    266             } else
    267                 ++error;   /* not expecting any other options */
    268         }
    269     }
    270 
    271     if (!filename)
    272         ++error;
    273 
    274 
    275     /* print usage screen if any errors up to this point */
    276 
    277     if (error) {
    278         fprintf(stderr, "\n%s %s:  %s\n", PROGNAME, VERSION, appname);
    279         readpng_version_info();
    280         fprintf(stderr, "\n"
    281           "Usage:  %s [-display xdpy] [-gamma exp] [-bgcolor bg] file.png\n"
    282           "    xdpy\tname of the target X display (e.g., ``hostname:0'')\n"
    283           "    exp \ttransfer-function exponent (``gamma'') of the display\n"
    284           "\t\t  system in floating-point format (e.g., ``%.1f''); equal\n",
    285           PROGNAME, default_display_exponent);
    286 
    287         fprintf(stderr, "\n"
    288           "\t\t  to the product of the lookup-table exponent (varies)\n"
    289           "\t\t  and the CRT exponent (usually 2.2); must be positive\n"
    290           "    bg  \tdesired background color in 7-character hex RGB format\n"
    291           "\t\t  (e.g., ``#ff7700'' for orange:  same as HTML colors);\n"
    292           "\t\t  used with transparent images\n"
    293           "\nPress Q, Esc or mouse button 1 (within image window, after image\n"
    294           "is displayed) to quit.\n");
    295         exit(1);
    296     }
    297 
    298 
    299     if (!(infile = fopen(filename, "rb"))) {
    300         fprintf(stderr, PROGNAME ":  can't open PNG file [%s]\n", filename);
    301         ++error;
    302     } else {
    303         if ((rc = readpng_init(infile, &image_width, &image_height)) != 0) {
    304             switch (rc) {
    305                 case 1:
    306                     fprintf(stderr, PROGNAME
    307                       ":  [%s] is not a PNG file: incorrect signature\n",
    308                       filename);
    309                     break;
    310                 case 2:
    311                     fprintf(stderr, PROGNAME
    312                       ":  [%s] has bad IHDR (libpng longjmp)\n", filename);
    313                     break;
    314                 case 4:
    315                     fprintf(stderr, PROGNAME ":  insufficient memory\n");
    316                     break;
    317                 default:
    318                     fprintf(stderr, PROGNAME
    319                       ":  unknown readpng_init() error\n");
    320                     break;
    321             }
    322             ++error;
    323         } else {
    324             display = XOpenDisplay(displayname);
    325             if (!display) {
    326                 readpng_cleanup(TRUE);
    327                 fprintf(stderr, PROGNAME ":  can't open X display [%s]\n",
    328                   displayname? displayname : "default");
    329                 ++error;
    330             }
    331         }
    332         if (error)
    333             fclose(infile);
    334     }
    335 
    336 
    337     if (error) {
    338         fprintf(stderr, PROGNAME ":  aborting.\n");
    339         exit(2);
    340     }
    341 
    342 
    343     /* set the title-bar string, but make sure buffer doesn't overflow */
    344 
    345     alen = strlen(appname);
    346     flen = strlen(filename);
    347     if (alen + flen + 3 > 1023)
    348         sprintf(titlebar, "%s:  ...%s", appname, filename+(alen+flen+6-1023));
    349     else
    350         sprintf(titlebar, "%s:  %s", appname, filename);
    351 
    352 
    353     /* if the user didn't specify a background color on the command line,
    354      * check for one in the PNG file--if not, the initialized values of 0
    355      * (black) will be used */
    356 
    357     if (have_bg) {
    358         unsigned r, g, b;   /* this approach quiets compiler warnings */
    359 
    360         sscanf(bgstr+1, "%2x%2x%2x", &r, &g, &b);
    361         bg_red   = (uch)r;
    362         bg_green = (uch)g;
    363         bg_blue  = (uch)b;
    364     } else if (readpng_get_bgcolor(&bg_red, &bg_green, &bg_blue) > 1) {
    365         readpng_cleanup(TRUE);
    366         fprintf(stderr, PROGNAME
    367           ":  libpng error while checking for background color\n");
    368         exit(2);
    369     }
    370 
    371 
    372     /* do the basic X initialization stuff, make the window and fill it
    373      * with the background color */
    374 
    375     if (rpng_x_create_window())
