1 /*---------------------------------------------------------------------------
3 rpng - simple PNG display program rpng-win.c
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 32-bit Windows; it may compile under 16-bit Windows
9 with a little tweaking (or maybe not).
12 - handle quoted command-line args (especially filenames with spaces)
13 - have minimum window width: oh well
14 - use %.1023s to simplify truncation of title-bar string?
16 ---------------------------------------------------------------------------
19 - 1.00: initial public release
20 - 1.01: modified to allow abbreviated options; fixed long/ulong mis-
21 match; switched to png_jmpbuf() macro
22 - 1.02: added extra set of parentheses to png_jmpbuf() macro; fixed
23 command-line parsing bug
24 - 1.10: enabled "message window"/console (thanks to David Geldreich)
25 - 2.00: dual-licensed (added GNU GPL)
26 - 2.01: fixed improper display of usage screen on PNG error(s)
28 ---------------------------------------------------------------------------
30 Copyright (c) 1998-2008 Greg Roelofs. All rights reserved.
32 This software is provided "as is," without warranty of any kind,
33 express or implied. In no event shall the author or contributors
34 be held liable for any damages arising in any way from the use of
37 The contents of this file are DUAL-LICENSED. You may modify and/or
38 redistribute this software according to the terms of one of the
39 following two licenses (at your option):
42 LICENSE 1 ("BSD-like with advertising clause"):
44 Permission is granted to anyone to use this software for any purpose,
45 including commercial applications, and to alter it and redistribute
46 it freely, subject to the following restrictions:
48 1. Redistributions of source code must retain the above copyright
49 notice, disclaimer, and this list of conditions.
50 2. Redistributions in binary form must reproduce the above copyright
51 notice, disclaimer, and this list of conditions in the documenta-
52 tion and/or other materials provided with the distribution.
53 3. All advertising materials mentioning features or use of this
54 software must display the following acknowledgment:
56 This product includes software developed by Greg Roelofs
57 and contributors for the book, "PNG: The Definitive Guide,"
58 published by O'Reilly and Associates.
61 LICENSE 2 (GNU GPL v2 or later):
63 This program is free software; you can redistribute it and/or modify
64 it under the terms of the GNU General Public License as published by
65 the Free Software Foundation; either version 2 of the License, or
66 (at your option) any later version.
68 This program is distributed in the hope that it will be useful,
69 but WITHOUT ANY WARRANTY; without even the implied warranty of
70 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
71 GNU General Public License for more details.
73 You should have received a copy of the GNU General Public License
74 along with this program; if not, write to the Free Software Foundation,
75 Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
77 ---------------------------------------------------------------------------*/
79 #define PROGNAME "rpng-win"
80 #define LONGNAME "Simple PNG Viewer for Windows"
81 #define VERSION "2.01 of 16 March 2008"
88 #include <conio.h> /* only for _getch() */
90 /* #define DEBUG : this enables the Trace() macros */
92 #include "readpng.h" /* typedefs, common macros, readpng prototypes */
95 /* could just include png.h, but this macro is the only thing we need
96 * (name and typedefs changed to local versions); note that side effects
97 * only happen with alpha (which could easily be avoided with
98 * "ush acopy = (alpha);") */
100 #define alpha_composite(composite, fg, alpha, bg) { \
101 ush temp = ((ush)(fg)*(ush)(alpha) + \
102 (ush)(bg)*(ush)(255 - (ush)(alpha)) + (ush)128); \
103 (composite) = (uch)((temp + (temp >> 8)) >> 8); \
107 /* local prototypes */
108 static int rpng_win_create_window(HINSTANCE hInst, int showmode);
109 static int rpng_win_display_image(void);
110 static void rpng_win_cleanup(void);
111 LRESULT CALLBACK rpng_win_wndproc(HWND, UINT, WPARAM, LPARAM);
114 static char titlebar[1024];
115 static char *progname = PROGNAME;
116 static char *appname = LONGNAME;
117 static char *filename;
121 static uch bg_red=0, bg_green=0, bg_blue=0;
123 static double display_exponent;
