File Add-GtkHdyViewSwitcher.patch of Package gtk3

From: Adrien Plazas <kekun.plazas@laposte.net>
Date: Mon, 31 Aug 2020 10:40:08 +0200
Subject: Add GtkHdyViewSwitcher

This is imported from HdyViewSwitcher from libhandy 1.0.1.
---
 gtk/gtkprivate.h                |   1 +
 gtk/hdy-css-private.h           |  25 ++
 gtk/hdy-css.c                   |  74 ++++
 gtk/hdy-view-switcher-private.h |  43 +++
 gtk/hdy-view-switcher.c         | 733 ++++++++++++++++++++++++++++++++++++++++
 gtk/meson.build                 |   4 +
 6 files changed, 880 insertions(+)
 create mode 100644 gtk/hdy-css-private.h
 create mode 100644 gtk/hdy-css.c
 create mode 100644 gtk/hdy-view-switcher-private.h
 create mode 100644 gtk/hdy-view-switcher.c

diff --git a/gtk/gtkprivate.h b/gtk/gtkprivate.h
index 40936b9..da05e4e 100644
--- a/gtk/gtkprivate.h
+++ b/gtk/gtkprivate.h
@@ -30,6 +30,7 @@
 
 #include "gtkcsstypesprivate.h"
 #include "gtktexthandleprivate.h"
+#include "hdy-view-switcher-private.h"
 
 G_BEGIN_DECLS
 
diff --git a/gtk/hdy-css-private.h b/gtk/hdy-css-private.h
new file mode 100644
index 0000000..3f5fca8
--- /dev/null
+++ b/gtk/hdy-css-private.h
@@ -0,0 +1,25 @@
+/*
+ * Copyright (C) 2020 Purism SPC
+ *
+ * SPDX-License-Identifier: LGPL-2.1+
+ */
+
+#pragma once
+
+#if !defined (__GTK_H_INSIDE__) && !defined (GTK_COMPILATION)
+#error "Only <gtk/gtk.h> can be included directly."
+#endif
+
+#include "gtkwidget.h"
+
+G_BEGIN_DECLS
+
+void gtk_hdy_css_measure (GtkWidget      *widget,
+                          GtkOrientation  orientation,
+                          gint           *minimum,
+                          gint           *natural);
+
+void gtk_hdy_css_size_allocate (GtkWidget     *widget,
+                                GtkAllocation *allocation);
+
+G_END_DECLS
diff --git a/gtk/hdy-css.c b/gtk/hdy-css.c
new file mode 100644
index 0000000..16cbc01
--- /dev/null
+++ b/gtk/hdy-css.c
@@ -0,0 +1,74 @@
+/*
+ * Copyright (C) 2020 Purism SPC
+ *
+ * SPDX-License-Identifier: LGPL-2.1+
+ */
+
+#include "config.h"
+
+#include "hdy-css-private.h"
+#include "gtkstylecontext.h"
+
+void
+gtk_hdy_css_measure (GtkWidget      *widget,
+                     GtkOrientation  orientation,
+                     gint           *minimum,
+                     gint           *natural)
+{
+  GtkStyleContext *style_context = gtk_widget_get_style_context (widget);
+  GtkStateFlags state_flags = gtk_widget_get_state_flags (widget);
+  GtkBorder border, margin, padding;
+  gint css_width, css_height;
+
+  /* Manually apply minimum sizes, the border, the padding and the margin as we
+   * can't use the private GtkGagdet.
+   */
+  gtk_style_context_get (style_context, state_flags,
+                         "min-width", &css_width,
+                         "min-height", &css_height,
+                         NULL);
+  gtk_style_context_get_border (style_context, state_flags, &border);
+  gtk_style_context_get_margin (style_context, state_flags, &margin);
+  gtk_style_context_get_padding (style_context, state_flags, &padding);
+  if (orientation == GTK_ORIENTATION_VERTICAL) {
+    *minimum = MAX (*minimum, css_height) +
+               border.top + margin.top + padding.top +
+               border.bottom + margin.bottom + padding.bottom;
+    *natural = MAX (*natural, css_height) +
+               border.top + margin.top + padding.top +
+               border.bottom + margin.bottom + padding.bottom;
+  } else {
+    *minimum = MAX (*minimum, css_width) +
+               border.left + margin.left + padding.left +
+               border.right + margin.right + padding.right;
+    *natural = MAX (*natural, css_width) +
+               border.left + margin.left + padding.left +
+               border.right + margin.right + padding.right;
+  }
+}
+
+void
+gtk_hdy_css_size_allocate (GtkWidget     *widget,
+                           GtkAllocation *allocation)
+{
+  GtkStyleContext *style_context;
+  GtkStateFlags state_flags;
+  GtkBorder border, margin, padding;
+
+  /* Manually apply the border, the padding and the margin as we can't use the
+   * private GtkGagdet.
