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_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 /* looks for a cached size request for this for_size. If not
129 * found, returns the oldest entry so it can be overwritten
131 * Note that this caching code was directly derived from
132 * the Clutter toolkit.
135 get_cached_size (SizeRequestCache *cache,
136 GtkSizeGroupMode orientation,
138 SizeRequest **result)
141 SizeRequest *cached_sizes;
143 if (orientation == GTK_SIZE_GROUP_HORIZONTAL)
145 cached_sizes = cache->widths;
146 n_sizes = cache->cached_widths;
150 cached_sizes = cache->heights;
151 n_sizes = cache->cached_widths;
154 /* Search for an already cached size */
155 for (i = 0; i < n_sizes; i++)
157 if (cached_sizes[i].for_size == for_size)
159 *result = &cached_sizes[i];
164 /* If not found, pull a new size from the cache, the returned size cache
165 * will immediately be used to cache the new computed size so we go ahead
166 * and increment the last_cached_width/height right away */
167 if (orientation == GTK_SIZE_GROUP_HORIZONTAL)
169 if (cache->cached_widths < GTK_SIZE_REQUEST_CACHED_SIZES)
171 cache->cached_widths++;
172 cache->last_cached_width = cache->cached_widths - 1;
176 if (++cache->last_cached_width == GTK_SIZE_REQUEST_CACHED_SIZES)
177 cache->last_cached_width = 0;
180 *result = &cache->widths[cache->last_cached_width];
182 else /* GTK_SIZE_GROUP_VERTICAL */
184 if (cache->cached_heights < GTK_SIZE_REQUEST_CACHED_SIZES)
186 cache->cached_heights++;
187 cache->last_cached_height = cache->cached_heights - 1;
191 if (++cache->last_cached_height == GTK_SIZE_REQUEST_CACHED_SIZES)
192 cache->last_cached_height = 0;
195 *result = &cache->heights[cache->last_cached_height];
202 do_size_request (GtkWidget *widget,
203 GtkRequisition *requisition)
205 /* Now we dont bother caching the deprecated "size-request" returns,
206 * just unconditionally invoke here just in case we run into legacy stuff */
207 gtk_widget_ensure_style (widget);
208 g_signal_emit_by_name (widget, "size-request", requisition);
211 #ifndef G_DISABLE_CHECKS
212 static GQuark recursion_check_quark = 0;
213 #endif /* G_DISABLE_CHECKS */
216 push_recursion_check (GtkWidget *request,
217 GtkSizeGroupMode orientation,
220 #ifndef G_DISABLE_CHECKS
221 const char *previous_method;
224 if (recursion_check_quark == 0)
225 recursion_check_quark = g_quark_from_static_string ("gtk-size-request-in-progress");
227 previous_method = g_object_get_qdata (G_OBJECT (request), recursion_check_quark);
229 if (orientation == GTK_SIZE_GROUP_HORIZONTAL)
231 method = for_size < 0 ? "get_width" : "get_width_for_height";
235 method = for_size < 0 ? "get_height" : "get_height_for_width";
238 if (previous_method != NULL)
240 g_warning ("%s %p: widget tried to gtk_widget_%s inside "
241 " GtkWidget ::%s implementation. "
242 "Should just invoke GTK_WIDGET_GET_CLASS(widget)->%s "
243 "directly rather than using gtk_widget_%s",
244 G_OBJECT_TYPE_NAME (request), request,
245 method, previous_method,
249 g_object_set_qdata (G_OBJECT (request), recursion_check_quark, (char*) method);
250 #endif /* G_DISABLE_CHECKS */
254 pop_recursion_check (GtkWidget *request,
255 GtkSizeGroupMode orientation)
257 #ifndef G_DISABLE_CHECKS
258 g_object_set_qdata (G_OBJECT (request), recursion_check_quark, NULL);
263 compute_size_for_orientation (GtkWidget *request,
264 GtkSizeGroupMode orientation,
269 SizeRequestCache *cache;
270 SizeRequest *cached_size;
272 gboolean found_in_cache = FALSE;
273 int adjusted_min, adjusted_natural;
275 g_return_if_fail (GTK_IS_WIDGET (request));
276 g_return_if_fail (minimum_size != NULL || natural_size != NULL);
278 widget = GTK_WIDGET (request);
279 cache = _gtk_widget_peek_request_cache (widget);
281 if (orientation == GTK_SIZE_GROUP_HORIZONTAL)
283 cached_size = &cache->widths[0];
285 if (!GTK_WIDGET_WIDTH_REQUEST_NEEDED (request))
286 found_in_cache = get_cached_size (cache, orientation, for_size, &cached_size);
