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 typedef GtkSizeRequestIface GtkSizeRequestInterface;
102 G_DEFINE_INTERFACE (GtkSizeRequest,
108 gtk_size_request_default_init (GtkSizeRequestInterface *iface)
113 /* looks for a cached size request for this for_size. If not
114 * found, returns the oldest entry so it can be overwritten
116 * Note that this caching code was directly derived from
117 * the Clutter toolkit.
120 get_cached_size (gint for_size,
121 SizeRequest *cached_sizes,
122 SizeRequest **result)
126 *result = &cached_sizes[0];
128 for (i = 0; i < GTK_SIZE_REQUEST_CACHED_SIZES; i++)
132 cs = &cached_sizes[i];
134 if (cs->age > 0 && cs->for_size == for_size)
139 else if (cs->age < (*result)->age)
149 do_size_request (GtkWidget *widget,
150 GtkRequisition *requisition)
152 /* Now we dont bother caching the deprecated "size-request" returns,
153 * just unconditionally invoke here just in case we run into legacy stuff */
154 gtk_widget_ensure_style (widget);
155 g_signal_emit_by_name (widget, "size-request", requisition);
158 #ifndef G_DISABLE_CHECKS
159 static GQuark recursion_check_quark = 0;
160 #endif /* G_DISABLE_CHECKS */
163 push_recursion_check (GtkSizeRequest *request,
164 GtkSizeGroupMode orientation,
167 #ifndef G_DISABLE_CHECKS
168 const char *previous_method;
171 if (recursion_check_quark == 0)
172 recursion_check_quark = g_quark_from_static_string ("gtk-size-request-in-progress");
174 previous_method = g_object_get_qdata (G_OBJECT (request), recursion_check_quark);
176 if (orientation == GTK_SIZE_GROUP_HORIZONTAL)
178 method = for_size < 0 ? "get_width" : "get_width_for_height";
182 method = for_size < 0 ? "get_height" : "get_height_for_width";
185 if (previous_method != NULL)
187 g_warning ("%s %p: widget tried to gtk_size_request_%s inside "
188 " GtkSizeRequest::%s implementation. "
189 "Should just invoke GTK_SIZE_REQUEST_GET_IFACE(widget)->%s "
190 "directly rather than using gtk_size_request_%s",
191 G_OBJECT_TYPE_NAME (request), request,
192 method, previous_method,
196 g_object_set_qdata (G_OBJECT (request), recursion_check_quark, (char*) method);
197 #endif /* G_DISABLE_CHECKS */
201 pop_recursion_check (GtkSizeRequest *request,
202 GtkSizeGroupMode orientation)
204 #ifndef G_DISABLE_CHECKS
205 g_object_set_qdata (G_OBJECT (request), recursion_check_quark, NULL);
210 compute_size_for_orientation (GtkSizeRequest *request,
211 GtkSizeGroupMode orientation,
216 SizeRequestCache *cache;
217 SizeRequest *cached_size;
219 gboolean found_in_cache = FALSE;
220 int adjusted_min, adjusted_natural;
222 g_return_if_fail (GTK_IS_SIZE_REQUEST (request));
223 g_return_if_fail (minimum_size != NULL || natural_size != NULL);
225 widget = GTK_WIDGET (request);
226 cache = _gtk_widget_peek_request_cache (widget);
228 if (orientation == GTK_SIZE_GROUP_HORIZONTAL)
230 cached_size = &cache->widths[0];
232 if (!GTK_WIDGET_WIDTH_REQUEST_NEEDED (request))
233 found_in_cache = get_cached_size (for_size, cache->widths, &cached_size);
236 memset (cache->widths, 0, GTK_SIZE_REQUEST_CACHED_SIZES * sizeof (SizeRequest));
237 cache->cached_width_age = 1;
242 cached_size = &cache->heights[0];
244 if (!GTK_WIDGET_HEIGHT_REQUEST_NEEDED (request))
245 found_in_cache = get_cached_size (for_size, cache->heights, &cached_size);
248 memset (cache->heights, 0, GTK_SIZE_REQUEST_CACHED_SIZES * sizeof (SizeRequest));
249 cache->cached_height_age = 1;
255 GtkRequisition requisition = { 0, 0 };
256 gint min_size = 0, nat_size = 0;
257 gint group_size, requisition_size;
259 /* Unconditional size request runs but is often unhandled. */
