gtk2/gtk/gtkfixed.c

/* GTK - The GIMP Toolkit
 * Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library. If not, see <http://www.gnu.org/licenses/>.
 */

/*
 * Modified by the GTK+ Team and others 1997-2000.  See the AUTHORS
 * file for a list of people on the GTK+ Team.  See the ChangeLog
 * files for a list of changes.  These files are distributed with
 * GTK+ at ftp://ftp.gtk.org/pub/gtk/.
 */

/**
 * SECTION:gtkfixed
 * @Short_description: A container which allows you to position
 * widgets at fixed coordinates
 * @Title: GtkFixed
 * @See_also: #GtkLayout
 *
 * The #GtkFixed widget is a container which can place child widgets
 * at fixed positions and with fixed sizes, given in pixels. #GtkFixed
 * performs no automatic layout management.
 *
 * For most applications, you should not use this container! It keeps
 * you from having to learn about the other GTK+ containers, but it
 * results in broken applications.  With #GtkFixed, the following
 * things will result in truncated text, overlapping widgets, and
 * other display bugs:
 *
 * - Themes, which may change widget sizes.
 *
 * - Fonts other than the one you used to write the app will of course
 *   change the size of widgets containing text; keep in mind that
 *   users may use a larger font because of difficulty reading the
 *   default, or they may be using a different OS that provides different fonts.
 *
 * - Translation of text into other languages changes its size. Also,
 *   display of non-English text will use a different font in many
 *   cases.
 *
 * In addition, #GtkFixed does not pay attention to text direction and thus may
 * produce unwanted results if your app is run under right-to-left languages
 * such as Hebrew or Arabic. That is: normally GTK+ will order containers
 * appropriately for the text direction, e.g. to put labels to the right of the
 * thing they label when using an RTL language, but it can’t do that with
 * #GtkFixed. So if you need to reorder widgets depending on the text direction,
 * you would need to manually detect it and adjust child positions accordingly.
 *
 * Finally, fixed positioning makes it kind of annoying to add/remove
 * GUI elements, since you have to reposition all the other
 * elements. This is a long-term maintenance problem for your
 * application.
 *
 * If you know none of these things are an issue for your application,
 * and prefer the simplicity of #GtkFixed, by all means use the
 * widget. But you should be aware of the tradeoffs.
 *
 * See also #GtkLayout, which shares the ability to perform fixed positioning
 * of child widgets and additionally adds custom drawing and scrollability.
 */

#include "config.h"

#include "gtkfixed.h"

#include "gtkcontainerprivate.h"
#include "gtkwidgetprivate.h"
#include "gtkprivate.h"
#include "gtkintl.h"

typedef struct
{
  GtkWidget *widget;
  gint x;
  gint y;
} GtkFixedChild;

enum {
  CHILD_PROP_0,
  CHILD_PROP_X,
  CHILD_PROP_Y
};

static GQuark child_data_quark = 0;

static void gtk_fixed_measure (GtkWidget      *widget,
                               GtkOrientation  orientation,
                               int             for_size,
                               int            *minimum,
                               int            *natural,
                               int            *minimum_baseline,
                               int            *natural_baseline);


static void gtk_fixed_size_allocate (GtkWidget           *widget,
                                     const GtkAllocation *allocation,
                                     int                  baseline);
static void gtk_fixed_add           (GtkContainer     *container,
                                     GtkWidget        *widget);
static void gtk_fixed_remove        (GtkContainer     *container,
                                     GtkWidget        *widget);
static void gtk_fixed_forall        (GtkContainer     *container,
                                     GtkCallback       callback,
                                     gpointer          callback_data);
static GType gtk_fixed_child_type   (GtkContainer     *container);

static void gtk_fixed_set_child_property (GtkContainer *container,
                                          GtkWidget    *child,
                                          guint         property_id,
                                          const GValue *value,
                                          GParamSpec   *pspec);
static void gtk_fixed_get_child_property (GtkContainer *container,
                                          GtkWidget    *child,
                                          guint         property_id,
                                          GValue       *value,
                                          GParamSpec   *pspec);

