Add a basic .png loader using libpng

If you use that, you also need to link on libpng.

Only quickly tested for now, there are some weird things with
libpng that I might not have gotten right, some comments are
welcome.


Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

2 files changed, 214 insertions, 0 deletions

diff --git a/twin_png.c b/twin_png.c
new file mode 100644
index 0000000..afe492a
--- /dev/null
+++ b/twin_png.c
@@ -0,0 +1,184 @@
+/*
+ * Libpng interface to twin
+ *
+ * Copyright 2006 Benjamin Herrenschmidt <benh@kernel.crashing.org>
+ *
+ * This Library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This Library 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
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with the Twin Library; see the file COPYING.  If not,
+ * write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include <stdlib.h>
+#include <unistd.h>
+#include <signal.h>
+#include <string.h>
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+#include "twin_png.h"
+
+#if 0
+#include <stdio.h>
+#define DEBUG(fmt...)	printf(fmt)
+#else
+#define DEBUG(fmt...)
+#endif
+
+typedef struct  _twin_png_priv {
+	int	fd;
+} twin_png_priv_t;
+
+static void twin_png_read_fn(png_structp png, png_bytep data, png_size_t size)
+{
+	twin_png_priv_t	*priv = png_get_io_ptr(png);
+	int n;
+
+	n = read(priv->fd, data, size);
+	DEBUG(" twin_png_read_fn size=%d, got=%d\n", size, n);
+	if (n < size)
+		png_error(png, "end of file !\n");	
+}
+
+twin_pixmap_t *twin_png_to_pixmap(const char *filepath, twin_format_t fmt)
+{
+	uint8_t		signature[8];
+	int		fd, i, rb = 0;
+	size_t		n;
+	png_structp	png = NULL;
+	png_infop	info = NULL;
+	twin_pixmap_t	*pix = NULL;
+	twin_png_priv_t priv;
+	png_uint_32	width, height;
+	int		depth, ctype, interlace;
+	png_bytep	*rowp = NULL;
+
+	DEBUG("png read for %s, format=%d\n", filepath, fmt);
+
+	fd = open(filepath, O_RDONLY);
+	if (fd < 0)
+		goto fail;
+
+	DEBUG("checking signature...\n");
+
+	n = read(fd, signature, 8);
+	if (png_sig_cmp(signature, 0, n) != 0)
+		goto fail_close;
+
+	DEBUG("creating libpng structures...\n");
+
+	png = png_create_read_struct(PNG_LIBPNG_VER_STRING,
+				     NULL, NULL, NULL);
+	if (png == NULL)
+		goto fail_close;
+
+	info = png_create_info_struct(png);
+	if (info == NULL)
+		goto fail_free;
+	    
+	if (setjmp(png_jmpbuf(png))) {
+		DEBUG("* error callback *\n");
+		if (pix)
+			twin_pixmap_destroy(pix);
+		pix = NULL;
+		goto fail_free;
+	}
+	priv.fd = fd;
+	png_set_read_fn(png, &priv, twin_png_read_fn);
+
+	png_set_sig_bytes(png, n);
+
+	DEBUG("reading picture infos ...\n");
+	png_read_info(png, info);
+	png_get_IHDR(png, info, &width, &height, &depth, &ctype, &interlace,
+		     int_p_NULL, int_p_NULL);
+	
+	DEBUG(" 1- size/depth/ctype/int = %ldx%ld/%d/%d/%d\n",
+	      width, height, depth, ctype, interlace);
+
+	if (depth == 16)
+		png_set_strip_16(png);
+	if (ctype == PNG_COLOR_TYPE_PALETTE)
+		png_set_palette_to_rgb(png);
+	if (ctype == PNG_COLOR_TYPE_GRAY && depth < 8)
+		png_set_gray_1_2_4_to_8(png);
+	if (png_get_valid(png, info, PNG_INFO_tRNS))
+		png_set_tRNS_to_alpha(png);
+
+	png_get_IHDR(png, info, &width, &height, &depth, &ctype, &interlace,
+		     int_p_NULL, int_p_NULL);
+
+	DEBUG(" 2- size/depth/ctype/int = %ldx%ld/%d/%d/%d\n",
+	      width, height, depth, ctype, interlace);
+
+	switch(fmt) {
+	case TWIN_A8:
+		if (ctype != PNG_COLOR_TYPE_GRAY ||
+		    depth != 8)
+			goto fail_free;
+		rb = width;
+		break;
+	case TWIN_RGB16:
+		/* unsupported for now */
+		goto fail_free;
+	case TWIN_ARGB32:
+		if (ctype == PNG_COLOR_TYPE_RGB)
+			png_set_filler(png, 0xff, PNG_FILLER_BEFORE);
+		if (ctype == PNG_COLOR_TYPE_RGB_ALPHA)
+			png_set_swap_alpha(png);
+		if (ctype == PNG_COLOR_TYPE_GRAY ||
+		    ctype == PNG_COLOR_TYPE_GRAY_ALPHA)
+			png_set_gray_to_rgb(png);
+
+		png_get_IHDR(png, info, &width, &height, &depth, &ctype,
+			     &interlace, int_p_NULL, int_p_NULL);
+
+		DEBUG(" 3- size/depth/ctype/int = %ldx%ld/%d/%d/%d\n",
+		      width, height, depth, ctype, interlace);
+
+		if (depth != 8)
+			goto fail_free;
+		rb = width * 4;
+		break;
+	}
+	DEBUG(" rowbytes = %d\n", rb);
+
+	DEBUG("preparing pixmap & row pointer array...\n");
+
+	rowp = malloc(height * sizeof(png_bytep));
+	if (rowp == NULL)
+		goto fail_free;
+	pix = twin_pixmap_create(fmt, width, height);
+	if (pix == NULL)
+		goto fail_free;
+	for (i = 0; i < height; i++)
+		rowp[i] = pix->p.b + rb * i;
+
+	DEBUG("reading image...\n");
+
+	png_read_image(png, rowp);
+
+	png_read_end(png, NULL);
+
+ fail_free:
+	if (rowp)
+		free(rowp);
+	png_destroy_read_struct(&png, &info, png_infopp_NULL);
+ fail_close:
+	close(fd);
+ fail:
+	return pix;
+}
+
diff --git a/twin_png.h b/twin_png.h
new file mode 100644
index 0000000..a4f1e3b
--- /dev/null
+++ b/twin_png.h
@@ -0,0 +1,30 @@
+/*
+ * Libpng interface to twin
+ *
+ * Copyright 2006 Benjamin Herrenschmidt <benh@kernel.crashing.org>
+ *
+ * This Library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This Library 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
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with the Twin Library; see the file COPYING.  If not,
+ * write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+#ifndef _TWIN_PNG_H_
+#define _TWIN_PNG_H_
+
+#include "twin.h"
+
+#include <png.h>
+
+twin_pixmap_t *twin_png_to_pixmap(const char *filepath, twin_format_t fmt);
+
+#endif /* _TWIN_PNG_H_ */