Pileus Git - ~andy/gtk/blob - gtk/gtkscrolledwindow.c

   1 /* GTK - The GIMP Toolkit
   2  * Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
   3  *
   4  * This library is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU Library General Public
   6  * License as published by the Free Software Foundation; either
   7  * version 2 of the License, or (at your option) any later version.
   8  *
   9  * This library is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * Library General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Library General Public
  15  * License along with this library; if not, write to the
  16  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17  * Boston, MA 02111-1307, USA.
  18  */
  19 #include "gtkscrolledwindow.h"
  20 #include "gtksignal.h"
  21
  22
  23 #define SCROLLBAR_SPACING(w) (GTK_SCROLLED_WINDOW_CLASS (GTK_OBJECT (w)->klass)->scrollbar_spacing)
  24
  25
  26 static void gtk_scrolled_window_class_init         (GtkScrolledWindowClass *klass);
  27 static void gtk_scrolled_window_init               (GtkScrolledWindow      *scrolled_window);
  28 static void gtk_scrolled_window_destroy            (GtkObject              *object);
  29 static void gtk_scrolled_window_finalize           (GtkObject              *object);
  30 static void gtk_scrolled_window_map                (GtkWidget              *widget);
  31 static void gtk_scrolled_window_unmap              (GtkWidget              *widget);
  32 static void gtk_scrolled_window_draw               (GtkWidget              *widget,
  33                                                     GdkRectangle           *area);
  34 static void gtk_scrolled_window_size_request       (GtkWidget              *widget,
  35                                                     GtkRequisition         *requisition);
  36 static void gtk_scrolled_window_size_allocate      (GtkWidget              *widget,
  37                                                     GtkAllocation          *allocation);
  38 static void gtk_scrolled_window_add                (GtkContainer           *container,
  39                                                     GtkWidget              *widget);
  40 static void gtk_scrolled_window_remove             (GtkContainer           *container,
  41                                                     GtkWidget              *widget);
  42 static void gtk_scrolled_window_foreach            (GtkContainer           *container,
  43                                                     GtkCallback             callback,
  44                                                     gpointer                callback_data);
  45 static void gtk_scrolled_window_viewport_allocate  (GtkWidget              *widget,
  46                                                     GtkAllocation          *allocation);
  47 static void gtk_scrolled_window_adjustment_changed (GtkAdjustment          *adjustment,
  48                                                     gpointer                data);
  49
  50
  51 static GtkContainerClass *parent_class = NULL;
  52
  53
  54 guint
  55 gtk_scrolled_window_get_type ()
  56 {
  57   static guint scrolled_window_type = 0;
  58
  59   if (!scrolled_window_type)
  60     {
  61       GtkTypeInfo scrolled_window_info =
  62       {
  63         "GtkScrolledWindow",
  64         sizeof (GtkScrolledWindow),
  65         sizeof (GtkScrolledWindowClass),
  66         (GtkClassInitFunc) gtk_scrolled_window_class_init,
  67         (GtkObjectInitFunc) gtk_scrolled_window_init,
  68         (GtkArgSetFunc) NULL,
  69         (GtkArgGetFunc) NULL,
  70       };
  71
  72       scrolled_window_type = gtk_type_unique (gtk_container_get_type (), &scrolled_window_info);
