Simplified example of using libnsgif.

svn path=/branches/dynis/libnsgif/; revision=4413

3 files changed, 225 insertions, 1 deletions

diff --git a/Makefile b/Makefile
index 3955628..1ee8de8 100644
--- a/Makefile
+++ b/Makefile
@@ -23,7 +23,7 @@ DESTDIR ?=
 
 .PHONY: all clean docs install uninstall
 
-all: libnsgif.a
+all: libnsgif.a bin/decode_gif
 	
 libnsgif.a: libnsgif.o libnsgif.pc
 	${AR} ${ARFLAGS} libnsgif.a libnsgif.o
@@ -34,6 +34,9 @@ libnsgif.pc: libnsgif.pc.in
 %.o: %.c
 	${CC} -c ${CFLAGS} -o $@ $<
 
+bin/decode_gif: examples/decode_gif.c libnsgif.a
+	${CC} ${CFLAGS} -o $@ $< libnsgif.a
+
 docs:
 	${DOXYGEN}
 
diff --git a/examples/decode_gif.c b/examples/decode_gif.c
new file mode 100644
index 0000000..47cbc97
--- /dev/null
+++ b/examples/decode_gif.c
@@ -0,0 +1,221 @@
+/*
+ * Copyright 2008 Sean Fox <dyntryx@gmail.com>
+ * Copyright 2008 James Bursa <james@netsurf-browser.org>
+ *
+ * This file is part of NetSurf, http://www.netsurf-browser.org/
+ *
+ * NetSurf is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * NetSurf is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <assert.h>
+#include <errno.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <libnsgif.h>
+
+char *load_file(const char *path, size_t *data_size);
+void die(const char *context, int code);
+void *bitmap_create(int width, int height);
+void bitmap_set_opaque(void *bitmap, bool opaque);
+bool bitmap_test_opaque(void *bitmap);
+char *bitmap_get_buffer(void *bitmap);
+void bitmap_destroy(void *bitmap);
+void bitmap_modified(void *bitmap);
+
+
+gif_bitmap_callback_vt bitmap_callbacks = {
+	bitmap_create,
+	bitmap_destroy,
+	bitmap_get_buffer,
+	bitmap_set_opaque,
+	bitmap_test_opaque,
+	bitmap_modified
+};
+
+
+int main(int argc, char *argv[])
+{
+	struct gif_animation gif;
+	size_t size;
+	int code;
+	unsigned int i;
+
+	if (argc != 2) {
+		fprintf(stderr, "Usage: %s image.gif\n", argv[0]);
+		return 1;
+	}
+
+	/* load file into memory */
+	char *data = load_file(argv[1], &size);
+
+	/* initialise gif_animation structure */
+	gif.buffer_size = size;
+	gif.gif_data = (unsigned char *) data;
+	gif.buffer_position = 0;
+
+	/* begin decoding */
+	do {
+		code = gif_initialise(&gif, &bitmap_callbacks);
+		if (code != 0 && code != 1)
+			die("gif_initialise", code);
+	} while (code != 1);
+
+	printf("P3\n");
+	printf("# %s\n", argv[1]);
+	printf("# width                %u \n", gif.width);
+	printf("# height               %u \n", gif.height);
+	printf("# frame_count          %u \n", gif.frame_count);
+	printf("# frame_count_partial  %u \n", gif.frame_count_partial);
+	printf("# background_colour    %x \n", gif.background_colour);
+	printf("# loop_count           %u \n", gif.loop_count);
+	printf("%u %u 256\n", gif.width, gif.height * gif.frame_count);
+
+	/* decode the frames */
+	for (i = 0; i != gif.frame_count; i++) {
+		unsigned int row, col;
+		char *image;
+
+		code = gif_decode_frame(&gif, i, &bitmap_callbacks);
+		if (code != 0)
+			die("gif_decode_frame", code);
+
+		printf("# frame %u:\n", i);
+		image = (char *) gif.frame_image;
+		for (row = 0; row != gif.height; row++) {
+			for (col = 0; col != gif.width; col++) {
+				size_t z = (row * gif.width + col) * 4;
+				printf("%u %u %u ",
+					(unsigned char) image[z],
+					(unsigned char) image[z + 1],
+					(unsigned char) image[z + 2]);
+			}
+			printf("\n");
+		}
+	}
+
+	return 0;
+}
+
+
+char *load_file(const char *path, size_t *data_size)
+{
+	FILE *fd;
+	struct stat sb;
+	char *buffer;
+	size_t size;
+	size_t n;
+
+	fd = fopen(path, "rb");
+	if (!fd) {
+		perror(path);
+		exit(EXIT_FAILURE);
+	}
+
+	if (stat(path, &sb)) {
+		perror(path);
+		exit(EXIT_FAILURE);
+	}
+	size = sb.st_size;
+
+	buffer = malloc(size);
+	if (!buffer) {
+		fprintf(stderr, "Unable to allocate %lld bytes\n",
+				(long long) size);
+		exit(EXIT_FAILURE);
+	}
+
+	n = fread(buffer, 1, size, fd);
+	if (n != size) {
+		perror(path);
+		exit(EXIT_FAILURE);
+	}
+
+	fclose(fd);
+
+	*data_size = size;
+	return buffer;
+}
+
+
+void die(const char *context, int code)
+{
+	fprintf(stderr, "%s failed: ", context);
+	switch (code)
+	{
+	case GIF_INSUFFICIENT_FRAME_DATA:
+		fprintf(stderr, "GIF_INSUFFICIENT_FRAME_DATA");
+		break;
+	case GIF_FRAME_DATA_ERROR:
+		fprintf(stderr, "GIF_FRAME_DATA_ERROR");
+		break;
+	case GIF_INSUFFICIENT_DATA:
+		fprintf(stderr, "GIF_INSUFFICIENT_DATA");
+		break;
+	case GIF_DATA_ERROR:
+		fprintf(stderr, "GIF_DATA_ERROR");
+		break;
+	case GIF_INSUFFICIENT_MEMORY:
+		fprintf(stderr, "GIF_INSUFFICIENT_MEMORY");
+		break;
+	default:
+		fprintf(stderr, "unknown code %i", code);
+		break;
+	}
+	fprintf(stderr, "\n");
+	exit(EXIT_FAILURE);
+}
+
+
+void *bitmap_create(int width, int height)
+{
+	return calloc(width * height, 4);
+}
+
+
+void bitmap_set_opaque(void *bitmap, bool opaque)
+{
+	(void) opaque;  /* unused */
+	assert(bitmap);
+}
+
+
+bool bitmap_test_opaque(void *bitmap)
+{
+	assert(bitmap);
+	return false;
+}
+
+
+char *bitmap_get_buffer(void *bitmap)
+{
+	assert(bitmap);
+	return bitmap;
+}
+
+
+void bitmap_destroy(void *bitmap)
+{
+	assert(bitmap);
+	free(bitmap);
+}
+
+
+void bitmap_modified(void *bitmap)
+{
+	assert(bitmap);
+	return;
+}
+
diff --git a/examples/waves.gif b/examples/waves.gif
new file mode 100644
index 0000000..46a7da3
--- /dev/null
+++ b/examples/waves.gif