gtk2/gtk/gtkpicture.c
Timm Bäder 346ec706f7 picture: Fix up some docs
Use nullable instead of allow-none consistently, remove trailing
whitespace and fix some c&p problems.
2018-06-18 17:35:03 +02:00

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/*
* Copyright © 2018 Benjamin Otte
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library. If not, see <http://www.gnu.org/licenses/>.
*
* Authors: Benjamin Otte <otte@gnome.org>
*/
#include "config.h"
#include "gtkpicture.h"
#include "gtkcssnodeprivate.h"
#include "gtkcssnumbervalueprivate.h"
#include "gtkcssstyleprivate.h"
#include "gtkintl.h"
#include "gtkprivate.h"
#include "gtkscalerprivate.h"
#include "gtksnapshot.h"
#include "gtkwidgetprivate.h"
#include "a11y/gtkpictureaccessibleprivate.h"
/**
* SECTION:gtkpicture
* @Short_description: A widget displaying a #GdkPaintable
* @Title: GtkPicture
* @SeeAlso: #GdkPaintable, #GtkImage
*
* The #GtkPicture widget displays a #GdkPaintable. Many convenience functions
* are provided to make pictures simple to use. For example, if you want to load
* an image from a file, and then display that, theres a convenience function
* to do this:
* |[<!-- language="C" -->
* GtkWidget *widget;
* widget = gtk_picture_new_for_filename ("myfile.png");
* ]|
* If the file isnt loaded successfully, the picture will contain a
* “broken image” icon similar to that used in many web browsers.
* If you want to handle errors in loading the file yourself,
* for example by displaying an error message, then load the image with
* gdk_texture_new_for_file(), then create the #GtkPicture with
* gtk_picture_new_for_paintable().
*
* Sometimes an application will want to avoid depending on external data
* files, such as image files. See the documentation of #GResource for details.
* In this case, the #GtkPicture:resource property, gtk_picture_new_for_resource() and
* gtk_picture_set_resource() should be used.
*
* # CSS nodes
*
* GtkPicture has a single CSS node with the name picture.
*/
enum
{
PROP_0,
PROP_PAINTABLE,
PROP_FILE,
PROP_ALTERNATIVE_TEXT,
PROP_KEEP_ASPECT_RATIO,
PROP_CAN_SHRINK,
NUM_PROPERTIES
};
struct _GtkPicture
{
GtkWidget parent_instance;
GdkPaintable *paintable;
GFile *file;
char *alternative_text;
guint keep_aspect_ratio : 1;
guint can_shrink : 1;
};
struct _GtkPictureClass
{
GtkWidgetClass parent_class;
};
static GParamSpec *properties[NUM_PROPERTIES] = { NULL, };
G_DEFINE_TYPE (GtkPicture, gtk_picture, GTK_TYPE_WIDGET)
static void
gtk_picture_snapshot (GtkWidget *widget,
GtkSnapshot *snapshot)
{
GtkPicture *self = GTK_PICTURE (widget);
double ratio;
int x, y, width, height;
double w, h;
if (self->paintable == NULL)
return;
width = gtk_widget_get_width (widget);
height = gtk_widget_get_height (widget);
ratio = gdk_paintable_get_intrinsic_aspect_ratio (self->paintable);
if (!self->keep_aspect_ratio || ratio == 0)
{
gdk_paintable_snapshot (self->paintable, snapshot, width, height);
}
else
{
double picture_ratio = (double) width / height;
if (ratio > picture_ratio)
{
w = width;
h = width / ratio;
}
else
{
w = height * ratio;
h = height;
}
x = (width - ceil (w)) / 2;
y = floor(height - ceil (h)) / 2;
gtk_snapshot_offset (snapshot, x, y);
gdk_paintable_snapshot (self->paintable, snapshot, w, h);
gtk_snapshot_offset (snapshot, -x, -y);
}
}
static GtkSizeRequestMode
gtk_picture_get_request_mode (GtkWidget *widget)
{
return GTK_SIZE_REQUEST_HEIGHT_FOR_WIDTH;
}
static void
gtk_picture_measure (GtkWidget *widget,
GtkOrientation orientation,
int for_size,
int *minimum,
int *natural,
int *minimum_baseline,
int *natural_baseline)
{
GtkPicture *self = GTK_PICTURE (widget);
