gtkscrolledwindow.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/.
 */

#include "config.h"

#include "gtkscrolledwindow.h"

#include "gtkadjustment.h"
#include "gtkbindings.h"
#include "gtkdnd.h"
#include "gtkintl.h"
#include "gtkmain.h"
#include "gtkmarshalers.h"
#include "gtkprivate.h"
#include "gtkscrollable.h"
#include "gtkscrollbar.h"
#include "gtkrangeprivate.h"
#include "gtktypebuiltins.h"
#include "gtkviewport.h"
#include "gtkwidgetprivate.h"
#include "gtkwindow.h"
#include "a11y/gtkscrolledwindowaccessible.h"

#include <math.h>

/**
 * SECTION:gtkscrolledwindow
 * @Short_description: Adds scrollbars to its child widget
 * @Title: GtkScrolledWindow
 * @See_also: #GtkScrollable, #GtkViewport, #GtkAdjustment
 *
 * #GtkScrolledWindow is a #GtkBin subclass: it’s a container
 * the accepts a single child widget. #GtkScrolledWindow adds scrollbars
 * to the child widget and optionally draws a beveled frame around the
 * child widget.
 *
 * The scrolled window can work in two ways. Some widgets have native
 * scrolling support; these widgets implement the #GtkScrollable interface.
 * Widgets with native scroll support include #GtkTreeView, #GtkTextView,
 * and #GtkLayout.
 *
 * For widgets that lack native scrolling support, the #GtkViewport
 * widget acts as an adaptor class, implementing scrollability for child
 * widgets that lack their own scrolling capabilities. Use #GtkViewport
 * to scroll child widgets such as #GtkGrid, #GtkBox, and so on.
 *
 * If a widget has native scrolling abilities, it can be added to the
 * #GtkScrolledWindow with gtk_container_add(). If a widget does not, you
 * must first add the widget to a #GtkViewport, then add the #GtkViewport
 * to the scrolled window. gtk_container_add() will do this for you for
 * widgets that don’t implement #GtkScrollable natively, so you can
 * ignore the presence of the viewport.
 *
 * The position of the scrollbars is controlled by the scroll
 * adjustments. See #GtkAdjustment for the fields in an adjustment - for
 * #GtkScrollbar, used by #GtkScrolledWindow, the “value” field
 * represents the position of the scrollbar, which must be between the
 * “lower” field and “upper - page_size.” The “page_size” field
 * represents the size of the visible scrollable area. The
 * “step_increment” and “page_increment” fields are used when the user
 * asks to step down (using the small stepper arrows) or page down (using
 * for example the PageDown key).
 *
 * If a #GtkScrolledWindow doesn’t behave quite as you would like, or
 * doesn’t have exactly the right layout, it’s very possible to set up
 * your own scrolling with #GtkScrollbar and for example a #GtkGrid.
 */


/* scrolled window policy and size requisition handling:
 *
 * gtk size requisition works as follows:
 *   a widget upon size-request reports the width and height that it finds
 *   to be best suited to display its contents, including children.
 *   the width and/or height reported from a widget upon size requisition
 *   may be overidden by the user by specifying a width and/or height
 *   other than 0 through gtk_widget_set_size_request().
 *
 * a scrolled window needs (for implementing all three policy types) to
 * request its width and height based on two different rationales.
 * 1)   the user wants the scrolled window to just fit into the space
 *      that it gets allocated for a specifc dimension.
 * 1.1) this does not apply if the user specified a concrete value
 *      value for that specific dimension by either specifying usize for the
 *      scrolled window or for its child.
 * 2)   the user wants the scrolled window to take as much space up as
 *      is desired by the child for a specifc dimension (i.e. POLICY_NEVER).
 *
 * also, kinda obvious:
 * 3)   a user would certainly not have choosen a scrolled window as a container
 *      for the child, if the resulting allocation takes up more space than the
 *      child would have allocated without the scrolled window.
 *
 * conclusions:
 * A) from 1) follows: the scrolled window shouldn’t request more space for a
 *    specifc dimension than is required at minimum.
 * B) from 1.1) follows: the requisition may be overidden by usize of the scrolled
 *    window (done automatically) or by usize of the child (needs to be checked).
 * C) from 2) follows: for POLICY_NEVER, the scrolled window simply reports the
 *    child’s dimension.
 * D) from 3) follows: the scrolled window child’s minimum width and minimum height
 *    under A) at least correspond to the space taken up by its scrollbars.
 */

#define DEFAULT_SCROLLBAR_SPACING  3
#define TOUCH_BYPASS_CAPTURED_THRESHOLD 30

/* Kinetic scrolling */
#define MAX_OVERSHOOT_DISTANCE 50
#define FRICTION_DECELERATION 0.003
#define OVERSHOOT_INVERSE_ACCELERATION 0.003

struct _GtkScrolledWindowPrivate
{
  GtkWidget     *hscrollbar;
  GtkWidget     *vscrollbar;

  GtkCornerType  window_placement;
  guint16  shadow_type;

  guint    hscrollbar_policy      : 2;
  guint    vscrollbar_policy      : 2;
  guint    hscrollbar_visible     : 1;
  guint    vscrollbar_visible     : 1;
  guint    focus_out              : 1; /* Flag used by ::move-focus-out implementation */

  gint     min_content_width;
  gint     min_content_height;