+   */
+  style_context = gtk_widget_get_style_context (widget);
+  state_flags = gtk_widget_get_state_flags (widget);
+  gtk_style_context_get_border (style_context, state_flags, &border);
+  gtk_style_context_get_margin (style_context, state_flags, &margin);
+  gtk_style_context_get_padding (style_context, state_flags, &padding);
+  allocation->width -= border.left + border.right +
+                       margin.left + margin.right +
+                       padding.left + padding.right;
+  allocation->height -= border.top + border.bottom +
+                        margin.top + margin.bottom +
+                        padding.top + padding.bottom;
+  allocation->x += border.left + margin.left + padding.left;
+  allocation->y += border.top + margin.top + padding.top;
+}
diff --git a/gtk/hdy-view-switcher-private.h b/gtk/hdy-view-switcher-private.h
new file mode 100644
index 0000000..6267afd
--- /dev/null
+++ b/gtk/hdy-view-switcher-private.h
@@ -0,0 +1,43 @@
+/*
+ * Copyright (C) 2019 Zander Brown <zbrown@gnome.org>
+ * Copyright (C) 2019 Purism SPC
+ *
+ * SPDX-License-Identifier: LGPL-2.1+
+ */
+
+#pragma once
+
+#if !defined (__GTK_H_INSIDE__) && !defined (GTK_COMPILATION)
+#error "Only <gtk/gtk.h> can be included directly."
+#endif
+
+#include "gtkbin.h"
+#include "gtkstack.h"
+
+G_BEGIN_DECLS
+
+#define GTK_TYPE_HDY_VIEW_SWITCHER (gtk_hdy_view_switcher_get_type())
+
+typedef enum {
+  GTK_HDY_VIEW_SWITCHER_POLICY_AUTO,
+  GTK_HDY_VIEW_SWITCHER_POLICY_NARROW,
+  GTK_HDY_VIEW_SWITCHER_POLICY_WIDE,
+} GtkHdyViewSwitcherPolicy;
+
+G_DECLARE_FINAL_TYPE (GtkHdyViewSwitcher, gtk_hdy_view_switcher, GTK, HDY_VIEW_SWITCHER, GtkBin)
+
+GtkWidget *hdy_view_switcher_new (void);
+
+GtkHdyViewSwitcherPolicy gtk_hdy_view_switcher_get_policy (GtkHdyViewSwitcher *self);
+void                     gtk_hdy_view_switcher_set_policy (GtkHdyViewSwitcher       *self,
+                                                           GtkHdyViewSwitcherPolicy  policy);
+
+PangoEllipsizeMode gtk_hdy_view_switcher_get_narrow_ellipsize (GtkHdyViewSwitcher *self);
+void               gtk_hdy_view_switcher_set_narrow_ellipsize (GtkHdyViewSwitcher *self,
+                                                               PangoEllipsizeMode  mode);
+
+GtkStack *gtk_hdy_view_switcher_get_stack (GtkHdyViewSwitcher *self);
+void      gtk_hdy_view_switcher_set_stack (GtkHdyViewSwitcher *self,
+                                           GtkStack           *stack);
+
+G_END_DECLS
diff --git a/gtk/hdy-view-switcher.c b/gtk/hdy-view-switcher.c
new file mode 100644
index 0000000..2664b3e
--- /dev/null
+++ b/gtk/hdy-view-switcher.c
@@ -0,0 +1,733 @@
+/*
+ * Copyright (C) 2019 Zander Brown <zbrown@gnome.org>
+ * Copyright (C) 2019 Purism SPC
+ *
+ * Based on gtkstackswitcher.c, Copyright (c) 2013 Red Hat, Inc.
+ * https://gitlab.gnome.org/GNOME/gtk/blob/a0129f556b1fd655215165739d0277d7f7a2c1a8/gtk/gtkstackswitcher.c
+ *
+ * SPDX-License-Identifier: LGPL-2.1+
+ */
+
+#include "config.h"
+#include <glib/gi18n-lib.h>
+
+#include "gtkbox.h"
+#include "gtkdragdest.h"
+#include "gtkorientable.h"
+#include "gtkprivatetypebuiltins.h"
+#include "hdy-css-private.h"
+#include "hdy-view-switcher-button-private.h"
+#include "hdy-view-switcher-private.h"
+
+/**
+ * SECTION:gtk-hdy-view-switcher
+ * @short_description: An adaptive view switcher.