    376         exit(2);
    377 
    378 
    379     /* decode the image, all at once */
    380 
    381     Trace((stderr, "calling readpng_get_image()\n"))
    382     image_data = readpng_get_image(display_exponent, &image_channels,
    383       &image_rowbytes);
    384     Trace((stderr, "done with readpng_get_image()\n"))
    385 
    386 
    387     /* done with PNG file, so clean up to minimize memory usage (but do NOT
    388      * nuke image_data!) */
    389 
    390     readpng_cleanup(FALSE);
    391     fclose(infile);
    392 
    393     if (!image_data) {
    394         fprintf(stderr, PROGNAME ":  unable to decode PNG image\n");
    395         exit(3);
    396     }
    397 
    398 
    399     /* display image (composite with background if requested) */
    400 
    401     Trace((stderr, "calling rpng_x_display_image()\n"))
    402     if (rpng_x_display_image()) {
    403         free(image_data);
    404         exit(4);
    405     }
    406     Trace((stderr, "done with rpng_x_display_image()\n"))
    407 
    408 
    409     /* wait for the user to tell us when to quit */
    410 
    411     printf(
    412       "Done.  Press Q, Esc or mouse button 1 (within image window) to quit.\n");
    413     fflush(stdout);
    414 
    415     do
    416         XNextEvent(display, &e);
    417     while (!(e.type == ButtonPress && e.xbutton.button == Button1) &&
    418            !(e.type == KeyPress &&    /*  v--- or 1 for shifted keys */
    419              ((k = XLookupKeysym(&e.xkey, 0)) == XK_q || k == XK_Escape) ));
    420 
    421 
    422     /* OK, we're done:  clean up all image and X resources and go away */
    423 
    424     rpng_x_cleanup();
    425 
    426     (void)argc; /* Unused */
    427 
    428     return 0;
    429 }
    430 
    431 
    432 
    433 
    434 
    435 static int rpng_x_create_window(void)
    436 {
    437     uch *xdata;
    438     int need_colormap = FALSE;
    439     int screen, pad;
    440     ulg bg_pixel = 0L;
    441     ulg attrmask;
    442     Window root;
    443     XEvent e;
    444     XGCValues gcvalues;
    445     XSetWindowAttributes attr;
    446     XTextProperty windowName, *pWindowName = &windowName;
    447     XTextProperty iconName, *pIconName = &iconName;
    448     XVisualInfo visual_info;
    449     XSizeHints *size_hints;
    450     XWMHints *wm_hints;
    451     XClassHint *class_hints;
    452 
    453 
    454     screen = DefaultScreen(display);
    455     depth = DisplayPlanes(display, screen);
    456     root = RootWindow(display, screen);
    457 
    458 #ifdef DEBUG
    459     XSynchronize(display, True);
    460 #endif
    461 
    462 #if 0
    463 /* GRR:  add 8-bit support */
    464     if (/* depth != 8 && */ depth != 16 && depth != 24 && depth != 32) {
    465         fprintf(stderr,
    466           "screen depth %d not supported (only 16-, 24- or 32-bit TrueColor)\n",
    467           depth);
    468         return 2;
    469     }
    470 
    471     XMatchVisualInfo(display, screen, depth,
    472       (depth == 8)? PseudoColor : TrueColor, &visual_info);
    473     visual = visual_info.visual;
    474 #else
    475     if (depth != 16 && depth != 24 && depth != 32) {
    476         int visuals_matched = 0;
    477 
    478         Trace((stderr, "default depth is %d:  checking other visuals\n",
    479           depth))
    480 
    481         /* 24-bit first */
    482         visual_info.screen = screen;
    483         visual_info.depth = 24;
    484         visual_list = XGetVisualInfo(display,
    485           VisualScreenMask | VisualDepthMask, &visual_info, &visuals_matched);
    486         if (visuals_matched == 0) {
    487 /* GRR:  add 15-, 16- and 32-bit TrueColor visuals (also DirectColor?) */
    488             fprintf(stderr, "default screen depth %d not supported, and no"
    489               " 24-bit visuals found\n", depth);
    490             return 2;
    491         }
    492         Trace((stderr, "XGetVisualInfo() returned %d 24-bit visuals\n",
    493           visuals_matched))
    494         visual = visual_list[0].visual;
    495         depth = visual_list[0].depth;
    496 /*
    497         colormap_size = visual_list[0].colormap_size;
    498         visual_class = visual->class;
    499         visualID = XVisualIDFromVisual(visual);
    500  */
    501         have_nondefault_visual = TRUE;
    502         need_colormap = TRUE;
    503     } else {
    504         XMatchVisualInfo(display, screen, depth, TrueColor, &visual_info);