  /* Kinetic scrolling */
  GtkGesture *drag_gesture;
  GtkGesture *swipe_gesture;
  GtkGesture *long_press_gesture;
  gdouble drag_start_x;
  gdouble drag_start_y;

  GdkWindow             *overshoot_window;
  GdkDevice             *drag_device;
  guint                  kinetic_scrolling         : 1;
  guint                  capture_button_press      : 1;
  guint                  in_drag                   : 1;

  guint                  deceleration_id;

  gdouble                x_velocity;
  gdouble                y_velocity;

  gdouble                unclamped_hadj_value;
  gdouble                unclamped_vadj_value;
};

typedef struct
{
  GtkScrolledWindow     *scrolled_window;
  gint64                 last_deceleration_time;

  gdouble                x_velocity;
  gdouble                y_velocity;
  gdouble                vel_cosine;
  gdouble                vel_sine;
} KineticScrollData;

enum {
  PROP_0,
  PROP_HADJUSTMENT,
  PROP_VADJUSTMENT,
  PROP_HSCROLLBAR_POLICY,
  PROP_VSCROLLBAR_POLICY,
  PROP_WINDOW_PLACEMENT,
  PROP_WINDOW_PLACEMENT_SET,
  PROP_SHADOW_TYPE,
  PROP_MIN_CONTENT_WIDTH,
  PROP_MIN_CONTENT_HEIGHT,
  PROP_KINETIC_SCROLLING
};

/* Signals */
enum
{
  SCROLL_CHILD,
  MOVE_FOCUS_OUT,
  LAST_SIGNAL
};

static void     gtk_scrolled_window_set_property       (GObject           *object,
                                                        guint              prop_id,
                                                        const GValue      *value,
                                                        GParamSpec        *pspec);
static void     gtk_scrolled_window_get_property       (GObject           *object,
                                                        guint              prop_id,
                                                        GValue            *value,
                                                        GParamSpec        *pspec);

static void     gtk_scrolled_window_destroy            (GtkWidget         *widget);
static gboolean gtk_scrolled_window_draw               (GtkWidget         *widget,
                                                        cairo_t           *cr);
static void     gtk_scrolled_window_size_allocate      (GtkWidget         *widget,
                                                        GtkAllocation     *allocation);
static gboolean gtk_scrolled_window_scroll_event       (GtkWidget         *widget,
                                                        GdkEventScroll    *event);
static gboolean gtk_scrolled_window_focus              (GtkWidget         *widget,
                                                        GtkDirectionType   direction);
static void     gtk_scrolled_window_add                (GtkContainer      *container,
                                                        GtkWidget         *widget);
static void     gtk_scrolled_window_remove             (GtkContainer      *container,
                                                        GtkWidget         *widget);
static void     gtk_scrolled_window_forall             (GtkContainer      *container,
                                                        gboolean           include_internals,
                                                        GtkCallback        callback,
                                                        gpointer           callback_data);
static gboolean gtk_scrolled_window_scroll_child       (GtkScrolledWindow *scrolled_window,
                                                        GtkScrollType      scroll,
                                                        gboolean           horizontal);
static void     gtk_scrolled_window_move_focus_out     (GtkScrolledWindow *scrolled_window,
                                                        GtkDirectionType   direction_type);

static void     gtk_scrolled_window_relative_allocation(GtkWidget         *widget,
                                                        GtkAllocation     *allocation);
static void     gtk_scrolled_window_adjustment_changed (GtkAdjustment     *adjustment,
                                                        gpointer           data);
static void     gtk_scrolled_window_adjustment_value_changed (GtkAdjustment     *adjustment,
                                                              gpointer           data);

static void  gtk_scrolled_window_get_preferred_width   (GtkWidget           *widget,
							gint                *minimum_size,
							gint                *natural_size);
static void  gtk_scrolled_window_get_preferred_height  (GtkWidget           *widget,
							gint                *minimum_size,
							gint                *natural_size);
static void  gtk_scrolled_window_get_preferred_height_for_width  (GtkWidget           *layout,
							gint                 width,
							gint                *minimum_height,
							gint                *natural_height);
static void  gtk_scrolled_window_get_preferred_width_for_height  (GtkWidget           *layout,
							gint                 width,
							gint                *minimum_height,
							gint                *natural_height);

static void  gtk_scrolled_window_realize               (GtkWidget           *widget);
static void  gtk_scrolled_window_unrealize             (GtkWidget           *widget);
static void  gtk_scrolled_window_map                   (GtkWidget           *widget);
static void  gtk_scrolled_window_unmap                 (GtkWidget           *widget);

static void  gtk_scrolled_window_grab_notify           (GtkWidget           *widget,
                                                        gboolean             was_grabbed);

static gboolean _gtk_scrolled_window_set_adjustment_value      (GtkScrolledWindow *scrolled_window,
                                                                GtkAdjustment     *adjustment,
                                                                gdouble            value,
                                                                gboolean           allow_overshooting,
                                                                gboolean           snap_to_border);

static void gtk_scrolled_window_cancel_deceleration (GtkScrolledWindow *scrolled_window);

static gboolean _gtk_scrolled_window_get_overshoot (GtkScrolledWindow *scrolled_window,
                                                    gint              *overshoot_x,
                                                    gint              *overshoot_y);
static void     _gtk_scrolled_window_allocate_overshoot_window (GtkScrolledWindow *scrolled_window);

static void     gtk_scrolled_window_start_deceleration (GtkScrolledWindow *scrolled_window);

static guint signals[LAST_SIGNAL] = {0};