125 static ulg image_width, image_height, image_rowbytes;
126 static int image_channels;
127 static uch *image_data;
129 /* Windows-specific variables */
130 static ulg wimage_rowbytes;
132 static uch *wimage_data;
133 static BITMAPINFOHEADER *bmih;
135 static HWND global_hwnd;
140 int WINAPI WinMain(HINSTANCE hInst, HINSTANCE hPrevInst, PSTR cmd, int showmode)
142 char *args[1024]; /* arbitrary limit, but should suffice */
143 char *p, *q, **argv = args;
148 double LUT_exponent; /* just the lookup table */
149 double CRT_exponent = 2.2; /* just the monitor */
150 double default_display_exponent; /* whole display system */
154 filename = (char *)NULL;
157 /* First reenable console output, which normally goes to the bit bucket
158 * for windowed apps. Closing the console window will terminate the
159 * app. Thanks to David.Geldreich@realviz.com for supplying the magical
163 freopen("CONOUT$", "a", stderr);
164 freopen("CONOUT$", "a", stdout);
167 /* Next set the default value for our display-system exponent, i.e.,
168 * the product of the CRT exponent and the exponent corresponding to
169 * the frame-buffer's lookup table (LUT), if any. This is not an
170 * exhaustive list of LUT values (e.g., OpenStep has a lot of weird
171 * ones), but it should cover 99% of the current possibilities. And
172 * yes, these ifdefs are completely wasted in a Windows program... */
175 LUT_exponent = 1.0 / 2.2;
177 if (some_next_function_that_returns_gamma(&next_gamma))
178 LUT_exponent = 1.0 / next_gamma;
181 LUT_exponent = 1.0 / 1.7;
182 /* there doesn't seem to be any documented function to get the
183 * "gamma" value, so we do it the hard way */
184 infile = fopen("/etc/config/system.glGammaVal", "r");
188 fgets(tmpline, 80, infile);
190 sgi_gamma = atof(tmpline);
192 LUT_exponent = 1.0 / sgi_gamma;
194 #elif defined(Macintosh)
195 LUT_exponent = 1.8 / 2.61;
197 if (some_mac_function_that_returns_gamma(&mac_gamma))
198 LUT_exponent = mac_gamma / 2.61;
201 LUT_exponent = 1.0; /* assume no LUT: most PCs */
204 /* the defaults above give 1.0, 1.3, 1.5 and 2.2, respectively: */
205 default_display_exponent = LUT_exponent * CRT_exponent;
208 /* If the user has set the SCREEN_GAMMA environment variable as suggested
209 * (somewhat imprecisely) in the libpng documentation, use that; otherwise
210 * use the default value we just calculated. Either way, the user may
211 * override this via a command-line option. */
213 if ((p = getenv("SCREEN_GAMMA")) != NULL)
214 display_exponent = atof(p);
216 display_exponent = default_display_exponent;
219 /* Windows really hates command lines, so we have to set up our own argv.
220 * Note that we do NOT bother with quoted arguments here, so don't use
221 * filenames with spaces in 'em! */
223 argv[argc++] = PROGNAME;
229 /* now p points at the first non-space after some spaces */
231 break; /* nothing after the spaces: done */
232 argv[argc++] = q = p;
233 while (*q && *q != ' ')
235 /* now q points at a space or the end of the string */
237 break; /* last argv already terminated; quit */
238 *q = '\0'; /* change space to terminator */
241 argv[argc] = NULL; /* terminate the argv array itself */
244 /* Now parse the command line for options and the PNG filename. */
246 while (*++argv && !error) {
247 if (!strncmp(*argv, "-gamma", 2)) {
251 display_exponent = atof(*argv);
252 if (display_exponent <= 0.0)
255 } else if (!strncmp(*argv, "-bgcolor", 2)) {
260 if (strlen(bgstr) != 7 || bgstr[0] != '#')
268 if (argv[1]) /* shouldn't be any more args after filename */
271 ++error; /* not expecting any other options */
279 /* print usage screen if any errors up to this point */
284 fprintf(stderr, "\n%s %s: %s\n\n", PROGNAME, VERSION, appname);
285 readpng_version_info();
287 "Usage: %s [-gamma exp] [-bgcolor bg] file.png\n"
288 " exp \ttransfer-function exponent (``gamma'') of the display\n"
289 "\t\t system in floating-point format (e.g., ``%.1f''); equal\n"
290 "\t\t to the product of the lookup-table exponent (varies)\n"
291 "\t\t and the CRT exponent (usually 2.2); must be positive\n"
292 " bg \tdesired background color in 7-character hex RGB format\n"
293 "\t\t (e.g., ``#ff7700'' for orange: same as HTML colors);\n"
294 "\t\t used with transparent images\n"
295 "\nPress Q, Esc or mouse button 1 after image is displayed to quit.\n"
296 "Press Q or Esc to quit this usage screen.\n"
297 "\n", PROGNAME, default_display_exponent);
