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
30 * The GtkWidget 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 #GtkWidget interface for existing widgets,
40 * which always requests the same height, regardless of the available width.
43 * <title>Implementing GtkWidget</title>
45 * Some important things to keep in mind when implementing
46 * the GtkWidget 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_widget_get_preferred_width().
58 * Next, the toplevel will use the minimum width to query for the
59 * minimum height contextual to that width using
60 * gtk_widget_get_preferred_height_for_width(), which will also
61 * be a highly recursive operation. This minimum-for-minimum size can
62 * be 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. #GtkWidget 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_preferred_width() and get_preferred_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_preferred_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_WIDGET_GET_CLASS(widget)->get_preferred_width (widget), &min, &natural);
103 * It will not work to use the wrapper functions, such as
104 * gtk_widget_get_preferred_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 "gtkdebug.h"
126 #include "gtkprivate.h"
129 /* looks for a cached size request for this for_size. If not
130 * found, returns the oldest entry so it can be overwritten
132 * Note that this caching code was directly derived from
133 * the Clutter toolkit.
136 get_cached_size (SizeRequestCache *cache,
137 GtkSizeGroupMode orientation,
139 SizeRequest **result)
142 SizeRequest *cached_sizes;
144 if (orientation == GTK_SIZE_GROUP_HORIZONTAL)
146 cached_sizes = cache->widths;
147 n_sizes = cache->cached_widths;
151 cached_sizes = cache->heights;
152 n_sizes = cache->cached_widths;
155 /* Search for an already cached size */
156 for (i = 0; i < n_sizes; i++)
158 if (cached_sizes[i].for_size == for_size)
160 *result = &cached_sizes[i];
165 /* If not found, pull a new size from the cache, the returned size cache
166 * will immediately be used to cache the new computed size so we go ahead
167 * and increment the last_cached_width/height right away */
168 if (orientation == GTK_SIZE_GROUP_HORIZONTAL)
170 if (cache->cached_widths < GTK_SIZE_REQUEST_CACHED_SIZES)
172 cache->cached_widths++;
173 cache->last_cached_width = cache->cached_widths - 1;
177 if (++cache->last_cached_width == GTK_SIZE_REQUEST_CACHED_SIZES)
178 cache->last_cached_width = 0;
181 *result = &cache->widths[cache->last_cached_width];
183 else /* GTK_SIZE_GROUP_VERTICAL */
185 if (cache->cached_heights < GTK_SIZE_REQUEST_CACHED_SIZES)
187 cache->cached_heights++;
188 cache->last_cached_height = cache->cached_heights - 1;
192 if (++cache->last_cached_height == GTK_SIZE_REQUEST_CACHED_SIZES)
193 cache->last_cached_height = 0;
196 *result = &cache->heights[cache->last_cached_height];
203 do_size_request (GtkWidget *widget,
204 GtkRequisition *requisition)
206 /* Now we dont bother caching the deprecated "size-request" returns,
207 * just unconditionally invoke here just in case we run into legacy stuff */
208 gtk_widget_ensure_style (widget);
209 g_signal_emit_by_name (widget, "size-request", requisition);
212 #ifndef G_DISABLE_CHECKS
213 static GQuark recursion_check_quark = 0;
214 #endif /* G_DISABLE_CHECKS */
217 push_recursion_check (GtkWidget *request,
218 GtkSizeGroupMode orientation,
221 #ifndef G_DISABLE_CHECKS
222 const char *previous_method;
225 if (recursion_check_quark == 0)
226 recursion_check_quark = g_quark_from_static_string ("gtk-size-request-in-progress");
228 previous_method = g_object_get_qdata (G_OBJECT (request), recursion_check_quark);
