Re: patch for gdk-pixbuf to read and write PNG tEXt chunks
- From: Sven Neumann <sven gimp org>
- To: Owen Taylor <otaylor redhat com>
- Cc: Gtk+ Developers <gtk-devel-list gnome org>, Jens Finke <jens triq net>
- Subject: Re: patch for gdk-pixbuf to read and write PNG tEXt chunks
- Date: 01 Oct 2001 18:07:56 +0200
Hi,
Owen Taylor <otaylor redhat com> writes:
> > + creator = (const gchar *) g_object_get_data (G_OBJECT (pixbuf),
> > + "tEXt::Software");
> > + if (creator)
> > + g_print ("%s was created by '%s'\n", argv[1], creator);
>
> I don't like this -- better to add a real API:
>
> Something along the lines of:
>
> G_CONST_RETURN char *gdk_pixbuf_get_option (GdkPixbuf *pixbuf,
> const char *key);
>
> And as part of this, you probably should hang all options off of
> a single object data key rather than using a bunch of object data
> keys.
>
> Something like:
>
> void gdk_pixbuf_get_options (GdkPixbuf *pixbuf,
> GdkPixbufOption ***options,
> gint *n_options);
> void gdk_pixbuf_free_options (GdkPixbufOption *options,
> gint n_options);
>
> Might be nice as well, though that could (should?) be added later.
>
> The final comment is that I think that the code in io-png should
> translate the values of the keys to/from UTF-8 and error if
> the key value is not representable in ISO-8859-1.
>
> (tEXt is specified to be in iso-8859-1, ugh. There is a "internationalized
> text segment in later versions of png, but we presumbaly don't want
> to assume sufficiently new libpng.)
attached is a revised patch that addresses the encoding conversion and
introduces a GdkPixbufOption struct that is however only used internally.
It adds the gdk_pixbuf_get_option() API that you suggested. The helper
functions _gdk_pixbuf_set_options() and _gdk_pixbuf_free_options() are
not exported since I think the user shouldn't have to know anything about
the implementation.
I have not addressed the error handling issues since I would prefer to
discuss this problem first and if necessary handle it in a seperate
patch. At the moment there are a few places where gdk_pixbuf functions
return FALSE without setting GError. Havoc mentioned that this might be
intentional as it indicates a bug in the application that is not
recoverable and I think I agree with him. What do you think?
Salut, Sven
Index: gdk-pixbuf/gdk-pixbuf-io.c
===================================================================
RCS file: /cvs/gnome/gtk+/gdk-pixbuf/gdk-pixbuf-io.c,v
retrieving revision 1.60
diff -u -r1.60 gdk-pixbuf-io.c
--- gdk-pixbuf/gdk-pixbuf-io.c 2001/09/14 22:04:55 1.60
+++ gdk-pixbuf/gdk-pixbuf-io.c 2001/10/01 15:55:16
@@ -731,8 +731,8 @@
* @Varargs: list of key-value save options
*
* Saves pixbuf to a file in @type, which is currently "jpeg" or
- * "png". If @error is set, FALSE will be returned. Possible errors include those
- * in the #GDK_PIXBUF_ERROR domain and those in the #G_FILE_ERROR domain.
+ * "png". If @error is set, FALSE will be returned. Possible errors include
+ * those in the #GDK_PIXBUF_ERROR domain and those in the #G_FILE_ERROR domain.
*
* The variable argument list should be NULL-terminated; if not empty,
* it should contain pairs of strings that modify the save
@@ -743,8 +743,13 @@
* "quality", "100", NULL);
* </programlisting>
*
- * The only save parameter that currently exists is the "quality" field
- * for JPEG images; its value should be in the range [0,100].
+ * Currently only few parameters exist. JPEG images can be saved with a
+ * "quality" parameter; its value should be in the range [0,100].
+ * Text chunks can be attached to PNG images by specifying parameters of
+ * the form "tEXt::key", where key is an ASCII string of length 1-79;
+ * the values being UTF-8 encoded strings. Note however that PNG text
+ * chunks are stored in ISO-8859-1 encoding, so you can only set texts
+ * that can be represented in this encoding.