289 memset (cache->widths, 0, GTK_SIZE_REQUEST_CACHED_SIZES * sizeof (SizeRequest));
290 cache->cached_widths = 1;
291 cache->last_cached_width = 0;
296 cached_size = &cache->heights[0];
298 if (!GTK_WIDGET_HEIGHT_REQUEST_NEEDED (request))
299 found_in_cache = get_cached_size (cache, orientation, for_size, &cached_size);
302 memset (cache->heights, 0, GTK_SIZE_REQUEST_CACHED_SIZES * sizeof (SizeRequest));
303 cache->cached_heights = 1;
304 cache->last_cached_height = 0;
310 GtkRequisition requisition = { 0, 0 };
311 gint min_size = 0, nat_size = 0;
312 gint requisition_size;
314 /* Unconditional size request runs but is often unhandled. */
315 do_size_request (widget, &requisition);
317 push_recursion_check (request, orientation, for_size);
318 if (orientation == GTK_SIZE_GROUP_HORIZONTAL)
320 requisition_size = requisition.width;
323 GTK_WIDGET_GET_CLASS (request)->get_preferred_width (request, &min_size, &nat_size);
325 GTK_WIDGET_GET_CLASS (request)->get_preferred_width_for_height (request, for_size,
326 &min_size, &nat_size);
330 requisition_size = requisition.height;
333 GTK_WIDGET_GET_CLASS (request)->get_preferred_height (request, &min_size, &nat_size);
335 GTK_WIDGET_GET_CLASS (request)->get_preferred_height_for_width (request, for_size,
336 &min_size, &nat_size);
338 pop_recursion_check (request, orientation);
340 if (min_size > nat_size)
342 g_warning ("%s %p reported min size %d and natural size %d; natural size must be >= min size",
343 G_OBJECT_TYPE_NAME (request), request, min_size, nat_size);
346 /* Support for dangling "size-request" signal implementations on
349 min_size = MAX (min_size, requisition_size);
350 nat_size = MAX (nat_size, requisition_size);
352 cached_size->minimum_size = min_size;
353 cached_size->natural_size = nat_size;
354 cached_size->for_size = for_size;
356 if (orientation == GTK_SIZE_GROUP_HORIZONTAL)
357 GTK_PRIVATE_UNSET_FLAG (request, GTK_WIDTH_REQUEST_NEEDED);
359 GTK_PRIVATE_UNSET_FLAG (request, GTK_HEIGHT_REQUEST_NEEDED);
361 adjusted_min = cached_size->minimum_size;
362 adjusted_natural = cached_size->natural_size;
363 GTK_WIDGET_GET_CLASS (request)->adjust_size_request (GTK_WIDGET (request),
364 orientation == GTK_SIZE_GROUP_HORIZONTAL ?
365 GTK_ORIENTATION_HORIZONTAL :
366 GTK_ORIENTATION_VERTICAL,
367 cached_size->for_size,
371 if (adjusted_min < cached_size->minimum_size ||
372 adjusted_natural < cached_size->natural_size)
374 g_warning ("%s %p adjusted size %s min %d natural %d must not decrease below min %d natural %d",
375 G_OBJECT_TYPE_NAME (request), request,
376 orientation == GTK_SIZE_GROUP_VERTICAL ? "vertical" : "horizontal",
377 adjusted_min, adjusted_natural,
378 cached_size->minimum_size, cached_size->natural_size);
379 /* don't use the adjustment */
381 else if (adjusted_min > adjusted_natural)
383 g_warning ("%s %p adjusted size %s min %d natural %d original min %d natural %d has min greater than natural",
384 G_OBJECT_TYPE_NAME (request), request,
385 orientation == GTK_SIZE_GROUP_VERTICAL ? "vertical" : "horizontal",
386 adjusted_min, adjusted_natural,
387 cached_size->minimum_size, cached_size->natural_size);
388 /* don't use the adjustment */
392 /* adjustment looks good */
393 cached_size->minimum_size = adjusted_min;
394 cached_size->natural_size = adjusted_natural;
397 /* Update size-groups with our request and update our cached requests
398 * with the size-group values in a single pass.
400 _gtk_size_group_bump_requisition (GTK_WIDGET (request),
402 &cached_size->minimum_size,
403 &cached_size->natural_size);
407 *minimum_size = cached_size->minimum_size;
410 *natural_size = cached_size->natural_size;
412 g_assert (cached_size->minimum_size <= cached_size->natural_size);
414 GTK_NOTE (SIZE_REQUEST,
415 g_print ("[%p] %s\t%s: %d is minimum %d and natural: %d (hit cache: %s)\n",
416 request, G_OBJECT_TYPE_NAME (request),
417 orientation == GTK_SIZE_GROUP_HORIZONTAL ?
