gtk2/gtk/gtksizerequest.c

542 lines
17 KiB
C

/* gtksizerequest.c
* Copyright (C) 2007-2010 Openismus GmbH
*
* Authors:
* Mathias Hasselmann <mathias@openismus.com>
* Tristan Van Berkom <tristan.van.berkom@gmail.com>
*
* 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.
*/
/**
* SECTION:gtksizerequest
* @Short_Description: Height-for-width geometry management
* @Title: GtkSizeRequest
*
* The GtkSizeRequest interface is GTK+'s height-for-width (and width-for-height)
* geometry management system. Height-for-width means that a widget can
* change how much vertical space it needs, depending on the amount
* of horizontal space that it is given (and similar for width-for-height).
* The most common example is a label that reflows to fill up the available
* width, wraps to fewer lines, and therefore needs less height.
*
* GTK+'s traditional two-pass <link linkend="size-allocation">size-allocation</link>
* algorithm does not allow this flexibility. #GtkWidget provides a default
* implementation of the #GtkSizeRequest interface for existing widgets,
* which always requests the same height, regardless of the available width.
*
* <refsect2>
* <title>Implementing GtkSizeRequest</title>
* <para>
* Some important things to keep in mind when implementing
* the GtkSizeRequest interface and when using it in container
* implementations.
*
* The geometry management system will query a logical hierarchy in
* only one orientation at a time. When widgets are initially queried
* for their minimum sizes it is generally done in a dual pass
* in the direction chosen by the toplevel.
*
* For instance when queried in the normal height-for-width mode:
* First the default minimum and natural width for each widget
* in the interface will computed and collectively returned to
* the toplevel by way of gtk_size_request_get_desired_width().
* Next, the toplevel will use the minimum width to query for the
* minimum height contextual to that width using
* gtk_size_request_get_height_for_width(), which will also be a
* highly recursive operation. This minimum-for-minimum size can be
* used to set the minimum size constraint on the toplevel.
*
* When allocating, each container can use the minimum and natural
* sizes reported by their children to allocate natural sizes and
* expose as much content as possible with the given allocation.
*
* That means that the request operation at allocation time will
* usually fire again in contexts of different allocated sizes than
* the ones originally queried for. #GtkSizeRequest caches a
* small number of results to avoid re-querying for the same
* allocated size in one allocation cycle.
*
* A widget that does not actually do height-for-width
* or width-for-height size negotiations only has to implement
* get_width() and get_height().
*
* If a widget does move content around to smartly use up the
* allocated size, then it must support the request properly in
* both orientations; even if the request only makes sense in
* one orientation.
*
* For instance, a GtkLabel that does height-for-width word wrapping
* will not expect to have get_height() called because that
* call is specific to a width-for-height request, in this case the
* label must return the heights contextual to its minimum possible
* width. By following this rule any widget that handles height-for-width
* or width-for-height requests will always be allocated at least
* enough space to fit its own content.
* </para>
* </refsect2>
*/
#include <config.h>
#include "gtksizerequest.h"
#include "gtksizegroup.h"
#include "gtkprivate.h"
#include "gtkintl.h"
#include "gtkalias.h"
/* With GtkSizeRequest, a widget may be requested
* its width for 2 or maximum 3 heights in one resize
*/
#define N_CACHED_SIZES 3
typedef struct
{
guint age;
gint for_size;
gint minimum_size;
gint natural_size;
} SizeRequest;
typedef struct {
SizeRequest widths[N_CACHED_SIZES];
SizeRequest heights[N_CACHED_SIZES];
guint8 cached_width_age;
guint8 cached_height_age;
} SizeRequestCache;
static GQuark quark_cache = 0;
GType
gtk_size_request_get_type (void)
{
static GType size_request_type = 0;
if (G_UNLIKELY(!size_request_type))
{
size_request_type =
g_type_register_static_simple (G_TYPE_INTERFACE, I_("GtkSizeRequest"),
sizeof (GtkSizeRequestIface),
NULL, 0, NULL, 0);
g_type_interface_add_prerequisite (size_request_type, GTK_TYPE_WIDGET);
quark_cache = g_quark_from_static_string ("gtk-size-request-cache");
}
return size_request_type;
}
/* looks for a cached size request for this for_size. If not
* found, returns the oldest entry so it can be overwritten
*
* Note that this caching code was directly derived from
* the Clutter toolkit.