+ * @title: GtkHdyViewSwitcher
+ *
+ * An adaptive view switcher, designed to switch between multiple views in a
+ * similar fashion than a #GtkStackSwitcher.
+ *
+ * Depending on the available width, the view switcher can adapt from a wide
+ * mode showing the view's icon and title side by side, to a narrow mode showing
+ * the view's icon and title one on top of the other, in a more compact way.
+ * This can be controlled via the policy property.
+ *
+ * To look good in a header bar, an #GtkHdyViewSwitcher requires to fill its full
+ * height. Contrary to #GtkHeaderBar, #GtkHdyHeaderBar doesn't force a vertical
+ * alignment on its title widget, so we recommend it over #GtkHeaderBar.
+ *
+ * # CSS nodes
+ *
+ * #GtkHdyViewSwitcher has a single CSS node with name viewswitcher.
+ *
+ * Since: 0.0.10
+ */
+
+#define MIN_NAT_BUTTON_WIDTH 100
+#define TIMEOUT_EXPAND 500
+
+enum {
+  PROP_0,
+  PROP_POLICY,
+  PROP_NARROW_ELLIPSIZE,
+  PROP_STACK,
+  LAST_PROP,
+};
+
+struct _GtkHdyViewSwitcher
+{
+  GtkBin parent_instance;
+
+  GtkWidget *box;
+  GHashTable *buttons;
+  gboolean in_child_changed;
+  GtkWidget *switch_button;
+  guint switch_timer;
+
+  GtkHdyViewSwitcherPolicy policy;
+  PangoEllipsizeMode narrow_ellipsize;
+  GtkStack *stack;
+};
+
+static GParamSpec *props[LAST_PROP];
+
+G_DEFINE_TYPE (GtkHdyViewSwitcher, gtk_hdy_view_switcher, GTK_TYPE_BIN)
+
+static void
+set_visible_stack_child_for_button (GtkHdyViewSwitcher       *self,
+                                    GtkHdyViewSwitcherButton *button)
+{
+  if (self->in_child_changed)
+    return;
+
+  gtk_stack_set_visible_child (self->stack, GTK_WIDGET (g_object_get_data (G_OBJECT (button), "stack-child")));
+}
+
+static void
+update_button (GtkHdyViewSwitcher       *self,
+               GtkWidget             *widget,
+               GtkHdyViewSwitcherButton *button)
+{
+  g_autofree gchar *title = NULL;
+  g_autofree gchar *icon_name = NULL;
+  gboolean needs_attention;
+
+  gtk_container_child_get (GTK_CONTAINER (self->stack), widget,
+                           "title", &title,
+                           "icon-name", &icon_name,
+                           "needs-attention", &needs_attention,
+                           NULL);
+
+  g_object_set (G_OBJECT (button),
+                "icon-name", icon_name,
+                "icon-size", GTK_ICON_SIZE_BUTTON,
+                "label", title,
+                "needs-attention", needs_attention,
+                NULL);
+
+  gtk_widget_set_visible (GTK_WIDGET (button),
+                          gtk_widget_get_visible (widget) && (title != NULL || icon_name != NULL));
+}
+
+static void
+on_stack_child_updated (GtkWidget       *widget,
+                        GParamSpec      *pspec,
+                        GtkHdyViewSwitcher *self)
+{
+  update_button (self, widget, g_hash_table_lookup (self->buttons, widget));
+}
+
+static void
+on_position_updated (GtkWidget       *widget,
+                     GParamSpec      *pspec,
+                     GtkHdyViewSwitcher *self)
+{
+  GtkWidget *button = g_hash_table_lookup (self->buttons, widget);
+  gint position;
+
+  gtk_container_child_get (GTK_CONTAINER (self->stack), widget,
+                           "position", &position,
+                           NULL);
+  gtk_box_reorder_child (GTK_BOX (self->box), button, position);
+}
+
+static void
+remove_switch_timer (GtkHdyViewSwitcher *self)
+{
+  if (!self->switch_timer)
+    return;
+
+  g_source_remove (self->switch_timer);
+  self->switch_timer = 0;
+}
+
+static gboolean
+gtk_hdy_view_switcher_switch_timeout (gpointer data)
+{
+  GtkHdyViewSwitcher *self = GTK_HDY_VIEW_SWITCHER (data);
+  GtkWidget *button = self->switch_button;
+
+  self->switch_timer = 0;
+  self->switch_button = NULL;
+
+  if (button)
+    gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (button), TRUE);
