X-Git-Url: http://git.tdb.fi/?p=ttf2png.git;a=blobdiff_plain;f=ttf2png.c;h=b8f48a816c712612049dd21b0ee2b41fc3e83c16;hp=97be0f1fc6ef4934f991bfc323c5b80a02eecd93;hb=3722474e4fb8de564a4952e4cff24b926bc82743;hpb=4291a684d86dbd80880503d12e4a1f8db3a41579

diff --git a/ttf2png.c b/ttf2png.c
index 97be0f1..b8f48a8 100644
--- a/ttf2png.c
+++ b/ttf2png.c
@@ -1,6 +1,6 @@
 /*
 ttf2png - True Type Font to PNG converter
-Copyright (c) 2004 Mikkosoft Productions
+Copyright (c) 2004-2008 Mikko Rasa
 
 This program is free software; you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
@@ -18,37 +18,74 @@ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
 
 #include <stdio.h>
+#include <ctype.h>
 #include <unistd.h>
 #include <getopt.h>
 #include <png.h>
 #include <ft2build.h>
 #include FT_FREETYPE_H
 
+typedef struct sImage
+{
+	unsigned w, h;
+	char     *data;
+} Image;
+
+typedef struct sGlyph
+{
+	unsigned code;
+	Image    image;
+	unsigned x, y;
+	int      offset_x;
+	int      offset_y;
+	int      advance;
+} Glyph;
+
+typedef struct sFont
+{
+	unsigned size;
+	int      ascent;
+	int      descent;
+	unsigned n_glyphs;
+	Glyph    *glyphs;
+	Image    image;
+} Font;
+
+unsigned round_to_pot(unsigned);
 void usage();
-int save_png(char *, char *, int, int);
+void init_font(Font *, FT_Face, unsigned, unsigned, int);
+void render_grid(Font *, unsigned, unsigned, unsigned, int);
+void render_packed(Font *);
+int save_defs(const char *, const Font *);
+int save_png(const char *, const Image *, char);
+
+char verbose = 0;
 
 int main(int argc, char **argv)
 {
-	FT_Library	freetype;
-	FT_Face		face;
-	int	err;
-	int	o;
-	int	begin=0;
-	int	end=255;
-	char	*fn;
-	int	size=10;
-	int	cpl=16;
-	int	w,h;
-	int	i;
-	char	*data;
-	int	ch,cw;
-	int	cell=16;
-	int	ascent;
-	char	*out="font.png";
-	char	verbose=0;
-	const char	*name;
-	char	autohinter=0;
-	int	count;
+	char *fn;
+	int  begin = 0;
+	int  end = 255;
+	int  size = 10;
+	int  cpl = 0;
+	int  cellw = 0;
+	int  cellh = 0;
+	char autohinter = 0;
+	char seq = 0;
+	char alpha = 0;
+	char invert = 0;
+	char pack = 0;
+
+	FT_Library freetype;
+	FT_Face    face;
+
+	int  err;
+	int  i;
+
+	char *out_fn = "font.png";
+	char *def_fn = NULL;
+
+	Font font;
 
 	if(argc<2)
 	{
@@ -56,186 +93,585 @@ int main(int argc, char **argv)
 		return 1;
 	}
 