    505         visual = visual_info.visual;
    506     }
    507 #endif
    508 
    509     RMask = visual->red_mask;
    510     GMask = visual->green_mask;
    511     BMask = visual->blue_mask;
    512 
    513 /* GRR:  add/check 8-bit support */
    514     if (depth == 8 || need_colormap) {
    515         colormap = XCreateColormap(display, root, visual, AllocNone);
    516         if (!colormap) {
    517             fprintf(stderr, "XCreateColormap() failed\n");
    518             return 2;
    519         }
    520         have_colormap = TRUE;
    521     }
    522     if (depth == 15 || depth == 16) {
    523         RShift = 15 - rpng_x_msb(RMask);    /* these are right-shifts */
    524         GShift = 15 - rpng_x_msb(GMask);
    525         BShift = 15 - rpng_x_msb(BMask);
    526     } else if (depth > 16) {
    527 #define NO_24BIT_MASKS
    528 #ifdef NO_24BIT_MASKS
    529         RShift = rpng_x_msb(RMask) - 7;     /* these are left-shifts */
    530         GShift = rpng_x_msb(GMask) - 7;
    531         BShift = rpng_x_msb(BMask) - 7;
    532 #else
    533         RShift = 7 - rpng_x_msb(RMask);     /* these are right-shifts, too */
    534         GShift = 7 - rpng_x_msb(GMask);
    535         BShift = 7 - rpng_x_msb(BMask);
    536 #endif
    537     }
    538     if (depth >= 15 && (RShift < 0 || GShift < 0 || BShift < 0)) {
    539         fprintf(stderr, "rpng internal logic error:  negative X shift(s)!\n");
    540         return 2;
    541     }
    542 
    543 /*---------------------------------------------------------------------------
    544     Finally, create the window.
    545   ---------------------------------------------------------------------------*/
    546 
    547     attr.backing_store = Always;
    548     attr.event_mask = ExposureMask | KeyPressMask | ButtonPressMask;
    549     attrmask = CWBackingStore | CWEventMask;
    550     if (have_nondefault_visual) {
    551         attr.colormap = colormap;
    552         attr.background_pixel = 0;
    553         attr.border_pixel = 1;
    554         attrmask |= CWColormap | CWBackPixel | CWBorderPixel;
    555     }
    556 
    557     window = XCreateWindow(display, root, 0, 0, image_width, image_height, 0,
    558       depth, InputOutput, visual, attrmask, &attr);
    559 
    560     if (window == None) {
    561         fprintf(stderr, "XCreateWindow() failed\n");
    562         return 2;
    563     } else
    564         have_window = TRUE;
    565 
    566     if (depth == 8)
    567         XSetWindowColormap(display, window, colormap);
    568 
    569     if (!XStringListToTextProperty(&window_name, 1, pWindowName))
    570         pWindowName = NULL;
    571     if (!XStringListToTextProperty(&icon_name, 1, pIconName))
    572         pIconName = NULL;
    573 
    574     /* OK if any hints allocation fails; XSetWMProperties() allows NULLs */
    575 
    576     if ((size_hints = XAllocSizeHints()) != NULL) {
    577         /* window will not be resizable */
    578         size_hints->flags = PMinSize | PMaxSize;
    579         size_hints->min_width = size_hints->max_width = (int)image_width;
    580         size_hints->min_height = size_hints->max_height = (int)image_height;
    581     }
    582 
    583     if ((wm_hints = XAllocWMHints()) != NULL) {
    584         wm_hints->initial_state = NormalState;
    585         wm_hints->input = True;
    586      /* wm_hints->icon_pixmap = icon_pixmap; */
    587         wm_hints->flags = StateHint | InputHint  /* | IconPixmapHint */ ;
    588     }
    589 
    590     if ((class_hints = XAllocClassHint()) != NULL) {
    591         class_hints->res_name = res_name;
    592         class_hints->res_class = res_class;
    593     }
    594 
    595     XSetWMProperties(display, window, pWindowName, pIconName, NULL, 0,
    596       size_hints, wm_hints, class_hints);
    597 
    598     /* various properties and hints no longer needed; free memory */
    599     if (pWindowName)
    600        XFree(pWindowName->value);
    601     if (pIconName)
    602        XFree(pIconName->value);
    603     if (size_hints)
    604         XFree(size_hints);
    605     if (wm_hints)
    606        XFree(wm_hints);
    607     if (class_hints)
    608        XFree(class_hints);
    609 
    610     XMapWindow(display, window);
    611 
    612     gc = XCreateGC(display, window, 0, &gcvalues);
    613     have_gc = TRUE;
    614 
    615 /*---------------------------------------------------------------------------