+
+  return G_SOURCE_REMOVE;
+}
+
+static gboolean
+gtk_hdy_view_switcher_drag_motion (GtkWidget      *widget,
+                                   GdkDragContext *context,
+                                   gint            x,
+                                   gint            y,
+                                   guint           time)
+{
+  GtkHdyViewSwitcher *self = GTK_HDY_VIEW_SWITCHER (widget);
+  GtkAllocation allocation;
+  GtkWidget *button;
+  GHashTableIter iter;
+  gpointer value;
+  gboolean retval = FALSE;
+
+  gtk_widget_get_allocation (widget, &allocation);
+
+  x += allocation.x;
+  y += allocation.y;
+
+  button = NULL;
+  g_hash_table_iter_init (&iter, self->buttons);
+  while (g_hash_table_iter_next (&iter, NULL, &value)) {
+    gtk_widget_get_allocation (GTK_WIDGET (value), &allocation);
+    if (x >= allocation.x && x <= allocation.x + allocation.width &&
+        y >= allocation.y && y <= allocation.y + allocation.height) {
+      button = GTK_WIDGET (value);
+      retval = TRUE;
+
+      break;
+    }
+  }
+
+  if (button != self->switch_button)
+    remove_switch_timer (self);
+
+  self->switch_button = button;
+
+  if (button && !self->switch_timer) {
+    self->switch_timer = gdk_threads_add_timeout (TIMEOUT_EXPAND,
+                                                  gtk_hdy_view_switcher_switch_timeout,
+                                                  self);
+    g_source_set_name_by_id (self->switch_timer, "[gtk+] gtk_hdy_view_switcher_switch_timeout");
+  }
+
+  return retval;
+}
+
+static void
+gtk_hdy_view_switcher_drag_leave (GtkWidget      *widget,
+                                  GdkDragContext *context,
+                                  guint           time)
+{
+  GtkHdyViewSwitcher *self = GTK_HDY_VIEW_SWITCHER (widget);
+
+  remove_switch_timer (self);
+}
+
+static void
+add_button_for_stack_child (GtkHdyViewSwitcher *self,
+                            GtkWidget       *stack_child)
+{
+  g_autoptr (GList) children = gtk_container_get_children (GTK_CONTAINER (self->box));
+  GtkHdyViewSwitcherButton *button = GTK_HDY_VIEW_SWITCHER_BUTTON (gtk_hdy_view_switcher_button_new ());
+
+  g_object_set_data (G_OBJECT (button), "stack-child", stack_child);
+  gtk_hdy_view_switcher_button_set_narrow_ellipsize (button, self->narrow_ellipsize);
+
+  update_button (self, stack_child, button);
+
+  if (children != NULL)
+    gtk_radio_button_join_group (GTK_RADIO_BUTTON (button), GTK_RADIO_BUTTON (children->data));
+
+  gtk_container_add (GTK_CONTAINER (self->box), GTK_WIDGET (button));
+
+  g_signal_connect_swapped (button, "clicked", G_CALLBACK (set_visible_stack_child_for_button), self);
+  g_signal_connect (stack_child, "notify::visible", G_CALLBACK (on_stack_child_updated), self);
+  g_signal_connect (stack_child, "child-notify::title", G_CALLBACK (on_stack_child_updated), self);
+  g_signal_connect (stack_child, "child-notify::icon-name", G_CALLBACK (on_stack_child_updated), self);
+  g_signal_connect (stack_child, "child-notify::needs-attention", G_CALLBACK (on_stack_child_updated), self);
+  g_signal_connect (stack_child, "child-notify::position", G_CALLBACK (on_position_updated), self);
+
+  g_hash_table_insert (self->buttons, stack_child, button);
+}
+
+static void
+add_button_for_stack_child_cb (GtkWidget       *stack_child,
+                               GtkHdyViewSwitcher *self)
+{
+  g_return_if_fail (GTK_IS_HDY_VIEW_SWITCHER (self));
+  g_return_if_fail (GTK_IS_WIDGET (stack_child));
+
+  add_button_for_stack_child (self, stack_child);
+}
+
+static void
+remove_button_for_stack_child (GtkHdyViewSwitcher *self,
+                               GtkWidget       *stack_child)
+{
+  g_signal_handlers_disconnect_by_func (stack_child, on_stack_child_updated, self);
+  g_signal_handlers_disconnect_by_func (stack_child, on_position_updated, self);