260 do_size_request (widget, &requisition);
262 push_recursion_check (request, orientation, for_size);
263 if (orientation == GTK_SIZE_GROUP_HORIZONTAL)
265 requisition_size = requisition.width;
268 GTK_SIZE_REQUEST_GET_IFACE (request)->get_width (request, &min_size, &nat_size);
270 GTK_SIZE_REQUEST_GET_IFACE (request)->get_width_for_height (request, for_size,
271 &min_size, &nat_size);
275 requisition_size = requisition.height;
278 GTK_SIZE_REQUEST_GET_IFACE (request)->get_height (request, &min_size, &nat_size);
280 GTK_SIZE_REQUEST_GET_IFACE (request)->get_height_for_width (request, for_size,
281 &min_size, &nat_size);
283 pop_recursion_check (request, orientation);
285 if (min_size > nat_size)
287 g_warning ("%s %p reported min size %d and natural size %d; natural size must be >= min size",
288 G_OBJECT_TYPE_NAME (request), request, min_size, nat_size);
291 /* Support for dangling "size-request" signal implementations on
294 min_size = MAX (min_size, requisition_size);
295 nat_size = MAX (nat_size, requisition_size);
297 cached_size->minimum_size = min_size;
298 cached_size->natural_size = nat_size;
299 cached_size->for_size = for_size;
301 if (orientation == GTK_SIZE_GROUP_HORIZONTAL)
303 cached_size->age = cache->cached_width_age;
304 cache->cached_width_age++;
306 GTK_PRIVATE_UNSET_FLAG (request, GTK_WIDTH_REQUEST_NEEDED);
310 cached_size->age = cache->cached_height_age;
311 cache->cached_height_age++;
313 GTK_PRIVATE_UNSET_FLAG (request, GTK_HEIGHT_REQUEST_NEEDED);
316 adjusted_min = cached_size->minimum_size;
317 adjusted_natural = cached_size->natural_size;
318 GTK_WIDGET_GET_CLASS (request)->adjust_size_request (GTK_WIDGET (request),
319 orientation == GTK_SIZE_GROUP_HORIZONTAL ?
320 GTK_ORIENTATION_HORIZONTAL :
321 GTK_ORIENTATION_VERTICAL,
322 cached_size->for_size,
326 if (adjusted_min < cached_size->minimum_size ||
327 adjusted_natural < cached_size->natural_size)
329 g_warning ("%s %p adjusted size %s min %d natural %d must not decrease below min %d natural %d",
330 G_OBJECT_TYPE_NAME (request), request,
331 orientation == GTK_SIZE_GROUP_VERTICAL ? "vertical" : "horizontal",
332 adjusted_min, adjusted_natural,
333 cached_size->minimum_size, cached_size->natural_size);
334 /* don't use the adjustment */
336 else if (adjusted_min > adjusted_natural)
338 g_warning ("%s %p adjusted size %s min %d natural %d original min %d natural %d has min greater than natural",
339 G_OBJECT_TYPE_NAME (request), request,
340 orientation == GTK_SIZE_GROUP_VERTICAL ? "vertical" : "horizontal",
341 adjusted_min, adjusted_natural,
342 cached_size->minimum_size, cached_size->natural_size);
343 /* don't use the adjustment */
347 /* adjustment looks good */
348 cached_size->minimum_size = adjusted_min;
349 cached_size->natural_size = adjusted_natural;
352 /* Get size groups to compute the base requisition once one
353 * of the values have been cached, then go ahead and update
354 * the cache with the sizegroup computed value.
357 _gtk_size_group_bump_requisition (GTK_WIDGET (request),
358 orientation, cached_size->minimum_size);
360 cached_size->minimum_size = MAX (cached_size->minimum_size, group_size);
361 cached_size->natural_size = MAX (cached_size->natural_size, group_size);
365 *minimum_size = cached_size->minimum_size;
368 *natural_size = cached_size->natural_size;
370 g_assert (cached_size->minimum_size <= cached_size->natural_size);
372 GTK_NOTE (SIZE_REQUEST,
373 g_print ("[%p] %s\t%s: %d is minimum %d and natural: %d (hit cache: %s)\n",
374 request, G_OBJECT_TYPE_NAME (request),
375 orientation == GTK_SIZE_GROUP_HORIZONTAL ?