G_DEFINE_TYPE_WITH_PRIVATE (GtkScrolledWindow, gtk_scrolled_window, GTK_TYPE_BIN)

static void
add_scroll_binding (GtkBindingSet  *binding_set,
		    guint           keyval,
		    GdkModifierType mask,
		    GtkScrollType   scroll,
		    gboolean        horizontal)
{
  guint keypad_keyval = keyval - GDK_KEY_Left + GDK_KEY_KP_Left;
  
  gtk_binding_entry_add_signal (binding_set, keyval, mask,
                                "scroll-child", 2,
                                GTK_TYPE_SCROLL_TYPE, scroll,
				G_TYPE_BOOLEAN, horizontal);
  gtk_binding_entry_add_signal (binding_set, keypad_keyval, mask,
                                "scroll-child", 2,
                                GTK_TYPE_SCROLL_TYPE, scroll,
				G_TYPE_BOOLEAN, horizontal);
}

static void
add_tab_bindings (GtkBindingSet    *binding_set,
		  GdkModifierType   modifiers,
		  GtkDirectionType  direction)
{
  gtk_binding_entry_add_signal (binding_set, GDK_KEY_Tab, modifiers,
                                "move-focus-out", 1,
                                GTK_TYPE_DIRECTION_TYPE, direction);
  gtk_binding_entry_add_signal (binding_set, GDK_KEY_KP_Tab, modifiers,
                                "move-focus-out", 1,
                                GTK_TYPE_DIRECTION_TYPE, direction);
}

static void
gtk_scrolled_window_class_init (GtkScrolledWindowClass *class)
{
  GObjectClass *gobject_class = G_OBJECT_CLASS (class);
  GtkWidgetClass *widget_class;
  GtkContainerClass *container_class;
  GtkBindingSet *binding_set;

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

  gobject_class->set_property = gtk_scrolled_window_set_property;
  gobject_class->get_property = gtk_scrolled_window_get_property;

  widget_class->destroy = gtk_scrolled_window_destroy;
  widget_class->draw = gtk_scrolled_window_draw;
  widget_class->size_allocate = gtk_scrolled_window_size_allocate;
  widget_class->scroll_event = gtk_scrolled_window_scroll_event;
  widget_class->focus = gtk_scrolled_window_focus;
  widget_class->get_preferred_width = gtk_scrolled_window_get_preferred_width;
  widget_class->get_preferred_height = gtk_scrolled_window_get_preferred_height;
  widget_class->get_preferred_height_for_width = gtk_scrolled_window_get_preferred_height_for_width;
  widget_class->get_preferred_width_for_height = gtk_scrolled_window_get_preferred_width_for_height;
  widget_class->realize = gtk_scrolled_window_realize;
  widget_class->unrealize = gtk_scrolled_window_unrealize;
  widget_class->map = gtk_scrolled_window_map;
  widget_class->unmap = gtk_scrolled_window_unmap;
  widget_class->grab_notify = gtk_scrolled_window_grab_notify;

  container_class->add = gtk_scrolled_window_add;
  container_class->remove = gtk_scrolled_window_remove;
  container_class->forall = gtk_scrolled_window_forall;
  gtk_container_class_handle_border_width (container_class);

  class->scrollbar_spacing = -1;

  class->scroll_child = gtk_scrolled_window_scroll_child;
  class->move_focus_out = gtk_scrolled_window_move_focus_out;
  
  g_object_class_install_property (gobject_class,
				   PROP_HADJUSTMENT,
				   g_param_spec_object ("hadjustment",
							P_("Horizontal Adjustment"),
							P_("The GtkAdjustment for the horizontal position"),
							GTK_TYPE_ADJUSTMENT,
							GTK_PARAM_READWRITE | G_PARAM_CONSTRUCT));
  g_object_class_install_property (gobject_class,
				   PROP_VADJUSTMENT,
				   g_param_spec_object ("vadjustment",
							P_("Vertical Adjustment"),
							P_("The GtkAdjustment for the vertical position"),
							GTK_TYPE_ADJUSTMENT,
							GTK_PARAM_READWRITE | G_PARAM_CONSTRUCT));
  g_object_class_install_property (gobject_class,
                                   PROP_HSCROLLBAR_POLICY,
                                   g_param_spec_enum ("hscrollbar-policy",
                                                      P_("Horizontal Scrollbar Policy"),
                                                      P_("When the horizontal scrollbar is displayed"),
						      GTK_TYPE_POLICY_TYPE,
						      GTK_POLICY_AUTOMATIC,
                                                      GTK_PARAM_READABLE | GTK_PARAM_WRITABLE));
  g_object_class_install_property (gobject_class,
                                   PROP_VSCROLLBAR_POLICY,
                                   g_param_spec_enum ("vscrollbar-policy",
                                                      P_("Vertical Scrollbar Policy"),
                                                      P_("When the vertical scrollbar is displayed"),
						      GTK_TYPE_POLICY_TYPE,
						      GTK_POLICY_AUTOMATIC,
                                                      GTK_PARAM_READABLE | GTK_PARAM_WRITABLE));

  g_object_class_install_property (gobject_class,
                                   PROP_WINDOW_PLACEMENT,
                                   g_param_spec_enum ("window-placement",
                                                      P_("Window Placement"),
                                                      P_("Where the contents are located with respect to the scrollbars."),
						      GTK_TYPE_CORNER_TYPE,
						      GTK_CORNER_TOP_LEFT,
                                                      GTK_PARAM_READABLE | GTK_PARAM_WRITABLE));
  