300 while (ch != 'q' && ch != 'Q' && ch != 0x1B);
305 if (!(infile = fopen(filename, "rb"))) {
306 fprintf(stderr, PROGNAME ": can't open PNG file [%s]\n", filename);
309 if ((rc = readpng_init(infile, &image_width, &image_height)) != 0) {
312 fprintf(stderr, PROGNAME
313 ": [%s] is not a PNG file: incorrect signature\n",
317 fprintf(stderr, PROGNAME
318 ": [%s] has bad IHDR (libpng longjmp)\n", filename);
321 fprintf(stderr, PROGNAME ": insufficient memory\n");
324 fprintf(stderr, PROGNAME
325 ": unknown readpng_init() error\n");
338 fprintf(stderr, PROGNAME ": aborting.\n");
341 while (ch != 'q' && ch != 'Q' && ch != 0x1B);
344 fprintf(stderr, "\n%s %s: %s\n", PROGNAME, VERSION, appname);
346 "\n [console window: closing this window will terminate %s]\n\n",
351 /* set the title-bar string, but make sure buffer doesn't overflow */
353 alen = strlen(appname);
354 flen = strlen(filename);
355 if (alen + flen + 3 > 1023)
356 sprintf(titlebar, "%s: ...%s", appname, filename+(alen+flen+6-1023));
358 sprintf(titlebar, "%s: %s", appname, filename);
361 /* if the user didn't specify a background color on the command line,
362 * check for one in the PNG file--if not, the initialized values of 0
363 * (black) will be used */
366 unsigned r, g, b; /* this approach quiets compiler warnings */
368 sscanf(bgstr+1, "%2x%2x%2x", &r, &g, &b);
372 } else if (readpng_get_bgcolor(&bg_red, &bg_green, &bg_blue) > 1) {
373 readpng_cleanup(TRUE);
374 fprintf(stderr, PROGNAME
375 ": libpng error while checking for background color\n");
380 /* do the basic Windows initialization stuff, make the window and fill it
381 * with the background color */
383 if (rpng_win_create_window(hInst, showmode))
387 /* decode the image, all at once */
389 Trace((stderr, "calling readpng_get_image()\n"))
390 image_data = readpng_get_image(display_exponent, &image_channels,
392 Trace((stderr, "done with readpng_get_image()\n"))
395 /* done with PNG file, so clean up to minimize memory usage (but do NOT
396 * nuke image_data!) */
398 readpng_cleanup(FALSE);
402 fprintf(stderr, PROGNAME ": unable to decode PNG image\n");
407 /* display image (composite with background if requested) */
409 Trace((stderr, "calling rpng_win_display_image()\n"))
410 if (rpng_win_display_image()) {
414 Trace((stderr, "done with rpng_win_display_image()\n"))
417 /* wait for the user to tell us when to quit */
420 "Done. Press Q, Esc or mouse button 1 (within image window) to quit.\n");
423 while (GetMessage(&msg, NULL, 0, 0)) {
424 TranslateMessage(&msg);
425 DispatchMessage(&msg);
429 /* OK, we're done: clean up all image and Windows resources and go away */
440 static int rpng_win_create_window(HINSTANCE hInst, int showmode)
443 int extra_width, extra_height;
448 /*---------------------------------------------------------------------------
449 Allocate memory for the display-specific version of the image (round up
450 to multiple of 4 for Windows DIB).
451 ---------------------------------------------------------------------------*/
453 wimage_rowbytes = ((3*image_width + 3L) >> 2) << 2;
455 if (!(dib = (uch *)malloc(sizeof(BITMAPINFOHEADER) +
456 wimage_rowbytes*image_height)))
461 /*---------------------------------------------------------------------------
462 Initialize the DIB. Negative height means to use top-down BMP ordering
463 (must be uncompressed, but that's what we want). Bit count of 1, 4 or 8
464 implies a colormap of RGBX quads, but 24-bit BMPs just use B,G,R values
465 directly => wimage_data begins immediately after BMP header.
466 ---------------------------------------------------------------------------*/
468 memset(dib, 0, sizeof(BITMAPINFOHEADER));
469 bmih = (BITMAPINFOHEADER *)dib;
470 bmih->biSize = sizeof(BITMAPINFOHEADER);
471 bmih->biWidth = image_width;
472 bmih->biHeight = -((long)image_height);
474 bmih->biBitCount = 24;
475 bmih->biCompression = 0;
476 wimage_data = dib + sizeof(BITMAPINFOHEADER);
478 /*---------------------------------------------------------------------------
479 Fill in background color (black by default); data are in BGR order.
480 ---------------------------------------------------------------------------*/
482 for (j = 0; j < image_height; ++j) {
483 dest = wimage_data + j*wimage_rowbytes;
484 for (i = image_width; i > 0; --i) {
491 /*---------------------------------------------------------------------------