-	while((o=getopt(argc,argv,"r:s:l:c:o:avh?"))!=-1)
+	while((i = getopt(argc, argv, "r:s:l:c:o:atvh?ed:pi")) != -1)
 	{
-		char	*ptr;
-		int	temp;
-		switch(o)
+		char *ptr;
+		int  temp;
+		switch(i)
 		{
 		case 'r':
-			if(!isdigit(optarg[0])) temp=-1;
-			else
+			if(!strcmp(optarg, "all"))
 			{
-				temp=strtol(optarg,&ptr,0);
-				if(ptr[0]!=',' || !isdigit(ptr[1])) temp=-1;
+				begin = 0;
+				end = 0x110000;
 			}
-			if(temp<0)
-				printf("Not a valid range: %s\n",optarg);
 			else
 			{
-				begin=temp;
-				end=strtol(ptr+1,NULL,0);
+				if(!isdigit(optarg[0]))
+					temp = -1;
+				else
+				{
+					temp = strtol(optarg, &ptr, 0);
+					if(ptr[0]!=',' || !isdigit(ptr[1]))
+						temp = -1;
+				}
+				if(temp<0)
+				{
+					printf("Not a valid range: %s\n", optarg);
+					exit(1);
+				}
+				else
+				{
+					begin = temp;
+					end = strtol(ptr+1, NULL, 0);
+				}
 			}
 			break;
 		case 's':
-			size=strtol(optarg,NULL,0);
+			size = strtol(optarg, NULL, 0);
 			break;
 		case 'l':
-			cpl=strtol(optarg,NULL,0);
+			cpl = strtol(optarg, NULL, 0);
 			break;
 		case 'c':
-			cell=strtol(optarg,NULL,0);
+			if(!strcmp(optarg, "auto"))
+			{
+				cellw = 0;
+				cellh = 0;
+			}
+			else if(!strcmp(optarg, "autorect"))
+			{
+				cellw = 0;
+				cellh = 1;
+			}
+			else
+			{
+				cellw = strtol(optarg, &ptr, 0);
+				if(ptr[0]=='x' && isdigit(ptr[1]))
+					cellh = strtol(ptr+1, NULL, 0);
+			}
 			break;
 		case 'o':
-			out=optarg;
+			out_fn = optarg;
 			break;
 		case 'a':
-			autohinter=1;
+			autohinter = 1;
+			break;
+		case 't':
+			alpha = 1;
 			break;
 		case 'v':
-			verbose=1;
+			++verbose;
 			break;
 		case 'h':
 		case '?':
 			usage();
 			return 0;
+		case 'e':
+			seq = 1;
+			break;
+		case 'd':
+			def_fn = optarg;
+			break;
+		case 'p':
+			pack = 1;
+			break;
+		case 'i':
+			invert = 1;
+			break;
 		}
 	}
+	if(!strcmp(out_fn, "-"))
+		verbose = 0;
 
-	if(optind>=argc)
+	if(optind!=argc-1)
 	{
 		usage();
 		return 1;
 	}
-	fn=argv[optind];
 
-	err=FT_Init_FreeType(&freetype);
+	fn = argv[optind];
+
+	err = FT_Init_FreeType(&freetype);
 	if(err)
 	{
-		fprintf(stderr,"Couldn't initialize FreeType library\n");
+		fprintf(stderr, "Couldn't initialize FreeType library\n");
 		return 1;
 	}
 
-	err=FT_New_Face(freetype,fn,0,&face);
+	err = FT_New_Face(freetype, fn, 0, &face);
 	if(err)
 	{
-		fprintf(stderr,"Couldn't load font file\n");
+		fprintf(stderr, "Couldn't load font file\n");
 		if(err==FT_Err_Unknown_File_Format)
-			fprintf(stderr,"Unknown file format\n");
+			fprintf(stderr, "Unknown file format\n");
 		return 1;
 	}
 
-	name=FT_Get_Postscript_Name(face);
-	if(verbose) printf("Font name: %s\n",name);
+	if(verbose)
+	{
+		const char *name = FT_Get_Postscript_Name(face);
+		printf("Font name: %s\n", name);
+		printf("Glyphs:    %ld\n", face->num_glyphs);
+	}
 