  73     }
  74
  75   return scrolled_window_type;
  76 }
  77
  78 static void
  79 gtk_scrolled_window_class_init (GtkScrolledWindowClass *class)
  80 {
  81   GtkObjectClass *object_class;
  82   GtkWidgetClass *widget_class;
  83   GtkContainerClass *container_class;
  84
  85   object_class = (GtkObjectClass*) class;
  86   widget_class = (GtkWidgetClass*) class;
  87   container_class = (GtkContainerClass*) class;
  88
  89   parent_class = gtk_type_class (gtk_container_get_type ());
  90
  91   object_class->destroy = gtk_scrolled_window_destroy;
  92   object_class->finalize = gtk_scrolled_window_finalize;
  93
  94   widget_class->map = gtk_scrolled_window_map;
  95   widget_class->unmap = gtk_scrolled_window_unmap;
  96   widget_class->draw = gtk_scrolled_window_draw;
  97   widget_class->size_request = gtk_scrolled_window_size_request;
  98   widget_class->size_allocate = gtk_scrolled_window_size_allocate;
  99
 100   container_class->add = gtk_scrolled_window_add;
 101   container_class->remove = gtk_scrolled_window_remove;
 102   container_class->foreach = gtk_scrolled_window_foreach;
 103
 104   class->scrollbar_spacing = 5;
 105 }
 106
 107 static void
 108 gtk_scrolled_window_init (GtkScrolledWindow *scrolled_window)
 109 {
 110   GTK_WIDGET_SET_FLAGS (scrolled_window, GTK_NO_WINDOW);
 111
 112   scrolled_window->hscrollbar = NULL;
 113   scrolled_window->vscrollbar = NULL;
 114   scrolled_window->hscrollbar_policy = GTK_POLICY_ALWAYS;
 115   scrolled_window->vscrollbar_policy = GTK_POLICY_ALWAYS;
 116 }
 117
 118 GtkWidget*
 119 gtk_scrolled_window_new (GtkAdjustment *hadjustment,
 120                          GtkAdjustment *vadjustment)
 121 {
 122   GtkWidget *scrolled_window;
 123
 124   scrolled_window = gtk_type_new (gtk_scrolled_window_get_type ());
 125
 126   gtk_scrolled_window_construct (GTK_SCROLLED_WINDOW (scrolled_window), hadjustment, vadjustment);
 127
 128   return scrolled_window;
 129 }
 130
 131 void
 132 gtk_scrolled_window_construct (GtkScrolledWindow *scrolled_window,
 133                                GtkAdjustment     *hadjustment,
 134                                GtkAdjustment     *vadjustment)
 135 {
 136   g_return_if_fail (scrolled_window != NULL);
 137   g_return_if_fail (GTK_IS_SCROLLED_WINDOW (scrolled_window));
 138   g_return_if_fail (scrolled_window->viewport == NULL);
 139
 140   scrolled_window->viewport = gtk_viewport_new (hadjustment, vadjustment);
 141   hadjustment = gtk_viewport_get_hadjustment (GTK_VIEWPORT (scrolled_window->viewport));
 142   vadjustment = gtk_viewport_get_vadjustment (GTK_VIEWPORT (scrolled_window->viewport));
 143
 144   gtk_signal_connect (GTK_OBJECT (hadjustment), "changed",
 145                       (GtkSignalFunc) gtk_scrolled_window_adjustment_changed,
 146                       (gpointer) scrolled_window);
 147   gtk_signal_connect (GTK_OBJECT (vadjustment), "changed",
 148                       (GtkSignalFunc) gtk_scrolled_window_adjustment_changed,
 149                       (gpointer) scrolled_window);
 150
 151   scrolled_window->hscrollbar = gtk_hscrollbar_new (hadjustment);
 152   scrolled_window->vscrollbar = gtk_vscrollbar_new (vadjustment);
 153
 154   gtk_widget_set_parent (scrolled_window->viewport, GTK_WIDGET (scrolled_window));
 155   gtk_widget_set_parent (scrolled_window->hscrollbar, GTK_WIDGET (scrolled_window));
 156   gtk_widget_set_parent (scrolled_window->vscrollbar, GTK_WIDGET (scrolled_window));
 157
 158   gtk_widget_show (scrolled_window->viewport);
 159   gtk_widget_show (scrolled_window->hscrollbar);
 160   gtk_widget_show (scrolled_window->vscrollbar);
 161
 162   gtk_widget_ref (scrolled_window->viewport);
 163   gtk_widget_ref (scrolled_window->hscrollbar);
