2 * Copyright (C) 2007-2010 Openismus GmbH
5 * Mathias Hasselmann <mathias@openismus.com>
6 * Tristan Van Berkom <tristan.van.berkom@gmail.com>
8 * This library is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Library General Public
10 * License as published by the Free Software Foundation; either
11 * version 2 of the License, or (at your option) any later version.
13 * This library is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Library General Public License for more details.
18 * You should have received a copy of the GNU Library General Public
19 * License along with this library; if not, write to the
20 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
21 * Boston, MA 02111-1307, USA.
26 * SECTION:gtksizerequest
27 * @Short_Description: Height-for-width geometry management
28 * @Title: GtkSizeRequest
30 * The GtkSizeRequest interface is GTK+'s height-for-width (and width-for-height)
31 * geometry management system. Height-for-width means that a widget can
32 * change how much vertical space it needs, depending on the amount
33 * of horizontal space that it is given (and similar for width-for-height).
34 * The most common example is a label that reflows to fill up the available
35 * width, wraps to fewer lines, and therefore needs less height.
37 * GTK+'s traditional two-pass <link linkend="size-allocation">size-allocation</link>
38 * algorithm does not allow this flexibility. #GtkWidget provides a default
39 * implementation of the #GtkSizeRequest interface for existing widgets,
40 * which always requests the same height, regardless of the available width.
43 * <title>Implementing GtkSizeRequest</title>
45 * Some important things to keep in mind when implementing
46 * the GtkSizeRequest interface and when using it in container
49 * The geometry management system will query a logical hierarchy in
50 * only one orientation at a time. When widgets are initially queried
51 * for their minimum sizes it is generally done in a dual pass
52 * in the direction chosen by the toplevel.
54 * For instance when queried in the normal height-for-width mode:
55 * First the default minimum and natural width for each widget
56 * in the interface will computed and collectively returned to
57 * the toplevel by way of gtk_size_request_get_width().
58 * Next, the toplevel will use the minimum width to query for the
59 * minimum height contextual to that width using
60 * gtk_size_request_get_height_for_width(), which will also be a
61 * highly recursive operation. This minimum-for-minimum size can be
62 * used to set the minimum size constraint on the toplevel.
64 * When allocating, each container can use the minimum and natural
65 * sizes reported by their children to allocate natural sizes and
66 * expose as much content as possible with the given allocation.
68 * That means that the request operation at allocation time will
69 * usually fire again in contexts of different allocated sizes than
70 * the ones originally queried for. #GtkSizeRequest caches a
71 * small number of results to avoid re-querying for the same
72 * allocated size in one allocation cycle.
74 * A widget that does not actually do height-for-width
75 * or width-for-height size negotiations only has to implement
76 * get_width() and get_height().
78 * If a widget does move content around to smartly use up the
79 * allocated size, then it must support the request properly in
80 * both orientations; even if the request only makes sense in
83 * For instance, a GtkLabel that does height-for-width word wrapping
84 * will not expect to have get_height() called because that
85 * call is specific to a width-for-height request, in this case the
86 * label must return the heights contextual to its minimum possible
87 * width. By following this rule any widget that handles height-for-width
88 * or width-for-height requests will always be allocated at least
89 * enough space to fit its own content.
96 #include "gtksizerequest.h"
97 #include "gtksizegroup.h"
98 #include "gtkprivate.h"
101 /* With GtkSizeRequest, a widget may be requested
102 * its width for 2 or maximum 3 heights in one resize
104 #define N_CACHED_SIZES 3
115 SizeRequest widths[N_CACHED_SIZES];
116 SizeRequest heights[N_CACHED_SIZES];
117 guint8 cached_width_age;
118 guint8 cached_height_age;
121 static GQuark quark_cache = 0;
124 typedef GtkSizeRequestIface GtkSizeRequestInterface;
125 G_DEFINE_INTERFACE_WITH_CODE (GtkSizeRequest,
128 quark_cache = g_quark_from_static_string ("gtk-size-request-cache"));
132 gtk_size_request_default_init (GtkSizeRequestInterface *iface)
137 /* looks for a cached size request for this for_size. If not
138 * found, returns the oldest entry so it can be overwritten
140 * Note that this caching code was directly derived from
141 * the Clutter toolkit.
