/* gtksizerequest.c * Copyright (C) 2007-2010 Openismus GmbH * * Authors: * Mathias Hasselmann * Tristan Van Berkom * * 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 size-allocation * 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. * * * Implementing GtkSizeRequest * * 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_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. * * */ #include #include "gtksizerequest.h" #include "gtksizegroup.h" #include "gtkprivate.h" #include "gtkintl.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; typedef GtkSizeRequestIface GtkSizeRequestInterface; G_DEFINE_INTERFACE_WITH_CODE (GtkSizeRequest, gtk_size_request, GTK_TYPE_WIDGET, quark_cache = g_quark_from_static_string ("gtk-size-request-cache")); static void gtk_size_request_default_init (GtkSizeRequestInterface *iface) { } /* 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_get_request_mode: * @widget: a #GtkSizeRequest instance * * Gets whether the widget prefers a height-for-width layout * or a width-for-height layout. * * #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. * * Returns: The #GtkSizeRequestMode preferred by @widget. * * 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. * * This call is specific to height-for-width * requests. * * 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. * * This call is specific to width-for-height requests. * * 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 minimum and natural 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 minimum and natural 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_WIDTH_FOR_HEIGHT */ { 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); } } } static gint compare_gap (gconstpointer p1, gconstpointer p2, gpointer data) { GtkRequestedSize *sizes = data; const guint *c1 = p1; const guint *c2 = p2; const gint d1 = MAX (sizes[*c1].natural_size - sizes[*c1].minimum_size, 0); const gint d2 = MAX (sizes[*c2].natural_size - sizes[*c2].minimum_size, 0); gint delta = (d2 - d1); if (0 == delta) delta = (*c2 - *c1); return delta; } /** * gtk_distribute_natural_allocation: * @extra_space: Extra space to redistribute among children after subtracting * minimum sizes and any child padding from the overall allocation * @n_requested_sizes: Number of requests to fit into the allocation * @sizes: An array of structs with a client pointer and a minimum/natural size * in the orientation of the allocation. * * Distributes @extra_space to child @sizes by bringing up smaller * children up to natural size first. * * The remaining space will be added to the @minimum_size member of the * GtkRequestedSize struct. If all sizes reach their natural size then * the remaining space is returned. * * Returns: The remainder of @extra_space after redistributing space * to @sizes. */ gint gtk_distribute_natural_allocation (gint extra_space, guint n_requested_sizes, GtkRequestedSize *sizes) { guint *spreading = g_newa (guint, n_requested_sizes); gint i; g_return_val_if_fail (extra_space >= 0, 0); for (i = 0; i < n_requested_sizes; i++) spreading[i] = i; /* Distribute the container's extra space c_gap. We want to assign * this space such that the sum of extra space assigned to children * (c^i_gap) is equal to c_cap. The case that there's not enough * space for all children to take their natural size needs some * attention. The goals we want to achieve are: * * a) Maximize number of children taking their natural size. * b) The allocated size of children should be a continuous * function of c_gap. That is, increasing the container size by * one pixel should never make drastic changes in the distribution. * c) If child i takes its natural size and child j doesn't, * child j should have received at least as much gap as child i. * * The following code distributes the additional space by following * these rules. */ /* Sort descending by gap and position. */ g_qsort_with_data (spreading, n_requested_sizes, sizeof (guint), compare_gap, sizes); /* Distribute available space. * This master piece of a loop was conceived by Behdad Esfahbod. */ for (i = n_requested_sizes - 1; extra_space > 0 && i >= 0; --i) { /* Divide remaining space by number of remaining children. * Sort order and reducing remaining space by assigned space * ensures that space is distributed equally. */ gint glue = (extra_space + i) / (i + 1); gint gap = sizes[(spreading[i])].natural_size - sizes[(spreading[i])].minimum_size; gint extra = MIN (glue, gap); sizes[spreading[i]].minimum_size += extra; extra_space -= extra; } return extra_space; }