  /**
   * GtkScrolledWindow:window-placement-set:
   *
   * Whether "window-placement" should be used to determine the location 
   * of the contents with respect to the scrollbars.
   *
   * Since: 2.10
   *
   * Deprecated: 3.10: This value is ignored and
   * #GtkScrolledWindow:window-placement value is always honored.
   */
  g_object_class_install_property (gobject_class,
                                   PROP_WINDOW_PLACEMENT_SET,
                                   g_param_spec_boolean ("window-placement-set",
					   		 P_("Window Placement Set"),
							 P_("Whether \"window-placement\" should be used to determine the location of the contents with respect to the scrollbars."),
							 TRUE,
							 GTK_PARAM_READABLE | GTK_PARAM_WRITABLE));
  g_object_class_install_property (gobject_class,
                                   PROP_SHADOW_TYPE,
                                   g_param_spec_enum ("shadow-type",
                                                      P_("Shadow Type"),
                                                      P_("Style of bevel around the contents"),
						      GTK_TYPE_SHADOW_TYPE,
						      GTK_SHADOW_NONE,
                                                      GTK_PARAM_READABLE | GTK_PARAM_WRITABLE));

  /**
   * GtkScrolledWindow:scrollbars-within-bevel:
   *
   * Whether to place scrollbars within the scrolled window's bevel.
   *
   * Since: 2.12
   */
  gtk_widget_class_install_style_property (widget_class,
					   g_param_spec_boolean ("scrollbars-within-bevel",
							         P_("Scrollbars within bevel"),
							         P_("Place scrollbars within the scrolled window's bevel"),
							         FALSE,
							         GTK_PARAM_READABLE));

  gtk_widget_class_install_style_property (widget_class,
					   g_param_spec_int ("scrollbar-spacing",
							     P_("Scrollbar spacing"),
							     P_("Number of pixels between the scrollbars and the scrolled window"),
							     0,
							     G_MAXINT,
							     DEFAULT_SCROLLBAR_SPACING,
							     GTK_PARAM_READABLE));

  /**
   * GtkScrolledWindow:min-content-width:
   *
   * The minimum content width of @scrolled_window, or -1 if not set.
   *
   * Since: 3.0
   */
  g_object_class_install_property (gobject_class,
                                   PROP_MIN_CONTENT_WIDTH,
                                   g_param_spec_int ("min-content-width",
                                                     P_("Minimum Content Width"),
                                                     P_("The minimum width that the scrolled window will allocate to its content"),
                                                     -1, G_MAXINT, -1,
                                                     GTK_PARAM_READWRITE));

  /**
   * GtkScrolledWindow:min-content-height:
   *
   * The minimum content height of @scrolled_window, or -1 if not set.
   *
   * Since: 3.0
   */
  g_object_class_install_property (gobject_class,
                                   PROP_MIN_CONTENT_HEIGHT,
                                   g_param_spec_int ("min-content-height",
                                                     P_("Minimum Content Height"),
                                                     P_("The minimum height that the scrolled window will allocate to its content"),
                                                     -1, G_MAXINT, -1,
                                                     GTK_PARAM_READWRITE));

  /**
   * GtkScrolledWindow:kinetic-scrolling:
   *
   * The kinetic scrolling behavior flags. Kinetic scrolling
   * only applies to devices with source %GDK_SOURCE_TOUCHSCREEN
   *
   * Since: 3.4
   */
  g_object_class_install_property (gobject_class,
                                   PROP_KINETIC_SCROLLING,
                                   g_param_spec_boolean ("kinetic-scrolling",
                                                         P_("Kinetic Scrolling"),
                                                         P_("Kinetic scrolling mode."),
                                                         TRUE,
                                                         GTK_PARAM_READABLE |
                                                         GTK_PARAM_WRITABLE));
  /**
   * GtkScrolledWindow::scroll-child:
   * @scrolled_window: a #GtkScrolledWindow
   * @scroll: a #GtkScrollType describing how much to scroll
   * @horizontal: whether the keybinding scrolls the child
   *   horizontally or not
   *
   * The ::scroll-child signal is a
   * [keybinding signal][GtkBindingSignal]
   * which gets emitted when a keybinding that scrolls is pressed.
   * The horizontal or vertical adjustment is updated which triggers a
   * signal that the scrolled windows child may listen to and scroll itself.
   */
  signals[SCROLL_CHILD] =
    g_signal_new (I_("scroll-child"),
                  G_TYPE_FROM_CLASS (gobject_class),
                  G_SIGNAL_RUN_LAST | G_SIGNAL_ACTION,
                  G_STRUCT_OFFSET (GtkScrolledWindowClass, scroll_child),
                  NULL, NULL,
                  _gtk_marshal_BOOLEAN__ENUM_BOOLEAN,
                  G_TYPE_BOOLEAN, 2,
                  GTK_TYPE_SCROLL_TYPE,
		  G_TYPE_BOOLEAN);