 164   gtk_widget_ref (scrolled_window->vscrollbar);
 165 }
 166
 167 GtkAdjustment*
 168 gtk_scrolled_window_get_hadjustment (GtkScrolledWindow *scrolled_window)
 169 {
 170   g_return_val_if_fail (scrolled_window != NULL, NULL);
 171   g_return_val_if_fail (GTK_IS_SCROLLED_WINDOW (scrolled_window), NULL);
 172
 173   return gtk_range_get_adjustment (GTK_RANGE (scrolled_window->hscrollbar));
 174 }
 175
 176 GtkAdjustment*
 177 gtk_scrolled_window_get_vadjustment (GtkScrolledWindow *scrolled_window)
 178 {
 179   g_return_val_if_fail (scrolled_window != NULL, NULL);
 180   g_return_val_if_fail (GTK_IS_SCROLLED_WINDOW (scrolled_window), NULL);
 181
 182   return gtk_range_get_adjustment (GTK_RANGE (scrolled_window->vscrollbar));
 183 }
 184
 185 void
 186 gtk_scrolled_window_set_policy (GtkScrolledWindow *scrolled_window,
 187                                 GtkPolicyType      hscrollbar_policy,
 188                                 GtkPolicyType      vscrollbar_policy)
 189 {
 190   g_return_if_fail (scrolled_window != NULL);
 191   g_return_if_fail (GTK_IS_SCROLLED_WINDOW (scrolled_window));
 192
 193   if ((scrolled_window->hscrollbar_policy != hscrollbar_policy) ||
 194       (scrolled_window->vscrollbar_policy != vscrollbar_policy))
 195     {
 196       scrolled_window->hscrollbar_policy = hscrollbar_policy;
 197       scrolled_window->vscrollbar_policy = vscrollbar_policy;
 198
 199       if (GTK_WIDGET (scrolled_window)->parent)
 200         gtk_widget_queue_resize (GTK_WIDGET (scrolled_window));
 201     }
 202 }
 203
 204
 205 static void
 206 gtk_scrolled_window_destroy (GtkObject *object)
 207 {
 208   GtkScrolledWindow *scrolled_window;
 209
 210   g_return_if_fail (object != NULL);
 211   g_return_if_fail (GTK_IS_SCROLLED_WINDOW (object));
 212
 213   scrolled_window = GTK_SCROLLED_WINDOW (object);
 214
 215   gtk_widget_destroy (scrolled_window->viewport);
 216   gtk_widget_destroy (scrolled_window->hscrollbar);
 217   gtk_widget_destroy (scrolled_window->vscrollbar);
 218
 219   if (GTK_OBJECT_CLASS (parent_class)->destroy)
 220     (* GTK_OBJECT_CLASS (parent_class)->destroy) (object);
 221 }
 222
 223 static void
 224 gtk_scrolled_window_finalize (GtkObject *object)
 225 {
 226   GtkScrolledWindow *scrolled_window;
 227
 228   scrolled_window = GTK_SCROLLED_WINDOW (object);
 229   gtk_widget_unref (scrolled_window->viewport);
 230   gtk_widget_unref (scrolled_window->hscrollbar);
 231   gtk_widget_unref (scrolled_window->vscrollbar);
 232
 233   GTK_OBJECT_CLASS (parent_class)->finalize (object);
 234 }
 235
 236 static void
 237 gtk_scrolled_window_map (GtkWidget *widget)
 238 {
 239   GtkScrolledWindow *scrolled_window;
 240
 241   g_return_if_fail (widget != NULL);
 242   g_return_if_fail (GTK_IS_SCROLLED_WINDOW (widget));
 243
 244   if (!GTK_WIDGET_MAPPED (widget))
 245     {
 246       GTK_WIDGET_SET_FLAGS (widget, GTK_MAPPED);
 247       scrolled_window = GTK_SCROLLED_WINDOW (widget);
 248
 249       if (GTK_WIDGET_VISIBLE (scrolled_window->viewport) &&
 250           !GTK_WIDGET_MAPPED (scrolled_window->viewport))
 251         gtk_widget_map (scrolled_window->viewport);
 252
 253       if (GTK_WIDGET_VISIBLE (scrolled_window->hscrollbar) &&
 254           !GTK_WIDGET_MAPPED (scrolled_window->hscrollbar))
 255         gtk_widget_map (scrolled_window->hscrollbar);
 256
 257       if (GTK_WIDGET_VISIBLE (scrolled_window->vscrollbar) &&
 258           !GTK_WIDGET_MAPPED (scrolled_window->vscrollbar))
 259         gtk_widget_map (scrolled_window->vscrollbar);
 260     }
 261 }
 262
 263 static void
 264 gtk_scrolled_window_unmap (GtkWidget *widget)
 265 {
 266   GtkScrolledWindow *scrolled_window;
 267
 268   g_return_if_fail (widget != NULL);