double min_width, min_height, nat_width, nat_height;
double default_size;
if (self->paintable == NULL)
{
*minimum = 0;
*natural = 0;
return;
}
default_size = _gtk_css_number_value_get (gtk_css_style_get_value (gtk_css_node_get_style (gtk_widget_get_css_node (widget)), GTK_CSS_PROPERTY_ICON_SIZE), 100);
if (self->can_shrink)
{
min_width = min_height = 0;
}
else
{
gdk_paintable_compute_concrete_size (self->paintable,
0, 0,
default_size, default_size,
&min_width, &min_height);
}
if (orientation == GTK_ORIENTATION_HORIZONTAL)
{
gdk_paintable_compute_concrete_size (self->paintable,
0,
for_size < 0 ? 0 : for_size,
default_size, default_size,
&nat_width, &nat_height);
*minimum = ceil (min_width);
*natural = ceil (nat_width);
}
else
{
gdk_paintable_compute_concrete_size (self->paintable,
for_size < 0 ? 0 : for_size,
0,
default_size, default_size,
&nat_width, &nat_height);
*minimum = ceil (min_height);
*natural = ceil (nat_height);
}
}
static void
gtk_picture_set_property (GObject *object,
guint prop_id,
const GValue *value,
GParamSpec *pspec)
{
GtkPicture *self = GTK_PICTURE (object);
switch (prop_id)
{
case PROP_PAINTABLE:
gtk_picture_set_paintable (self, g_value_get_object (value));
break;
case PROP_FILE:
gtk_picture_set_file (self, g_value_get_object (value));
break;
case PROP_ALTERNATIVE_TEXT:
gtk_picture_set_alternative_text (self, g_value_get_string (value));
break;
case PROP_KEEP_ASPECT_RATIO:
gtk_picture_set_keep_aspect_ratio (self, g_value_get_boolean (value));
break;
case PROP_CAN_SHRINK:
gtk_picture_set_can_shrink (self, g_value_get_boolean (value));
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
break;
}
}
static void
gtk_picture_get_property (GObject *object,
guint prop_id,
GValue *value,
GParamSpec *pspec)
{
GtkPicture *self = GTK_PICTURE (object);
switch (prop_id)
{
case PROP_PAINTABLE:
g_value_set_object (value, self->paintable);
break;
case PROP_FILE:
g_value_set_object (value, self->file);
break;
case PROP_ALTERNATIVE_TEXT:
g_value_set_string (value, self->alternative_text);
break;
case PROP_KEEP_ASPECT_RATIO:
g_value_set_boolean (value, self->keep_aspect_ratio);
break;
case PROP_CAN_SHRINK:
g_value_set_boolean (value, self->can_shrink);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
break;
}
}
static void
gtk_picture_dispose (GObject *object)
{
GtkPicture *self = GTK_PICTURE (object);
gtk_picture_set_paintable (self, NULL);
g_clear_object (&self->file);
G_OBJECT_CLASS (gtk_picture_parent_class)->dispose (object);
};
static void
gtk_picture_class_init (GtkPictureClass *class)
{
GObjectClass *gobject_class = G_OBJECT_CLASS (class);
GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (class);
gobject_class->set_property = gtk_picture_set_property;
gobject_class->get_property = gtk_picture_get_property;
gobject_class->dispose = gtk_picture_dispose;
widget_class->snapshot = gtk_picture_snapshot;
widget_class->get_request_mode = gtk_picture_get_request_mode;
widget_class->measure = gtk_picture_measure;
/**
* GtkPicture:paintable:
*
* The #GdkPaintable to be displayed by this #GtkPicture.
*/
properties[PROP_PAINTABLE] =
g_param_spec_object ("paintable",
P_("Paintable"),
P_("The GdkPaintable to display"),
GDK_TYPE_PAINTABLE,
GTK_PARAM_READWRITE | G_PARAM_EXPLICIT_NOTIFY);
/**
* GtkPicture:file:
*
* The #GFile that is displayed or %NULL if none.
*/
properties[PROP_FILE] =
g_param_spec_object ("file",
P_("File"),
P_("File to load and display"),
G_TYPE_FILE,
GTK_PARAM_READWRITE | G_PARAM_EXPLICIT_NOTIFY);
/**
* GtkPicture:alternative-text:
*
* The alternative textual description for the picture.
