Add stupid PNG support

It's stupid because:
 - it's fixed to output 128x128 png images (think preview icons)
 - it doesn't actually draw lines, it just does them as dots at the endpoints
but it does kind of work.

3 files changed, 56 insertions, 4 deletions

diff --git a/Makefile b/Makefile
index e2ebd02..091b838 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,5 @@
 CC=gcc
-CFLAGS=-Wall
+CFLAGS=-Wall -g
 
-pesconvert: pes.o svg.o
-	$(CC) -o $@ $^
+pesconvert: pes.o svg.o png.o
+	$(CC) -o $@ $^ -lpng
diff --git a/pes.c b/pes.c
index 7a9a0e9..7bd6f3e 100644
--- a/pes.c
+++ b/pes.c
@@ -321,7 +321,7 @@ int main(int argc, char **argv)
 	if (parse_pes(&region, &pes) < 0)
 		die("Unable to parse PES file\n");
 
-	output_svg(&pes);
+	output_png(&pes);
 
 	return 0;
 }
diff --git a/png.c b/png.c
new file mode 100644
index 0000000..25a5967
--- /dev/null
+++ b/png.c
@@ -0,0 +1,52 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <png.h>
+
+#include "pes.h"
+
+void output_png(struct pes *pes)
+{
+	int i;
+	int width  = pes->max_x - pes->min_x + 1;
+	int height = pes->max_y - pes->min_y + 1;
+	int outw = 128, outh = 128;
+	png_byte **rows;
+	struct pes_block *block;
+	png_structp png_ptr;
+	png_infop info_ptr;
+
+	rows = calloc(sizeof(*rows), outh);
+	for (i = 0; i < height; i++)
+		rows[i] = calloc(sizeof(png_byte)*4, outw);
+
+	block = pes->blocks;
+	while (block) {
+		struct color *c = block->color;
+		struct stitch *stitch = block->stitch;
+		int i;
+
+		for (i = 0; i < block->nr_stitches; i++, stitch++) {
+			int x = (stitch->x - pes->min_x) * outw / width;
+			int y = (stitch->y - pes->min_y) * outh / height;
+			png_byte *ptr = rows[y] + x*4;
+
+			ptr[0] = c->r;
+			ptr[1] = c->g;
+			ptr[2] = c->b;
+			ptr[3] = 255;
+		}
+		block = block->next;
+	}
+
+	png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
+	info_ptr = png_create_info_struct(png_ptr);
+	png_init_io(png_ptr, stdout);
+	png_set_IHDR(png_ptr, info_ptr, outw, outh,
+		8, PNG_COLOR_TYPE_RGBA, PNG_INTERLACE_NONE,
+		PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
+
+	png_write_info(png_ptr, info_ptr);
+
+	png_write_image(png_ptr, rows);
+	png_write_end(png_ptr, NULL);
+}