Support farbfeld as an intermediate format

Sent now uses farbfeld[0] as an intermediate format.  A series of
filters is specified in config.h that matches file extensions to
filter programs.  The programs will convert between formats such as
png to farbfeld.  Internally in sent we do not need to worry on how
to parse png or any other format.

This also works with jpg and gif and others.  The 2ff wrapper will
use imagemagick conversion tools.  This is temporary as jpg2ff and
gif2ff will also be implemented.

To make this work, you will have to clone[0] and put png2ff and 2ff
in your PATH.

[0] http://git.2f30.org/farbfeld/

6 files changed, 119 insertions, 96 deletions

diff --git a/LICENSE b/LICENSE
index d1da8fc..8d5665e 100644
--- a/LICENSE
+++ b/LICENSE
@@ -2,8 +2,6 @@ The MIT License (MIT)
 
 Copyright (c) 2014-2015 Markus Teich
 
-png handling stuff adapted from meh by John Hawthorn
-
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
 in the Software without restriction, including without limitation the rights
diff --git a/README.md b/README.md
index 007564b..e213efb 100644
--- a/README.md
+++ b/README.md
@@ -33,7 +33,6 @@ presentation file could look like this:
 	
 	depends on
 	- Xlib
-	- libpng
 	
 	sent FILENAME
 	one slide per paragraph
diff --git a/config.def.h b/config.def.h
index 2dae620..94ed09e 100644
--- a/config.def.h
+++ b/config.def.h
@@ -45,3 +45,8 @@ static Shortcut shortcuts[] = {
 	{ XK_n,           advance,        {.i = +1} },
 	{ XK_p,           advance,        {.i = -1} },
 };
+
+static Filter filters[] = {
+	{ "\\.png$",       "png2ff" },
+	{ "\\.(jpg|gif)$", "2ff" },
+};
diff --git a/config.mk b/config.mk
index ed08199..52d5fb1 100644
--- a/config.mk
+++ b/config.mk
@@ -12,7 +12,7 @@ X11LIB = /usr/X11R6/lib
 
 # includes and libs
 INCS = -I. -I/usr/include -I/usr/include/freetype2 -I${X11INC}
-LIBS = -L/usr/lib -lc -lm -L${X11LIB} -lXft -lfontconfig -lX11 -lpng
+LIBS = -L/usr/lib -lc -lm -L${X11LIB} -lXft -lfontconfig -lX11
 
 # flags
 CPPFLAGS = -DVERSION=\"${VERSION}\" -D_XOPEN_SOURCE=600
diff --git a/example b/example
index 39e0206..d4b62d2 100644
--- a/example
+++ b/example
@@ -20,7 +20,6 @@ easy to use
 
 depends on
 ♽ Xlib
-☢ libpng
 
 ~1000 lines of code
 
diff --git a/sent.c b/sent.c
index e717a69..eb3aadc 100644
--- a/sent.c
+++ b/sent.c
@@ -1,12 +1,17 @@
 /* See LICENSE for licence details. */
+#include <sys/types.h>
+#include <arpa/inet.h>
+
 #include <errno.h>
+#include <fcntl.h>
 #include <math.h>
-#include <png.h>
+#include <regex.h>
 #include <stdarg.h>
 #include <stdio.h>
 #include <stdint.h>
 #include <stdlib.h>
 #include <string.h>
+#include <unistd.h>
 #include <X11/keysym.h>
 #include <X11/XKBlib.h>
 #include <X11/Xatom.h>
@@ -36,13 +41,16 @@ typedef struct {
 	unsigned int bufwidth, bufheight;
 	imgstate state;
 	XImage *ximg;
-	FILE *f;
-	png_structp png_ptr;
-	png_infop info_ptr;
+	int fd;
 	int numpasses;
 } Image;
 
 typedef struct {
+	char *regex;
+	char *bin;
+} Filter;
+
+typedef struct {
 	unsigned int linecount;
 	char **lines;
 	Image *img;
@@ -79,12 +87,12 @@ typedef struct {
 	const Arg arg;
 } Shortcut;
 
-static Image *pngopen(char *filename);
-static void pngfree(Image *img);
-static int pngread(Image *img);
-static int pngprepare(Image *img);
-static void pngscale(Image *img);
-static void pngdraw(Image *img);
+static Image *ffopen(char *filename);
+static void fffree(Image *img);
+static int ffread(Image *img);
+static int ffprepare(Image *img);
+static void ffscale(Image *img);
+static void ffdraw(Image *img);
 
 static void getfontsize(Slide *s, unsigned int *width, unsigned int *height);
 static void cleanup();
@@ -128,56 +136,87 @@ static void (*handler[LASTEvent])(XEvent *) = {
 	[KeyPress] = kpress,
 };
 