    616     Fill window with the specified background color.
    617   ---------------------------------------------------------------------------*/
    618 
    619     if (depth == 24 || depth == 32) {
    620         bg_pixel = ((ulg)bg_red   << RShift) |
    621                    ((ulg)bg_green << GShift) |
    622                    ((ulg)bg_blue  << BShift);
    623     } else if (depth == 16) {
    624         bg_pixel = ((((ulg)bg_red   << 8) >> RShift) & RMask) |
    625                    ((((ulg)bg_green << 8) >> GShift) & GMask) |
    626                    ((((ulg)bg_blue  << 8) >> BShift) & BMask);
    627     } else /* depth == 8 */ {
    628 
    629         /* GRR:  add 8-bit support */
    630 
    631     }
    632 
    633     XSetForeground(display, gc, bg_pixel);
    634     XFillRectangle(display, window, gc, 0, 0, image_width, image_height);
    635 
    636 /*---------------------------------------------------------------------------
    637     Wait for first Expose event to do any drawing, then flush.
    638   ---------------------------------------------------------------------------*/
    639 
    640     do
    641         XNextEvent(display, &e);
    642     while (e.type != Expose || e.xexpose.count);
    643 
    644     XFlush(display);
    645 
    646 /*---------------------------------------------------------------------------
    647     Allocate memory for the X- and display-specific version of the image.
    648   ---------------------------------------------------------------------------*/
    649 
    650     if (depth == 24 || depth == 32) {
    651         xdata = (uch *)malloc(4*image_width*image_height);
    652         pad = 32;
    653     } else if (depth == 16) {
    654         xdata = (uch *)malloc(2*image_width*image_height);
    655         pad = 16;
    656     } else /* depth == 8 */ {
    657         xdata = (uch *)malloc(image_width*image_height);
    658         pad = 8;
    659     }
    660 
    661     if (!xdata) {
    662         fprintf(stderr, PROGNAME ":  unable to allocate image memory\n");
    663         return 4;
    664     }
    665 
    666     ximage = XCreateImage(display, visual, depth, ZPixmap, 0,
    667       (char *)xdata, image_width, image_height, pad, 0);
    668 
    669     if (!ximage) {
    670         fprintf(stderr, PROGNAME ":  XCreateImage() failed\n");
    671         free(xdata);
    672         return 3;
    673     }
    674 
    675     /* to avoid testing the byte order every pixel (or doubling the size of
    676      * the drawing routine with a giant if-test), we arbitrarily set the byte
    677      * order to MSBFirst and let Xlib worry about inverting things on little-
    678      * endian machines (like Linux/x86, old VAXen, etc.)--this is not the most
    679      * efficient approach (the giant if-test would be better), but in the
    680      * interest of clarity, we take the easy way out... */
    681 
    682     ximage->byte_order = MSBFirst;
    683 
    684     return 0;
    685 
    686 } /* end function rpng_x_create_window() */
    687 
    688 
    689 
    690 
    691 
    692 static int rpng_x_display_image(void)
    693 {
    694     uch *src;
    695     char *dest;
    696     uch r, g, b, a;
    697     ulg i, row, lastrow = 0;
    698     ulg pixel;
    699     int ximage_rowbytes = ximage->bytes_per_line;
    700 /*  int bpp = ximage->bits_per_pixel;  */
    701 
    702 
    703     Trace((stderr, "beginning display loop (image_channels == %d)\n",
    704       image_channels))
    705     Trace((stderr, "   (width = %ld, rowbytes = %ld, ximage_rowbytes = %d)\n",
    706       image_width, image_rowbytes, ximage_rowbytes))