*/
properties[PROP_ALTERNATIVE_TEXT] =
g_param_spec_string ("alternative-text",
P_("Alternative text"),
P_("The alternative textual description"),
NULL,
GTK_PARAM_READWRITE | G_PARAM_EXPLICIT_NOTIFY);
/**
* GtkPicture:keep-aspect-ratio:
*
* Whether the GtkPicture will render its contents trying to preserve the aspect
* ratio of the contents.
*/
properties[PROP_KEEP_ASPECT_RATIO] =
g_param_spec_boolean ("keep-aspect-ratio",
P_("Keep aspect ratio"),
P_("Render contents respecting the aspect ratio"),
TRUE,
GTK_PARAM_READWRITE | G_PARAM_EXPLICIT_NOTIFY);
/**
* GtkPicture:can-shrink
*
* If the #GtkPicture can be made smaller than the self it contains.
*/
properties[PROP_CAN_SHRINK] =
g_param_spec_boolean ("can-shrink",
P_("Can shrink"),
P_("Allow self to be smaller than contents"),
TRUE,
GTK_PARAM_READWRITE | G_PARAM_EXPLICIT_NOTIFY);
g_object_class_install_properties (gobject_class, NUM_PROPERTIES, properties);
gtk_widget_class_set_accessible_type (widget_class, GTK_TYPE_PICTURE_ACCESSIBLE);
gtk_widget_class_set_css_name (widget_class, I_("picture"));
}
static void
gtk_picture_init (GtkPicture *self)
{
gtk_widget_set_has_surface (GTK_WIDGET (self), FALSE);
self->can_shrink = TRUE;
self->keep_aspect_ratio = TRUE;
}
/**
* gtk_picture_new:
*
* Creates a new empty #GtkPicture widget.
*
* Returns: a newly created #GtkPicture widget.
**/
GtkWidget*
gtk_picture_new (void)
{
return g_object_new (GTK_TYPE_PICTURE, NULL);
}
/**
* gtk_picture_new_for_paintable:
* @paintable: (nullable): a #GdkPaintable, or %NULL
*
* Creates a new #GtkPicture displaying @paintable.
*
* The #GtkPicture will track changes to the @paintable and update
* its size and contents in response to it.
*
* Returns: a new #GtkPicture
**/
GtkWidget*
gtk_picture_new_for_paintable (GdkPaintable *paintable)
{
g_return_val_if_fail (paintable == NULL || GDK_IS_PAINTABLE (paintable), NULL);
return g_object_new (GTK_TYPE_PICTURE,
"paintable", paintable,
NULL);
}
/**
* gtk_picture_new_for_pixbuf:
* @pixbuf: (nullable): a #GdkPixbuf, or %NULL
*
* Creates a new #GtkPicture displaying @pixbuf.
*
* This is a utility function that calls gtk_picture_new_for_paintable(),
* See that function for details.
*
* The pixbuf must not be modified after passing it to this function.
*
* Returns: a new #GtkPicture
**/
GtkWidget*
gtk_picture_new_for_pixbuf (GdkPixbuf *pixbuf)
{
GtkWidget *result;
GdkPaintable *paintable;
g_return_val_if_fail (pixbuf == NULL || GDK_IS_PIXBUF (pixbuf), NULL);
if (pixbuf)
paintable = GDK_PAINTABLE (gdk_texture_new_for_pixbuf (pixbuf));
else
paintable = NULL;
result = gtk_picture_new_for_paintable (paintable);
if (paintable)
g_object_unref (paintable);
return result;
}
/**
* gtk_picture_new_for_file:
* @file: (nullable): a #GFile
*
* Creates a new #GtkPicture displaying the given @file. If the file
* isnt found or cant be loaded, the resulting #GtkPicture be empty.
*
* If you need to detect failures to load the file, use
* gdk_texture_new_for_file() to load the file yourself, then create
* the #GtkPicture from the texture.
*
* Returns: a new #GtkPicture
**/
GtkWidget*
gtk_picture_new_for_file (GFile *file)
{
g_return_val_if_fail (file == NULL || G_IS_FILE (file), NULL);
return g_object_new (GTK_TYPE_PICTURE,
"file", file,
NULL);
}
/**
* gtk_picture_new_for_filename:
* @filename: (type filename) (nullable): a filename
*
* Creates a new #GtkPicture displaying the file @filename.