376 "width for height" : "height for width" ,
378 cached_size->minimum_size,
379 cached_size->natural_size,
380 found_in_cache ? "yes" : "no"));
385 * gtk_size_request_get_request_mode:
386 * @widget: a #GtkSizeRequest instance
388 * Gets whether the widget prefers a height-for-width layout
389 * or a width-for-height layout.
391 * <note><para>#GtkBin widgets generally propagate the preference of
392 * their child, container widgets need to request something either in
393 * context of their children or in context of their allocation
394 * capabilities.</para></note>
396 * Returns: The #GtkSizeRequestMode preferred by @widget.
401 gtk_size_request_get_request_mode (GtkSizeRequest *widget)
403 GtkSizeRequestIface *iface;
405 g_return_val_if_fail (GTK_IS_SIZE_REQUEST (widget), GTK_SIZE_REQUEST_HEIGHT_FOR_WIDTH);
407 iface = GTK_SIZE_REQUEST_GET_IFACE (widget);
408 if (iface->get_request_mode)
409 return iface->get_request_mode (widget);
411 /* By default widgets are height-for-width. */
412 return GTK_SIZE_REQUEST_HEIGHT_FOR_WIDTH;
416 * gtk_size_request_get_width:
417 * @widget: a #GtkSizeRequest instance
418 * @minimum_width: (out) (allow-none): location to store the minimum width, or %NULL
419 * @natural_width: (out) (allow-none): location to store the natural width, or %NULL
421 * Retrieves a widget's initial minimum and natural width.
423 * <note><para>This call is specific to height-for-width
424 * requests.</para></note>
429 gtk_size_request_get_width (GtkSizeRequest *widget,
433 compute_size_for_orientation (widget, GTK_SIZE_GROUP_HORIZONTAL,
434 -1, minimum_width, natural_width);
439 * gtk_size_request_get_height:
440 * @widget: a #GtkSizeRequest instance
441 * @minimum_height: (out) (allow-none): location to store the minimum height, or %NULL
442 * @natural_height: (out) (allow-none): location to store the natural height, or %NULL
444 * Retrieves a widget's initial minimum and natural height.
446 * <note><para>This call is specific to width-for-height requests.</para></note>
451 gtk_size_request_get_height (GtkSizeRequest *widget,
452 gint *minimum_height,
453 gint *natural_height)
455 compute_size_for_orientation (widget, GTK_SIZE_GROUP_VERTICAL,
456 -1, minimum_height, natural_height);
462 * gtk_size_request_get_width_for_height:
463 * @widget: a #GtkSizeRequest instance
464 * @height: the height which is available for allocation
465 * @minimum_width: (out) (allow-none): location for storing the minimum width, or %NULL
466 * @natural_width: (out) (allow-none): location for storing the natural width, or %NULL
468 * Retrieves a widget's minimum and natural width if it would be given
469 * the specified @height.
474 gtk_size_request_get_width_for_height (GtkSizeRequest *widget,
479 compute_size_for_orientation (widget, GTK_SIZE_GROUP_HORIZONTAL,
480 height, minimum_width, natural_width);
484 * gtk_size_request_get_height_for_width:
485 * @widget: a #GtkSizeRequest instance
486 * @width: the width which is available for allocation
487 * @minimum_height: (out) (allow-none): location for storing the minimum height, or %NULL
488 * @natural_height: (out) (allow-none): location for storing the natural height, or %NULL
490 * Retrieves a widget's minimum and natural height if it would be given
491 * the specified @width.
496 gtk_size_request_get_height_for_width (GtkSizeRequest *widget,
498 gint *minimum_height,
499 gint *natural_height)
501 compute_size_for_orientation (widget, GTK_SIZE_GROUP_VERTICAL,
502 width, minimum_height, natural_height);
506 * gtk_size_request_get_size:
507 * @widget: a #GtkSizeRequest instance
508 * @minimum_size: (out) (allow-none): location for storing the minimum size, or %NULL
509 * @natural_size: (out) (allow-none): location for storing the natural size, or %NULL
511 * Retrieves the minimum and natural size of a widget taking
512 * into account the widget's preference for height-for-width management.
