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.
91 * Often a widget needs to get its own request during size request or
92 * allocation, for example when computing height it may need to also
93 * compute width, or when deciding how to use an allocation the widget may
94 * need to know its natural size. In these cases, the widget should be
95 * careful to call its virtual methods directly, like this:
97 * <title>Widget calling its own size request method.</title>
99 * GTK_SIZE_REQUEST_GET_IFACE(widget)->get_width(GTK_SIZE_REQUEST(widget), &min, &natural);
103 * It will not work to use the wrapper functions, such as
104 * gtk_size_request_get_width(), inside your own size request
105 * implementation. These return a request adjusted by #GtkSizeGroup
106 * and by the GtkWidgetClass::adjust_size_request virtual method. If a
107 * widget used the wrappers inside its virtual method implementations,
108 * then the adjustments (such as widget margins) would be applied
109 * twice. GTK+ therefore does not allow this and will warn if you try
112 * Of course if you are getting the size request for
113 * <emphasis>another</emphasis> widget, such as a child of a
114 * container, you <emphasis>must</emphasis> use the wrapper APIs;
115 * otherwise, you would not properly consider widget margins,
116 * #GtkSizeGroup, and so forth.
123 #include "gtksizerequest.h"
124 #include "gtksizegroup.h"
125 #include "gtkprivate.h"
128 typedef GtkSizeRequestIface GtkSizeRequestInterface;
129 G_DEFINE_INTERFACE (GtkSizeRequest,
135 gtk_size_request_default_init (GtkSizeRequestInterface *iface)
140 /* looks for a cached size request for this for_size. If not
141 * found, returns the oldest entry so it can be overwritten
143 * Note that this caching code was directly derived from
144 * the Clutter toolkit.
147 get_cached_size (SizeRequestCache *cache,
148 GtkSizeGroupMode orientation,
150 SizeRequest **result)
153 SizeRequest *cached_sizes;
155 if (orientation == GTK_SIZE_GROUP_HORIZONTAL)
157 cached_sizes = cache->widths;
158 n_sizes = cache->cached_widths;
162 cached_sizes = cache->heights;
163 n_sizes = cache->cached_widths;
166 /* Search for an already cached size */
167 for (i = 0; i < n_sizes; i++)
169 if (cached_sizes[i].for_size == for_size)
171 *result = &cached_sizes[i];
176 /* If not found, pull a new size from the cache, the returned size cache
177 * will immediately be used to cache the new computed size so we go ahead
178 * and increment the last_cached_width/height right away */
179 if (orientation == GTK_SIZE_GROUP_HORIZONTAL)
181 if (cache->cached_widths < GTK_SIZE_REQUEST_CACHED_SIZES)
183 cache->cached_widths++;
184 cache->last_cached_width = cache->cached_widths - 1;
188 if (++cache->last_cached_width == GTK_SIZE_REQUEST_CACHED_SIZES)
189 cache->last_cached_width = 0;
192 *result = &cache->widths[cache->last_cached_width];
194 else /* GTK_SIZE_GROUP_VERTICAL */
196 if (cache->cached_heights < GTK_SIZE_REQUEST_CACHED_SIZES)
198 cache->cached_heights++;
199 cache->last_cached_height = cache->cached_heights - 1;
203 if (++cache->last_cached_height == GTK_SIZE_REQUEST_CACHED_SIZES)
204 cache->last_cached_height = 0;
207 *result = &cache->heights[cache->last_cached_height];
214 do_size_request (GtkWidget *widget,
215 GtkRequisition *requisition)
217 /* Now we dont bother caching the deprecated "size-request" returns,
218 * just unconditionally invoke here just in case we run into legacy stuff */
219 gtk_widget_ensure_style (widget);
220 g_signal_emit_by_name (widget, "size-request", requisition);
223 #ifndef G_DISABLE_CHECKS
224 static GQuark recursion_check_quark = 0;
225 #endif /* G_DISABLE_CHECKS */
228 push_recursion_check (GtkSizeRequest *request,
229 GtkSizeGroupMode orientation,
232 #ifndef G_DISABLE_CHECKS
233 const char *previous_method;
236 if (recursion_check_quark == 0)