144 get_cached_size (gint for_size,
145 SizeRequest *cached_sizes,
146 SizeRequest **result)
150 *result = &cached_sizes[0];
152 for (i = 0; i < N_CACHED_SIZES; i++)
156 cs = &cached_sizes[i];
158 if (cs->age > 0 && cs->for_size == for_size)
163 else if (cs->age < (*result)->age)
173 destroy_cache (SizeRequestCache *cache)
175 g_slice_free (SizeRequestCache, cache);
178 static SizeRequestCache *
179 get_cache (GtkSizeRequest *widget,
182 SizeRequestCache *cache;
184 cache = g_object_get_qdata (G_OBJECT (widget), quark_cache);
185 if (!cache && create)
187 cache = g_slice_new0 (SizeRequestCache);
189 cache->cached_width_age = 1;
190 cache->cached_height_age = 1;
192 g_object_set_qdata_full (G_OBJECT (widget), quark_cache, cache,
193 (GDestroyNotify)destroy_cache);
200 do_size_request (GtkWidget *widget,
201 GtkRequisition *requisition)
203 /* Now we dont bother caching the deprecated "size-request" returns,
204 * just unconditionally invoke here just in case we run into legacy stuff */
205 gtk_widget_ensure_style (widget);
206 g_signal_emit_by_name (widget, "size-request", requisition);
210 compute_size_for_orientation (GtkSizeRequest *request,
211 GtkSizeGroupMode orientation,
216 SizeRequestCache *cache;
217 SizeRequest *cached_size;
219 gboolean found_in_cache = FALSE;
221 g_return_if_fail (GTK_IS_SIZE_REQUEST (request));
222 g_return_if_fail (minimum_size != NULL || natural_size != NULL);
224 widget = GTK_WIDGET (request);
225 cache = get_cache (request, TRUE);
227 if (orientation == GTK_SIZE_GROUP_HORIZONTAL)
229 cached_size = &cache->widths[0];
231 if (!GTK_WIDGET_WIDTH_REQUEST_NEEDED (request))
232 found_in_cache = get_cached_size (for_size, cache->widths, &cached_size);
235 memset (cache->widths, 0, N_CACHED_SIZES * sizeof (SizeRequest));
236 cache->cached_width_age = 1;
241 cached_size = &cache->heights[0];
243 if (!GTK_WIDGET_HEIGHT_REQUEST_NEEDED (request))
244 found_in_cache = get_cached_size (for_size, cache->heights, &cached_size);
247 memset (cache->heights, 0, N_CACHED_SIZES * sizeof (SizeRequest));
248 cache->cached_height_age = 1;
254 GtkRequisition requisition = { 0, 0 };
255 gint min_size = 0, nat_size = 0;
256 gint group_size, requisition_size;
258 /* Unconditional size request runs but is often unhandled. */
259 do_size_request (widget, &requisition);
261 if (orientation == GTK_SIZE_GROUP_HORIZONTAL)
263 requisition_size = requisition.width;
266 GTK_SIZE_REQUEST_GET_IFACE (request)->get_width (request, &min_size, &nat_size);
268 GTK_SIZE_REQUEST_GET_IFACE (request)->get_width_for_height (request, for_size,
269 &min_size, &nat_size);
273 requisition_size = requisition.height;
276 GTK_SIZE_REQUEST_GET_IFACE (request)->get_height (request, &min_size, &nat_size);
278 GTK_SIZE_REQUEST_GET_IFACE (request)->get_height_for_width (request, for_size,
279 &min_size, &nat_size);
282 if (min_size > nat_size)
284 g_warning ("%s %p reported min size %d and natural size %d; natural size must be >= min size",
285 G_OBJECT_TYPE_NAME (request), request, min_size, nat_size);
288 /* Support for dangling "size-request" signal implementations on
291 min_size = MAX (min_size, requisition_size);
292 nat_size = MAX (nat_size, requisition_size);
294 cached_size->minimum_size = min_size;
295 cached_size->natural_size = nat_size;
296 cached_size->for_size = for_size;
298 if (orientation == GTK_SIZE_GROUP_HORIZONTAL)
300 cached_size->age = cache->cached_width_age;
301 cache->cached_width_age++;
303 GTK_PRIVATE_UNSET_FLAG (request, GTK_WIDTH_REQUEST_NEEDED);
307 cached_size->age = cache->cached_height_age;
308 cache->cached_height_age++;
310 GTK_PRIVATE_UNSET_FLAG (request, GTK_HEIGHT_REQUEST_NEEDED);
313 /* Get size groups to compute the base requisition once one
314 * of the values have been cached, then go ahead and update
315 * the cache with the sizegroup computed value.