230 if (orientation == GTK_SIZE_GROUP_HORIZONTAL)
232 method = for_size < 0 ? "get_width" : "get_width_for_height";
236 method = for_size < 0 ? "get_height" : "get_height_for_width";
239 if (previous_method != NULL)
241 g_warning ("%s %p: widget tried to gtk_widget_%s inside "
242 " GtkWidget ::%s implementation. "
243 "Should just invoke GTK_WIDGET_GET_CLASS(widget)->%s "
244 "directly rather than using gtk_widget_%s",
245 G_OBJECT_TYPE_NAME (request), request,
246 method, previous_method,
250 g_object_set_qdata (G_OBJECT (request), recursion_check_quark, (char*) method);
251 #endif /* G_DISABLE_CHECKS */
255 pop_recursion_check (GtkWidget *request,
256 GtkSizeGroupMode orientation)
258 #ifndef G_DISABLE_CHECKS
259 g_object_set_qdata (G_OBJECT (request), recursion_check_quark, NULL);
264 compute_size_for_orientation (GtkWidget *request,
265 GtkSizeGroupMode orientation,
270 SizeRequestCache *cache;
271 SizeRequest *cached_size;
273 gboolean found_in_cache = FALSE;
274 int adjusted_min, adjusted_natural;
276 g_return_if_fail (GTK_IS_WIDGET (request));
277 g_return_if_fail (minimum_size != NULL || natural_size != NULL);
279 widget = GTK_WIDGET (request);
280 cache = _gtk_widget_peek_request_cache (widget);
282 if (orientation == GTK_SIZE_GROUP_HORIZONTAL)
284 cached_size = &cache->widths[0];
286 if (!_gtk_widget_get_width_request_needed (widget))
287 found_in_cache = get_cached_size (cache, orientation, for_size, &cached_size);
290 memset (cache->widths, 0, GTK_SIZE_REQUEST_CACHED_SIZES * sizeof (SizeRequest));
291 cache->cached_widths = 1;
292 cache->last_cached_width = 0;
297 cached_size = &cache->heights[0];
299 if (!_gtk_widget_get_height_request_needed (widget))
300 found_in_cache = get_cached_size (cache, orientation, for_size, &cached_size);
303 memset (cache->heights, 0, GTK_SIZE_REQUEST_CACHED_SIZES * sizeof (SizeRequest));
304 cache->cached_heights = 1;
305 cache->last_cached_height = 0;
311 GtkRequisition requisition = { 0, 0 };
312 gint min_size = 0, nat_size = 0;
313 gint requisition_size;
315 /* Unconditional size request runs but is often unhandled. */
316 do_size_request (widget, &requisition);
318 push_recursion_check (request, orientation, for_size);
319 if (orientation == GTK_SIZE_GROUP_HORIZONTAL)
321 requisition_size = requisition.width;
324 GTK_WIDGET_GET_CLASS (request)->get_preferred_width (request, &min_size, &nat_size);
326 GTK_WIDGET_GET_CLASS (request)->get_preferred_width_for_height (request, for_size,
327 &min_size, &nat_size);
331 requisition_size = requisition.height;
334 GTK_WIDGET_GET_CLASS (request)->get_preferred_height (request, &min_size, &nat_size);
336 GTK_WIDGET_GET_CLASS (request)->get_preferred_height_for_width (request, for_size,
337 &min_size, &nat_size);
339 pop_recursion_check (request, orientation);
341 if (min_size > nat_size)
343 g_warning ("%s %p reported min size %d and natural size %d; natural size must be >= min size",
344 G_OBJECT_TYPE_NAME (request), request, min_size, nat_size);
347 /* Support for dangling "size-request" signal implementations on
350 min_size = MAX (min_size, requisition_size);
351 nat_size = MAX (nat_size, requisition_size);
353 cached_size->minimum_size = min_size;
354 cached_size->natural_size = nat_size;
355 cached_size->for_size = for_size;
357 if (orientation == GTK_SIZE_GROUP_HORIZONTAL)
358 _gtk_widget_set_width_request_needed (widget, FALSE);
360 _gtk_widget_set_height_request_needed (widget, FALSE);
362 adjusted_min = cached_size->minimum_size;
363 adjusted_natural = cached_size->natural_size;
364 GTK_WIDGET_GET_CLASS (request)->adjust_size_request (GTK_WIDGET (request),
365 orientation == GTK_SIZE_GROUP_HORIZONTAL ?