    707     Trace((stderr, "   (bpp = %d)\n", ximage->bits_per_pixel))
    708     Trace((stderr, "   (byte_order = %s)\n", ximage->byte_order == MSBFirst?
    709       "MSBFirst" : (ximage->byte_order == LSBFirst? "LSBFirst" : "unknown")))
    710 
    711     if (depth == 24 || depth == 32) {
    712         ulg red, green, blue;
    713 
    714         for (lastrow = row = 0;  row < image_height;  ++row) {
    715             src = image_data + row*image_rowbytes;
    716             dest = ximage->data + row*ximage_rowbytes;
    717             if (image_channels == 3) {
    718                 for (i = image_width;  i > 0;  --i) {
    719                     red   = *src++;
    720                     green = *src++;
    721                     blue  = *src++;
    722 #ifdef NO_24BIT_MASKS
    723                     pixel = (red   << RShift) |
    724                             (green << GShift) |
    725                             (blue  << BShift);
    726                     /* recall that we set ximage->byte_order = MSBFirst above */
    727                     /* GRR BUG:  this assumes bpp == 32, but may be 24: */
    728                     *dest++ = (char)((pixel >> 24) & 0xff);
    729                     *dest++ = (char)((pixel >> 16) & 0xff);
    730                     *dest++ = (char)((pixel >>  8) & 0xff);
    731                     *dest++ = (char)( pixel        & 0xff);
    732 #else
    733                     red   = (RShift < 0)? red   << (-RShift) : red   >> RShift;
    734                     green = (GShift < 0)? green << (-GShift) : green >> GShift;
    735                     blue  = (BShift < 0)? blue  << (-BShift) : blue  >> BShift;
    736                     pixel = (red & RMask) | (green & GMask) | (blue & BMask);
    737                     /* recall that we set ximage->byte_order = MSBFirst above */
    738                     *dest++ = (char)((pixel >> 24) & 0xff);
    739                     *dest++ = (char)((pixel >> 16) & 0xff);
    740                     *dest++ = (char)((pixel >>  8) & 0xff);
    741                     *dest++ = (char)( pixel        & 0xff);
    742 #endif
    743                 }
    744             } else /* if (image_channels == 4) */ {
    745                 for (i = image_width;  i > 0;  --i) {
    746                     r = *src++;
    747                     g = *src++;
    748                     b = *src++;
    749                     a = *src++;
    750                     if (a == 255) {
    751                         red   = r;
    752                         green = g;
    753                         blue  = b;
    754                     } else if (a == 0) {
    755                         red   = bg_red;
    756                         green = bg_green;
    757                         blue  = bg_blue;
    758                     } else {
    759                         /* this macro (from png.h) composites the foreground
    760                          * and background values and puts the result into the
    761                          * first argument */
    762                         alpha_composite(red,   r, a, bg_red);
    763                         alpha_composite(green, g, a, bg_green);
    764                         alpha_composite(blue,  b, a, bg_blue);
    765                     }
    766                     pixel = (red   << RShift) |
    767                             (green << GShift) |
    768                             (blue  << BShift);
    769                     /* recall that we set ximage->byte_order = MSBFirst above */
    770                     *dest++ = (char)((pixel >> 24) & 0xff);
    771                     *dest++ = (char)((pixel >> 16) & 0xff);
    772                     *dest++ = (char)((pixel >>  8) & 0xff);
    773                     *dest++ = (char)( pixel        & 0xff);
    774                 }
    775             }
    776             /* display after every 16 lines */
    777             if (((row+1) & 0xf) == 0) {
    778                 XPutImage(display, window, gc, ximage, 0, (int)lastrow, 0,
    779                   (int)lastrow, image_width, 16);
    780                 XFlush(display);
    781                 lastrow = row + 1;
    782             }
    783         }
    784 
    785     } else if (depth == 16) {
    786         ush red, green, blue;
    787 
    788         for (lastrow = row = 0;  row < image_height;  ++row) {
    789             src = image_data + row*image_rowbytes;
    790             dest = ximage->data + row*ximage_rowbytes;
    791             if (image_channels == 3) {
    792                 for (i = image_width;  i > 0;  --i) {