237 recursion_check_quark = g_quark_from_static_string ("gtk-size-request-in-progress");
239 previous_method = g_object_get_qdata (G_OBJECT (request), recursion_check_quark);
241 if (orientation == GTK_SIZE_GROUP_HORIZONTAL)
243 method = for_size < 0 ? "get_width" : "get_width_for_height";
247 method = for_size < 0 ? "get_height" : "get_height_for_width";
250 if (previous_method != NULL)
252 g_warning ("%s %p: widget tried to gtk_size_request_%s inside "
253 " GtkSizeRequest::%s implementation. "
254 "Should just invoke GTK_SIZE_REQUEST_GET_IFACE(widget)->%s "
255 "directly rather than using gtk_size_request_%s",
256 G_OBJECT_TYPE_NAME (request), request,
257 method, previous_method,
261 g_object_set_qdata (G_OBJECT (request), recursion_check_quark, (char*) method);
262 #endif /* G_DISABLE_CHECKS */
266 pop_recursion_check (GtkSizeRequest *request,
267 GtkSizeGroupMode orientation)
269 #ifndef G_DISABLE_CHECKS
270 g_object_set_qdata (G_OBJECT (request), recursion_check_quark, NULL);
275 compute_size_for_orientation (GtkSizeRequest *request,
276 GtkSizeGroupMode orientation,
281 SizeRequestCache *cache;
282 SizeRequest *cached_size;
284 gboolean found_in_cache = FALSE;
285 int adjusted_min, adjusted_natural;
287 g_return_if_fail (GTK_IS_SIZE_REQUEST (request));
288 g_return_if_fail (minimum_size != NULL || natural_size != NULL);
290 widget = GTK_WIDGET (request);
291 cache = _gtk_widget_peek_request_cache (widget);
293 if (orientation == GTK_SIZE_GROUP_HORIZONTAL)
295 cached_size = &cache->widths[0];
297 if (!GTK_WIDGET_WIDTH_REQUEST_NEEDED (request))
298 found_in_cache = get_cached_size (cache, orientation, for_size, &cached_size);
301 memset (cache->widths, 0, GTK_SIZE_REQUEST_CACHED_SIZES * sizeof (SizeRequest));
302 cache->cached_widths = 1;
303 cache->last_cached_width = 0;
308 cached_size = &cache->heights[0];
310 if (!GTK_WIDGET_HEIGHT_REQUEST_NEEDED (request))
311 found_in_cache = get_cached_size (cache, orientation, for_size, &cached_size);
314 memset (cache->heights, 0, GTK_SIZE_REQUEST_CACHED_SIZES * sizeof (SizeRequest));
315 cache->cached_heights = 1;
316 cache->last_cached_height = 0;
322 GtkRequisition requisition = { 0, 0 };
323 gint min_size = 0, nat_size = 0;
324 gint requisition_size;
326 /* Unconditional size request runs but is often unhandled. */
327 do_size_request (widget, &requisition);
329 push_recursion_check (request, orientation, for_size);
330 if (orientation == GTK_SIZE_GROUP_HORIZONTAL)
332 requisition_size = requisition.width;
335 GTK_SIZE_REQUEST_GET_IFACE (request)->get_width (request, &min_size, &nat_size);
337 GTK_SIZE_REQUEST_GET_IFACE (request)->get_width_for_height (request, for_size,
338 &min_size, &nat_size);
342 requisition_size = requisition.height;
345 GTK_SIZE_REQUEST_GET_IFACE (request)->get_height (request, &min_size, &nat_size);
347 GTK_SIZE_REQUEST_GET_IFACE (request)->get_height_for_width (request, for_size,
348 &min_size, &nat_size);
350 pop_recursion_check (request, orientation);
352 if (min_size > nat_size)
354 g_warning ("%s %p reported min size %d and natural size %d; natural size must be >= min size",
355 G_OBJECT_TYPE_NAME (request), request, min_size, nat_size);
358 /* Support for dangling "size-request" signal implementations on
361 min_size = MAX (min_size, requisition_size);
362 nat_size = MAX (nat_size, requisition_size);
364 cached_size->minimum_size = min_size;
365 cached_size->natural_size = nat_size;
366 cached_size->for_size = for_size;
368 if (orientation == GTK_SIZE_GROUP_HORIZONTAL)
369 GTK_PRIVATE_UNSET_FLAG (request, GTK_WIDTH_REQUEST_NEEDED);
371 GTK_PRIVATE_UNSET_FLAG (request, GTK_HEIGHT_REQUEST_NEEDED);
373 adjusted_min = cached_size->minimum_size;
374 adjusted_natural = cached_size->natural_size;
375 GTK_WIDGET_GET_CLASS (request)->adjust_size_request (GTK_WIDGET (request),
376 orientation == GTK_SIZE_GROUP_HORIZONTAL ?