  /**
   * GtkScrolledWindow::move-focus-out:
   * @scrolled_window: a #GtkScrolledWindow
   * @direction_type: either %GTK_DIR_TAB_FORWARD or
   *   %GTK_DIR_TAB_BACKWARD
   *
   * The ::move-focus-out signal is a
   * [keybinding signal][GtkBindingSignal] which gets
   * emitted when focus is moved away from the scrolled window by a
   * keybinding.  The #GtkWidget::move-focus signal is emitted with
   * @direction_type on this scrolled windows toplevel parent in the
   * container hierarchy.  The default bindings for this signal are
   * `Tab + Ctrl` and `Tab + Ctrl + Shift`.
   */
  signals[MOVE_FOCUS_OUT] =
    g_signal_new (I_("move-focus-out"),
                  G_TYPE_FROM_CLASS (gobject_class),
                  G_SIGNAL_RUN_LAST | G_SIGNAL_ACTION,
                  G_STRUCT_OFFSET (GtkScrolledWindowClass, move_focus_out),
                  NULL, NULL,
                  _gtk_marshal_VOID__ENUM,
                  G_TYPE_NONE, 1,
                  GTK_TYPE_DIRECTION_TYPE);
  
  binding_set = gtk_binding_set_by_class (class);

  add_scroll_binding (binding_set, GDK_KEY_Left,  GDK_CONTROL_MASK, GTK_SCROLL_STEP_BACKWARD, TRUE);
  add_scroll_binding (binding_set, GDK_KEY_Right, GDK_CONTROL_MASK, GTK_SCROLL_STEP_FORWARD,  TRUE);
  add_scroll_binding (binding_set, GDK_KEY_Up,    GDK_CONTROL_MASK, GTK_SCROLL_STEP_BACKWARD, FALSE);
  add_scroll_binding (binding_set, GDK_KEY_Down,  GDK_CONTROL_MASK, GTK_SCROLL_STEP_FORWARD,  FALSE);

  add_scroll_binding (binding_set, GDK_KEY_Page_Up,   GDK_CONTROL_MASK, GTK_SCROLL_PAGE_BACKWARD, TRUE);
  add_scroll_binding (binding_set, GDK_KEY_Page_Down, GDK_CONTROL_MASK, GTK_SCROLL_PAGE_FORWARD,  TRUE);
  add_scroll_binding (binding_set, GDK_KEY_Page_Up,   0,                GTK_SCROLL_PAGE_BACKWARD, FALSE);
  add_scroll_binding (binding_set, GDK_KEY_Page_Down, 0,                GTK_SCROLL_PAGE_FORWARD,  FALSE);

  add_scroll_binding (binding_set, GDK_KEY_Home, GDK_CONTROL_MASK, GTK_SCROLL_START, TRUE);
  add_scroll_binding (binding_set, GDK_KEY_End,  GDK_CONTROL_MASK, GTK_SCROLL_END,   TRUE);
  add_scroll_binding (binding_set, GDK_KEY_Home, 0,                GTK_SCROLL_START, FALSE);
  add_scroll_binding (binding_set, GDK_KEY_End,  0,                GTK_SCROLL_END,   FALSE);

  add_tab_bindings (binding_set, GDK_CONTROL_MASK, GTK_DIR_TAB_FORWARD);
  add_tab_bindings (binding_set, GDK_CONTROL_MASK | GDK_SHIFT_MASK, GTK_DIR_TAB_BACKWARD);

  gtk_widget_class_set_accessible_type (widget_class, GTK_TYPE_SCROLLED_WINDOW_ACCESSIBLE);
}

static void
scrolled_window_drag_begin_cb (GtkScrolledWindow *scrolled_window,
                               gdouble            start_x,
                               gdouble            start_y,
                               GtkGesture        *gesture)
{
  GtkScrolledWindowPrivate *priv = scrolled_window->priv;
  GtkEventSequenceState state;
  GdkEventSequence *sequence;

  priv->in_drag = FALSE;
  priv->drag_start_x = priv->unclamped_hadj_value;
  priv->drag_start_y = priv->unclamped_vadj_value;
  gtk_scrolled_window_cancel_deceleration (scrolled_window);

  if (!priv->hscrollbar_visible && !priv->vscrollbar_visible)
    state = GTK_EVENT_SEQUENCE_DENIED;
  else if (priv->capture_button_press)
    state = GTK_EVENT_SEQUENCE_CLAIMED;
  else
    return;

  sequence = gtk_gesture_get_last_updated_sequence (gesture);
  gtk_widget_set_sequence_state (GTK_WIDGET (scrolled_window),
                                 sequence, state);
}

static void
scrolled_window_drag_update_cb (GtkScrolledWindow *scrolled_window,
                                gdouble            offset_x,
                                gdouble            offset_y,
                                GtkGesture        *gesture)
{
  GtkScrolledWindowPrivate *priv = scrolled_window->priv;
  gint old_overshoot_x, old_overshoot_y;
  gint new_overshoot_x, new_overshoot_y;
  GtkAdjustment *hadjustment;
  GtkAdjustment *vadjustment;
  gdouble dx, dy;

  if (!priv->capture_button_press)
    {
      GdkEventSequence *sequence;

      sequence = gtk_gesture_get_last_updated_sequence (gesture);
      gtk_widget_set_sequence_state (GTK_WIDGET (scrolled_window),
                                     sequence, GTK_EVENT_SEQUENCE_CLAIMED);
    }

