GtkScrolledWindow: Allow scrolling without bars

Add a new policy, GTK_POLICY_EXTERNAL, which hides the scrollbar,
but does not force the scrolled windows size to be determined by
its child. This can be used to keep two scrolled windows in sync,
while sharing a single scrollbar.

https://bugzilla.gnome.org/show_bug.cgi?id=730730

diff --git a/gtk/gtkscrolledwindow.c b/gtk/gtkscrolledwindow.c
index ff3ff065cbca3e6766b4ee676cf05123aa773491..c5ca398689da0c4fc93dc04abf07a267a3a10d45 100644 (file)
--- a/gtk/gtkscrolledwindow.c
+++ b/gtk/gtkscrolledwindow.c
@@ -569,6 +569,22 @@ gtk_scrolled_window_class_init (GtkScrolledWindowClass *class)
   gtk_widget_class_set_accessible_type (widget_class, GTK_TYPE_SCROLLED_WINDOW_ACCESSIBLE);
 }
 
+static gboolean
+may_hscroll (GtkScrolledWindow *scrolled_window)
+{
+  GtkScrolledWindowPrivate *priv = scrolled_window->priv;
+
+  return priv->hscrollbar_visible || priv->hscrollbar_policy == GTK_POLICY_EXTERNAL;
+}
+
+static gboolean
+may_vscroll (GtkScrolledWindow *scrolled_window)
+{
+  GtkScrolledWindowPrivate *priv = scrolled_window->priv;
+
+  return priv->vscrollbar_visible || priv->vscrollbar_policy == GTK_POLICY_EXTERNAL;
+}
+
 static void
 scrolled_window_drag_begin_cb (GtkScrolledWindow *scrolled_window,
                                gdouble            start_x,
@@ -589,9 +605,8 @@ scrolled_window_drag_begin_cb (GtkScrolledWindow *scrolled_window,
   event = gtk_gesture_get_last_event (gesture, sequence);
   event_widget = gtk_get_event_widget ((GdkEvent *) event);
 
-  if (event_widget == priv->vscrollbar ||
-      event_widget == priv->hscrollbar ||
-      (!priv->hscrollbar_visible && !priv->vscrollbar_visible))
+  if (event_widget == priv->vscrollbar || event_widget == priv->hscrollbar ||
+      (!may_hscroll (scrolled_window) && !may_vscroll (scrolled_window)))
     state = GTK_EVENT_SEQUENCE_DENIED;
   else if (priv->capture_button_press)
     state = GTK_EVENT_SEQUENCE_CLAIMED;
@@ -671,7 +686,7 @@ scrolled_window_drag_update_cb (GtkScrolledWindow *scrolled_window,
     }
 
   hadjustment = gtk_range_get_adjustment (GTK_RANGE (priv->hscrollbar));
-  if (hadjustment && priv->hscrollbar_visible)
+  if (hadjustment && may_hscroll (scrolled_window))
     {
       dx = priv->drag_start_x - offset_x;
       _gtk_scrolled_window_set_adjustment_value (scrolled_window, hadjustment,
@@ -679,7 +694,7 @@ scrolled_window_drag_update_cb (GtkScrolledWindow *scrolled_window,
     }
 
   vadjustment = gtk_range_get_adjustment (GTK_RANGE (priv->vscrollbar));
-  if (vadjustment && priv->vscrollbar_visible)
+  if (vadjustment && may_vscroll (scrolled_window))
     {
       dy = priv->drag_start_y - offset_y;
       _gtk_scrolled_window_set_adjustment_value (scrolled_window, vadjustment,
@@ -712,10 +727,10 @@ scrolled_window_swipe_cb (GtkScrolledWindow *scrolled_window,
   priv->x_velocity = -x_velocity;
   priv->y_velocity = -y_velocity;
 