366 GTK_ORIENTATION_HORIZONTAL :
367 GTK_ORIENTATION_VERTICAL,
368 cached_size->for_size,
372 if (adjusted_min < cached_size->minimum_size ||
373 adjusted_natural < cached_size->natural_size)
375 g_warning ("%s %p adjusted size %s min %d natural %d must not decrease below min %d natural %d",
376 G_OBJECT_TYPE_NAME (request), request,
377 orientation == GTK_SIZE_GROUP_VERTICAL ? "vertical" : "horizontal",
378 adjusted_min, adjusted_natural,
379 cached_size->minimum_size, cached_size->natural_size);
380 /* don't use the adjustment */
382 else if (adjusted_min > adjusted_natural)
384 g_warning ("%s %p adjusted size %s min %d natural %d original min %d natural %d has min greater than natural",
385 G_OBJECT_TYPE_NAME (request), request,
386 orientation == GTK_SIZE_GROUP_VERTICAL ? "vertical" : "horizontal",
387 adjusted_min, adjusted_natural,
388 cached_size->minimum_size, cached_size->natural_size);
389 /* don't use the adjustment */
393 /* adjustment looks good */
394 cached_size->minimum_size = adjusted_min;
395 cached_size->natural_size = adjusted_natural;
398 /* Update size-groups with our request and update our cached requests
399 * with the size-group values in a single pass.
401 _gtk_size_group_bump_requisition (GTK_WIDGET (request),
403 &cached_size->minimum_size,
404 &cached_size->natural_size);
408 *minimum_size = cached_size->minimum_size;
411 *natural_size = cached_size->natural_size;
413 g_assert (cached_size->minimum_size <= cached_size->natural_size);
415 GTK_NOTE (SIZE_REQUEST,
416 g_print ("[%p] %s\t%s: %d is minimum %d and natural: %d (hit cache: %s)\n",
417 request, G_OBJECT_TYPE_NAME (request),
418 orientation == GTK_SIZE_GROUP_HORIZONTAL ?
419 "width for height" : "height for width" ,
421 cached_size->minimum_size,
422 cached_size->natural_size,
423 found_in_cache ? "yes" : "no"));
428 * gtk_widget_get_request_mode:
429 * @widget: a #GtkWidget instance
431 * Gets whether the widget prefers a height-for-width layout
432 * or a width-for-height layout.
434 * <note><para>#GtkBin widgets generally propagate the preference of
435 * their child, container widgets need to request something either in
436 * context of their children or in context of their allocation
437 * capabilities.</para></note>
439 * Returns: The #GtkSizeRequestMode preferred by @widget.
444 gtk_widget_get_request_mode (GtkWidget *widget)
446 GtkWidgetClass *klass;
448 g_return_val_if_fail (GTK_IS_WIDGET (widget), GTK_SIZE_REQUEST_HEIGHT_FOR_WIDTH);
450 klass = GTK_WIDGET_GET_CLASS (widget);
451 if (klass->get_request_mode)
452 return klass->get_request_mode (widget);
454 /* By default widgets are height-for-width. */
455 return GTK_SIZE_REQUEST_HEIGHT_FOR_WIDTH;
459 * gtk_widget_get_preferred_width:
460 * @widget: a #GtkWidget instance
461 * @minimum_width: (out) (allow-none): location to store the minimum width, or %NULL
462 * @natural_width: (out) (allow-none): location to store the natural width, or %NULL
464 * Retrieves a widget's initial minimum and natural width.