492 Set the window parameters.
493 ---------------------------------------------------------------------------*/
495 memset(&wndclass, 0, sizeof(wndclass));
497 wndclass.cbSize = sizeof(wndclass);
498 wndclass.style = CS_HREDRAW | CS_VREDRAW;
499 wndclass.lpfnWndProc = rpng_win_wndproc;
500 wndclass.hInstance = hInst;
501 wndclass.hIcon = LoadIcon(NULL, IDI_APPLICATION);
502 wndclass.hCursor = LoadCursor(NULL, IDC_ARROW);
503 wndclass.hbrBackground = (HBRUSH)GetStockObject(DKGRAY_BRUSH);
504 wndclass.lpszMenuName = NULL;
505 wndclass.lpszClassName = progname;
506 wndclass.hIconSm = LoadIcon(NULL, IDI_APPLICATION);
508 RegisterClassEx(&wndclass);
510 /*---------------------------------------------------------------------------
511 Finally, create the window.
512 ---------------------------------------------------------------------------*/
514 extra_width = 2*(GetSystemMetrics(SM_CXBORDER) +
515 GetSystemMetrics(SM_CXDLGFRAME));
516 extra_height = 2*(GetSystemMetrics(SM_CYBORDER) +
517 GetSystemMetrics(SM_CYDLGFRAME)) +
518 GetSystemMetrics(SM_CYCAPTION);
520 global_hwnd = CreateWindow(progname, titlebar, WS_OVERLAPPEDWINDOW,
521 CW_USEDEFAULT, CW_USEDEFAULT, image_width+extra_width,
522 image_height+extra_height, NULL, NULL, hInst, NULL);
524 ShowWindow(global_hwnd, showmode);
525 UpdateWindow(global_hwnd);
529 } /* end function rpng_win_create_window() */
535 static int rpng_win_display_image()
543 Trace((stderr, "beginning display loop (image_channels == %d)\n",
545 Trace((stderr, "(width = %ld, rowbytes = %ld, wimage_rowbytes = %d)\n",
546 image_width, image_rowbytes, wimage_rowbytes))
549 /*---------------------------------------------------------------------------
550 Blast image data to buffer. This whole routine takes place before the
551 message loop begins, so there's no real point in any pseudo-progressive
553 ---------------------------------------------------------------------------*/
555 for (lastrow = row = 0; row < image_height; ++row) {
556 src = image_data + row*image_rowbytes;
557 dest = wimage_data + row*wimage_rowbytes;
558 if (image_channels == 3) {
559 for (i = image_width; i > 0; --i) {
564 *dest++ = g; /* note reverse order */
567 } else /* if (image_channels == 4) */ {
568 for (i = image_width; i > 0; --i) {
582 /* this macro (copied from png.h) composites the
583 * foreground and background values and puts the
584 * result into the first argument; there are no
585 * side effects with the first argument */
586 alpha_composite(*dest++, b, a, bg_blue);
587 alpha_composite(*dest++, g, a, bg_green);
588 alpha_composite(*dest++, r, a, bg_red);
592 /* display after every 16 lines */
593 if (((row+1) & 0xf) == 0) {
595 rect.top = (LONG)lastrow;
596 rect.right = (LONG)image_width; /* possibly off by one? */
597 rect.bottom = (LONG)lastrow + 16L; /* possibly off by one? */
598 InvalidateRect(global_hwnd, &rect, FALSE);
599 UpdateWindow(global_hwnd); /* similar to XFlush() */
604 Trace((stderr, "calling final image-flush routine\n"))
605 if (lastrow < image_height) {
607 rect.top = (LONG)lastrow;
608 rect.right = (LONG)image_width; /* possibly off by one? */
609 rect.bottom = (LONG)image_height; /* possibly off by one? */
610 InvalidateRect(global_hwnd, &rect, FALSE);
611 UpdateWindow(global_hwnd); /* similar to XFlush() */
615 last param determines whether or not background is wiped before paint
616 InvalidateRect(global_hwnd, NULL, TRUE);
617 UpdateWindow(global_hwnd);
627 static void rpng_win_cleanup()
644 LRESULT CALLBACK rpng_win_wndproc(HWND hwnd, UINT iMsg, WPARAM wP, LPARAM lP)
652 /* one-time processing here, if any */
656 hdc = BeginPaint(hwnd, &ps);
658 rc = StretchDIBits(hdc, 0, 0, image_width, image_height,
660 0, 0, image_width, image_height,
661 wimage_data, (BITMAPINFO *)bmih,
662 /* iUsage: no clue */
667 /* wait for the user to tell us when to quit */
669 switch (wP) { /* only need one, so ignore repeat count */
672 case 0x1B: /* Esc key */
677 case WM_LBUTTONDOWN: /* another way of quitting */
683 return DefWindowProc(hwnd, iMsg, wP, lP);