dw_gtk_viewport.c

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         world_y = y + gtk_layout_get_vadjustment(GTK_LAYOUT(viewport))->value;
         dw_widget =
            Dw_gtk_viewport_widget_at_point (viewport, world_x, world_y);

         return Dw_widget_mouse_event (dw_widget, widget,
                                       world_x, world_y, event);
      }
   }

   return FALSE;
}


/*
 * Standard Gtk+ function
 */
static gint Dw_gtk_viewport_button_press (GtkWidget *widget,
                                          GdkEventButton *event)
{
   /* We focus always the viewport window (i.e., more precisely, the
    * GktDwScrolledFrame). */
   if (widget->parent)
      gtk_widget_grab_focus(widget->parent);

   return Dw_gtk_viewport_mouse_event (widget, event->x, event->y,
                                       (GdkEvent*) event);
}


/*
 * Standard Gtk+ function
 */
static gint Dw_gtk_viewport_button_release (GtkWidget *widget,
                                            GdkEventButton *event)
{
   return Dw_gtk_viewport_mouse_event (widget, event->x, event->y,
                                       (GdkEvent*) event);
}


/*
 * Standard Gtk+ function
 */
static gint Dw_gtk_viewport_motion_notify (GtkWidget *widget,
                                           GdkEventMotion *event)
{
   GtkDwViewport *viewport = GTK_DW_VIEWPORT (widget);

   viewport->mouse_x = event->x;
   viewport->mouse_y = event->y;
   return Dw_gtk_viewport_mouse_event (widget, event->x, event->y,
                                       (GdkEvent*) event);
}


/*
 * Standard Gtk+ function
 */
static gint Dw_gtk_viewport_enter_notify (GtkWidget *widget,
                                          GdkEventCrossing *event)
{
   return Dw_gtk_viewport_mouse_event (widget, event->x, event->y, NULL);
}


/*
 * Standard Gtk+ function
 */
static gint Dw_gtk_viewport_leave_notify (GtkWidget *widget,
                                          GdkEventCrossing *event)
{
   /* There will anyway be no Dw widget, thus this simple call */
   return Dw_widget_mouse_event (NULL, widget, 0, 0, NULL);
}


/*
 * This function is called when the viewport changes, and causes
 * motion_notify events to be simulated.
 */
static void Dw_gtk_viewport_adj_changed (GtkAdjustment *adj,
                                         GtkDwViewport *viewport)
{
   Dw_gtk_viewport_mouse_event (GTK_WIDGET (viewport),
                                viewport->mouse_x, viewport->mouse_y, NULL);
}

/**********************
 *                    *
 *  public functions  *
 *                    *
 **********************/

/*
 * Set the top-level Dw widget.
 * If there is already one, you must destroy it before, otherwise the
 * function will fail.
 */
void a_Dw_gtk_viewport_add_dw (GtkDwViewport *viewport,
                               DwWidget *widget)
{
   g_return_if_fail (viewport->child == NULL);

   viewport->child = widget;
   DBG_OBJ_ASSOC(widget, viewport);

   widget->parent = NULL;
   widget->viewport = GTK_WIDGET (viewport);
   /*widget->window = viewport->back_pixmap;*/

   if (GTK_WIDGET_REALIZED (viewport))
      a_Dw_widget_realize (widget);

   Dw_gtk_viewport_calc_size (viewport);
   Dw_gtk_viewport_remove_anchor (viewport);

   a_Findtext_state_set_widget (viewport->findtext_state, widget);
   a_Selection_reset (viewport->selection);
}

/**************************************************
 *                                                *
 *  Functions used by GtkDwViewport and DwWidget  *
 *                                                *
 **************************************************/

/*
 * This function only *recognizes* that the top-level Dw widget is to
 * be removed. It is called by Dw_widget_shutdown.
 * Don't use this function directly!
 */
void Dw_gtk_viewport_remove_dw (GtkDwViewport *viewport)
{
   a_Findtext_state_set_widget (viewport->findtext_state, NULL);
   viewport->child = NULL;
   Dw_gtk_viewport_remove_anchor (viewport);
   Dw_gtk_viewport_calc_size (viewport);
}


/*
 * Used by Dw_gtk_viewport_calc_size.
 */
static void Dw_gtk_viewport_calc_child_size (GtkDwViewport *viewport,
                                             gint32 child_width,
                                             gint32 child_height,
                                             DwRequisition *child_requisition)
{
   if (child_width < 0) child_width = 0;
   if (child_height < 0) child_height = 0;