*
* This is a utility function that calls gtk_picture_new_for_file().
* See that function for details.
*
* Returns: a new #GtkPicture
**/
GtkWidget*
gtk_picture_new_for_filename (const char *filename)
{
GtkWidget *result;
GFile *file;
if (filename)
file = g_file_new_for_path (filename);
else
file = NULL;
result = gtk_picture_new_for_file (file);
if (file)
g_object_unref (file);
return result;
}
/**
* gtk_picture_new_for_resource:
* @resource_path: (nullable): resource path to play back
*
* Creates a new #GtkPicture displaying the file @filename.
*
* This is a utility function that calls gtk_picture_new_for_file().
* See that function for details.
*
* Returns: a new #GtkPicture
**/
GtkWidget *
gtk_picture_new_for_resource (const char *resource_path)
{
GtkWidget *result;
GFile *file;
if (resource_path)
{
char *uri, *escaped;
escaped = g_uri_escape_string (resource_path,
G_URI_RESERVED_CHARS_ALLOWED_IN_PATH, FALSE);
uri = g_strconcat ("resource://", escaped, NULL);
g_free (escaped);
file = g_file_new_for_uri (uri);
g_free (uri);
}
else
{
file = NULL;
}
result = gtk_picture_new_for_file (file);
if (file)
g_object_unref (file);
return result;
}
typedef struct {
gint scale_factor;
} LoaderData;
static void
on_loader_size_prepared (GdkPixbufLoader *loader,
gint width,
gint height,
gpointer user_data)
{
LoaderData *loader_data = user_data;
GdkPixbufFormat *format;
/* Let the regular icon helper code path handle non-scalable pictures */
format = gdk_pixbuf_loader_get_format (loader);
if (!gdk_pixbuf_format_is_scalable (format))
{
loader_data->scale_factor = 1;
return;
}
gdk_pixbuf_loader_set_size (loader,
width * loader_data->scale_factor,
height * loader_data->scale_factor);
}
static GdkPaintable *
load_scalable_with_loader (GFile *file,
gint scale_factor)
{
GdkPixbufLoader *loader;
GBytes *bytes;
GdkPixbufAnimation *animation;
GdkPaintable *result, *scaler;
LoaderData loader_data;
result = NULL;
loader = gdk_pixbuf_loader_new ();
loader_data.scale_factor = scale_factor;
g_signal_connect (loader, "size-prepared", G_CALLBACK (on_loader_size_prepared), &loader_data);
bytes = g_file_load_bytes (file, NULL, NULL, NULL);
if (bytes == NULL)
goto out1;
if (!gdk_pixbuf_loader_write_bytes (loader, bytes, NULL))
goto out2;
if (!gdk_pixbuf_loader_close (loader, NULL))
goto out2;
animation = gdk_pixbuf_loader_get_animation (loader);
if (animation == NULL)
goto out2;
result = GDK_PAINTABLE (gdk_texture_new_for_pixbuf (gdk_pixbuf_animation_get_static_image (animation)));
scaler = gtk_scaler_new (result, loader_data.scale_factor);
g_object_unref (result);
result = scaler;
out2:
g_bytes_unref (bytes);
out1:
g_object_unref (loader);
return result;
}
/**
* gtk_picture_set_file:
* @self: a #GtkPicture
* @file: (nullable): a %GFile or %NULL
*
* Makes @self load and display @file.
*
* See gtk_picture_new_for_file() for details.
**/
void
gtk_picture_set_file (GtkPicture *self,
GFile *file)
{
GdkPaintable *paintable;
g_return_if_fail (GTK_IS_PICTURE (self));
g_return_if_fail (file == NULL || G_IS_FILE (file));
if (self->file == file)
return;
g_object_freeze_notify (G_OBJECT (self));
g_set_object (&self->file, file);
g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_FILE]);
paintable = load_scalable_with_loader (file, gtk_widget_get_scale_factor (GTK_WIDGET (self)));
gtk_picture_set_paintable (self, paintable);
g_object_unref (paintable);
g_object_thaw_notify (G_OBJECT (self));
}
/**
* gtk_picture_get_file:
* @self: a #GtkPicture
*
* Gets the #GFile currently displayed if @self is displaying a file.