-  /* Zero out vector components without a visible scrollbar */
-  if (!priv->hscrollbar_visible)
+  /* Zero out vector components for which we don't scroll */
+  if (!may_hscroll (scrolled_window))
     priv->x_velocity = 0;
-  if (!priv->vscrollbar_visible)
+  if (!may_vscroll (scrolled_window))
     priv->y_velocity = 0;
 
   if (priv->x_velocity != 0 || priv->y_velocity != 0 || overshoot)
@@ -765,12 +780,12 @@ gtk_scrolled_window_check_attach_pan_gesture (GtkScrolledWindow *sw)
   GtkScrolledWindowPrivate *priv = sw->priv;
 
   if (priv->kinetic_scrolling &&
-      ((priv->hscrollbar_visible && !priv->vscrollbar_visible) ||
-       (!priv->hscrollbar_visible && priv->vscrollbar_visible)))
+      ((may_hscroll (sw) && !may_vscroll (sw)) ||
+       (!may_hscroll (sw) && may_vscroll (sw))))
     {
       GtkOrientation orientation;
 
-      if (priv->hscrollbar_visible)
+      if (may_hscroll (sw))
         orientation = GTK_ORIENTATION_HORIZONTAL;
       else
         orientation = GTK_ORIENTATION_VERTICAL;
@@ -1697,7 +1712,7 @@ gtk_scrolled_window_draw (GtkWidget *widget,
                          gtk_widget_get_allocated_width (widget),
                          gtk_widget_get_allocated_height (widget));
 
-  if (priv->hscrollbar_visible && 
+  if (priv->hscrollbar_visible &&
       priv->vscrollbar_visible)
     gtk_scrolled_window_draw_scrollbars_junction (scrolled_window, cr);
 
@@ -1817,10 +1832,6 @@ gtk_scrolled_window_scroll_child (GtkScrolledWindow *scrolled_window,
       return FALSE;
     }
 
-  if ((horizontal && !priv->hscrollbar_visible) ||
-      (!horizontal && !priv->vscrollbar_visible))
-    return FALSE;
-
   if (horizontal)
     adjustment = gtk_range_get_adjustment (GTK_RANGE (priv->hscrollbar));
   else
@@ -2075,11 +2086,14 @@ gtk_scrolled_window_size_allocate (GtkWidget     *widget,
 
   if (priv->hscrollbar_policy == GTK_POLICY_ALWAYS)
     priv->hscrollbar_visible = TRUE;
-  else if (priv->hscrollbar_policy == GTK_POLICY_NEVER)
+  else if (priv->hscrollbar_policy == GTK_POLICY_NEVER ||
+           priv->hscrollbar_policy == GTK_POLICY_EXTERNAL)
     priv->hscrollbar_visible = FALSE;
+
   if (priv->vscrollbar_policy == GTK_POLICY_ALWAYS)
     priv->vscrollbar_visible = TRUE;
-  else if (priv->vscrollbar_policy == GTK_POLICY_NEVER)
+  else if (priv->vscrollbar_policy == GTK_POLICY_NEVER ||
+           priv->vscrollbar_policy == GTK_POLICY_EXTERNAL)
     priv->vscrollbar_visible = FALSE;
 
   child = gtk_bin_get_child (bin);
@@ -2145,21 +2159,21 @@ gtk_scrolled_window_size_allocate (GtkWidget     *widget,
                }
              else /* priv->hscrollbar_policy != GTK_POLICY_AUTOMATIC */
                {
-                 priv->hscrollbar_visible = priv->hscrollbar_policy != GTK_POLICY_NEVER;
+                 priv->hscrollbar_visible = priv->hscrollbar_policy < GTK_POLICY_NEVER;
                  priv->vscrollbar_visible = child_scroll_height > allocation->height - 
                    (priv->hscrollbar_visible ? sb_height + sb_spacing : 0);
                }
            }
          else /* priv->vscrollbar_policy != GTK_POLICY_AUTOMATIC */
            {
-             priv->vscrollbar_visible = priv->vscrollbar_policy != GTK_POLICY_NEVER;
+             priv->vscrollbar_visible = priv->vscrollbar_policy < GTK_POLICY_NEVER;
              