466 * <note><para>This call is specific to height-for-width
467 * requests.</para></note>
469 * The returned request will be modified by the
470 * GtkWidgetClass::adjust_size_request virtual method and by any
471 * #GtkSizeGroup that have been applied. That is, the returned request
472 * is the one that should be used for layout, not necessarily the one
473 * returned by the widget itself.
478 gtk_widget_get_preferred_width (GtkWidget *widget,
482 compute_size_for_orientation (widget, GTK_SIZE_GROUP_HORIZONTAL,
483 -1, minimum_width, natural_width);
488 * gtk_widget_get_preferred_height:
489 * @widget: a #GtkWidget instance
490 * @minimum_height: (out) (allow-none): location to store the minimum height, or %NULL
491 * @natural_height: (out) (allow-none): location to store the natural height, or %NULL
493 * Retrieves a widget's initial minimum and natural height.
495 * <note><para>This call is specific to width-for-height requests.</para></note>
497 * The returned request will be modified by the
498 * GtkWidgetClass::adjust_size_request virtual method and by any
499 * #GtkSizeGroup that have been applied. That is, the returned request
500 * is the one that should be used for layout, not necessarily the one
501 * returned by the widget itself.
506 gtk_widget_get_preferred_height (GtkWidget *widget,
507 gint *minimum_height,
508 gint *natural_height)
510 compute_size_for_orientation (widget, GTK_SIZE_GROUP_VERTICAL,
511 -1, minimum_height, natural_height);
517 * gtk_widget_get_preferred_width_for_height:
518 * @widget: a #GtkWidget instance
519 * @height: the height which is available for allocation
520 * @minimum_width: (out) (allow-none): location for storing the minimum width, or %NULL
521 * @natural_width: (out) (allow-none): location for storing the natural width, or %NULL
523 * Retrieves a widget's minimum and natural width if it would be given
524 * the specified @height.
526 * The returned request will be modified by the
527 * GtkWidgetClass::adjust_size_request virtual method and by any
528 * #GtkSizeGroup that have been applied. That is, the returned request
529 * is the one that should be used for layout, not necessarily the one
530 * returned by the widget itself.
535 gtk_widget_get_preferred_width_for_height (GtkWidget *widget,
540 compute_size_for_orientation (widget, GTK_SIZE_GROUP_HORIZONTAL,
541 height, minimum_width, natural_width);
545 * gtk_widget_get_preferred_height_for_width:
546 * @widget: a #GtkWidget instance
547 * @width: the width which is available for allocation
548 * @minimum_height: (out) (allow-none): location for storing the minimum height, or %NULL
549 * @natural_height: (out) (allow-none): location for storing the natural height, or %NULL
551 * Retrieves a widget's minimum and natural height if it would be given
552 * the specified @width.
554 * The returned request will be modified by the
555 * GtkWidgetClass::adjust_size_request virtual method and by any
556 * #GtkSizeGroup that have been applied. That is, the returned request
557 * is the one that should be used for layout, not necessarily the one
558 * returned by the widget itself.
563 gtk_widget_get_preferred_height_for_width (GtkWidget *widget,
565 gint *minimum_height,
566 gint *natural_height)
568 compute_size_for_orientation (widget, GTK_SIZE_GROUP_VERTICAL,
569 width, minimum_height, natural_height);
573 * gtk_widget_get_preferred_size:
574 * @widget: a #GtkWidget instance
575 * @minimum_size: (out) (allow-none): location for storing the minimum size, or %NULL
576 * @natural_size: (out) (allow-none): location for storing the natural size, or %NULL
578 * Retrieves the minimum and natural size of a widget taking
579 * into account the widget's preference for height-for-width management.
581 * This is used to retrieve a suitable size by container widgets which do
582 * not impose any restrictions on the child placement.