-Image *pngopen(char *filename)
+int
+filter(int fd, const char *cmd)
+{
+	int fds[2];
+
+	if (pipe(fds) < 0)
+		eprintf("pipe:");
+
+	switch (fork()) {
+	case -1:
+		eprintf("fork:");
+	case 0:
+		dup2(fd, 0);
+		dup2(fds[1], 1);
+		close(fds[0]);
+		close(fds[1]);
+		execlp(cmd, cmd, (char *)0);
+		eprintf("execlp %s:", cmd);
+	}
+	close(fds[1]);
+	return fds[0];
+}
+
+Image *ffopen(char *filename)
 {
-	FILE *f;
-	unsigned char buf[8];
+	unsigned char hdr[16];
+	char *bin;
+	regex_t regex;
 	Image *img;
+	size_t i;
+	int tmpfd, fd;
+
+	for (bin = NULL, i = 0; i < LEN(filters); i++) {
+		if (regcomp(&regex, filters[i].regex,
+		            REG_NOSUB | REG_EXTENDED | REG_ICASE))
+			continue;
+		if (!regexec(&regex, filename, 0, NULL, 0)) {
+			bin = filters[i].bin;
+			break;
+		}
+	}
 
-	if (!(f = fopen(filename, "rb"))) {
+	if ((fd = open(filename, O_RDONLY)) < 0) {
 		eprintf("Unable to open file %s:", filename);
 		return NULL;
 	}
 
-	if (fread(buf, 1, 8, f) != 8 || png_sig_cmp(buf, 1, 8))
-		return NULL;
+	tmpfd = fd;
+	fd = filter(fd, bin);
+	if (fd < 0)
+		eprintf("could not filter %s:", filename);
+	close(tmpfd);
 
-	img = malloc(sizeof(Image));
-	memset(img, 0, sizeof(Image));
-	if (!(img->png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL,
-					NULL, NULL))) {
-		free(img);
+	if (read(fd, hdr, 16) != 16)
 		return NULL;
-	}
-	if (!(img->info_ptr = png_create_info_struct(img->png_ptr))
-	    || setjmp(png_jmpbuf(img->png_ptr))) {
-		pngfree(img);
+
+	if (memcmp("farbfeld", hdr, 8))
 		return NULL;
-	}
 
-	img->f = f;
-	rewind(f);
-	png_init_io(img->png_ptr, f);
-	png_read_info(img->png_ptr, img->info_ptr);
-	img->bufwidth = png_get_image_width(img->png_ptr, img->info_ptr);
-	img->bufheight = png_get_image_height(img->png_ptr, img->info_ptr);
+	img = calloc(1, sizeof(Image));
+	img->fd = fd;
+	img->bufwidth = ntohl(*(uint32_t *)&hdr[8]);
+	img->bufheight = ntohl(*(uint32_t *)&hdr[12]);
 
 	return img;
 }
 
-void pngfree(Image *img)
+void fffree(Image *img)
 {
-	png_destroy_read_struct(&img->png_ptr, img->info_ptr ? &img->info_ptr : NULL, NULL);
 	free(img->buf);
 	if (img->ximg)
 		XDestroyImage(img->ximg);
 	free(img);
 }
 
-int pngread(Image *img)
+int ffread(Image *img)
 {
-	unsigned int y;
-	png_bytepp row_pointers;
+	uint32_t y, x;
+	uint16_t *row;
+	size_t rowlen, off, nbytes;
+	ssize_t r;
 
 	if (!img)
 		return 0;
@@ -187,59 +226,42 @@ int pngread(Image *img)
 
 	if (img->buf)
 		free(img->buf);
+	/* internally the image is stored in 888 format */
 	if (!(img->buf = malloc(3 * img->bufwidth * img->bufheight)))
 		return 0;
 
-	if (setjmp(png_jmpbuf(img->png_ptr))) {
-		png_destroy_read_struct(&img->png_ptr, &img->info_ptr, NULL);
+	/* scratch buffer to read row by row */
+	rowlen = img->bufwidth * 2 * strlen("RGBA");
+	row = malloc(rowlen);
+	if (!row) {
+		free(img->buf);
+		img->buf = NULL;
 		return 0;
 	}
 
-	{
-		int color_type = png_get_color_type(img->png_ptr, img->info_ptr);
-		int bit_depth = png_get_bit_depth(img->png_ptr, img->info_ptr);
-		if (color_type == PNG_COLOR_TYPE_PALETTE)
-			png_set_expand(img->png_ptr);
-		if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8)
-			png_set_expand(img->png_ptr);
-		if (png_get_valid(img->png_ptr, img->info_ptr, PNG_INFO_tRNS))
-			png_set_expand(img->png_ptr);
-		if (bit_depth == 16)
-			png_set_strip_16(img->png_ptr);
-		if (color_type == PNG_COLOR_TYPE_GRAY
-				|| color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
-			png_set_gray_to_rgb(img->png_ptr);
-
-		png_color_16 my_background = {.red = 0xff, .green = 0xff, .blue = 0xff};
-		png_color_16p image_background;
-
-		if (png_get_bKGD(img->png_ptr, img->info_ptr, &image_background))
-			png_set_background(img->png_ptr, image_background, PNG_BACKGROUND_GAMMA_FILE, 1, 1.0);
-		else
-			png_set_background(img->png_ptr, &my_background, PNG_BACKGROUND_GAMMA_SCREEN, 2, 1.0);
-
-		if (png_get_interlace_type(img->png_ptr, img->info_ptr) == PNG_INTERLACE_ADAM7)
-			img->numpasses = png_set_interlace_handling(img->png_ptr);
-		else
-			img->numpasses = 1;
-		png_read_update_info(img->png_ptr, img->info_ptr);
+	for (off = 0, y = 0; y < img->bufheight; y++) {
+		nbytes = 0;
+		while (nbytes < rowlen) {
+			r = read(img->fd, (char *)row + nbytes, rowlen - nbytes);
+			if (r < 0)
+				eprintf("read:");
+			nbytes += r;
+		}
+		for (x = 0; x < rowlen / 2; x += 4) {
+			img->buf[off++] = ntohs(row[x + 0]) / 257;
+			img->buf[off++] = ntohs(row[x + 1]) / 257;
+			img->buf[off++] = ntohs(row[x + 2]) / 257;
+		}
 	}
 