418 "width for height" : "height for width" ,
420 cached_size->minimum_size,
421 cached_size->natural_size,
422 found_in_cache ? "yes" : "no"));
427 * gtk_widget_get_preferred:
428 * @widget: a #GtkWidget instance
430 * Gets whether the widget prefers a height-for-width layout
431 * or a width-for-height layout.
433 * <note><para>#GtkBin widgets generally propagate the preference of
434 * their child, container widgets need to request something either in
435 * context of their children or in context of their allocation
436 * capabilities.</para></note>
438 * Returns: The #GtkSizeRequestMode preferred by @widget.
443 gtk_widget_get_request_mode (GtkWidget *widget)
445 GtkWidgetClass *klass;
447 g_return_val_if_fail (GTK_IS_WIDGET (widget), GTK_SIZE_REQUEST_HEIGHT_FOR_WIDTH);
449 klass = GTK_WIDGET_GET_CLASS (widget);
450 if (klass->get_request_mode)
451 return klass->get_request_mode (widget);
453 /* By default widgets are height-for-width. */
454 return GTK_SIZE_REQUEST_HEIGHT_FOR_WIDTH;
458 * gtk_widget_get_preferred_width:
459 * @widget: a #GtkWidget instance
460 * @minimum_width: (out) (allow-none): location to store the minimum width, or %NULL
461 * @natural_width: (out) (allow-none): location to store the natural width, or %NULL
463 * Retrieves a widget's initial minimum and natural width.
465 * <note><para>This call is specific to height-for-width
466 * requests.</para></note>
468 * The returned request will be modified by the
469 * GtkWidgetClass::adjust_size_request virtual method and by any
470 * #GtkSizeGroup that have been applied. That is, the returned request
471 * is the one that should be used for layout, not necessarily the one
472 * returned by the widget itself.
477 gtk_widget_get_preferred_width (GtkWidget *widget,
481 compute_size_for_orientation (widget, GTK_SIZE_GROUP_HORIZONTAL,
482 -1, minimum_width, natural_width);
487 * gtk_widget_get_preferred_height:
488 * @widget: a #GtkWidget instance
489 * @minimum_height: (out) (allow-none): location to store the minimum height, or %NULL
490 * @natural_height: (out) (allow-none): location to store the natural height, or %NULL
492 * Retrieves a widget's initial minimum and natural height.
494 * <note><para>This call is specific to width-for-height requests.</para></note>
496 * The returned request will be modified by the
497 * GtkWidgetClass::adjust_size_request virtual method and by any
498 * #GtkSizeGroup that have been applied. That is, the returned request
499 * is the one that should be used for layout, not necessarily the one
500 * returned by the widget itself.
505 gtk_widget_get_preferred_height (GtkWidget *widget,
506 gint *minimum_height,
507 gint *natural_height)
509 compute_size_for_orientation (widget, GTK_SIZE_GROUP_VERTICAL,
510 -1, minimum_height, natural_height);
516 * gtk_widget_get_preferred_width_for_height:
517 * @widget: a #GtkWidget instance
518 * @height: the height which is available for allocation
519 * @minimum_width: (out) (allow-none): location for storing the minimum width, or %NULL
520 * @natural_width: (out) (allow-none): location for storing the natural width, or %NULL
522 * Retrieves a widget's minimum and natural width if it would be given
523 * the specified @height.
525 * The returned request will be modified by the
526 * GtkWidgetClass::adjust_size_request virtual method and by any
527 * #GtkSizeGroup that have been applied. That is, the returned request
528 * is the one that should be used for layout, not necessarily the one
529 * returned by the widget itself.
534 gtk_widget_get_preferred_width_for_height (GtkWidget *widget,
539 compute_size_for_orientation (widget, GTK_SIZE_GROUP_HORIZONTAL,
540 height, minimum_width, natural_width);
544 * gtk_widget_get_preferred_height_for_width:
545 * @widget: a #GtkWidget instance
546 * @width: the width which is available for allocation
547 * @minimum_height: (out) (allow-none): location for storing the minimum height, or %NULL
548 * @natural_height: (out) (allow-none): location for storing the natural height, or %NULL
550 * Retrieves a widget's minimum and natural height if it would be given
551 * the specified @width.
553 * The returned request will be modified by the
554 * GtkWidgetClass::adjust_size_request virtual method and by any
555 * #GtkSizeGroup that have been applied. That is, the returned request
556 * is the one that should be used for layout, not necessarily the one
557 * returned by the widget itself.
