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/* GStreamer
* Copyright (C) 2009 Benjamin Otte <otte@gnome.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 this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#include "gstcairocaps.h"
#include <string.h>
#include <gobject/gvaluecollector.h>
#include "gstcairocapsany.h"
/**
* SECTION:gstcairocaps
* @title: Caps
* @short_description: caps negotiation and format handling
*
* This section describes how to handle #GstCaps inside an element that
* uses this library.
*
* Fixed caps as passed to a setcaps function are converted into a
* #GstCairoFormat using gst_cairo_format_new(), which is a simple and
* fast wrapper around a static caps. It is suggested that you do not store
* things like framerate, width or height, but use a #GstCairoFormat instead.
* These formats are also required when converting a #GstBuffer into a
* #cairo_surface_t.
*
* The GStreamer Cairo library also provides some utility function that
* help during caps negotiation. Those are listed here, too. The most
* important one certainly is gst_cairo_caps_expand() that eases caps
* transformations.
*/
/**
* gst_cairo_caps_any:
*
* Returns a #GstCaps that references all formats that can be handled by
* this library. The returned caps will not be writable. Use
* gst_caps_make_writable() if you want to change them.
* <note>The caps returned by this function can change between versions
* of this library as new formats are added.</note>
*
* Returns: a #GstCaps, use gst_caps_unref() to get rid of it. The caps will
* not be writable.
**/
GstCaps *
gst_cairo_caps_any (void)
{
GstCaps *any = NULL;
if (g_once_init_enter ((gsize *) & any)) {
GstCaps *caps = gst_caps_from_string (GST_CAIRO_CAPS_ANY);
g_once_init_leave ((gsize *) & any, GPOINTER_TO_SIZE (caps));
}
return gst_caps_copy (any);
}
/**
* gst_cairo_caps_expand:
* @caps: a valid cairo caps to expand
* @expand: parts of the caps that should be expanded
*
* Expands the given @caps so that all options set in @expand are expanded
* to all their options. This function is useful in caps negotiation when
* your element is transforming the Cairo data given to it, like in a
* colorspace or scaling element.
*
* Returns: a new caps with the expanded fields.
**/
GstCaps *
gst_cairo_caps_expand (const GstCaps * caps, GstCairoFormatOption expand)
{
GstCaps *expanded;
guint i;
g_return_val_if_fail (GST_IS_CAPS (caps), NULL);
/* start with a copy of the current caps - we prefer unchanged caps */
expanded = gst_caps_copy (caps);
for (i = 0; i < gst_caps_get_size (caps); i++) {
GstStructure *expand_me = gst_caps_get_structure (caps, i);
GstCaps *copy;
if (expand & GST_CAIRO_FORMAT_FORMAT) {
copy = gst_caps_make_writable (gst_cairo_caps_any ());
} else {
copy = gst_caps_copy_nth (caps, i);
}
if (expand & GST_CAIRO_FORMAT_WIDTH) {
gst_caps_set_simple (copy, "width", GST_TYPE_INT_RANGE, 1, G_MAXINT,
NULL);
} else {
gst_caps_set_value (copy, "width",
gst_structure_get_value (expand_me, "width"));
}
if (expand & GST_CAIRO_FORMAT_HEIGHT) {
gst_caps_set_simple (copy, "height", GST_TYPE_INT_RANGE, 1,
G_MAXINT, NULL);
} else {
gst_caps_set_value (copy, "height",
gst_structure_get_value (expand_me, "height"));
}
if (expand & GST_CAIRO_FORMAT_FRAMERATE) {
gst_caps_set_simple (copy, "framerate", GST_TYPE_FRACTION_RANGE, 0,
1, G_MAXINT, 1, NULL);
} else {
gst_caps_set_value (copy, "framerate",
gst_structure_get_value (expand_me, "framerate"));
}
if (expand & GST_CAIRO_FORMAT_PAR) {
guint j;
for (j = 0; j < gst_caps_get_size (copy); j++) {
gst_structure_remove_field (gst_caps_get_structure (copy, j),
"pixel-aspect-ratio");
}
} else {
const GValue *value =
gst_structure_get_value (expand_me, "pixel-aspect-ratio");
if (value)
gst_caps_set_value (copy, "pixel-aspect-ratio", value);
}
gst_caps_append (expanded, copy);
}
return expanded;
}
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