 269   g_return_if_fail (GTK_IS_SCROLLED_WINDOW (widget));
 270
 271   if (GTK_WIDGET_MAPPED (widget))
 272     {
 273       GTK_WIDGET_UNSET_FLAGS (widget, GTK_MAPPED);
 274       scrolled_window = GTK_SCROLLED_WINDOW (widget);
 275
 276       if (GTK_WIDGET_MAPPED (scrolled_window->viewport))
 277         gtk_widget_unmap (scrolled_window->viewport);
 278
 279       if (GTK_WIDGET_MAPPED (scrolled_window->hscrollbar))
 280         gtk_widget_unmap (scrolled_window->hscrollbar);
 281
 282       if (GTK_WIDGET_MAPPED (scrolled_window->vscrollbar))
 283         gtk_widget_unmap (scrolled_window->vscrollbar);
 284     }
 285 }
 286
 287 static void
 288 gtk_scrolled_window_draw (GtkWidget    *widget,
 289                           GdkRectangle *area)
 290 {
 291   GtkScrolledWindow *scrolled_window;
 292   GdkRectangle child_area;
 293
 294   g_return_if_fail (widget != NULL);
 295   g_return_if_fail (GTK_IS_SCROLLED_WINDOW (widget));
 296   g_return_if_fail (area != NULL);
 297
 298   if (GTK_WIDGET_DRAWABLE (widget))
 299     {
 300       scrolled_window = GTK_SCROLLED_WINDOW (widget);
 301
 302       if (gtk_widget_intersect (scrolled_window->viewport, area, &child_area))
 303         gtk_widget_draw (scrolled_window->viewport, &child_area);
 304
 305       if (gtk_widget_intersect (scrolled_window->hscrollbar, area, &child_area))
 306         gtk_widget_draw (scrolled_window->hscrollbar, &child_area);
 307
 308       if (gtk_widget_intersect (scrolled_window->vscrollbar, area, &child_area))
 309         gtk_widget_draw (scrolled_window->vscrollbar, &child_area);
 310     }
 311 }
 312
 313 static void
 314 gtk_scrolled_window_size_request (GtkWidget      *widget,
 315                                   GtkRequisition *requisition)
 316 {
 317   GtkScrolledWindow *scrolled_window;
 318   gint extra_height;
 319   gint extra_width;
 320
 321   g_return_if_fail (widget != NULL);
 322   g_return_if_fail (GTK_IS_SCROLLED_WINDOW (widget));
 323   g_return_if_fail (requisition != NULL);
 324
 325   scrolled_window = GTK_SCROLLED_WINDOW (widget);
 326
 327   requisition->width = 0;
 328   requisition->height = 0;
 329
 330   if (GTK_WIDGET_VISIBLE (scrolled_window->viewport))
 331     {
 332       gtk_widget_size_request (scrolled_window->viewport, &scrolled_window->viewport->requisition);
 333
 334       requisition->width += scrolled_window->viewport->requisition.width;
 335       requisition->height += scrolled_window->viewport->requisition.height;
 336     }
 337
 338   extra_width = 0;
 339   extra_height = 0;
 340
 341   if ((scrolled_window->hscrollbar_policy == GTK_POLICY_AUTOMATIC) ||
 342       GTK_WIDGET_VISIBLE (scrolled_window->hscrollbar))
 343     {
 344       gtk_widget_size_request (scrolled_window->hscrollbar,
 345                                &scrolled_window->hscrollbar->requisition);
 346
 347       requisition->width = MAX (requisition->width, scrolled_window->hscrollbar->requisition.width);
 348       extra_height = SCROLLBAR_SPACING (scrolled_window) + scrolled_window->hscrollbar->requisition.height;
 349     }
 350
 351   if ((scrolled_window->vscrollbar_policy == GTK_POLICY_AUTOMATIC) ||
 352       GTK_WIDGET_VISIBLE (scrolled_window->vscrollbar))
 353     {
 354       gtk_widget_size_request (scrolled_window->vscrollbar,
 355                                &scrolled_window->vscrollbar->requisition);
 356
 357       requisition->height = MAX (requisition->height, scrolled_window->vscrollbar->requisition.height);
 358       extra_width = SCROLLBAR_SPACING (scrolled_window) + scrolled_window->vscrollbar->requisition.width;
 359     }
 360
 361   requisition->width += GTK_CONTAINER (widget)->border_width * 2 + extra_width;