587 gtk_widget_get_preferred_size (GtkWidget *widget,
588 GtkRequisition *minimum_size,
589 GtkRequisition *natural_size)
591 gint min_width, nat_width;
592 gint min_height, nat_height;
594 g_return_if_fail (GTK_IS_WIDGET (widget));
596 if (gtk_widget_get_request_mode (widget) == GTK_SIZE_REQUEST_HEIGHT_FOR_WIDTH)
598 gtk_widget_get_preferred_width (widget, &min_width, &nat_width);
602 minimum_size->width = min_width;
603 gtk_widget_get_preferred_height_for_width (widget, min_width,
604 &minimum_size->height, NULL);
609 natural_size->width = nat_width;
610 gtk_widget_get_preferred_height_for_width (widget, nat_width,
611 NULL, &natural_size->height);
614 else /* GTK_SIZE_REQUEST_WIDTH_FOR_HEIGHT */
616 gtk_widget_get_preferred_height (widget, &min_height, &nat_height);
620 minimum_size->height = min_height;
621 gtk_widget_get_preferred_width_for_height (widget, min_height,
622 &minimum_size->width, NULL);
627 natural_size->height = nat_height;
628 gtk_widget_get_preferred_width_for_height (widget, nat_height,
629 NULL, &natural_size->width);
636 compare_gap (gconstpointer p1,
640 GtkRequestedSize *sizes = data;
641 const guint *c1 = p1;
642 const guint *c2 = p2;
644 const gint d1 = MAX (sizes[*c1].natural_size -
645 sizes[*c1].minimum_size,
647 const gint d2 = MAX (sizes[*c2].natural_size -
648 sizes[*c2].minimum_size,
651 gint delta = (d2 - d1);
660 * gtk_distribute_natural_allocation:
661 * @extra_space: Extra space to redistribute among children after subtracting
662 * minimum sizes and any child padding from the overall allocation
663 * @n_requested_sizes: Number of requests to fit into the allocation
664 * @sizes: An array of structs with a client pointer and a minimum/natural size
665 * in the orientation of the allocation.
667 * Distributes @extra_space to child @sizes by bringing up smaller
668 * children up to natural size first.
670 * The remaining space will be added to the @minimum_size member of the
671 * GtkRequestedSize struct. If all sizes reach their natural size then
672 * the remaining space is returned.
674 * Returns: The remainder of @extra_space after redistributing space
678 gtk_distribute_natural_allocation (gint extra_space,
679 guint n_requested_sizes,
680 GtkRequestedSize *sizes)
685 g_return_val_if_fail (extra_space >= 0, 0);
687 spreading = g_newa (guint, n_requested_sizes);
689 for (i = 0; i < n_requested_sizes; i++)
692 /* Distribute the container's extra space c_gap. We want to assign
693 * this space such that the sum of extra space assigned to children
694 * (c^i_gap) is equal to c_cap. The case that there's not enough
695 * space for all children to take their natural size needs some
696 * attention. The goals we want to achieve are:
698 * a) Maximize number of children taking their natural size.
699 * b) The allocated size of children should be a continuous
700 * function of c_gap. That is, increasing the container size by
701 * one pixel should never make drastic changes in the distribution.
702 * c) If child i takes its natural size and child j doesn't,
703 * child j should have received at least as much gap as child i.
705 * The following code distributes the additional space by following
709 /* Sort descending by gap and position. */
710 g_qsort_with_data (spreading,
711 n_requested_sizes, sizeof (guint),
714 /* Distribute available space.
715 * This master piece of a loop was conceived by Behdad Esfahbod.
717 for (i = n_requested_sizes - 1; extra_space > 0 && i >= 0; --i)
719 /* Divide remaining space by number of remaining children.
720 * Sort order and reducing remaining space by assigned space
721 * ensures that space is distributed equally.
723 gint glue = (extra_space + i) / (i + 1);
724 gint gap = sizes[(spreading[i])].natural_size
725 - sizes[(spreading[i])].minimum_size;
727 gint extra = MIN (glue, gap);
729 sizes[spreading[i]].minimum_size += extra;
731 extra_space -= extra;