377 GTK_ORIENTATION_HORIZONTAL :
378 GTK_ORIENTATION_VERTICAL,
379 cached_size->for_size,
383 if (adjusted_min < cached_size->minimum_size ||
384 adjusted_natural < cached_size->natural_size)
386 g_warning ("%s %p adjusted size %s min %d natural %d must not decrease below min %d natural %d",
387 G_OBJECT_TYPE_NAME (request), request,
388 orientation == GTK_SIZE_GROUP_VERTICAL ? "vertical" : "horizontal",
389 adjusted_min, adjusted_natural,
390 cached_size->minimum_size, cached_size->natural_size);
391 /* don't use the adjustment */
393 else if (adjusted_min > adjusted_natural)
395 g_warning ("%s %p adjusted size %s min %d natural %d original min %d natural %d has min greater than natural",
396 G_OBJECT_TYPE_NAME (request), request,
397 orientation == GTK_SIZE_GROUP_VERTICAL ? "vertical" : "horizontal",
398 adjusted_min, adjusted_natural,
399 cached_size->minimum_size, cached_size->natural_size);
400 /* don't use the adjustment */
404 /* adjustment looks good */
405 cached_size->minimum_size = adjusted_min;
406 cached_size->natural_size = adjusted_natural;
409 /* Update size-groups with our request and update our cached requests
410 * with the size-group values in a single pass.
412 _gtk_size_group_bump_requisition (GTK_WIDGET (request),
414 &cached_size->minimum_size,
415 &cached_size->natural_size);
419 *minimum_size = cached_size->minimum_size;
422 *natural_size = cached_size->natural_size;
424 g_assert (cached_size->minimum_size <= cached_size->natural_size);
426 GTK_NOTE (SIZE_REQUEST,
427 g_print ("[%p] %s\t%s: %d is minimum %d and natural: %d (hit cache: %s)\n",
428 request, G_OBJECT_TYPE_NAME (request),
429 orientation == GTK_SIZE_GROUP_HORIZONTAL ?
430 "width for height" : "height for width" ,
432 cached_size->minimum_size,
433 cached_size->natural_size,
434 found_in_cache ? "yes" : "no"));
439 * gtk_size_request_get_request_mode:
440 * @widget: a #GtkSizeRequest instance
442 * Gets whether the widget prefers a height-for-width layout
443 * or a width-for-height layout.
445 * <note><para>#GtkBin widgets generally propagate the preference of
446 * their child, container widgets need to request something either in
447 * context of their children or in context of their allocation
448 * capabilities.</para></note>
450 * Returns: The #GtkSizeRequestMode preferred by @widget.
455 gtk_size_request_get_request_mode (GtkSizeRequest *widget)
457 GtkSizeRequestIface *iface;
459 g_return_val_if_fail (GTK_IS_SIZE_REQUEST (widget), GTK_SIZE_REQUEST_HEIGHT_FOR_WIDTH);
461 iface = GTK_SIZE_REQUEST_GET_IFACE (widget);
462 if (iface->get_request_mode)
463 return iface->get_request_mode (widget);
465 /* By default widgets are height-for-width. */
466 return GTK_SIZE_REQUEST_HEIGHT_FOR_WIDTH;
470 * gtk_size_request_get_width:
471 * @widget: a #GtkSizeRequest instance
472 * @minimum_width: (out) (allow-none): location to store the minimum width, or %NULL
473 * @natural_width: (out) (allow-none): location to store the natural width, or %NULL
475 * Retrieves a widget's initial minimum and natural width.