-	err=FT_Set_Pixel_Sizes(face,0,size);
+	err = FT_Set_Pixel_Sizes(face, 0, size);
 	if(err)
 	{
-		fprintf(stderr,"Couldn't set size\n");
+		fprintf(stderr, "Couldn't set size\n");
 		return 1;
 	}
-	ascent=face->size->metrics.ascender/64;
-	ch=(face->size->metrics.ascender-face->size->metrics.descender)/64;
-	cw=face->size->metrics.max_advance/64;
-	if(verbose)
+
+	font.size = size;
+	init_font(&font, face, begin, end, autohinter);
+	if(pack)
+		render_packed(&font);
+	else
+		render_grid(&font, cellw, cellh, cpl, seq);
+	if(invert)
 	{
-		printf("Ascent %d\n",ascent);
-		printf("Descent %ld\n",face->size->metrics.descender/64);
-		printf("Height %d\n",ch);
-		printf("Width %d\n",cw);
-	}
-	if(ch>cell || cw>cell) fprintf(stderr,"ttf2png: Warning: character size exceeds cell size\n");
-
-	w=cpl*cell;
-	h=(end-begin+cpl-1)/cpl*cell;
-	data=(char *)malloc(w*h);
-	memset(data,255,w*h);
-
-	count=0;
-	for(i=begin;i<=end;++i)
-	{
-		int			glyph=FT_Get_Char_Index(face,i);
-		FT_Bitmap	*bmp=&face->glyph->bitmap;
-		int			x,y;
-		int			cx=(i%cpl)*cell+(cell-cw)/2;
-		int			cy=(i/cpl)*cell;
-		int			flags=0;
-		if(!glyph) continue;
-		fflush(stdout);
-		if(autohinter) flags|=FT_LOAD_FORCE_AUTOHINT;
-		FT_Load_Glyph(face,glyph,flags);
-		FT_Render_Glyph(face->glyph,FT_RENDER_MODE_NORMAL);
-		cx+=face->glyph->bitmap_left;
-		cy+=ascent-face->glyph->bitmap_top;
-		for(y=0;y<bmp->rows;++y) for(x=0;x<bmp->width;++x)
-		{
-			if(cx+x<0 || cx+x>=w || cy+y<0 || cy+y>=h) continue;
-			if(bmp->pitch>0)
-				data[cx+x+(cy+y)*w]=255-bmp->buffer[x+y*bmp->pitch];
-		}
-		++count;
+		for(i=0; i<font.image.w*font.image.h; ++i)
+			font.image.data[i] = 255-font.image.data[i];
 	}
+	save_png(out_fn, &font.image, alpha);
+	if(def_fn)
+		save_defs(def_fn, &font);
 
-	save_png(out,data,w,h);
+	for(i=0; i<font.n_glyphs; ++i)
+		free(font.glyphs[i].image.data);
+	free(font.glyphs);
+	free(font.image.data);
 
-	if(verbose) printf("Converted %d glyphs\n",count);
+	FT_Done_Face(face);
+	FT_Done_FreeType(freetype);
 
 	return 0;
 }
 
+unsigned round_to_pot(unsigned n)
+{
+	n -= 1;
+	n |= n>>1;
+	n |= n>>2;
+	n |= n>>4;
+	n |= n>>8;
+	n |= n>>16;
+
+	return n+1;
+}
+
 void usage()
 {
 	printf("ttf2png - True Type Font to PNG converter\n"
-		"Copyright (c) 2004 Mikkosoft Productions\n"
+		"Copyright (c) 2004-2008  Mikko Rasa, Mikkosoft Productions\n"
 		"Distributed under the GNU General Public License\n\n"
 		"Usage: ttf2png [options] <TTF file>\n\n"
 		"Accepted options (default values in [brackets])\n"
-		"  -r  Range of characters to convert in the format low,high [0,255]\n"
+		"  -r  Range of characters to convert [0,255]\n"
 		"  -s  Font size to use, in pixels [10]\n"
-		"  -l  Number of characters to put in one line [16]\n"
-		"  -c  Character cell size, in pixels [16]\n"
-		"  -o  Output file name [font.png]\n"
+		"  -l  Number of characters to put in one line [auto]\n"
+		"  -c  Character cell size, in pixels [auto]\n"
+		"  -o  Output file name (or - for stdout) [font.png]\n"
 		"  -a  Force autohinter\n"
-		"  -v  Enable verbose mode\n"
+		"  -t  Render glyphs to alpha channel\n"
+		"  -i  Invert colors of the glyphs\n"
+		"  -v  Increase the level of verbosity\n"
+		"  -e  Use cells in sequence, without gaps\n"
+		"  -p  Pack the glyphs tightly instead of in a grid\n"
+		"  -d  File name for writing glyph definitions\n"
 		"  -h  Print this message\n");
 }
 