* If @self is not displaying a file, for example when gtk_picture_set_paintable()
* was used, then %NULL is returned.
*
* Returns: (nullable) (transfer none): The #GFile displayed by @self.
**/
GFile *
gtk_picture_get_file (GtkPicture *self)
{
g_return_val_if_fail (GTK_IS_PICTURE (self), FALSE);
return self->file;
}
/**
* gtk_picture_set_filename:
* @self: a #GtkPicture
* @filename: (nullable): the filename to play
*
* Makes @self load and display the given @filename.
*
* This is a utility function that calls gtk_picture_set_file().
**/
void
gtk_picture_set_filename (GtkPicture *self,
const char *filename)
{
GFile *file;
g_return_if_fail (GTK_IS_PICTURE (self));
if (filename)
file = g_file_new_for_path (filename);
else
file = NULL;
gtk_picture_set_file (self, file);
if (file)
g_object_unref (file);
}
/**
* gtk_picture_set_resource:
* @self: a #GtkPicture
* @resource_path: (nullable): the resource to set
*
* Makes @self load and display the resource at the given
* @resource_path.
*
* This is a utility function that calls gtk_picture_set_file(),
**/
void
gtk_picture_set_resource (GtkPicture *self,
const char *resource_path)
{
GFile *file;
g_return_if_fail (GTK_IS_PICTURE (self));
if (resource_path)
{
char *uri, *escaped;
escaped = g_uri_escape_string (resource_path,
G_URI_RESERVED_CHARS_ALLOWED_IN_PATH, FALSE);
uri = g_strconcat ("resource://", escaped, NULL);
g_free (escaped);
file = g_file_new_for_uri (uri);
g_free (uri);
}
else
{
file = NULL;
}
gtk_picture_set_file (self, file);
if (file)
g_object_unref (file);
}
/**
* gtk_picture_set_pixbuf:
* @self: a #GtkPicture
* @pixbuf: (nullable): a #GdkPixbuf or %NULL
*
* See gtk_picture_new_for_pixbuf() for details.
*
* This is a utility function that calls gtk_picture_set_paintable(),
**/
void
gtk_picture_set_pixbuf (GtkPicture *self,
GdkPixbuf *pixbuf)
{
GdkTexture *texture;
g_return_if_fail (GTK_IS_PICTURE (self));
g_return_if_fail (pixbuf == NULL || GDK_IS_PIXBUF (pixbuf));
if (pixbuf)
texture = gdk_texture_new_for_pixbuf (pixbuf);
else
texture = NULL;
gtk_picture_set_paintable (self, GDK_PAINTABLE (texture));
if (texture)
g_object_unref (texture);
}
static void
gtk_picture_paintable_invalidate_contents (GdkPaintable *paintable,
GtkPicture *self)
{
gtk_widget_queue_draw (GTK_WIDGET (self));
}
static void
gtk_picture_paintable_invalidate_size (GdkPaintable *paintable,
GtkPicture *self)
{
gtk_widget_queue_resize (GTK_WIDGET (self));
}
/**
* gtk_picture_set_paintable:
* @self: a #GtkPicture
* @paintable: (nullable): a #GdkPaintable or %NULL
*
* Makes @self display the given @paintable. If @paintable is %NULL,
* nothing will be displayed.
*
* See gtk_picture_new_for_paintable() for details.
**/
void
gtk_picture_set_paintable (GtkPicture *self,
GdkPaintable *paintable)
{
g_return_if_fail (GTK_IS_PICTURE (self));
g_return_if_fail (paintable == NULL || GDK_IS_PAINTABLE (paintable));
if (self->paintable == paintable)
return;
g_object_freeze_notify (G_OBJECT (self));
if (paintable)
g_object_ref (paintable);
if (self->paintable)
{
g_signal_handlers_disconnect_by_func (self->paintable,
gtk_picture_paintable_invalidate_contents,
self);
g_signal_handlers_disconnect_by_func (self->paintable,
gtk_picture_paintable_invalidate_size,
self);
}
self->paintable = paintable;
if (paintable)
{
g_signal_connect (paintable,
"invalidate-contents",
G_CALLBACK (gtk_picture_paintable_invalidate_contents),
self);
g_signal_connect (paintable,
"invalidate-size",
G_CALLBACK (gtk_picture_paintable_invalidate_size),
self);
}
gtk_widget_queue_resize (GTK_WIDGET (self));
g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_PAINTABLE]);
g_object_thaw_notify (G_OBJECT (self));
}
/**
* gtk_picture_get_paintable:
* @self: a #GtkPicture
*
* Gets the #GdkPaintable being displayed by the #GtkPicture.