G_DEFINE_TYPE (GtkFixed, gtk_fixed, GTK_TYPE_CONTAINER)

static GtkFixedChild *
get_fixed_child (GtkWidget *widget)
{
  g_assert (GTK_IS_FIXED (gtk_widget_get_parent (widget)));

  return (GtkFixedChild *) g_object_get_qdata (G_OBJECT (widget), child_data_quark);
}

static void
gtk_fixed_class_init (GtkFixedClass *class)
{
  GtkWidgetClass *widget_class;
  GtkContainerClass *container_class;

  widget_class = (GtkWidgetClass*) class;
  container_class = (GtkContainerClass*) class;

  widget_class->measure = gtk_fixed_measure;
  widget_class->size_allocate = gtk_fixed_size_allocate;

  container_class->add = gtk_fixed_add;
  container_class->remove = gtk_fixed_remove;
  container_class->forall = gtk_fixed_forall;
  container_class->child_type = gtk_fixed_child_type;
  container_class->set_child_property = gtk_fixed_set_child_property;
  container_class->get_child_property = gtk_fixed_get_child_property;

  gtk_container_class_install_child_property (container_class,
                                              CHILD_PROP_X,
                                              g_param_spec_int ("x",
                                                                P_("X position"),
                                                                P_("X position of child widget"),
                                                                G_MININT, G_MAXINT, 0,
                                                                GTK_PARAM_READWRITE));

  gtk_container_class_install_child_property (container_class,
                                              CHILD_PROP_Y,
                                              g_param_spec_int ("y",
                                                                P_("Y position"),
                                                                P_("Y position of child widget"),
                                                                G_MININT, G_MAXINT, 0,
                                                                GTK_PARAM_READWRITE));

  child_data_quark = g_quark_from_static_string ("gtk-fixed-child-data");
}

static GType
gtk_fixed_child_type (GtkContainer *container)
{
  return GTK_TYPE_WIDGET;
}

static void
gtk_fixed_init (GtkFixed *fixed)
{
  gtk_widget_set_has_surface (GTK_WIDGET (fixed), FALSE);
}

/**
 * gtk_fixed_new:
 *
 * Creates a new #GtkFixed.
 *
 * Returns: a new #GtkFixed.
 */
GtkWidget*
gtk_fixed_new (void)
{
  return g_object_new (GTK_TYPE_FIXED, NULL);
}

/**
 * gtk_fixed_put:
 * @fixed: a #GtkFixed.
 * @widget: the widget to add.
 * @x: the horizontal position to place the widget at.
 * @y: the vertical position to place the widget at.
 *
 * Adds a widget to a #GtkFixed container at the given position.
 */
void
gtk_fixed_put (GtkFixed  *fixed,
               GtkWidget *widget,
               gint       x,
               gint       y)
{
  GtkFixedChild *child_info;

  g_return_if_fail (GTK_IS_FIXED (fixed));
  g_return_if_fail (GTK_IS_WIDGET (widget));
  g_return_if_fail (_gtk_widget_get_parent (widget) == NULL);

  child_info = g_new (GtkFixedChild, 1);
  child_info->x = x;
  child_info->y = y;

  g_object_set_qdata_full (G_OBJECT (widget), child_data_quark, child_info, g_free);
  gtk_widget_set_parent (widget, GTK_WIDGET (fixed));
}

static void
gtk_fixed_move_internal (GtkFixed      *fixed,
                         GtkWidget     *widget,
                         GtkFixedChild *child,
                         gint           x,
                         gint           y)
{
  g_return_if_fail (GTK_IS_FIXED (fixed));

  gtk_widget_freeze_child_notify (widget);

  if (child->x != x)
    {
      child->x = x;
      gtk_widget_child_notify (widget, "x");
    }

  if (child->y != y)
    {
      child->y = y;
      gtk_widget_child_notify (widget, "y");
    }

  gtk_widget_thaw_child_notify (widget);

  if (gtk_widget_get_visible (widget) &&
      gtk_widget_get_visible (GTK_WIDGET (fixed)))
    gtk_widget_queue_resize (GTK_WIDGET (fixed));
}