514 * This is used to retrieve a suitable size by container widgets which do
515 * not impose any restrictions on the child placement.
520 gtk_size_request_get_size (GtkSizeRequest *widget,
521 GtkRequisition *minimum_size,
522 GtkRequisition *natural_size)
524 gint min_width, nat_width;
525 gint min_height, nat_height;
527 g_return_if_fail (GTK_IS_SIZE_REQUEST (widget));
529 if (gtk_size_request_get_request_mode (widget) == GTK_SIZE_REQUEST_HEIGHT_FOR_WIDTH)
531 gtk_size_request_get_width (widget, &min_width, &nat_width);
535 minimum_size->width = min_width;
536 gtk_size_request_get_height_for_width (widget, min_width,
537 &minimum_size->height, NULL);
542 natural_size->width = nat_width;
543 gtk_size_request_get_height_for_width (widget, nat_width,
544 NULL, &natural_size->height);
547 else /* GTK_SIZE_REQUEST_WIDTH_FOR_HEIGHT */
549 gtk_size_request_get_height (widget, &min_height, &nat_height);
553 minimum_size->height = min_height;
554 gtk_size_request_get_width_for_height (widget, min_height,
555 &minimum_size->width, NULL);
560 natural_size->height = nat_height;
561 gtk_size_request_get_width_for_height (widget, nat_height,
562 NULL, &natural_size->width);
569 compare_gap (gconstpointer p1,
573 GtkRequestedSize *sizes = data;
574 const guint *c1 = p1;
575 const guint *c2 = p2;
577 const gint d1 = MAX (sizes[*c1].natural_size -
578 sizes[*c1].minimum_size,
580 const gint d2 = MAX (sizes[*c2].natural_size -
581 sizes[*c2].minimum_size,
584 gint delta = (d2 - d1);
593 * gtk_distribute_natural_allocation:
594 * @extra_space: Extra space to redistribute among children after subtracting
595 * minimum sizes and any child padding from the overall allocation
596 * @n_requested_sizes: Number of requests to fit into the allocation
597 * @sizes: An array of structs with a client pointer and a minimum/natural size
598 * in the orientation of the allocation.
600 * Distributes @extra_space to child @sizes by bringing up smaller
601 * children up to natural size first.
603 * The remaining space will be added to the @minimum_size member of the
604 * GtkRequestedSize struct. If all sizes reach their natural size then
605 * the remaining space is returned.
607 * Returns: The remainder of @extra_space after redistributing space
611 gtk_distribute_natural_allocation (gint extra_space,
612 guint n_requested_sizes,
613 GtkRequestedSize *sizes)
615 guint *spreading = g_newa (guint, n_requested_sizes);
618 g_return_val_if_fail (extra_space >= 0, 0);
620 for (i = 0; i < n_requested_sizes; i++)
623 /* Distribute the container's extra space c_gap. We want to assign
624 * this space such that the sum of extra space assigned to children
625 * (c^i_gap) is equal to c_cap. The case that there's not enough
626 * space for all children to take their natural size needs some
627 * attention. The goals we want to achieve are:
629 * a) Maximize number of children taking their natural size.
630 * b) The allocated size of children should be a continuous
631 * function of c_gap. That is, increasing the container size by
632 * one pixel should never make drastic changes in the distribution.
633 * c) If child i takes its natural size and child j doesn't,
634 * child j should have received at least as much gap as child i.
636 * The following code distributes the additional space by following
640 /* Sort descending by gap and position. */
641 g_qsort_with_data (spreading,
642 n_requested_sizes, sizeof (guint),
645 /* Distribute available space.
646 * This master piece of a loop was conceived by Behdad Esfahbod.
648 for (i = n_requested_sizes - 1; extra_space > 0 && i >= 0; --i)
650 /* Divide remaining space by number of remaining children.
651 * Sort order and reducing remaining space by assigned space
652 * ensures that space is distributed equally.
654 gint glue = (extra_space + i) / (i + 1);
655 gint gap = sizes[(spreading[i])].natural_size
656 - sizes[(spreading[i])].minimum_size;
658 gint extra = MIN (glue, gap);
660 sizes[spreading[i]].minimum_size += extra;
662 extra_space -= extra;