*
* Returns: (nullable) (transfer none): the displayed paintable, or %NULL if
* the picture is empty
**/
GdkPaintable *
gtk_picture_get_paintable (GtkPicture *self)
{
g_return_val_if_fail (GTK_IS_PICTURE (self), NULL);
return self->paintable;
}
/**
* gtk_picture_set_keep_aspect_ratio:
* @self: a #GtkPicture
* @keep_aspect_ratio: whether to keep aspect ratio
*
* If set to %TRUE, the @self will render its contents according to
* their aspect ratio. That means that empty space may show up at the
* top/bottom or left/right of @self.
*
* If set to %FALSE or if the contents provide no aspect ratio, the
* contents will be stretched over the picture's whole area.
*/
void
gtk_picture_set_keep_aspect_ratio (GtkPicture *self,
gboolean keep_aspect_ratio)
{
g_return_if_fail (GTK_IS_PICTURE (self));
if (self->keep_aspect_ratio == keep_aspect_ratio)
return;
self->keep_aspect_ratio = keep_aspect_ratio;
g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_KEEP_ASPECT_RATIO]);
}
/**
* gtk_picture_get_keep_aspect_ratio:
* @self: a #GtkPicture
*
* Gets the value set via gtk_picture_set_keep_aspect_ratio().
*
* Returns: %TRUE if the self tries to keep the contents' aspect ratio
**/
gboolean
gtk_picture_get_keep_aspect_ratio (GtkPicture *self)
{
g_return_val_if_fail (GTK_IS_PICTURE (self), TRUE);
return self->keep_aspect_ratio;
}
/**
* gtk_picture_set_can_shrink:
* @self: a #GtkPicture
* @can_shrink: if @self can be made smaller than its contents
*
* If set to %TRUE, the @self can be made smaller than its contents.
* The contents will then be scaled down when rendering.
*
* If you want to still force a minimum size manually, consider using
* gtk_widget_set_size_request().
*
* Also of note is that a similar function for growing does not exist
* because the grow behavior can be controlled via
* gtk_widget_set_halign() and gtk_widget_set_valign().
*/
void
gtk_picture_set_can_shrink (GtkPicture *self,
gboolean can_shrink)
{
g_return_if_fail (GTK_IS_PICTURE (self));
if (self->can_shrink == can_shrink)
return;
self->can_shrink = can_shrink;
g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_CAN_SHRINK]);
}
/**
* gtk_picture_get_can_shrink:
* @self: a #GtkPicture
*
* Gets the value set via gtk_picture_set_can_shrink().
*
* Returns: %TRUE if the picture can be made smaller than its contents
**/
gboolean
gtk_picture_get_can_shrink (GtkPicture *self)
{
g_return_val_if_fail (GTK_IS_PICTURE (self), FALSE);
return self->can_shrink;
}
/**
* gtk_picture_set_alternative_text:
* @self: a #GtkPicture
* @alternative_text: (nullable): a textual description of the contents
*
* Sets an alternative textual description for the picture contents.
* It is equivalent to the "alt" attribute for images on websites.
*
* This text will be made available to accessibility tools.
*
* If the picture cannot be described textually, set this proeprty to %NULL.
*/
void
gtk_picture_set_alternative_text (GtkPicture *self,
const char *alternative_text)
{
g_return_if_fail (GTK_IS_PICTURE (self));
if (g_strcmp0 (self->alternative_text, alternative_text) == 0)
return;
g_free (self->alternative_text);
self->alternative_text = g_strdup (alternative_text);
g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_ALTERNATIVE_TEXT]);
}
/**
* gtk_picture_get_alternative_text:
* @self: a #GtkPicture
*
* Gets the alternative textual description of the picture or returns %NULL if
* the picture cannot be described textually.
*
* Returns: (nullable) (transfer none): the alternative textual description
* of @self.
**/
const char *
gtk_picture_get_alternative_text (GtkPicture *self)
{
g_return_val_if_fail (GTK_IS_PICTURE (self), NULL);
return self->alternative_text;
}