              if (priv->hscrollbar_policy == GTK_POLICY_AUTOMATIC)
                priv->hscrollbar_visible = 
                  child_scroll_width > allocation->width - 
                  (priv->vscrollbar_visible ? 0 : sb_width + sb_spacing);
              else
-               priv->hscrollbar_visible = priv->hscrollbar_policy != GTK_POLICY_NEVER;
+               priv->hscrollbar_visible = priv->hscrollbar_policy < GTK_POLICY_NEVER;
            }
        } 
       else /* GTK_SIZE_REQUEST_WIDTH_FOR_HEIGHT */
@@ -2206,21 +2220,21 @@ gtk_scrolled_window_size_allocate (GtkWidget     *widget,
                }
              else /* priv->vscrollbar_policy != GTK_POLICY_AUTOMATIC */
                {
-                 priv->vscrollbar_visible = priv->vscrollbar_policy != GTK_POLICY_NEVER;
+                 priv->vscrollbar_visible = priv->vscrollbar_policy < GTK_POLICY_NEVER;
                  priv->hscrollbar_visible = child_scroll_width > allocation->width - 
                    (priv->vscrollbar_visible ? sb_width + sb_spacing : 0);
                }
            }
          else /* priv->hscrollbar_policy != GTK_POLICY_AUTOMATIC */
            {
-             priv->hscrollbar_visible = priv->hscrollbar_policy != GTK_POLICY_NEVER;
+             priv->hscrollbar_visible = priv->hscrollbar_policy < GTK_POLICY_NEVER;
              
              if (priv->vscrollbar_policy == GTK_POLICY_AUTOMATIC)
                priv->vscrollbar_visible = 
                  child_scroll_height > allocation->height - 
                  (priv->hscrollbar_visible ? 0 : sb_height + sb_spacing);
              else
-               priv->vscrollbar_visible = priv->vscrollbar_policy != GTK_POLICY_NEVER;
+               priv->vscrollbar_visible = priv->vscrollbar_policy < GTK_POLICY_NEVER;
            }
        }
 
@@ -2240,12 +2254,12 @@ gtk_scrolled_window_size_allocate (GtkWidget     *widget,
           * if they logically did not change since the last configuration
           */
          if (priv->hscrollbar)
-           gtk_scrolled_window_adjustment_changed 
-             (gtk_range_get_adjustment (GTK_RANGE (priv->hscrollbar)), scrolled_window);
+           gtk_scrolled_window_adjustment_changed
+              (gtk_range_get_adjustment (GTK_RANGE (priv->hscrollbar)), scrolled_window);
 
          if (priv->vscrollbar)
-           gtk_scrolled_window_adjustment_changed 
-             (gtk_range_get_adjustment (GTK_RANGE (priv->vscrollbar)), scrolled_window);
+           gtk_scrolled_window_adjustment_changed
+              (gtk_range_get_adjustment (GTK_RANGE (priv->vscrollbar)), scrolled_window);
 
          /* If, after the first iteration, the hscrollbar and the
           * vscrollbar flip visiblity... or if one of the scrollbars flip
@@ -2374,7 +2388,7 @@ gtk_scrolled_window_scroll_event (GtkWidget      *widget,
   if (gdk_event_get_scroll_deltas ((GdkEvent *) event, &delta_x, &delta_y))
     {
       if (delta_x != 0.0 &&
-          gtk_widget_get_visible (priv->hscrollbar))
+          may_hscroll (scrolled_window))
         {
           GtkAdjustment *adj;
           gdouble new_value;
@@ -2401,7 +2415,7 @@ gtk_scrolled_window_scroll_event (GtkWidget      *widget,
         }
 