  _gtk_scrolled_window_get_overshoot (scrolled_window,
                                      &old_overshoot_x, &old_overshoot_y);

  hadjustment = gtk_range_get_adjustment (GTK_RANGE (priv->hscrollbar));
  if (hadjustment && priv->hscrollbar_visible)
    {
      dx = priv->drag_start_x - offset_x;
      _gtk_scrolled_window_set_adjustment_value (scrolled_window, hadjustment,
                                                 dx, TRUE, FALSE);
    }

  vadjustment = gtk_range_get_adjustment (GTK_RANGE (priv->vscrollbar));
  if (vadjustment && priv->vscrollbar_visible)
    {
      dy = priv->drag_start_y - offset_y;
      _gtk_scrolled_window_set_adjustment_value (scrolled_window, vadjustment,
                                                 dy, TRUE, FALSE);
    }

  _gtk_scrolled_window_get_overshoot (scrolled_window,
                                      &new_overshoot_x, &new_overshoot_y);

  if (old_overshoot_x != new_overshoot_x ||
      old_overshoot_y != new_overshoot_y)
    {
      if (new_overshoot_x >= 0 || new_overshoot_y >= 0)
        {
          /* We need to reallocate the widget to have it at
           * negative offset, so there's a "gravity" on the
           * bottom/right corner
           */
          gtk_widget_queue_resize (GTK_WIDGET (scrolled_window));
        }
      else if (new_overshoot_x < 0 || new_overshoot_y < 0)
        _gtk_scrolled_window_allocate_overshoot_window (scrolled_window);
    }
}

static void
scrolled_window_drag_end_cb (GtkScrolledWindow *scrolled_window,
                             gdouble            offset_x,
                             gdouble            offset_y,
                             GtkGesture        *gesture)
{
  GtkScrolledWindowPrivate *priv = scrolled_window->priv;

  if (!priv->in_drag)
    {
      GdkEventSequence *sequence;

      sequence = gtk_gesture_get_last_updated_sequence (gesture);
      gtk_widget_set_sequence_state (GTK_WIDGET (scrolled_window),
                                     sequence, GTK_EVENT_SEQUENCE_DENIED);
    }
}

static void
scrolled_window_swipe_cb (GtkScrolledWindow *scrolled_window,
                          gdouble            x_velocity,
                          gdouble            y_velocity)
{
  GtkScrolledWindowPrivate *priv = scrolled_window->priv;
  gboolean overshoot;

  overshoot = _gtk_scrolled_window_get_overshoot (scrolled_window, NULL, NULL);
  priv->x_velocity = -x_velocity / 1000;
  priv->y_velocity = -y_velocity / 1000;

  /* Zero out vector components without a visible scrollbar */
  if (!priv->hscrollbar_visible)
    priv->x_velocity = 0;
  if (!priv->vscrollbar_visible)
    priv->y_velocity = 0;

  if (priv->x_velocity != 0 || priv->y_velocity != 0 || overshoot)
    {
      gtk_scrolled_window_start_deceleration (scrolled_window);
      priv->x_velocity = priv->y_velocity = 0;
    }
}

static void
scrolled_window_long_press_cb (GtkScrolledWindow *scrolled_window,
                               gdouble            x,
                               gdouble            y,
                               GtkGesture        *gesture)
{
  GdkEventSequence *sequence;

  sequence = gtk_gesture_get_last_updated_sequence (gesture);
  gtk_widget_set_sequence_state (GTK_WIDGET (scrolled_window),
                                 sequence, GTK_EVENT_SEQUENCE_DENIED);
}

static void
scrolled_window_long_press_cancelled_cb (GtkScrolledWindow *scrolled_window,
                                         GtkGesture        *gesture)
{
  GtkScrolledWindowPrivate *priv = scrolled_window->priv;
  GdkEventSequence *sequence;
  const GdkEvent *event;

  sequence = gtk_gesture_get_last_updated_sequence (gesture);
  event = gtk_gesture_get_last_event (gesture, sequence);

  if (event->type != GDK_TOUCH_END &&
      event->type != GDK_BUTTON_RELEASE)
    priv->in_drag = TRUE;
}

static void
gtk_scrolled_window_init (GtkScrolledWindow *scrolled_window)
{
  GtkWidget *widget = GTK_WIDGET (scrolled_window);
  GtkScrolledWindowPrivate *priv;

  scrolled_window->priv = priv =
    gtk_scrolled_window_get_instance_private (scrolled_window);

  gtk_widget_set_has_window (widget, FALSE);
  gtk_widget_set_can_focus (widget, TRUE);