*
* Return value: whether an error was set
**/
Index: gdk-pixbuf/gdk-pixbuf-private.h
===================================================================
RCS file: /cvs/gnome/gtk+/gdk-pixbuf/gdk-pixbuf-private.h,v
retrieving revision 1.9
diff -u -r1.9 gdk-pixbuf-private.h
--- gdk-pixbuf/gdk-pixbuf-private.h 2001/06/26 20:56:32 1.9
+++ gdk-pixbuf/gdk-pixbuf-private.h 2001/10/01 15:55:16
@@ -128,8 +128,22 @@
const GTimeVal *current_time);
};
-
GdkPixbufAnimation* gdk_pixbuf_non_anim_new (GdkPixbuf *pixbuf);
+
+
+
+/* key/value pairs that can be attached by the pixbuf loader */
+
+typedef struct _GdkPixbufOption GdkPixbufOption;
+struct _GdkPixbufOption {
+ gchar *key;
+ gchar *value;
+};
+
+void _gdk_pixbuf_set_options (GdkPixbuf *pixbuf,
+ GdkPixbufOption **options);
+void _gdk_pixbuf_free_options (GdkPixbufOption **options);
+
#endif
Index: gdk-pixbuf/gdk-pixbuf.c
===================================================================
RCS file: /cvs/gnome/gtk+/gdk-pixbuf/gdk-pixbuf.c,v
retrieving revision 1.45
diff -u -r1.45 gdk-pixbuf.c
--- gdk-pixbuf/gdk-pixbuf.c 2001/08/07 17:49:09 1.45
+++ gdk-pixbuf/gdk-pixbuf.c 2001/10/01 15:55:16
@@ -1,3 +1,4 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 8 -*- */
/* GdkPixbuf library - Basic memory management
*
* Copyright (C) 1999 The Free Software Foundation
@@ -479,6 +480,62 @@
}
}
+
+
+/**
+ * gdk_pixbuf_get_option:
+ * @pixbuf: a #GdkPixbuf
+ * @key: a nul-terminated string.
+ *
+ * Looks up @key in the list of options that may have been attached to the
+ * @pixbuf when it was loaded.
+ *
+ * Return value: the value associated with @key. This is a nul-terminated
+ * string that should not be freed or %NULL if @key was not found.
+ **/
+G_CONST_RETURN gchar *
+gdk_pixbuf_get_option (GdkPixbuf *pixbuf,
+ const gchar *key)
+{
+ GdkPixbufOption **options;
+
+ g_return_val_if_fail (GDK_IS_PIXBUF (pixbuf), NULL);
+ g_return_val_if_fail (key != NULL, NULL);
+
+ options = g_object_get_qdata (G_OBJECT (pixbuf),
+ g_quark_from_static_string ("gdk_pixbuf_options"));
+ if (options) {
+ while (*options) {
+ if (strcmp ((*options)->key, key) == 0)
+ return (*options)->value;
+ options++;
+ }
+ }
+
+ return NULL;
+}
+
+void
+_gdk_pixbuf_set_options (GdkPixbuf *pixbuf,
+ GdkPixbufOption **options)
+{
+ g_object_set_qdata_full (G_OBJECT (pixbuf),
+ g_quark_from_static_string ("gdk_pixbuf_options"),
+ options,
+ (GDestroyNotify) _gdk_pixbuf_free_options);
+}
+
+void
+_gdk_pixbuf_free_options (GdkPixbufOption **options)
+{
+ while (*options) {
+ g_free ((*options)->key);
+ g_free ((*options)->value);
+ options++;
+ }
+}
+
+
/* Include the marshallers */
#include <glib-object.h>
Index: gdk-pixbuf/gdk-pixbuf.h
===================================================================
RCS file: /cvs/gnome/gtk+/gdk-pixbuf/gdk-pixbuf.h,v
retrieving revision 1.62
diff -u -r1.62 gdk-pixbuf.h
--- gdk-pixbuf/gdk-pixbuf.h 2001/09/16 23:54:37 1.62
+++ gdk-pixbuf/gdk-pixbuf.h 2001/10/01 15:55:16
@@ -286,6 +286,12 @@
const GTimeVal *current_time);
+
+
+G_CONST_RETURN gchar * gdk_pixbuf_get_option (GdkPixbuf *pixbuf,
+ const gchar *key);
+
+
#include <gdk-pixbuf/gdk-pixbuf-loader.h>