-	row_pointers = (png_bytepp)malloc(img->bufheight * sizeof(png_bytep));
-	for (y = 0; y < img->bufheight; y++)
-		row_pointers[y] = img->buf + y * img->bufwidth * 3;
-
-	png_read_image(img->png_ptr, row_pointers);
-	free(row_pointers);
-
-	png_destroy_read_struct(&img->png_ptr, &img->info_ptr, NULL);
-	fclose(img->f);
+	free(row);
+	close(img->fd);
 	img->state |= LOADED;
 
 	return 1;
 }
 
-int pngprepare(Image *img)
+int ffprepare(Image *img)
 {
 	int depth = DefaultDepth(xw.dpy, xw.scr);
 	int width = xw.uw;
@@ -276,12 +298,12 @@ int pngprepare(Image *img)
 		return 0;
 	}
 
-	pngscale(img);
+	ffscale(img);
 	img->state |= SCALED;
 	return 1;
 }
 
-void pngscale(Image *img)
+void ffscale(Image *img)
 {
 	unsigned int x, y;
 	unsigned int width = img->ximg->width;
@@ -306,7 +328,7 @@ void pngscale(Image *img)
 	}
 }
 
-void pngdraw(Image *img)
+void ffdraw(Image *img)
 {
 	int xoffset = (xw.w - img->ximg->width) / 2;
 	int yoffset = (xw.h - img->ximg->height) / 2;
@@ -364,7 +386,7 @@ void cleanup()
 				free(slides[i].lines[j]);
 			free(slides[i].lines);
 			if (slides[i].img)
-				pngfree(slides[i].img);
+				fffree(slides[i].img);
 		}
 		free(slides);
 		slides = NULL;
@@ -443,7 +465,7 @@ void load(FILE *fp)
 			/* only make image slide if first line of a slide starts with @ */
 			if (s->linecount == 0 && s->lines[0][0] == '@') {
 				memmove(s->lines[0], &s->lines[0][1], blen);
-				s->img = pngopen(s->lines[0]);
+				s->img = ffopen(s->lines[0]);
 			}
 
 			if (s->lines[s->linecount][0] == '\\')
@@ -465,10 +487,10 @@ void advance(const Arg *arg)
 			slides[idx].img->state &= ~(DRAWN | SCALED);
 		idx = new_idx;
 		xdraw();
-		if (slidecount > idx + 1 && slides[idx + 1].img && !pngread(slides[idx + 1].img))
-			die("Unable to read image %s.", slides[idx + 1].lines[0]);
-		if (0 < idx && slides[idx - 1].img && !pngread(slides[idx - 1].img))
-			die("Unable to read image %s.", slides[idx - 1].lines[0]);
+		if (slidecount > idx + 1 && slides[idx + 1].img && !ffread(slides[idx + 1].img))
+			die("Unable to read image %s", slides[idx + 1].lines[0]);
+		if (0 < idx && slides[idx - 1].img && !ffread(slides[idx - 1].img))
+			die("Unable to read image %s", slides[idx - 1].lines[0]);
 	}
 }
 
@@ -532,12 +554,12 @@ void xdraw()
 			         slides[idx].lines[i],
 			         0);
 		drw_map(d, xw.win, 0, 0, xw.w, xw.h);
-	} else if (!(im->state & LOADED) && !pngread(im)) {
-		eprintf("Unable to read image %s.", slides[idx].lines[0]);
-	} else if (!(im->state & SCALED) && !pngprepare(im)) {
-		eprintf("Unable to prepare image %s for drawing.", slides[idx].lines[0]);
+	} else if (!(im->state & LOADED) && !ffread(im)) {
+		eprintf("Unable to read image %s", slides[idx].lines[0]);
+	} else if (!(im->state & SCALED) && !ffprepare(im)) {
+		eprintf("Unable to prepare image %s for drawing", slides[idx].lines[0]);
 	} else if (!(im->state & DRAWN)) {
-		pngdraw(im);
+		ffdraw(im);
 	}
 }