477 * <note><para>This call is specific to height-for-width
478 * requests.</para></note>
480 * The returned request will be modified by the
481 * GtkWidgetClass::adjust_size_request virtual method and by any
482 * #GtkSizeGroup that have been applied. That is, the returned request
483 * is the one that should be used for layout, not necessarily the one
484 * returned by the widget itself.
489 gtk_size_request_get_width (GtkSizeRequest *widget,
493 compute_size_for_orientation (widget, GTK_SIZE_GROUP_HORIZONTAL,
494 -1, minimum_width, natural_width);
499 * gtk_size_request_get_height:
500 * @widget: a #GtkSizeRequest instance
501 * @minimum_height: (out) (allow-none): location to store the minimum height, or %NULL
502 * @natural_height: (out) (allow-none): location to store the natural height, or %NULL
504 * Retrieves a widget's initial minimum and natural height.
506 * <note><para>This call is specific to width-for-height requests.</para></note>
508 * The returned request will be modified by the
509 * GtkWidgetClass::adjust_size_request virtual method and by any
510 * #GtkSizeGroup that have been applied. That is, the returned request
511 * is the one that should be used for layout, not necessarily the one
512 * returned by the widget itself.
517 gtk_size_request_get_height (GtkSizeRequest *widget,
518 gint *minimum_height,
519 gint *natural_height)
521 compute_size_for_orientation (widget, GTK_SIZE_GROUP_VERTICAL,
522 -1, minimum_height, natural_height);
528 * gtk_size_request_get_width_for_height:
529 * @widget: a #GtkSizeRequest instance
530 * @height: the height which is available for allocation
531 * @minimum_width: (out) (allow-none): location for storing the minimum width, or %NULL
532 * @natural_width: (out) (allow-none): location for storing the natural width, or %NULL
534 * Retrieves a widget's minimum and natural width if it would be given
535 * the specified @height.
537 * The returned request will be modified by the
538 * GtkWidgetClass::adjust_size_request virtual method and by any
539 * #GtkSizeGroup that have been applied. That is, the returned request
540 * is the one that should be used for layout, not necessarily the one
541 * returned by the widget itself.
546 gtk_size_request_get_width_for_height (GtkSizeRequest *widget,
551 compute_size_for_orientation (widget, GTK_SIZE_GROUP_HORIZONTAL,
552 height, minimum_width, natural_width);
556 * gtk_size_request_get_height_for_width:
557 * @widget: a #GtkSizeRequest instance
558 * @width: the width which is available for allocation
559 * @minimum_height: (out) (allow-none): location for storing the minimum height, or %NULL
560 * @natural_height: (out) (allow-none): location for storing the natural height, or %NULL
562 * Retrieves a widget's minimum and natural height if it would be given
563 * the specified @width.
565 * The returned request will be modified by the
566 * GtkWidgetClass::adjust_size_request virtual method and by any
567 * #GtkSizeGroup that have been applied. That is, the returned request
568 * is the one that should be used for layout, not necessarily the one
569 * returned by the widget itself.
574 gtk_size_request_get_height_for_width (GtkSizeRequest *widget,
576 gint *minimum_height,
577 gint *natural_height)
579 compute_size_for_orientation (widget, GTK_SIZE_GROUP_VERTICAL,
580 width, minimum_height, natural_height);
584 * gtk_size_request_get_size:
585 * @widget: a #GtkSizeRequest instance
586 * @minimum_size: (out) (allow-none): location for storing the minimum size, or %NULL
587 * @natural_size: (out) (allow-none): location for storing the natural size, or %NULL
589 * Retrieves the minimum and natural size of a widget taking
590 * into account the widget's preference for height-for-width management.
592 * This is used to retrieve a suitable size by container widgets which do
593 * not impose any restrictions on the child placement.