317 * Note this is also where values from gtk_widget_set_size_request()
321 _gtk_size_group_bump_requisition (GTK_WIDGET (request),
322 orientation, cached_size->minimum_size);
324 cached_size->minimum_size = MAX (cached_size->minimum_size, group_size);
325 cached_size->natural_size = MAX (cached_size->natural_size, group_size);
329 *minimum_size = cached_size->minimum_size;
332 *natural_size = cached_size->natural_size;
334 g_assert (cached_size->minimum_size <= cached_size->natural_size);
336 GTK_NOTE (SIZE_REQUEST,
337 g_print ("[%p] %s\t%s: %d is minimum %d and natural: %d (hit cache: %s)\n",
338 request, G_OBJECT_TYPE_NAME (request),
339 orientation == GTK_SIZE_GROUP_HORIZONTAL ?
340 "width for height" : "height for width" ,
342 cached_size->minimum_size,
343 cached_size->natural_size,
344 found_in_cache ? "yes" : "no"));
349 * gtk_size_request_get_request_mode:
350 * @widget: a #GtkSizeRequest instance
352 * Gets whether the widget prefers a height-for-width layout
353 * or a width-for-height layout.
355 * <note><para>#GtkBin widgets generally propagate the preference of
356 * their child, container widgets need to request something either in
357 * context of their children or in context of their allocation
358 * capabilities.</para></note>
360 * Returns: The #GtkSizeRequestMode preferred by @widget.
365 gtk_size_request_get_request_mode (GtkSizeRequest *widget)
367 GtkSizeRequestIface *iface;
369 g_return_val_if_fail (GTK_IS_SIZE_REQUEST (widget), GTK_SIZE_REQUEST_HEIGHT_FOR_WIDTH);
371 iface = GTK_SIZE_REQUEST_GET_IFACE (widget);
372 if (iface->get_request_mode)
373 return iface->get_request_mode (widget);
375 /* By default widgets are height-for-width. */
376 return GTK_SIZE_REQUEST_HEIGHT_FOR_WIDTH;
380 * gtk_size_request_get_width:
381 * @widget: a #GtkSizeRequest instance
382 * @minimum_width: (out) (allow-none): location to store the minimum width, or %NULL
383 * @natural_width: (out) (allow-none): location to store the natural width, or %NULL
385 * Retrieves a widget's initial minimum and natural width.
387 * <note><para>This call is specific to height-for-width
388 * requests.</para></note>
393 gtk_size_request_get_width (GtkSizeRequest *widget,
397 compute_size_for_orientation (widget, GTK_SIZE_GROUP_HORIZONTAL,
398 -1, minimum_width, natural_width);
403 * gtk_size_request_get_height:
404 * @widget: a #GtkSizeRequest instance
405 * @minimum_height: (out) (allow-none): location to store the minimum height, or %NULL
406 * @natural_height: (out) (allow-none): location to store the natural height, or %NULL
408 * Retrieves a widget's initial minimum and natural height.
410 * <note><para>This call is specific to width-for-height requests.</para></note>
415 gtk_size_request_get_height (GtkSizeRequest *widget,
416 gint *minimum_height,
417 gint *natural_height)
419 compute_size_for_orientation (widget, GTK_SIZE_GROUP_VERTICAL,
420 -1, minimum_height, natural_height);
426 * gtk_size_request_get_width_for_height:
427 * @widget: a #GtkSizeRequest instance
428 * @height: the height which is available for allocation
429 * @minimum_width: (out) (allow-none): location for storing the minimum width, or %NULL
430 * @natural_width: (out) (allow-none): location for storing the natural width, or %NULL
432 * Retrieves a widget's minimum and natural width if it would be given
433 * the specified @height.
438 gtk_size_request_get_width_for_height (GtkSizeRequest *widget,
443 compute_size_for_orientation (widget, GTK_SIZE_GROUP_HORIZONTAL,
444 height, minimum_width, natural_width);
448 * gtk_size_request_get_height_for_width:
449 * @widget: a #GtkSizeRequest instance
450 * @width: the width which is available for allocation
451 * @minimum_height: (out) (allow-none): location for storing the minimum height, or %NULL
452 * @natural_height: (out) (allow-none): location for storing the natural height, or %NULL
454 * Retrieves a widget's minimum and natural height if it would be given
455 * the specified @width.