*/
static gboolean
get_cached_size (gint for_size,
SizeRequest *cached_sizes,
SizeRequest **result)
{
guint i;
*result = &cached_sizes[0];
for (i = 0; i < N_CACHED_SIZES; i++)
{
SizeRequest *cs;
cs = &cached_sizes[i];
if (cs->age > 0 && cs->for_size == for_size)
{
*result = cs;
return TRUE;
}
else if (cs->age < (*result)->age)
{
*result = cs;
}
}
return FALSE;
}
static void
destroy_cache (SizeRequestCache *cache)
{
g_slice_free (SizeRequestCache, cache);
}
static SizeRequestCache *
get_cache (GtkSizeRequest *widget,
gboolean create)
{
SizeRequestCache *cache;
cache = g_object_get_qdata (G_OBJECT (widget), quark_cache);
if (!cache && create)
{
cache = g_slice_new0 (SizeRequestCache);
cache->cached_width_age = 1;
cache->cached_height_age = 1;
g_object_set_qdata_full (G_OBJECT (widget), quark_cache, cache,
(GDestroyNotify)destroy_cache);
}
return cache;
}
static void
do_size_request (GtkWidget *widget)
{
if (GTK_WIDGET_REQUEST_NEEDED (widget))
{
gtk_widget_ensure_style (widget);
GTK_PRIVATE_UNSET_FLAG (widget, GTK_REQUEST_NEEDED);
g_signal_emit_by_name (widget,
"size-request",
&widget->requisition);
}
}
static void
compute_size_for_orientation (GtkSizeRequest *request,
GtkSizeGroupMode orientation,
gint for_size,
gint *minimum_size,
gint *natural_size)
{
SizeRequestCache *cache;
SizeRequest *cached_size;
GtkWidget *widget;
gboolean found_in_cache = FALSE;
g_return_if_fail (GTK_IS_SIZE_REQUEST (request));
g_return_if_fail (minimum_size != NULL || natural_size != NULL);
widget = GTK_WIDGET (request);
cache = get_cache (request, TRUE);
if (orientation == GTK_SIZE_GROUP_HORIZONTAL)
{
cached_size = &cache->widths[0];
if (!GTK_WIDGET_WIDTH_REQUEST_NEEDED (request))
found_in_cache = get_cached_size (for_size, cache->widths, &cached_size);
else
{
memset (cache->widths, 0, N_CACHED_SIZES * sizeof (SizeRequest));
cache->cached_width_age = 1;
}
}
else
{
cached_size = &cache->heights[0];
if (!GTK_WIDGET_HEIGHT_REQUEST_NEEDED (request))
found_in_cache = get_cached_size (for_size, cache->heights, &cached_size);
else
{
memset (cache->heights, 0, N_CACHED_SIZES * sizeof (SizeRequest));
cache->cached_height_age = 1;
}
}
if (!found_in_cache)
{
gint min_size = 0, nat_size = 0;
gint group_size, requisition_size;
/* Unconditional size request runs but is often unhandled. */
do_size_request (widget);
if (orientation == GTK_SIZE_GROUP_HORIZONTAL)
{
requisition_size = widget->requisition.width;
if (for_size < 0)
GTK_SIZE_REQUEST_GET_IFACE (request)->get_width (request, &min_size, &nat_size);
else
GTK_SIZE_REQUEST_GET_IFACE (request)->get_width_for_height (request, for_size,
&min_size, &nat_size);
}
else
{
requisition_size = widget->requisition.height;
if (for_size < 0)
GTK_SIZE_REQUEST_GET_IFACE (request)->get_height (request, &min_size, &nat_size);
else
GTK_SIZE_REQUEST_GET_IFACE (request)->get_height_for_width (request, for_size,
&min_size, &nat_size);
}
/* Support for dangling "size-request" signals and forward derived
* classes that will not default to a ->get_width() that
* returns the values in the ->requisition cache.