#include <gdk-pixbuf/gdk-pixbuf-enum-types.h>
Index: gdk-pixbuf/io-png.c
===================================================================
RCS file: /cvs/gnome/gtk+/gdk-pixbuf/io-png.c,v
retrieving revision 1.41
diff -u -r1.41 io-png.c
--- gdk-pixbuf/io-png.c 2001/08/30 07:21:13 1.41
+++ gdk-pixbuf/io-png.c 2001/10/01 15:55:16
@@ -182,17 +182,47 @@
g_free (pixels);
}
+static GdkPixbufOption **
+png_text_to_pixbuf_options(png_textp text_ptr,
+ gint num_texts)
+{
+ GdkPixbufOption **options;
+ gchar *value;
+ gint i, n;
+
+ options = g_new0 (GdkPixbufOption *, num_texts + 1);
+ for (i = 0, n = 0; i < num_texts; i++) {
+ value = g_convert (text_ptr[i].text, -1,
+ "UTF-8", "ISO-8859-1",
+ NULL, NULL, NULL);
+ if (value) {
+ options[n] = g_new (GdkPixbufOption, 1);
+ options[n]->key = g_strconcat ("tEXt::",
+ text_ptr[i].key,
+ NULL);
+ options[n]->value = value;
+ n++;
+ }
+ }
+
+ return options;
+}
+
/* Shared library entry point */
static GdkPixbuf *
gdk_pixbuf__png_image_load (FILE *f, GError **error)
{
+ GdkPixbuf *pixbuf;
png_structp png_ptr;
png_infop info_ptr, end_info;
+ png_textp text_ptr;
gboolean failed = FALSE;
gint i, ctype, bpp;
png_uint_32 w, h;
png_bytepp rows;
guchar *pixels;
+ gint num_texts;
+ GdkPixbufOption **options = NULL;
png_ptr = png_create_read_struct (PNG_LIBPNG_VER_STRING,
error,
@@ -255,17 +285,30 @@
rows[i] = pixels + i * w * bpp;
png_read_image (png_ptr, rows);
+
+ if (png_get_text (png_ptr, info_ptr, &text_ptr, &num_texts))
+ options = png_text_to_pixbuf_options (text_ptr, num_texts);
+
png_destroy_read_struct (&png_ptr, &info_ptr, &end_info);
g_free (rows);
if (ctype & PNG_COLOR_MASK_ALPHA)
- return gdk_pixbuf_new_from_data (pixels, GDK_COLORSPACE_RGB, TRUE, 8,
- w, h, w * 4,
- free_buffer, NULL);
+ pixbuf = gdk_pixbuf_new_from_data (pixels, GDK_COLORSPACE_RGB, TRUE, 8,
+ w, h, w * 4,
+ free_buffer, NULL);
else
- return gdk_pixbuf_new_from_data (pixels, GDK_COLORSPACE_RGB, FALSE, 8,
- w, h, w * 3,
- free_buffer, NULL);
+ pixbuf = gdk_pixbuf_new_from_data (pixels, GDK_COLORSPACE_RGB, FALSE, 8,
+ w, h, w * 3,
+ free_buffer, NULL);
+
+ if (options) {
+ if (pixbuf)
+ _gdk_pixbuf_set_options (pixbuf, options);
+ else
+ _gdk_pixbuf_free_options (options);
+ }
+
+ return pixbuf;
}
/* I wish these avoided the setjmp()/longjmp() crap in libpng instead
@@ -501,6 +544,8 @@
{
LoadContext* lc;
png_uint_32 width, height;
+ png_textp png_text_ptr;
+ int num_texts;
int color_type;
gboolean have_alpha = FALSE;
gboolean failed = FALSE;
@@ -538,7 +583,16 @@
}
return;
}
+
+ /* Extract tEXt chunks and attach them as pixbuf options */
+ if (png_get_text (png_read_ptr, png_info_ptr, &png_text_ptr, &num_texts)) {
+ GdkPixbufOption **options;
+ options = png_text_to_pixbuf_options (png_text_ptr, num_texts);
+ if (options)
+ _gdk_pixbuf_set_options (lc->pixbuf, options);
+ }
+
/* Notify the client that we are ready to go */
if (lc->prepare_func)
@@ -653,32 +707,58 @@
{
png_structp png_ptr;
png_infop info_ptr;
+ png_textp text_ptr = NULL;
guchar *ptr;
guchar *pixels;
- int x, y, j;
+ int x, y;
+ int i, j;
png_bytep row_ptr;
png_bytep data;
png_color_8 sig_bit;
int w, h, rowstride;
int has_alpha;