/**
 * gtk_fixed_move:
 * @fixed: a #GtkFixed.
 * @widget: the child widget.
 * @x: the horizontal position to move the widget to.
 * @y: the vertical position to move the widget to.
 *
 * Moves a child of a #GtkFixed container to the given position.
 */
void
gtk_fixed_move (GtkFixed  *fixed,
                GtkWidget *widget,
                gint       x,
                gint       y)
{
  g_return_if_fail (gtk_widget_get_parent (widget) == GTK_WIDGET (fixed));

  gtk_fixed_move_internal (fixed, widget, get_fixed_child (widget), x, y);
}

static void
gtk_fixed_set_child_property (GtkContainer *container,
                              GtkWidget    *child,
                              guint         property_id,
                              const GValue *value,
                              GParamSpec   *pspec)
{
  GtkFixed *fixed = GTK_FIXED (container);
  GtkFixedChild *fixed_child = get_fixed_child (child);

  switch (property_id)
    {
    case CHILD_PROP_X:
      gtk_fixed_move_internal (fixed,
                               child,
                               fixed_child,
                               g_value_get_int (value),
                               fixed_child->y);
      break;
    case CHILD_PROP_Y:
      gtk_fixed_move_internal (fixed,
                               child,
                               fixed_child,
                               fixed_child->x,
                               g_value_get_int (value));
      break;
    default:
      GTK_CONTAINER_WARN_INVALID_CHILD_PROPERTY_ID (container, property_id, pspec);
      break;
    }
}

static void
gtk_fixed_get_child_property (GtkContainer *container,
                              GtkWidget    *child,
                              guint         property_id,
                              GValue       *value,
                              GParamSpec   *pspec)
{
  GtkFixedChild *fixed_child = get_fixed_child (child);

  switch (property_id)
    {
    case CHILD_PROP_X:
      g_value_set_int (value, fixed_child->x);
      break;
    case CHILD_PROP_Y:
      g_value_set_int (value, fixed_child->y);
      break;
    default:
      GTK_CONTAINER_WARN_INVALID_CHILD_PROPERTY_ID (container, property_id, pspec);
      break;
    }
}

static void
gtk_fixed_measure (GtkWidget      *widget,
                   GtkOrientation  orientation,
                   int             for_size,
                   int            *minimum,
                   int            *natural,
                   int            *minimum_baseline,
                   int            *natural_baseline)
{
  int child_min, child_nat;
  GtkWidget *child;
  GtkFixedChild *child_info;

  for (child = gtk_widget_get_first_child (widget);
       child != NULL;
       child = gtk_widget_get_next_sibling (child))
    {
      child_info = get_fixed_child (child);

      if (!gtk_widget_get_visible (child))
        continue;

      gtk_widget_measure (child, orientation, -1, &child_min, &child_nat, NULL, NULL);

      if (orientation == GTK_ORIENTATION_HORIZONTAL)
        {
          *minimum = MAX (*minimum, child_info->x + child_min);
          *natural = MAX (*natural, child_info->x + child_nat);
        }
      else /* VERTICAL */
        { 
          *minimum = MAX (*minimum, child_info->y + child_min);
          *natural = MAX (*natural, child_info->y + child_nat);
        }
    }
}

static void
gtk_fixed_size_allocate (GtkWidget           *widget,
                         const GtkAllocation *allocation,
                         int                  baseline)
{
  GtkWidget *child;
  GtkFixedChild *child_info;
  GtkAllocation child_allocation;
  GtkRequisition child_requisition;

  for (child = gtk_widget_get_first_child (widget);
       child != NULL;
       child = gtk_widget_get_next_sibling (child))
    {
      child_info = get_fixed_child (child);

      if (!gtk_widget_get_visible (child))
        continue;

      gtk_widget_get_preferred_size (child, &child_requisition, NULL);
      child_allocation.x = child_info->x;
      child_allocation.y = child_info->y;

      child_allocation.width = child_requisition.width;
      child_allocation.height = child_requisition.height;
      gtk_widget_size_allocate (child, &child_allocation, -1);
    }
}

static void
gtk_fixed_add (GtkContainer *container,
               GtkWidget    *widget)
{
  gtk_fixed_put (GTK_FIXED (container), widget, 0, 0);
}

static void
gtk_fixed_remove (GtkContainer *container,
                  GtkWidget    *widget)
{
  gtk_widget_unparent (widget);
}

static void
gtk_fixed_forall (GtkContainer *container,
                  GtkCallback   callback,
                  gpointer      callback_data)
{
  GtkWidget *widget = GTK_WIDGET (container);
  GtkWidget *child;

  child = gtk_widget_get_first_child (widget);
  while (child)
    {
      GtkWidget *next = gtk_widget_get_next_sibling (child);

      (* callback) (child, callback_data);

      child = next;
    }
}