       if (delta_y != 0.0 &&
-          gtk_widget_get_visible (priv->vscrollbar))
+          may_vscroll (scrolled_window))
         {
           GtkAdjustment *adj;
           gdouble new_value;
@@ -2430,13 +2444,20 @@ gtk_scrolled_window_scroll_event (GtkWidget      *widget,
   else
     {
       GtkWidget *range;
+      gboolean may_scroll;
 
       if (event->direction == GDK_SCROLL_UP || event->direction == GDK_SCROLL_DOWN)
-        range = priv->vscrollbar;
+        {
+          range = priv->vscrollbar;
+          may_scroll = may_vscroll (scrolled_window);
+        }
       else
-        range = priv->hscrollbar;
+        {
+          range = priv->hscrollbar;
+          may_scroll = may_hscroll (scrolled_window);
+        }
 
-      if (range && gtk_widget_get_visible (range))
+      if (range && may_scroll)
         {
           GtkAdjustment *adj = gtk_range_get_adjustment (GTK_RANGE (range));
           gdouble new_value;
@@ -2587,7 +2608,7 @@ gtk_scrolled_window_start_deceleration (GtkScrolledWindow *scrolled_window)
   data->scrolled_window = scrolled_window;
   data->last_deceleration_time = gdk_frame_clock_get_frame_time (frame_clock);
 
-  if (priv->hscrollbar_visible)
+  if (may_hscroll (scrolled_window))
     {
       gdouble lower,upper;
       GtkAdjustment *hadjustment;
@@ -2606,7 +2627,7 @@ gtk_scrolled_window_start_deceleration (GtkScrolledWindow *scrolled_window)
                                    priv->x_velocity);
     }
 
-  if (priv->vscrollbar_visible)
+  if (may_vscroll (scrolled_window))
     {
       gdouble lower,upper;
       GtkAdjustment *vadjustment;
@@ -2938,7 +2959,7 @@ gtk_scrolled_window_get_preferred_size (GtkWidget      *widget,
                  natural_req.width = MAX (natural_req.width, min_content_width);
                  extra_width = -1;
                }
-             else
+             else if (priv->vscrollbar_policy < GTK_POLICY_NEVER)
                {
                  minimum_req.width += vscrollbar_requisition.width;
                  natural_req.width += vscrollbar_requisition.width;
@@ -2966,7 +2987,7 @@ gtk_scrolled_window_get_preferred_size (GtkWidget      *widget,
                  natural_req.height = MAX (natural_req.height, min_content_height);
                  extra_height = -1;
                }
-             else
+             else if (priv->vscrollbar_policy < GTK_POLICY_NEVER)
                {
                  minimum_req.height += vscrollbar_requisition.height;
                  natural_req.height += vscrollbar_requisition.height;

diff --git a/gtk/gtkscrolledwindow.h b/gtk/gtkscrolledwindow.h
index bbe9ee0265dea7640fc7cdd64e89ad5130f992a0..f6f6df51cbcd39f4ba75cad46493dba87422132d 100644 (file)
--- a/gtk/gtkscrolledwindow.h
+++ b/gtk/gtkscrolledwindow.h
@@ -126,6 +126,9 @@ typedef enum
  *  For example, when all of a #GtkTreeView can not be seen.
  * @GTK_POLICY_NEVER: The scrollbar should never appear. In this mode the
  *  content determines the size.
+ * @GTK_POLICY_EXTERNAL: Don't show a scrollbar, but don't force the
+ *  size to follow the content. This can be used e.g. to make multiple
+ *  scrolled windows share a scrollbar. Since: 3.16
  *
  * Determines how the size should be computed to achieve the one of the
  * visibility mode for the scrollbars.
@@ -134,7 +137,8 @@ typedef enum
 {
   GTK_POLICY_ALWAYS,
   GTK_POLICY_AUTOMATIC,
-  GTK_POLICY_NEVER
+  GTK_POLICY_NEVER,
+  GTK_POLICY_EXTERNAL
 } GtkPolicyType;