   DEBUG_MSG (2, "   width = %d, height = %d ...\n",
              child_width, child_height);

   a_Dw_widget_set_width (viewport->child, child_width);
   a_Dw_widget_set_ascent (viewport->child, child_height);
   a_Dw_widget_set_descent (viewport->child, 0);

   a_Dw_widget_size_request (viewport->child, child_requisition);
}


/*
 * Calculate the size of the scrolled area and allocate the top-level
 * widget. This function is called when the top-level Dw widget has
 * changed its size etc.
 */
void Dw_gtk_viewport_calc_size (GtkDwViewport *viewport)
{
   GtkWidget *widget;
   GtkScrolledWindow *scrolled;

   DwRequisition child_requisition;
   DwAllocation child_allocation;
   gint border_width,  space;

   GtkRequisition bar_requisition;
   gint max_width, max_height, bar_width_diff, bar_height_diff, child_height;

   if (viewport->calc_size_blocked)
      return;

   viewport->calc_size_blocked = TRUE;

   if (viewport->child) {
      /*
       * Determine the size hints for the Dw widget. This is a bit
       * tricky, because you must know if scrollbars are visible or
       * not, which depends on the size of the Dw widget, which then
       * depends on the hints. The idea is to test several
       * configurations, there are four of them, from combining the
       * cases horizontal/vertical scrollbar visible/invisible.
       *
       * For optimization, the horizontal scrollbar is currently not
       * regarded, the height hint is always the same, as if the
       * scrollbar was allways visible. In future, this may be
       * implemented correctly, by using the minimal width to optimize
       * most cases. (Minimal widths will also be used by tables.)
       *
       * Furthermore, the last result (vertical scrollbar visible or
       * not) is stored in the viewport, and tested first. This will
       * make a second test only necessary when the visibility
       * switches, which normally happens only once when filling the
       * page with text. (Actually, this assumes that the page size is
       * always *growing*, but this is nevertheless true in dillo.)
       */

      widget = GTK_WIDGET (viewport);
      scrolled = GTK_SCROLLED_WINDOW (widget->parent->parent);
      space = GTK_SCROLLED_WINDOW_CLASS(GTK_OBJECT(scrolled)->klass)
         ->scrollbar_spacing;
      border_width = GTK_CONTAINER(viewport)->border_width;

      gtk_widget_size_request (scrolled->vscrollbar, &bar_requisition);
      bar_width_diff = bar_requisition.width + space;
      max_width = widget->allocation.width - 2 * border_width;
      if (scrolled->vscrollbar_visible)
         max_width += bar_width_diff;

      gtk_widget_size_request (scrolled->hscrollbar, &bar_requisition);
      bar_height_diff = bar_requisition.height + space;
      max_height = widget->allocation.height - 2 * border_width;
      if (scrolled->hscrollbar_visible)
         max_height += bar_height_diff;

      DEBUG_MSG (2, "------------------------------------------------->\n");
      DEBUG_MSG (2, "Dw_gtk_viewport_calc_size: %d x %d (%c/%c) -> %d x %d\n",
                 widget->allocation.width, widget->allocation.height,
                 scrolled->vscrollbar_visible ? 't' : 'f',
                 scrolled->hscrollbar_visible ? 't' : 'f',
                 max_width, max_height);

      if (scrolled->vscrollbar_policy == GTK_POLICY_NEVER)
         child_height = max_height;
      else
         child_height = max_height - bar_height_diff;

      switch (scrolled->vscrollbar_policy) {
      case GTK_POLICY_ALWAYS:
         Dw_gtk_viewport_calc_child_size (viewport, max_width - bar_width_diff,
                                          child_height,
                                          &child_requisition);
         break;

      case GTK_POLICY_AUTOMATIC:
         if (viewport->vscrollbar_used) {
            DEBUG_MSG (2, "Testing with vertical scrollbar ...\n");
            Dw_gtk_viewport_calc_child_size (viewport,
                                             max_width - bar_width_diff,
                                             child_height,
                                             &child_requisition);

            if (child_requisition.ascent
                + child_requisition.descent <= child_height) {
               DEBUG_MSG (2, "   failed!\n");
               Dw_gtk_viewport_calc_child_size (viewport, max_width,
                                                child_height,
                                                &child_requisition);
               viewport->vscrollbar_used = TRUE;
            }

         } else {
            DEBUG_MSG (2, "Testing without vertical scrollbar ...\n");
            Dw_gtk_viewport_calc_child_size (viewport, max_width,
                                             child_height,
                                             &child_requisition);