 362   requisition->height += GTK_CONTAINER (widget)->border_width * 2 + extra_height;
 363 }
 364
 365 static void
 366 gtk_scrolled_window_size_allocate (GtkWidget     *widget,
 367                                    GtkAllocation *allocation)
 368 {
 369   GtkScrolledWindow *scrolled_window;
 370   GtkAllocation viewport_allocation;
 371   GtkAllocation child_allocation;
 372   guint previous_hvis;
 373   guint previous_vvis;
 374
 375   g_return_if_fail (widget != NULL);
 376   g_return_if_fail (GTK_IS_SCROLLED_WINDOW (widget));
 377   g_return_if_fail (allocation != NULL);
 378
 379   scrolled_window = GTK_SCROLLED_WINDOW (widget);
 380   widget->allocation = *allocation;
 381
 382   gtk_scrolled_window_viewport_allocate (widget, &viewport_allocation);
 383
 384   gtk_container_disable_resize (GTK_CONTAINER (scrolled_window));
 385
 386   if (GTK_WIDGET_VISIBLE (scrolled_window->viewport))
 387     {
 388       do {
 389         gtk_scrolled_window_viewport_allocate (widget, &viewport_allocation);
 390
 391         child_allocation.x = viewport_allocation.x + allocation->x;
 392         child_allocation.y = viewport_allocation.y + allocation->y;
 393         child_allocation.width = viewport_allocation.width;
 394         child_allocation.height = viewport_allocation.height;
 395
 396         previous_hvis = GTK_WIDGET_VISIBLE (scrolled_window->hscrollbar);
 397         previous_vvis = GTK_WIDGET_VISIBLE (scrolled_window->vscrollbar);
 398
 399         gtk_widget_size_allocate (scrolled_window->viewport, &child_allocation);
 400       } while ((previous_hvis != GTK_WIDGET_VISIBLE (scrolled_window->hscrollbar)) ||
 401                (previous_vvis != GTK_WIDGET_VISIBLE (scrolled_window->vscrollbar)));
 402     }
 403
 404   if (GTK_WIDGET_VISIBLE (scrolled_window->hscrollbar))
 405     {
 406       child_allocation.x = viewport_allocation.x;
 407       child_allocation.y = viewport_allocation.y + viewport_allocation.height + SCROLLBAR_SPACING (scrolled_window);
 408       child_allocation.width = viewport_allocation.width;
 409       child_allocation.height = scrolled_window->hscrollbar->requisition.height;
 410       child_allocation.x += allocation->x;
 411       child_allocation.y += allocation->y;
 412
 413       gtk_widget_size_allocate (scrolled_window->hscrollbar, &child_allocation);
 414     }
 415
 416   if (GTK_WIDGET_VISIBLE (scrolled_window->vscrollbar))
 417     {
 418       child_allocation.x = viewport_allocation.x + viewport_allocation.width + SCROLLBAR_SPACING (scrolled_window);
 419       child_allocation.y = viewport_allocation.y;
 420       child_allocation.width = scrolled_window->vscrollbar->requisition.width;
 421       child_allocation.height = viewport_allocation.height;
 422       child_allocation.x += allocation->x;
 423       child_allocation.y += allocation->y;
 424
 425       gtk_widget_size_allocate (scrolled_window->vscrollbar, &child_allocation);
 426     }
 427
 428   gtk_container_enable_resize (GTK_CONTAINER (scrolled_window));
 429 }
 430
 431 static void
 432 gtk_scrolled_window_add (GtkContainer *container,
 433                          GtkWidget    *widget)
 434 {
 435   GtkScrolledWindow *scrolled_window;
 436
 437   g_return_if_fail (container != NULL);
 438   g_return_if_fail (GTK_IS_SCROLLED_WINDOW (container));
 439   g_return_if_fail (widget != NULL);
 440
 441   scrolled_window = GTK_SCROLLED_WINDOW (container);
 442   gtk_container_add (GTK_CONTAINER (scrolled_window->viewport), widget);
 443 }
 444
 445 static void
 446 gtk_scrolled_window_remove (GtkContainer *container,
 447                             GtkWidget    *widget)
 448 {
 449   GtkScrolledWindow *scrolled_window;
 450
 451   g_return_if_fail (container != NULL);