int bpc;
+ int num_keys;
+
+ num_keys = 0;
if (keys && *keys) {
- g_warning ("Bad option name '%s' passed to PNG saver",
- *keys);
- return FALSE;
-#if 0
- gchar **kiter = keys;
- gchar **viter = values;
-
-
- while (*kiter) {
-
- ++kiter;
- ++viter;
+ gchar **kiter;
+ int len;
+
+ for (kiter = keys; *kiter; kiter++) {
+ len = strlen (*kiter);
+ if (len < 6 || strncmp (*kiter, "tEXt::", 6)) {
+ g_warning ("Bad option name '%s' passed to PNG saver",
+ *kiter);
+ return FALSE;
+ }
+ len -= 6;
+ if (len < 1 || len > 79) {
+ g_warning ("tEXt keys passed as option to PNG saver must be of length 1-79");
+ return FALSE;
+ }
+ num_keys++;
}
-#endif
}
+
+ if (num_keys > 0) {
+ text_ptr = g_new0 (png_text, num_keys);
+ for (i = 0; i < num_keys; i++) {
+ text_ptr[i].compression = PNG_TEXT_COMPRESSION_NONE;
+ text_ptr[i].key = keys[i]+6;
+ text_ptr[i].text = g_convert (values[i], -1,
+ "ISO-8859-1", "UTF-8",
+ NULL, &text_ptr[i].text_length,
+ NULL);
+ if (!text_ptr[i].text) {
+ g_warning ("Value for key '%s' can not be represented in ISO-8859-1 encoding as specified for PNG tEXt chunks.", keys[i]);
+ return FALSE;
+
+ }
+ }
+ }
+
data = NULL;
bpc = gdk_pixbuf_get_bits_per_sample (pixbuf);
@@ -704,7 +784,13 @@
png_destroy_write_struct (&png_ptr, (png_infopp) NULL);
return FALSE;
}
+
+ if (num_keys > 0) {
+ png_set_text (png_ptr, info_ptr, text_ptr, num_keys);
+ }
+
png_init_io (png_ptr, f);
+
if (has_alpha) {
png_set_IHDR (png_ptr, info_ptr, w, h, bpc,
PNG_COLOR_TYPE_RGB_ALPHA, PNG_INTERLACE_NONE,
@@ -762,6 +848,12 @@
png_write_end (png_ptr, info_ptr);
png_destroy_write_struct (&png_ptr, (png_infopp) NULL);
+
+ if (num_keys > 0) {
+ for (i = 0; i < num_keys; i++)
+ g_free (text_ptr[i].text);
+ g_free (text_ptr);
+ }
return TRUE;
}
Index: demos/testpixbuf-save.c
===================================================================
RCS file: /cvs/gnome/gtk+/demos/testpixbuf-save.c,v
retrieving revision 1.7
diff -u -r1.7 testpixbuf-save.c
--- demos/testpixbuf-save.c 2001/09/07 21:49:33 1.7
+++ demos/testpixbuf-save.c 2001/10/01 15:55:16
@@ -35,7 +35,10 @@
return;
}
- if (!gdk_pixbuf_save (pixbuf, "foo.png", "png", &err, NULL)) {
+ if (!gdk_pixbuf_save (pixbuf, "foo.png", "png",
+ &err,
+ "tEXt::Software", "testpixbuf-save",
+ NULL)) {
fprintf (stderr, "%s", err->message);
g_error_free (err);
}
Index: demos/testpixbuf-scale.c
===================================================================
RCS file: /cvs/gnome/gtk+/demos/testpixbuf-scale.c,v
retrieving revision 1.11
diff -u -r1.11 testpixbuf-scale.c
--- demos/testpixbuf-scale.c 2001/08/23 15:26:44 1.11
+++ demos/testpixbuf-scale.c 2001/10/01 15:55:16
@@ -63,6 +63,7 @@
GtkWidget *hbox, *label, *hscale;
GtkAdjustment *adjustment;
GtkRequisition scratch_requisition;
+ const gchar *creator;
GError *error;
pixbuf_init ();
@@ -82,6 +83,10 @@
g_error_free (error);
exit(1);
}
+
+ creator = gdk_pixbuf_get_option (pixbuf, "tEXt::Software");
+ if (creator)
+ g_print ("%s was created by '%s'\n", argv[1], creator);
window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
gtk_signal_connect (GTK_OBJECT (window), "destroy",
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