  /* Instantiated by gtk_scrolled_window_set_[hv]adjustment
   * which are both construct properties
   */
  priv->hscrollbar = NULL;
  priv->vscrollbar = NULL;
  priv->hscrollbar_policy = GTK_POLICY_AUTOMATIC;
  priv->vscrollbar_policy = GTK_POLICY_AUTOMATIC;
  priv->hscrollbar_visible = FALSE;
  priv->vscrollbar_visible = FALSE;
  priv->focus_out = FALSE;
  priv->window_placement = GTK_CORNER_TOP_LEFT;
  priv->min_content_width = -1;
  priv->min_content_height = -1;

  priv->drag_gesture = gtk_gesture_drag_new (widget);
  g_signal_connect_swapped (priv->drag_gesture, "drag-begin",
                            G_CALLBACK (scrolled_window_drag_begin_cb),
                            scrolled_window);
  g_signal_connect_swapped (priv->drag_gesture, "drag-update",
                            G_CALLBACK (scrolled_window_drag_update_cb),
                            scrolled_window);
  g_signal_connect_swapped (priv->drag_gesture, "drag-end",
                            G_CALLBACK (scrolled_window_drag_end_cb),
                            scrolled_window);

  priv->swipe_gesture = gtk_gesture_swipe_new (widget);
  g_signal_connect_swapped (priv->swipe_gesture, "swipe",
                            G_CALLBACK (scrolled_window_swipe_cb),
                            scrolled_window);
  priv->long_press_gesture = gtk_gesture_long_press_new (widget);
  gtk_gesture_single_set_button (GTK_GESTURE_SINGLE (priv->long_press_gesture), 1);
  g_signal_connect_swapped (priv->long_press_gesture, "pressed",
                            G_CALLBACK (scrolled_window_long_press_cb),
                            scrolled_window);
  g_signal_connect_swapped (priv->long_press_gesture, "cancelled",
                            G_CALLBACK (scrolled_window_long_press_cancelled_cb),
                            scrolled_window);

  gtk_scrolled_window_set_kinetic_scrolling (scrolled_window, TRUE);
  gtk_scrolled_window_set_capture_button_press (scrolled_window, TRUE);
}

/**
 * gtk_scrolled_window_new:
 * @hadjustment: (allow-none): horizontal adjustment
 * @vadjustment: (allow-none): vertical adjustment
 *
 * Creates a new scrolled window.
 *
 * The two arguments are the scrolled window’s adjustments; these will be
 * shared with the scrollbars and the child widget to keep the bars in sync 
 * with the child. Usually you want to pass %NULL for the adjustments, which 
 * will cause the scrolled window to create them for you.
 *
 * Returns: a new scrolled window
 */
GtkWidget*
gtk_scrolled_window_new (GtkAdjustment *hadjustment,
			 GtkAdjustment *vadjustment)
{
  GtkWidget *scrolled_window;

  if (hadjustment)
    g_return_val_if_fail (GTK_IS_ADJUSTMENT (hadjustment), NULL);

  if (vadjustment)
    g_return_val_if_fail (GTK_IS_ADJUSTMENT (vadjustment), NULL);

  scrolled_window = g_object_new (GTK_TYPE_SCROLLED_WINDOW,
				    "hadjustment", hadjustment,
				    "vadjustment", vadjustment,
				    NULL);

  return scrolled_window;
}

/**
 * gtk_scrolled_window_set_hadjustment:
 * @scrolled_window: a #GtkScrolledWindow
 * @hadjustment: horizontal scroll adjustment
 *
 * Sets the #GtkAdjustment for the horizontal scrollbar.
 */
void
gtk_scrolled_window_set_hadjustment (GtkScrolledWindow *scrolled_window,
				     GtkAdjustment     *hadjustment)
{
  GtkScrolledWindowPrivate *priv;
  GtkBin *bin;
  GtkWidget *child;

  g_return_if_fail (GTK_IS_SCROLLED_WINDOW (scrolled_window));
  if (hadjustment)
    g_return_if_fail (GTK_IS_ADJUSTMENT (hadjustment));
  else
    hadjustment = (GtkAdjustment*) g_object_new (GTK_TYPE_ADJUSTMENT, NULL);

  bin = GTK_BIN (scrolled_window);
  priv = scrolled_window->priv;

  if (!priv->hscrollbar)
    {
      priv->hscrollbar = gtk_scrollbar_new (GTK_ORIENTATION_HORIZONTAL, hadjustment);

      gtk_widget_set_parent (priv->hscrollbar, GTK_WIDGET (scrolled_window));
      g_object_ref (priv->hscrollbar);
      gtk_widget_show (priv->hscrollbar);
    }
  else
    {
      GtkAdjustment *old_adjustment;

      old_adjustment = gtk_range_get_adjustment (GTK_RANGE (priv->hscrollbar));
      if (old_adjustment == hadjustment)
	return;

      g_signal_handlers_disconnect_by_func (old_adjustment,
					    gtk_scrolled_window_adjustment_changed,
					    scrolled_window);
      gtk_range_set_adjustment (GTK_RANGE (priv->hscrollbar),
				hadjustment);
    }
  hadjustment = gtk_range_get_adjustment (GTK_RANGE (priv->hscrollbar));
  g_signal_connect (hadjustment,
		    "changed",
		    G_CALLBACK (gtk_scrolled_window_adjustment_changed),
		    scrolled_window);
  g_signal_connect (hadjustment,
		    "value-changed",
		    G_CALLBACK (gtk_scrolled_window_adjustment_value_changed),
		    scrolled_window);
  gtk_scrolled_window_adjustment_changed (hadjustment, scrolled_window);
  gtk_scrolled_window_adjustment_value_changed (hadjustment, scrolled_window);