460 gtk_size_request_get_height_for_width (GtkSizeRequest *widget,
462 gint *minimum_height,
463 gint *natural_height)
465 compute_size_for_orientation (widget, GTK_SIZE_GROUP_VERTICAL,
466 width, minimum_height, natural_height);
470 * gtk_size_request_get_size:
471 * @widget: a #GtkSizeRequest instance
472 * @minimum_size: (out) (allow-none): location for storing the minimum size, or %NULL
473 * @natural_size: (out) (allow-none): location for storing the natural size, or %NULL
475 * Retrieves the minimum and natural size of a widget taking
476 * into account the widget's preference for height-for-width management.
478 * This is used to retrieve a suitable size by container widgets which do
479 * not impose any restrictions on the child placement.
484 gtk_size_request_get_size (GtkSizeRequest *widget,
485 GtkRequisition *minimum_size,
486 GtkRequisition *natural_size)
488 gint min_width, nat_width;
489 gint min_height, nat_height;
491 g_return_if_fail (GTK_IS_SIZE_REQUEST (widget));
493 if (gtk_size_request_get_request_mode (widget) == GTK_SIZE_REQUEST_HEIGHT_FOR_WIDTH)
495 gtk_size_request_get_width (widget, &min_width, &nat_width);
499 minimum_size->width = min_width;
500 gtk_size_request_get_height_for_width (widget, min_width,
501 &minimum_size->height, NULL);
506 natural_size->width = nat_width;
507 gtk_size_request_get_height_for_width (widget, nat_width,
508 NULL, &natural_size->height);
511 else /* GTK_SIZE_REQUEST_WIDTH_FOR_HEIGHT */
513 gtk_size_request_get_height (widget, &min_height, &nat_height);
517 minimum_size->height = min_height;
518 gtk_size_request_get_width_for_height (widget, min_height,
519 &minimum_size->width, NULL);
524 natural_size->height = nat_height;
525 gtk_size_request_get_width_for_height (widget, nat_height,
526 NULL, &natural_size->width);
533 compare_gap (gconstpointer p1,
537 GtkRequestedSize *sizes = data;
538 const guint *c1 = p1;
539 const guint *c2 = p2;
541 const gint d1 = MAX (sizes[*c1].natural_size -
542 sizes[*c1].minimum_size,
544 const gint d2 = MAX (sizes[*c2].natural_size -
545 sizes[*c2].minimum_size,
548 gint delta = (d2 - d1);
557 * gtk_distribute_natural_allocation:
558 * @extra_space: Extra space to redistribute among children after subtracting
559 * minimum sizes and any child padding from the overall allocation
560 * @n_requested_sizes: Number of requests to fit into the allocation
561 * @sizes: An array of structs with a client pointer and a minimum/natural size
562 * in the orientation of the allocation.
564 * Distributes @extra_space to child @sizes by bringing up smaller
565 * children up to natural size first.
567 * The remaining space will be added to the @minimum_size member of the
568 * GtkRequestedSize struct. If all sizes reach their natural size then
569 * the remaining space is returned.
571 * Returns: The remainder of @extra_space after redistributing space
575 gtk_distribute_natural_allocation (gint extra_space,
576 guint n_requested_sizes,
577 GtkRequestedSize *sizes)
579 guint *spreading = g_newa (guint, n_requested_sizes);
582 g_return_val_if_fail (extra_space >= 0, 0);
584 for (i = 0; i < n_requested_sizes; i++)
587 /* Distribute the container's extra space c_gap. We want to assign
588 * this space such that the sum of extra space assigned to children
589 * (c^i_gap) is equal to c_cap. The case that there's not enough
590 * space for all children to take their natural size needs some
591 * attention. The goals we want to achieve are:
593 * a) Maximize number of children taking their natural size.
594 * b) The allocated size of children should be a continuous
595 * function of c_gap. That is, increasing the container size by
596 * one pixel should never make drastic changes in the distribution.
597 * c) If child i takes its natural size and child j doesn't,
598 * child j should have received at least as much gap as child i.
600 * The following code distributes the additional space by following
604 /* Sort descending by gap and position. */
605 g_qsort_with_data (spreading,
606 n_requested_sizes, sizeof (guint),
609 /* Distribute available space.
610 * This master piece of a loop was conceived by Behdad Esfahbod.
612 for (i = n_requested_sizes - 1; extra_space > 0 && i >= 0; --i)
614 /* Divide remaining space by number of remaining children.
615 * Sort order and reducing remaining space by assigned space
616 * ensures that space is distributed equally.
618 gint glue = (extra_space + i) / (i + 1);
619 gint gap = sizes[(spreading[i])].natural_size
620 - sizes[(spreading[i])].minimum_size;
622 gint extra = MIN (glue, gap);
624 sizes[spreading[i]].minimum_size += extra;
626 extra_space -= extra;