-int save_png(char *fn, char *data, int w, int h)
+void init_font(Font *font, FT_Face face, unsigned first, unsigned last, int autohinter)
+{
+	unsigned i;
+	unsigned size = 0;
+
+	font->ascent = (face->size->metrics.ascender+63)>>6;
+	font->descent = (face->size->metrics.descender+63)>>6;
+
+	if(verbose>=1)
+	{
+		printf("Ascent:    %d\n", font->ascent);
+		printf("Descent:   %d\n", font->descent);
+	}
+
+	font->n_glyphs = 0;
+	font->glyphs = NULL;
+	for(i=first; i<=last; ++i)
+	{
+		unsigned  n;
+		FT_Bitmap *bmp = &face->glyph->bitmap;
+		int       x, y;
+		int       flags = 0;
+		Glyph     *glyph;
+
+		n = FT_Get_Char_Index(face, i);
+		if(!n)
+			continue;
+
+		if(autohinter)
+			flags |= FT_LOAD_FORCE_AUTOHINT;
+		FT_Load_Glyph(face, n, flags);
+		FT_Render_Glyph(face->glyph, FT_RENDER_MODE_NORMAL);
+
+		if(verbose>=2)
+			printf("  Char %u: glyph %u, size %dx%d\n", i, n, bmp->width, bmp->rows);
+
+		if(bmp->pixel_mode!=FT_PIXEL_MODE_GRAY)
+		{
+			fprintf(stderr, "Warning: Glyph %u skipped, not grayscale\n", n);
+			continue;
+		}
+
+		if(font->n_glyphs>=size)
+		{
+			size += 16;
+			font->glyphs = (Glyph *)realloc(font->glyphs, size*sizeof(Glyph));
+		}
+
+		glyph = &font->glyphs[font->n_glyphs++];
+		glyph->code = i;
+		glyph->image.w = bmp->width;
+		glyph->image.h = bmp->rows;
+		glyph->image.data = (char *)malloc(bmp->width*bmp->rows);
+		glyph->offset_x = face->glyph->bitmap_left;
+		glyph->offset_y = face->glyph->bitmap_top-bmp->rows;
+		glyph->advance = (int)(face->glyph->advance.x+32)/64;
+
+		/* Copy the glyph image since FreeType uses a global buffer, which would
+		be overwritten by the next glyph.  Negative pitch means the scanlines
+		start from the bottom */
+		if(bmp->pitch<0)
+		{
+			for(y=0; y<bmp->rows; ++y) for(x=0; x<bmp->width; ++x)
+				glyph->image.data[x+(glyph->image.h-1-y)*glyph->image.w] = bmp->buffer[x-y*bmp->pitch];
+		}
+		else
+		{
+			for(y=0; y<bmp->rows; ++y) for(x=0; x<bmp->width; ++x)
+				glyph->image.data[x+y*glyph->image.w] = bmp->buffer[x+y*bmp->pitch];
+		}
+	}
+
+	if(verbose>=1)
+		printf("Loaded %u glyphs\n", font->n_glyphs);
+}
+
+void render_grid(Font *font, unsigned cellw, unsigned cellh, unsigned cpl, int seq)
+{
+	unsigned i;
+	int      top = 0, bot = 0;
+	unsigned first, last;
+	unsigned maxw = 0, maxh = 0;
+
+	/* Find extremes of the glyph images. */
+	for(i=0; i<font->n_glyphs; ++i)
+	{
+		int y;
+
+		y = font->glyphs[i].offset_y+font->glyphs[i].image.h;
+		if(y>top)
+			top = y;
+		if(font->glyphs[i].offset_y<bot)
+			bot = font->glyphs[i].offset_y;
+		if(font->glyphs[i].image.w>maxw)
+			maxw = font->glyphs[i].image.w;
+		if(font->glyphs[i].image.h>maxh)
+			maxh = font->glyphs[i].image.h;
+	}
+
+	if(cellw==0)
+	{
+		/* Establish a large enough cell to hold all glyphs in the range. */
+		int square = (cellh==cellw);
+		cellw = maxw;
+		cellh = top-bot;
+		if(square)
+		{
+			if(cellh>cellw)
+				cellw = cellh;
+			else
+				cellh = cellw;
+		}
+	}
+
+	if(verbose>=1)
+	{
+		printf("Max size:  %u x %u\n", maxw, maxh);
+		printf("Y range:   [%d %d]\n", bot, top);
+		printf("Cell size: %u x %u\n", cellw, cellh);
+		if(maxw>cellw || top-bot>cellh)
+			fprintf(stderr, "Warning: character size exceeds cell size\n");
+	}
+
+	if(cpl==0)
+	{
+		/* Determine number of characters per line, trying to fit all the glyphs
+		in a square image. */
+		for(i=1;; i<<=1)
+		{
+			cpl = i/cellw;
+			if(cpl>0 && font->n_glyphs/cpl*cellh<=cpl*cellw)
+				break;
+		}
+	}
+
+	first = font->glyphs[0].code;
+	if(!seq)
+		first -= first%cpl;
+	last = font->glyphs[font->n_glyphs-1].code;
+
+	font->image.w = round_to_pot(cpl*cellw);
+	font->image.h = round_to_pot((last-first+cpl)/cpl*cellh);
+
+	font->image.data = (char *)malloc(font->image.w*font->image.h);
+	memset(font->image.data, 255, font->image.w*font->image.h);
+
+	for(i=0; i<font->n_glyphs; ++i)
+	{
+		Glyph    *glyph;
+		int      ci, cx, cy;
+		unsigned x, y;
+