 452   g_return_if_fail (GTK_IS_SCROLLED_WINDOW (container));
 453   g_return_if_fail (widget != NULL);
 454
 455   scrolled_window = GTK_SCROLLED_WINDOW (container);
 456
 457   if (scrolled_window->viewport == widget ||
 458       scrolled_window->hscrollbar == widget ||
 459       scrolled_window->vscrollbar == widget)
 460     {
 461       /* this happens during destroy */
 462       gtk_widget_unparent (widget);
 463     }
 464   else
 465     gtk_container_remove (GTK_CONTAINER (scrolled_window->viewport), widget);
 466 }
 467
 468 static void
 469 gtk_scrolled_window_foreach (GtkContainer *container,
 470                              GtkCallback   callback,
 471                              gpointer      callback_data)
 472 {
 473   GtkScrolledWindow *scrolled_window;
 474
 475   g_return_if_fail (container != NULL);
 476   g_return_if_fail (GTK_IS_SCROLLED_WINDOW (container));
 477   g_return_if_fail (callback != NULL);
 478
 479   scrolled_window = GTK_SCROLLED_WINDOW (container);
 480
 481   (* callback) (scrolled_window->viewport, callback_data);
 482 }
 483
 484 static void
 485 gtk_scrolled_window_viewport_allocate (GtkWidget     *widget,
 486                                        GtkAllocation *allocation)
 487 {
 488   GtkScrolledWindow *scrolled_window;
 489
 490   g_return_if_fail (widget != NULL);
 491   g_return_if_fail (allocation != NULL);
 492
 493   scrolled_window = GTK_SCROLLED_WINDOW (widget);
 494
 495   allocation->x = GTK_CONTAINER (widget)->border_width;
 496   allocation->y = GTK_CONTAINER (widget)->border_width;
 497   allocation->width = MAX (1, widget->allocation.width - allocation->x * 2);
 498   allocation->height = MAX (1, widget->allocation.height - allocation->y * 2);
 499
 500   if (GTK_WIDGET_VISIBLE (scrolled_window->vscrollbar))
 501     allocation->width = MAX (1,
 502       allocation->width - (scrolled_window->vscrollbar->requisition.width + SCROLLBAR_SPACING (scrolled_window)));
 503   if (GTK_WIDGET_VISIBLE (scrolled_window->hscrollbar))
 504     allocation->height = MAX (1,
 505       allocation->height - (scrolled_window->hscrollbar->requisition.height + SCROLLBAR_SPACING (scrolled_window)));
 506 }
 507
 508 static void
 509 gtk_scrolled_window_adjustment_changed (GtkAdjustment *adjustment,
 510                                         gpointer       data)
 511 {
 512   GtkScrolledWindow *scrolled_win;
 513   GtkWidget *scrollbar;
 514   gint hide_scrollbar;
 515   gint policy;
 516
 517   g_return_if_fail (adjustment != NULL);
 518   g_return_if_fail (data != NULL);
 519
 520   scrolled_win = GTK_SCROLLED_WINDOW (data);
 521
 522   if (adjustment == gtk_range_get_adjustment (GTK_RANGE (scrolled_win->hscrollbar)))
 523     {
 524       scrollbar = scrolled_win->hscrollbar;
 525       policy = scrolled_win->hscrollbar_policy;
 526     }
 527   else if (adjustment == gtk_range_get_adjustment (GTK_RANGE (scrolled_win->vscrollbar)))
 528     {
 529       scrollbar = scrolled_win->vscrollbar;
 530       policy = scrolled_win->vscrollbar_policy;
 531     }
 532   else
 533     {
 534       g_warning ("could not determine which adjustment scrollbar received change signal for");
 535       return;
 536     }
 537
 538   if (policy == GTK_POLICY_AUTOMATIC)
 539     {
 540       hide_scrollbar = FALSE;
 541
 542       if ((adjustment->upper - adjustment->lower) <= adjustment->page_size)
 543         hide_scrollbar = TRUE;
 544
 545       if (hide_scrollbar)
 546         {
 547           if (GTK_WIDGET_VISIBLE (scrollbar))
 548             gtk_widget_hide (scrollbar);
 549         }
 550       else
 551         {
 552           if (!GTK_WIDGET_VISIBLE (scrollbar))
 553             gtk_widget_show (scrollbar);
 554         }
 555     }
 556 }