598 gtk_size_request_get_size (GtkSizeRequest *widget,
599 GtkRequisition *minimum_size,
600 GtkRequisition *natural_size)
602 gint min_width, nat_width;
603 gint min_height, nat_height;
605 g_return_if_fail (GTK_IS_SIZE_REQUEST (widget));
607 if (gtk_size_request_get_request_mode (widget) == GTK_SIZE_REQUEST_HEIGHT_FOR_WIDTH)
609 gtk_size_request_get_width (widget, &min_width, &nat_width);
613 minimum_size->width = min_width;
614 gtk_size_request_get_height_for_width (widget, min_width,
615 &minimum_size->height, NULL);
620 natural_size->width = nat_width;
621 gtk_size_request_get_height_for_width (widget, nat_width,
622 NULL, &natural_size->height);
625 else /* GTK_SIZE_REQUEST_WIDTH_FOR_HEIGHT */
627 gtk_size_request_get_height (widget, &min_height, &nat_height);
631 minimum_size->height = min_height;
632 gtk_size_request_get_width_for_height (widget, min_height,
633 &minimum_size->width, NULL);
638 natural_size->height = nat_height;
639 gtk_size_request_get_width_for_height (widget, nat_height,
640 NULL, &natural_size->width);
647 compare_gap (gconstpointer p1,
651 GtkRequestedSize *sizes = data;
652 const guint *c1 = p1;
653 const guint *c2 = p2;
655 const gint d1 = MAX (sizes[*c1].natural_size -
656 sizes[*c1].minimum_size,
658 const gint d2 = MAX (sizes[*c2].natural_size -
659 sizes[*c2].minimum_size,
662 gint delta = (d2 - d1);
671 * gtk_distribute_natural_allocation:
672 * @extra_space: Extra space to redistribute among children after subtracting
673 * minimum sizes and any child padding from the overall allocation
674 * @n_requested_sizes: Number of requests to fit into the allocation
675 * @sizes: An array of structs with a client pointer and a minimum/natural size
676 * in the orientation of the allocation.
678 * Distributes @extra_space to child @sizes by bringing up smaller
679 * children up to natural size first.
681 * The remaining space will be added to the @minimum_size member of the
682 * GtkRequestedSize struct. If all sizes reach their natural size then
683 * the remaining space is returned.
685 * Returns: The remainder of @extra_space after redistributing space
689 gtk_distribute_natural_allocation (gint extra_space,
690 guint n_requested_sizes,
691 GtkRequestedSize *sizes)
696 g_return_val_if_fail (extra_space >= 0, 0);
698 spreading = g_newa (guint, n_requested_sizes);
700 for (i = 0; i < n_requested_sizes; i++)
703 /* Distribute the container's extra space c_gap. We want to assign
704 * this space such that the sum of extra space assigned to children
705 * (c^i_gap) is equal to c_cap. The case that there's not enough
706 * space for all children to take their natural size needs some
707 * attention. The goals we want to achieve are:
709 * a) Maximize number of children taking their natural size.
710 * b) The allocated size of children should be a continuous
711 * function of c_gap. That is, increasing the container size by
712 * one pixel should never make drastic changes in the distribution.
713 * c) If child i takes its natural size and child j doesn't,
714 * child j should have received at least as much gap as child i.
716 * The following code distributes the additional space by following
720 /* Sort descending by gap and position. */
721 g_qsort_with_data (spreading,
722 n_requested_sizes, sizeof (guint),
725 /* Distribute available space.
726 * This master piece of a loop was conceived by Behdad Esfahbod.
728 for (i = n_requested_sizes - 1; extra_space > 0 && i >= 0; --i)
730 /* Divide remaining space by number of remaining children.
731 * Sort order and reducing remaining space by assigned space
732 * ensures that space is distributed equally.
734 gint glue = (extra_space + i) / (i + 1);
735 gint gap = sizes[(spreading[i])].natural_size
736 - sizes[(spreading[i])].minimum_size;
738 gint extra = MIN (glue, gap);
740 sizes[spreading[i]].minimum_size += extra;
742 extra_space -= extra;