    793                     red   = ((ush)(*src) << 8);
    794                     ++src;
    795                     green = ((ush)(*src) << 8);
    796                     ++src;
    797                     blue  = ((ush)(*src) << 8);
    798                     ++src;
    799                     pixel = ((red   >> RShift) & RMask) |
    800                             ((green >> GShift) & GMask) |
    801                             ((blue  >> BShift) & BMask);
    802                     /* recall that we set ximage->byte_order = MSBFirst above */
    803                     *dest++ = (char)((pixel >>  8) & 0xff);
    804                     *dest++ = (char)( pixel        & 0xff);
    805                 }
    806             } else /* if (image_channels == 4) */ {
    807                 for (i = image_width;  i > 0;  --i) {
    808                     r = *src++;
    809                     g = *src++;
    810                     b = *src++;
    811                     a = *src++;
    812                     if (a == 255) {
    813                         red   = ((ush)r << 8);
    814                         green = ((ush)g << 8);
    815                         blue  = ((ush)b << 8);
    816                     } else if (a == 0) {
    817                         red   = ((ush)bg_red   << 8);
    818                         green = ((ush)bg_green << 8);
    819                         blue  = ((ush)bg_blue  << 8);
    820                     } else {
    821                         /* this macro (from png.h) composites the foreground
    822                          * and background values and puts the result back into
    823                          * the first argument (== fg byte here:  safe) */
    824                         alpha_composite(r, r, a, bg_red);
    825                         alpha_composite(g, g, a, bg_green);
    826                         alpha_composite(b, b, a, bg_blue);
    827                         red   = ((ush)r << 8);
    828                         green = ((ush)g << 8);
    829                         blue  = ((ush)b << 8);
    830                     }
    831                     pixel = ((red   >> RShift) & RMask) |
    832                             ((green >> GShift) & GMask) |
    833                             ((blue  >> BShift) & BMask);
    834                     /* recall that we set ximage->byte_order = MSBFirst above */
    835                     *dest++ = (char)((pixel >>  8) & 0xff);
    836                     *dest++ = (char)( pixel        & 0xff);
    837                 }
    838             }
    839             /* display after every 16 lines */
    840             if (((row+1) & 0xf) == 0) {
    841                 XPutImage(display, window, gc, ximage, 0, (int)lastrow, 0,
    842                   (int)lastrow, image_width, 16);
    843                 XFlush(display);
    844                 lastrow = row + 1;
    845             }
    846         }
    847 
    848     } else /* depth == 8 */ {
    849 
    850         /* GRR:  add 8-bit support */
    851 
    852     }
    853 
    854     Trace((stderr, "calling final XPutImage()\n"))
    855     if (lastrow < image_height) {
    856         XPutImage(display, window, gc, ximage, 0, (int)lastrow, 0,
    857           (int)lastrow, image_width, image_height-lastrow);
    858         XFlush(display);
    859     }
    860 
    861     return 0;
    862 }
    863 
    864 
    865 
    866 
    867 static void rpng_x_cleanup(void)
    868 {
    869     if (image_data) {
    870         free(image_data);
    871         image_data = NULL;
    872     }
    873 
    874     if (ximage) {
    875         if (ximage->data) {
    876             free(ximage->data);           /* we allocated it, so we free it */
    877             ximage->data = (char *)NULL;  /*  instead of XDestroyImage() */
    878         }
    879         XDestroyImage(ximage);
    880         ximage = NULL;
    881     }
    882 
    883     if (have_gc)
    884         XFreeGC(display, gc);
    885 
    886     if (have_window)
    887         XDestroyWindow(display, window);
    888 
    889     if (have_colormap)
    890         XFreeColormap(display, colormap);
    891 
    892     if (have_nondefault_visual)
    893         XFree(visual_list);
    894 }
    895 
    896 
    897 
    898 
    899 
    900 static int rpng_x_msb(ulg u32val)
    901 {
    902     int i;
    903 
    904     for (i = 31;  i >= 0;  --i) {
    905         if (u32val & 0x80000000L)
    906             break;
    907         u32val <<= 1;
    908     }
    909     return i;
    910 }
    911