*/
min_size = MAX (min_size, requisition_size);
nat_size = MAX (nat_size, requisition_size);
cached_size->minimum_size = min_size;
cached_size->natural_size = nat_size;
cached_size->for_size = for_size;
if (orientation == GTK_SIZE_GROUP_HORIZONTAL)
{
cached_size->age = cache->cached_width_age;
cache->cached_width_age++;
GTK_PRIVATE_UNSET_FLAG (request, GTK_WIDTH_REQUEST_NEEDED);
}
else
{
cached_size->age = cache->cached_height_age;
cache->cached_height_age++;
GTK_PRIVATE_UNSET_FLAG (request, GTK_HEIGHT_REQUEST_NEEDED);
}
/* Get size groups to compute the base requisition once one
* of the values have been cached, then go ahead and update
* the cache with the sizegroup computed value.
*
* Note this is also where values from gtk_widget_set_size_request()
* are considered.
*/
group_size =
_gtk_size_group_bump_requisition (GTK_WIDGET (request),
orientation, cached_size->minimum_size);
cached_size->minimum_size = MAX (cached_size->minimum_size, group_size);
cached_size->natural_size = MAX (cached_size->natural_size, group_size);
}
if (minimum_size)
*minimum_size = cached_size->minimum_size;
if (natural_size)
*natural_size = cached_size->natural_size;
g_assert (cached_size->minimum_size <= cached_size->natural_size);
GTK_NOTE (SIZE_REQUEST,
g_print ("[%p] %s\t%s: %d is minimum %d and natural: %d (hit cache: %s)\n",
request, G_OBJECT_TYPE_NAME (request),
orientation == GTK_SIZE_GROUP_HORIZONTAL ?
"width for height" : "height for width" ,
for_size,
cached_size->minimum_size,
cached_size->natural_size,
found_in_cache ? "yes" : "no"));
}
/**
* gtk_size_request_is_height_for_width:
* @widget: a #GtkSizeRequest instance
*
* Gets whether the widget prefers a height-for-width layout
* or a width-for-height layout.
*
* <note><para>#GtkBin widgets generally propagate the preference of
* their child, container widgets need to request something either in
* context of their children or in context of their allocation
* capabilities.</para></note>
*
* Returns: %TRUE if the widget prefers height-for-width, %FALSE if
* the widget should be treated with a width-for-height preference.
*
* Since: 3.0
*/
GtkSizeRequestMode
gtk_size_request_get_request_mode (GtkSizeRequest *widget)
{
GtkSizeRequestIface *iface;
g_return_val_if_fail (GTK_IS_SIZE_REQUEST (widget), GTK_SIZE_REQUEST_HEIGHT_FOR_WIDTH);
iface = GTK_SIZE_REQUEST_GET_IFACE (widget);
if (iface->get_request_mode)
return iface->get_request_mode (widget);
/* By default widgets are height-for-width. */
return GTK_SIZE_REQUEST_HEIGHT_FOR_WIDTH;
}
/**
* gtk_size_request_get_width:
* @widget: a #GtkSizeRequest instance
* @minimum_width: (out) (allow-none): location to store the minimum width, or %NULL
* @natural_width: (out) (allow-none): location to store the natural width, or %NULL
*
* Retrieves a widget's initial minimum and natural width.