+		glyph = &font->glyphs[i];
+
+		if(seq)
+			ci = i;
+		else
+			ci = glyph->code-first;
+
+		cx = (ci%cpl)*cellw;
+		cy = (ci/cpl)*cellh;
+
+		if(cellw>glyph->image.w)
+			cx += (cellw-glyph->image.w)/2;
+		cy += top-glyph->offset_y-glyph->image.h;
+
+		glyph->x = cx;
+		glyph->y = cy;
+
+		for(y=0; y<glyph->image.h; ++y) for(x=0; x<glyph->image.w; ++x)
+		{
+			if(cx+x<0 || cx+x>=font->image.w || cy+y<0 || cy+y>=font->image.h)
+				continue;
+			font->image.data[cx+x+(cy+y)*font->image.w] = 255-glyph->image.data[x+y*glyph->image.w];
+		}
+	}
+}
+
+void render_packed(Font *font)
+{
+	unsigned i;
+	unsigned area = 0;
+	char     *used_glyphs;
+	unsigned *used_pixels;
+	unsigned cx = 0, cy;
+	unsigned used_h = 0;
+
+	/* Compute the total area occupied by glyphs and padding. */
+	for(i=0; i<font->n_glyphs; ++i)
+		area += (font->glyphs[i].image.w+1)*(font->glyphs[i].image.h+1);
+
+	/* Find an image size that's no higher than wide, allowing for some
+	imperfections in the packing. */
+	for(font->image.w=1;; font->image.w<<=1)
+	{
+		font->image.h = (area*5/4)/font->image.w;
+		if(font->image.h<=font->image.w)
+			break;
+	}
+	font->image.h = round_to_pot(font->image.h);
+
+	/* Allocate arrays for storing the image and keeping track of used pixels and
+	glyphs.  Since glyphs are rectangular and the image is filled starting from
+	the top, it's enough to track the number of used pixels at the top of each
+	column. */
+	font->image.data = (char *)malloc(font->image.w*font->image.h);
+	memset(font->image.data, 255, font->image.w*font->image.h);
+	used_pixels = (unsigned *)malloc(font->image.w*sizeof(unsigned));
+	memset(used_pixels, 0, font->image.w*sizeof(unsigned));
+	used_glyphs = (char *)malloc(font->n_glyphs);
+	memset(used_glyphs, 0, font->n_glyphs);
+
+	for(cy=0; cy<font->image.h;)
+	{
+		unsigned w;
+		unsigned x, y;
+		Glyph    *glyph = NULL;
+		unsigned best_score = 0;
+		unsigned target_h = 0;
+
+		/* Find the leftmost free pixel on this row.    Also record the lowest extent of glyphs
+		to the left of the free position. */
+		for(; (cx<font->image.w && used_pixels[cx]>cy); ++cx)
+			if(used_pixels[cx]-cy-1>target_h)
+				target_h = used_pixels[cx]-cy-1;
+
+		if(cx>=font->image.w)
+		{
+			cx = 0;
+			++cy;
+			continue;
+		}
+
+		/* Count the free pixel at this position. */
+		for(w=0; (cx+w<font->image.w && used_pixels[cx+w]<=cy); ++w) ;
+
+		/* Find a suitable glyph to put here. */
+		for(i=0; i<font->n_glyphs; ++i)
+		{
+			Glyph *g;
+
+			g = &font->glyphs[i];
+			if(!used_glyphs[i] && g->image.w<=w)
+			{
+				unsigned score;
+
+				/* Prefer glyphs that would reach exactly as low as the ones left
+				of here.  This aims to create a straight edge at the bottom for
+				lining up further glyphs. */
+				score = g->image.h+1;
+				if(g->image.h==target_h)
+					score *= g->image.w;
+				else
+					score += g->image.w;
+
+				if(score>best_score)
+				{
+					glyph = g;
+					best_score = score;
+				}
+			}
+		}
+
+		if(!glyph)
+		{
+			cx += w;
+			continue;
+		}
+
+		used_glyphs[glyph-font->glyphs] = 1;
+		glyph->x = cx;
+		glyph->y = cy;
+
+		for(y=0; y<glyph->image.h; ++y) for(x=0; x<glyph->image.w; ++x)
+		{
+			if(cx+x<0 || cx+x>=font->image.w || cy+y<0 || cy+y>=font->image.h)
+				continue;
+			font->image.data[cx+x+(cy+y)*font->image.w] = 255-glyph->image.data[x+y*glyph->image.w];
+		}
+		for(x=0; x<glyph->image.w+2; ++x)
+		{
+			if(cx+x<1 || cx+x>font->image.w)
+				continue;
+			if(used_pixels[cx+x-1]<cy+glyph->image.h+1)
+				used_pixels[cx+x-1] = cy+glyph->image.h+1;
+		}
+
+		if(cy+glyph->image.h>used_h)
+			used_h = cy+glyph->image.h;
+	}
+
+	/* Trim the image to the actually used size, in case the original estimate
+	was too pessimistic. */
+	font->image.h = round_to_pot(used_h);
+}
+
+int save_defs(const char *fn, const Font *font)
 {
-	FILE			*out;
-	png_struct	*pngs;
-	png_info		*pngi;
-	png_byte		*rows[h];
-	int			i;
+	FILE     *out;
+	unsigned i;
 