562 gtk_widget_get_preferred_height_for_width (GtkWidget *widget,
564 gint *minimum_height,
565 gint *natural_height)
567 compute_size_for_orientation (widget, GTK_SIZE_GROUP_VERTICAL,
568 width, minimum_height, natural_height);
572 * gtk_widget_get_preferred_size:
573 * @widget: a #GtkWidget instance
574 * @minimum_size: (out) (allow-none): location for storing the minimum size, or %NULL
575 * @natural_size: (out) (allow-none): location for storing the natural size, or %NULL
577 * Retrieves the minimum and natural size of a widget taking
578 * into account the widget's preference for height-for-width management.
580 * This is used to retrieve a suitable size by container widgets which do
581 * not impose any restrictions on the child placement.
586 gtk_widget_get_preferred_size (GtkWidget *widget,
587 GtkRequisition *minimum_size,
588 GtkRequisition *natural_size)
590 gint min_width, nat_width;
591 gint min_height, nat_height;
593 g_return_if_fail (GTK_IS_WIDGET (widget));
595 if (gtk_widget_get_request_mode (widget) == GTK_SIZE_REQUEST_HEIGHT_FOR_WIDTH)
597 gtk_widget_get_preferred_width (widget, &min_width, &nat_width);
601 minimum_size->width = min_width;
602 gtk_widget_get_preferred_height_for_width (widget, min_width,
603 &minimum_size->height, NULL);
608 natural_size->width = nat_width;
609 gtk_widget_get_preferred_height_for_width (widget, nat_width,
610 NULL, &natural_size->height);
613 else /* GTK_SIZE_REQUEST_WIDTH_FOR_HEIGHT */
615 gtk_widget_get_preferred_height (widget, &min_height, &nat_height);
619 minimum_size->height = min_height;
620 gtk_widget_get_preferred_width_for_height (widget, min_height,
621 &minimum_size->width, NULL);
626 natural_size->height = nat_height;
627 gtk_widget_get_preferred_width_for_height (widget, nat_height,
628 NULL, &natural_size->width);
635 compare_gap (gconstpointer p1,
639 GtkRequestedSize *sizes = data;
640 const guint *c1 = p1;
641 const guint *c2 = p2;
643 const gint d1 = MAX (sizes[*c1].natural_size -
644 sizes[*c1].minimum_size,
646 const gint d2 = MAX (sizes[*c2].natural_size -
647 sizes[*c2].minimum_size,
650 gint delta = (d2 - d1);
659 * gtk_distribute_natural_allocation:
660 * @extra_space: Extra space to redistribute among children after subtracting
661 * minimum sizes and any child padding from the overall allocation
662 * @n_requested_sizes: Number of requests to fit into the allocation
663 * @sizes: An array of structs with a client pointer and a minimum/natural size
664 * in the orientation of the allocation.
666 * Distributes @extra_space to child @sizes by bringing up smaller
667 * children up to natural size first.
669 * The remaining space will be added to the @minimum_size member of the
670 * GtkRequestedSize struct. If all sizes reach their natural size then
671 * the remaining space is returned.
673 * Returns: The remainder of @extra_space after redistributing space
677 gtk_distribute_natural_allocation (gint extra_space,
678 guint n_requested_sizes,
679 GtkRequestedSize *sizes)
684 g_return_val_if_fail (extra_space >= 0, 0);
686 spreading = g_newa (guint, n_requested_sizes);
688 for (i = 0; i < n_requested_sizes; i++)
691 /* Distribute the container's extra space c_gap. We want to assign
692 * this space such that the sum of extra space assigned to children
693 * (c^i_gap) is equal to c_cap. The case that there's not enough
694 * space for all children to take their natural size needs some
695 * attention. The goals we want to achieve are:
697 * a) Maximize number of children taking their natural size.
698 * b) The allocated size of children should be a continuous
699 * function of c_gap. That is, increasing the container size by
700 * one pixel should never make drastic changes in the distribution.
701 * c) If child i takes its natural size and child j doesn't,
702 * child j should have received at least as much gap as child i.
704 * The following code distributes the additional space by following
708 /* Sort descending by gap and position. */
709 g_qsort_with_data (spreading,
710 n_requested_sizes, sizeof (guint),
713 /* Distribute available space.
714 * This master piece of a loop was conceived by Behdad Esfahbod.
716 for (i = n_requested_sizes - 1; extra_space > 0 && i >= 0; --i)
718 /* Divide remaining space by number of remaining children.
719 * Sort order and reducing remaining space by assigned space
720 * ensures that space is distributed equally.
722 gint glue = (extra_space + i) / (i + 1);
723 gint gap = sizes[(spreading[i])].natural_size
724 - sizes[(spreading[i])].minimum_size;
726 gint extra = MIN (glue, gap);
728 sizes[spreading[i]].minimum_size += extra;
730 extra_space -= extra;