  child = gtk_bin_get_child (bin);
  if (GTK_IS_SCROLLABLE (child))
    gtk_scrollable_set_hadjustment (GTK_SCROLLABLE (child), hadjustment);

  g_object_notify (G_OBJECT (scrolled_window), "hadjustment");
}

/**
 * gtk_scrolled_window_set_vadjustment:
 * @scrolled_window: a #GtkScrolledWindow
 * @vadjustment: vertical scroll adjustment
 *
 * Sets the #GtkAdjustment for the vertical scrollbar.
 */
void
gtk_scrolled_window_set_vadjustment (GtkScrolledWindow *scrolled_window,
                                     GtkAdjustment     *vadjustment)
{
  GtkScrolledWindowPrivate *priv;
  GtkBin *bin;
  GtkWidget *child;

  g_return_if_fail (GTK_IS_SCROLLED_WINDOW (scrolled_window));
  if (vadjustment)
    g_return_if_fail (GTK_IS_ADJUSTMENT (vadjustment));
  else
    vadjustment = (GtkAdjustment*) g_object_new (GTK_TYPE_ADJUSTMENT, NULL);

  bin = GTK_BIN (scrolled_window);
  priv = scrolled_window->priv;

  if (!priv->vscrollbar)
    {
      priv->vscrollbar = gtk_scrollbar_new (GTK_ORIENTATION_VERTICAL, vadjustment);

      gtk_widget_set_parent (priv->vscrollbar, GTK_WIDGET (scrolled_window));
      g_object_ref (priv->vscrollbar);
      gtk_widget_show (priv->vscrollbar);
    }
  else
    {
      GtkAdjustment *old_adjustment;
      
      old_adjustment = gtk_range_get_adjustment (GTK_RANGE (priv->vscrollbar));
      if (old_adjustment == vadjustment)
	return;

      g_signal_handlers_disconnect_by_func (old_adjustment,
					    gtk_scrolled_window_adjustment_changed,
					    scrolled_window);
      gtk_range_set_adjustment (GTK_RANGE (priv->vscrollbar),
				vadjustment);
    }
  vadjustment = gtk_range_get_adjustment (GTK_RANGE (priv->vscrollbar));
  g_signal_connect (vadjustment,
		    "changed",
		    G_CALLBACK (gtk_scrolled_window_adjustment_changed),
		    scrolled_window);
  g_signal_connect (vadjustment,
		    "value-changed",
		    G_CALLBACK (gtk_scrolled_window_adjustment_value_changed),
		    scrolled_window);
  gtk_scrolled_window_adjustment_changed (vadjustment, scrolled_window);
  gtk_scrolled_window_adjustment_value_changed (vadjustment, scrolled_window);

  child = gtk_bin_get_child (bin);
  if (GTK_IS_SCROLLABLE (child))
    gtk_scrollable_set_vadjustment (GTK_SCROLLABLE (child), vadjustment);

  g_object_notify (G_OBJECT (scrolled_window), "vadjustment");
}

/**
 * gtk_scrolled_window_get_hadjustment:
 * @scrolled_window: a #GtkScrolledWindow
 *
 * Returns the horizontal scrollbar’s adjustment, used to connect the
 * horizontal scrollbar to the child widget’s horizontal scroll
 * functionality.
 *
 * Returns: (transfer none): the horizontal #GtkAdjustment
 */
GtkAdjustment*
gtk_scrolled_window_get_hadjustment (GtkScrolledWindow *scrolled_window)
{
  GtkScrolledWindowPrivate *priv;

  g_return_val_if_fail (GTK_IS_SCROLLED_WINDOW (scrolled_window), NULL);

  priv = scrolled_window->priv;

  return gtk_range_get_adjustment (GTK_RANGE (priv->hscrollbar));
}

/**
 * gtk_scrolled_window_get_vadjustment:
 * @scrolled_window: a #GtkScrolledWindow
 * 
 * Returns the vertical scrollbar’s adjustment, used to connect the
 * vertical scrollbar to the child widget’s vertical scroll functionality.
 * 
 * Returns: (transfer none): the vertical #GtkAdjustment
 */
GtkAdjustment*
gtk_scrolled_window_get_vadjustment (GtkScrolledWindow *scrolled_window)
{
  GtkScrolledWindowPrivate *priv;

  g_return_val_if_fail (GTK_IS_SCROLLED_WINDOW (scrolled_window), NULL);

  priv = scrolled_window->priv;

  return gtk_range_get_adjustment (GTK_RANGE (priv->vscrollbar));
}

/**
 * gtk_scrolled_window_get_hscrollbar:
 * @scrolled_window: a #GtkScrolledWindow
 *
 * Returns the horizontal scrollbar of @scrolled_window.
 *
 * Returns: (transfer none): the horizontal scrollbar of the scrolled window.
 *
 * Since: 2.8
 */
GtkWidget*
gtk_scrolled_window_get_hscrollbar (GtkScrolledWindow *scrolled_window)
{
  g_return_val_if_fail (GTK_IS_SCROLLED_WINDOW (scrolled_window), NULL);

  return scrolled_window->priv->hscrollbar;