Commit 6c76243f authored by Tristan Van Berkom's avatar Tristan Van Berkom

Added gtk_distribute_allocation()

Added a convenience api for containers to use when allocating
children (used to distribute space evenly to children).
parent 32869d43
......@@ -54,7 +54,7 @@
* For instance when queried in the normal height-for-width mode:
* First the default minimum and natural width for each widget
* in the interface will computed and collectively returned to
* the toplevel by way of gtk_size_request_get_desired_width().
* the toplevel by way of gtk_size_request_get_width().
* Next, the toplevel will use the minimum width to query for the
* minimum height contextual to that width using
* gtk_size_request_get_height_for_width(), which will also be a
......@@ -351,7 +351,7 @@ compute_size_for_orientation (GtkSizeRequest *request,
}
/**
* gtk_size_request_is_height_for_width:
* gtk_size_request_get_request_mode:
* @widget: a #GtkSizeRequest instance
*
* Gets whether the widget prefers a height-for-width layout
......@@ -362,8 +362,7 @@ compute_size_for_orientation (GtkSizeRequest *request,
* context of their children or in context of their allocation
* capabilities.</para></note>
*
* Returns: %TRUE if the widget prefers height-for-width, %FALSE if
* the widget should be treated with a width-for-height preference.
* Returns: The #GtkSizeRequestMode preferred by @widget.
*
* Since: 3.0
*/
......@@ -397,8 +396,8 @@ gtk_size_request_get_request_mode (GtkSizeRequest *widget)
*/
void
gtk_size_request_get_width (GtkSizeRequest *widget,
gint *minimum_width,
gint *natural_width)
gint *minimum_width,
gint *natural_width)
{
compute_size_for_orientation (widget, GTK_SIZE_GROUP_HORIZONTAL,
-1, minimum_width, natural_width);
......@@ -435,7 +434,7 @@ gtk_size_request_get_height (GtkSizeRequest *widget,
* @minimum_width: (out) (allow-none): location for storing the minimum width, or %NULL
* @natural_width: (out) (allow-none): location for storing the natural width, or %NULL
*
* Retrieves a widget's desired width if it would be given
* Retrieves a widget's minimum and natural width if it would be given
* the specified @height.
*
* Since: 3.0
......@@ -457,7 +456,7 @@ gtk_size_request_get_width_for_height (GtkSizeRequest *widget,
* @minimum_height: (out) (allow-none): location for storing the minimum height, or %NULL
* @natural_height: (out) (allow-none): location for storing the natural height, or %NULL
*
* Retrieves a widget's desired height if it would be given
* Retrieves a widget's minimum and natural height if it would be given
* the specified @width.
*
* Since: 3.0
......@@ -514,7 +513,7 @@ gtk_size_request_get_size (GtkSizeRequest *widget,
NULL, &natural_size->height);
}
}
else
else /* GTK_SIZE_REQUEST_WIDTH_FOR_HEIGHT */
{
gtk_size_request_get_height (widget, &min_height, &nat_height);
......@@ -533,3 +532,103 @@ gtk_size_request_get_size (GtkSizeRequest *widget,
}
}
}
static gint
compare_gap (gconstpointer p1,
gconstpointer p2,
gpointer data)
{
GtkRequestedSize *sizes = data;
const guint *c1 = p1;
const guint *c2 = p2;
const gint d1 = MAX (sizes[*c1].natural_size -
sizes[*c1].minimum_size,
0);
const gint d2 = MAX (sizes[*c2].natural_size -
sizes[*c2].minimum_size,
0);
gint delta = (d2 - d1);
if (0 == delta)
delta = (*c2 - *c1);
return delta;
}
/**
* gtk_distribute_natural_allocation:
* @extra_space: Extra space to redistribute among children after subtracting
* minimum sizes and any child padding from the overall allocation
* @n_requested_sizes: Number of requests to fit into the allocation
* @sizes: An array of structs with a client pointer and a minimum/natural size
* in the orientation of the allocation.
*
* Distributes @extra_space to child @sizes by bringing up smaller
* children up to natural size first.
*
* The remaining space will be added to the @minimum_size member of the
* GtkRequestedSize struct. If all sizes reach their natural size then
* the remaining space is returned.
*
* Returns: The remainder of @extra_space after redistributing space
* to @sizes.
*/
gint
gtk_distribute_natural_allocation (gint extra_space,
guint n_requested_sizes,
GtkRequestedSize *sizes)
{
guint *spreading = g_newa (guint, n_requested_sizes);
gint i;
for (i = 0; i < n_requested_sizes; i++)
spreading[i] = i;
/* Distribute the container's extra space c_gap. We want to assign
* this space such that the sum of extra space assigned to children
* (c^i_gap) is equal to c_cap. The case that there's not enough
* space for all children to take their natural size needs some
* attention. The goals we want to achieve are:
*
* a) Maximize number of children taking their natural size.
* b) The allocated size of children should be a continuous
* function of c_gap. That is, increasing the container size by
* one pixel should never make drastic changes in the distribution.
* c) If child i takes its natural size and child j doesn't,
* child j should have received at least as much gap as child i.
*
* The following code distributes the additional space by following
* these rules.
*/
/* Sort descending by gap and position. */
g_qsort_with_data (spreading,
n_requested_sizes, sizeof (guint),
compare_gap, sizes);
/* Distribute available space.
* This master piece of a loop was conceived by Behdad Esfahbod.
*/
for (i = n_requested_sizes - 1; extra_space > 0 && i >= 0; --i)
{
/* Divide remaining space by number of remaining children.
* Sort order and reducing remaining space by assigned space
* ensures that space is distributed equally.
*/
gint glue = (extra_space + i) / (i + 1);
gint gap = sizes[(spreading[i])].natural_size
- sizes[(spreading[i])].minimum_size;
gint extra = MIN (glue, gap);
sizes[spreading[i]].minimum_size += extra;
extra_space -= extra;
}
return extra_space;
}
......@@ -36,6 +36,24 @@ G_BEGIN_DECLS
typedef struct _GtkSizeRequest GtkSizeRequest;
typedef struct _GtkSizeRequestIface GtkSizeRequestIface;
typedef struct _GtkRequestedSize GtkRequestedSize;
/**
* GtkRequestedSize:
* @data: A client pointer
* @minimum_size: The minimum size needed for allocation in a given orientation
* @natural_size: The natural size for allocation in a given orientation
*
* Represents a request of a screen object in a given orientation. These
* are primarily used in container implementations when allocating a natural
* size for children calling. See gtk_distribute_natural_allocation().
*/
struct _GtkRequestedSize
{
gpointer data;
gint minimum_size;
gint natural_size;
};
struct _GtkSizeRequestIface
......@@ -82,6 +100,13 @@ void gtk_size_request_get_size (GtkSizeRequest *widge
GtkRequisition *minimum_size,
GtkRequisition *natural_size);
/* General convenience function to aid in allocating natural sizes */
gint gtk_distribute_natural_allocation (gint extra_space,
guint n_requested_sizes,
GtkRequestedSize *sizes);
G_END_DECLS
#endif /* __GTK_SIZE_REQUEST_H__ */
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