*
* <note><para>This call is specific to height-for-width
* requests.</para></note>
*
* Since: 3.0
*/
void
gtk_size_request_get_width (GtkSizeRequest *widget,
gint *minimum_width,
gint *natural_width)
{
compute_size_for_orientation (widget, GTK_SIZE_GROUP_HORIZONTAL,
-1, minimum_width, natural_width);
}
/**
* gtk_size_request_get_height:
* @widget: a #GtkSizeRequest instance
* @minimum_height: (out) (allow-none): location to store the minimum height, or %NULL
* @natural_height: (out) (allow-none): location to store the natural height, or %NULL
*
* Retrieves a widget's initial minimum and natural height.
*
* <note><para>This call is specific to width-for-height requests.</para></note>
*
* Since: 3.0
*/
void
gtk_size_request_get_height (GtkSizeRequest *widget,
gint *minimum_height,
gint *natural_height)
{
compute_size_for_orientation (widget, GTK_SIZE_GROUP_VERTICAL,
-1, minimum_height, natural_height);
}
/**
* gtk_size_request_get_width_for_height:
* @widget: a #GtkSizeRequest instance
* @height: the height which is available for allocation
* @minimum_width: (out) (allow-none): location for storing the minimum width, or %NULL
* @natural_width: (out) (allow-none): location for storing the natural width, or %NULL
*
* Retrieves a widget's desired width if it would be given
* the specified @height.
*
* Since: 3.0
*/
void
gtk_size_request_get_width_for_height (GtkSizeRequest *widget,
gint height,
gint *minimum_width,
gint *natural_width)
{
compute_size_for_orientation (widget, GTK_SIZE_GROUP_HORIZONTAL,
height, minimum_width, natural_width);
}
/**
* gtk_size_request_get_height_for_width:
* @widget: a #GtkSizeRequest instance
* @width: the width which is available for allocation
* @minimum_height: (out) (allow-none): location for storing the minimum height, or %NULL
* @natural_height: (out) (allow-none): location for storing the natural height, or %NULL
*
* Retrieves a widget's desired height if it would be given
* the specified @width.
*
* Since: 3.0
*/
void
gtk_size_request_get_height_for_width (GtkSizeRequest *widget,
gint width,
gint *minimum_height,
gint *natural_height)
{
compute_size_for_orientation (widget, GTK_SIZE_GROUP_VERTICAL,
width, minimum_height, natural_height);
}
/**
* gtk_size_request_get_size:
* @widget: a #GtkSizeRequest instance
* @minimum_size: (out) (allow-none): location for storing the minimum size, or %NULL
* @natural_size: (out) (allow-none): location for storing the natural size, or %NULL
*
* Retrieves the minimum and natural size of a widget taking
* into account the widget's preference for height-for-width management.
*
* This is used to retrieve a suitable size by container widgets which do
* not impose any restrictions on the child placement.
*
* Since: 3.0
*/
void
gtk_size_request_get_size (GtkSizeRequest *widget,
GtkRequisition *minimum_size,
GtkRequisition *natural_size)
{
gint min_width, nat_width;
gint min_height, nat_height;
g_return_if_fail (GTK_IS_SIZE_REQUEST (widget));
if (gtk_size_request_get_request_mode (widget) == GTK_SIZE_REQUEST_HEIGHT_FOR_WIDTH)
{
gtk_size_request_get_width (widget, &min_width, &nat_width);
if (minimum_size)
{
minimum_size->width = min_width;
gtk_size_request_get_height_for_width (widget, min_width,
&minimum_size->height, NULL);
}
if (natural_size)
{
natural_size->width = nat_width;
gtk_size_request_get_height_for_width (widget, nat_width,
NULL, &natural_size->height);
}
}
else
{
gtk_size_request_get_height (widget, &min_height, &nat_height);
if (minimum_size)
{
minimum_size->height = min_height;
gtk_size_request_get_width_for_height (widget, min_height,
&minimum_size->width, NULL);
}
if (natural_size)
{
natural_size->height = nat_height;
gtk_size_request_get_width_for_height (widget, nat_height,
NULL, &natural_size->width);
}
}
}
#define __GTK_SIZE_REQUEST_C__
#include "gtkaliasdef.c"