-	out=fopen(fn,"wb");
+	out = fopen(fn, "w");
 	if(!out)
 	{
-		fprintf(stderr,"Couldn't open output file\n");
+		fprintf(stderr, "Couldn't open %s\n",fn);
 		return -1;
 	}
 
-	pngs=png_create_write_struct(PNG_LIBPNG_VER_STRING,NULL,NULL,NULL);
+	fprintf(out, "# Image/font info:\n");
+	fprintf(out, "# width height size ascent descent\n");
+	fprintf(out, "%d %d %d %d %d\n", font->image.w, font->image.h, font->size, font->ascent, font->descent);
+	fprintf(out, "\n# Glyph info:\n");
+	fprintf(out, "# code x y width height offset_x offset_y advance\n");
+	for(i=0; i<font->n_glyphs; ++i)
+	{
+		const Glyph *g = &font->glyphs[i];
+		fprintf(out, "%u %u %u %u %u %d %d %d\n", g->code, g->x, g->y, g->image.w, g->image.h, g->offset_x, g->offset_y, g->advance);
+	}
+
+	fclose(out);
+
+	return 0;
+}
+
+int save_png(const char *fn, const Image *image, char alpha)
+{
+	FILE       *out;
+	png_struct *pngs;
+	png_info   *pngi;
+	png_byte   *rows[image->h];
+	int        i;
+	png_byte   *data2;
+	int        color;
+
+	if(!strcmp(fn, "-"))
+		out = stdout;
+	else
+	{
+		out = fopen(fn, "wb");
+		if(!out)
+		{
+			fprintf(stderr, "Couldn't open %s\n",fn);
+			return -1;
+		}
+	}
+
+	pngs = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
 	if(!pngs)
 	{
-		fprintf(stderr,"Error writing PNG file\n");
+		fprintf(stderr, "Error writing PNG file\n");
 		return -1;
 	}
-	pngi=png_create_info_struct(pngs);
+	pngi = png_create_info_struct(pngs);
 	if(!pngi)
 	{
-		png_destroy_write_struct(&pngs,NULL);
-		fprintf(stderr,"Error writing PNG file\n");
+		png_destroy_write_struct(&pngs, NULL);
+		fprintf(stderr, "Error writing PNG file\n");
 		return -1;
 	}
 