            /* todo: see above */
            if (child_requisition.ascent
                + child_requisition.descent > child_height) {
               DEBUG_MSG (2, "   failed!\n");
               Dw_gtk_viewport_calc_child_size (viewport,
                                                max_width - bar_width_diff,
                                                child_height,
                                                &child_requisition);
               viewport->vscrollbar_used = TRUE;
            }
         }
         break;

      case GTK_POLICY_NEVER:
         Dw_gtk_viewport_calc_child_size (viewport, max_width,
                                          child_height,
                                          &child_requisition);
      }

      child_allocation.x = border_width;
      child_allocation.y = border_width;
      child_allocation.width = child_requisition.width;
      child_allocation.ascent = child_requisition.ascent;
      child_allocation.descent = child_requisition.descent;
      a_Dw_widget_size_allocate (viewport->child, &child_allocation);

      gtk_layout_set_size (GTK_LAYOUT (viewport),
                           child_requisition.width + 2 * border_width,
                           child_requisition.ascent + child_requisition.descent
                           + 2 * border_width);

      DEBUG_MSG (1, "Setting size to %d x %d\n",
                 child_requisition.width + 2 * border_width,
                 child_requisition.ascent + child_requisition.descent
                 + 2 * border_width);

      DEBUG_MSG (2, "<-------------------------------------------------\n");
   } else {
      gtk_layout_set_size (GTK_LAYOUT (viewport), 1, 1);
      viewport->hscrollbar_used = FALSE;
      viewport->vscrollbar_used = FALSE;
   }

   Dw_gtk_viewport_update_anchor (viewport);
   gtk_widget_queue_draw (GTK_WIDGET (viewport));

   viewport->calc_size_blocked = FALSE;
}


/* used by Dw_gtk_viewport_widget_at_point */
typedef struct
{
   gint32 x;
   gint32 y;
   DwWidget *widget;
} WidgetAtPointData;

/* used by Dw_gtk_viewport_widget_at_point */
static void Dw_gtk_viewport_widget_at_point_callback (DwWidget *widget,
                                                      gpointer data)
{
   WidgetAtPointData *callback_data;

   callback_data = (WidgetAtPointData*) data;
   DEBUG_MSG (1, "  Checking %p ...\n", widget);

   if (/* As a special exception, for the top-level widget, not the
        * allocation is regarded, but the whole viewport. This makes
        * selections more useful, since so the user can start the
        * selection outside of the allocation. */
       widget->parent == NULL ||
       /* Otherwise, check whether pointer is in the allocation. */
       (callback_data->x >= widget->allocation.x &&
        callback_data->y >= widget->allocation.y &&
        callback_data->x < widget->allocation.x + widget->allocation.width &&
        callback_data->y < widget->allocation.y + DW_WIDGET_HEIGHT(widget))) {
      DEBUG_MSG (1, "    yes\n");
      if (DW_IS_CONTAINER (widget))
         a_Dw_container_forall (DW_CONTAINER (widget),
                                Dw_gtk_viewport_widget_at_point_callback,
                                data);

      if (callback_data->widget == NULL)
         callback_data->widget = widget;
   }
}

/*
 * Return the widget at point (x, y) (world coordinates).
 */
DwWidget* Dw_gtk_viewport_widget_at_point (GtkDwViewport *viewport,
                                           gint32 x,
                                           gint32 y)
{
   WidgetAtPointData callback_data;

   callback_data.x = x;
   callback_data.y = y;
   callback_data.widget = NULL;

   if (viewport->child)
      Dw_gtk_viewport_widget_at_point_callback (viewport->child,
                                                &callback_data);

   return callback_data.widget;
}


/*************
 *           *
 *  Anchors  *
 *           *
 *************/

/*
 * Add or change an anchor.
 * The widget is responsible for storing a copy of name.
 *
 * todo: Currently, no horizontal scrolling is done. This is generally
 * possible, DW_HPOS_INTO_VIEW should be used for this, but it is
 * rather complicated to determine the width of an anchor. This would
 * be the lenght of the region between <a> and </a>, the page widget
 * would have to have two kinds of content types (opening and closing
 * anchor), and some changes in the HTML parser are necessary.
 */
void p_Dw_gtk_viewport_put_anchor (DwWidget *widget,
                                   gchar *name,
                                   gint32 y)
{
   GtkDwViewport *viewport;
   GtkDwViewportAnchor *anchor;