-	png_init_io(pngs,out);
-	png_set_IHDR(pngs,pngi,w,h,8,PNG_COLOR_TYPE_GRAY,PNG_INTERLACE_NONE,PNG_COMPRESSION_TYPE_DEFAULT,PNG_FILTER_TYPE_DEFAULT);
-	for(i=0;i<h;++i)
-		rows[i]=(png_byte *)(data+i*w);
-	png_set_rows(pngs,pngi,rows);
-	png_write_png(pngs,pngi,PNG_TRANSFORM_IDENTITY,NULL);
-	png_destroy_write_struct(&pngs,&pngi);
+	png_init_io(pngs, out);
+	if(alpha)
+	{
+		data2 = (png_byte *)malloc(image->w*image->h*2);
+		for(i=0; i<image->w*image->h; ++i)
+		{
+			data2[i*2] = 255;
+			data2[i*2+1] = 255-image->data[i];
+		}
+		for(i=0; i<image->h; ++i)
+			rows[i] = (png_byte *)(data2+i*image->w*2);
+		color = PNG_COLOR_TYPE_GRAY_ALPHA;
+	}
+	else
+	{
+		for(i=0; i<image->h; ++i)
+			rows[i] = (png_byte *)(image->data+i*image->w);
+		color = PNG_COLOR_TYPE_GRAY;
+	}
+	png_set_IHDR(pngs, pngi, image->w, image->h, 8, color, PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
+	png_set_rows(pngs, pngi, rows);
+	png_write_png(pngs, pngi, PNG_TRANSFORM_IDENTITY, NULL);
+	png_destroy_write_struct(&pngs, &pngi);
+	if(alpha)
+		free(data2);
+
+	if(verbose)
+		printf("Saved %dx%d PNG image to %s\n", image->w, image->h, fn);
+
+	fclose(out);
 
 	return 0;
 }