+  gtk_container_remove (GTK_CONTAINER (self->box), g_hash_table_lookup (self->buttons, stack_child));
+  g_hash_table_remove (self->buttons, stack_child);
+}
+
+static void
+remove_button_for_stack_child_cb (GtkWidget       *stack_child,
+                                  GtkHdyViewSwitcher *self)
+{
+  g_return_if_fail (GTK_IS_HDY_VIEW_SWITCHER (self));
+  g_return_if_fail (GTK_IS_WIDGET (stack_child));
+
+  remove_button_for_stack_child (self, stack_child);
+}
+
+static void
+update_active_button_for_visible_stack_child (GtkHdyViewSwitcher *self)
+{
+  GtkWidget *visible_stack_child = gtk_stack_get_visible_child (self->stack);
+  GtkWidget *button = g_hash_table_lookup (self->buttons, visible_stack_child);
+
+  if (button == NULL)
+    return;
+
+  self->in_child_changed = TRUE;
+  gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (button), TRUE);
+  self->in_child_changed = FALSE;
+}
+
+static void
+disconnect_stack_signals (GtkHdyViewSwitcher *self)
+{
+  g_signal_handlers_disconnect_by_func (self->stack, add_button_for_stack_child, self);
+  g_signal_handlers_disconnect_by_func (self->stack, remove_button_for_stack_child, self);
+  g_signal_handlers_disconnect_by_func (self->stack, update_active_button_for_visible_stack_child, self);
+  g_signal_handlers_disconnect_by_func (self->stack, disconnect_stack_signals, self);
+}
+
+static void
+connect_stack_signals (GtkHdyViewSwitcher *self)
+{
+  g_signal_connect_object (self->stack, "add",
+                           G_CALLBACK (add_button_for_stack_child), self,
+                           G_CONNECT_AFTER | G_CONNECT_SWAPPED);
+  g_signal_connect_object (self->stack, "remove",
+                           G_CALLBACK (remove_button_for_stack_child), self,
+                           G_CONNECT_AFTER | G_CONNECT_SWAPPED);
+  g_signal_connect_object (self->stack, "notify::visible-child",
+                           G_CALLBACK (update_active_button_for_visible_stack_child), self,
+                           G_CONNECT_SWAPPED);
+  g_signal_connect_object (self->stack, "destroy",
+                           G_CALLBACK (disconnect_stack_signals), self,
+                           G_CONNECT_SWAPPED);
+}
+
+static void
+gtk_hdy_view_switcher_get_property (GObject    *object,
+                                    guint       prop_id,
+                                    GValue     *value,
+                                    GParamSpec *pspec)
+{
+  GtkHdyViewSwitcher *self = GTK_HDY_VIEW_SWITCHER (object);
+
+  switch (prop_id) {
+  case PROP_POLICY:
+    g_value_set_enum (value, gtk_hdy_view_switcher_get_policy (self));
+    break;
+  case PROP_NARROW_ELLIPSIZE:
+    g_value_set_enum (value, gtk_hdy_view_switcher_get_narrow_ellipsize (self));
+    break;
+  case PROP_STACK:
+    g_value_set_object (value, gtk_hdy_view_switcher_get_stack (self));
+    break;
+  default:
+    G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+    break;
+  }
+}
+
+static void
+gtk_hdy_view_switcher_set_property (GObject      *object,
+                                    guint         prop_id,
+                                    const GValue *value,
+                                    GParamSpec   *pspec)
+{
+  GtkHdyViewSwitcher *self = GTK_HDY_VIEW_SWITCHER (object);
+
+  switch (prop_id) {
+  case PROP_POLICY:
+    gtk_hdy_view_switcher_set_policy (self, g_value_get_enum (value));
+    break;
+  case PROP_NARROW_ELLIPSIZE:
+    gtk_hdy_view_switcher_set_narrow_ellipsize (self, g_value_get_enum (value));
+    break;
+  case PROP_STACK:
+    gtk_hdy_view_switcher_set_stack (self, g_value_get_object (value));
+    break;
+  default:
+    G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+    break;
+  }
+}
+
+static void
+gtk_hdy_view_switcher_dispose (GObject *object)
+{
+  GtkHdyViewSwitcher *self = GTK_HDY_VIEW_SWITCHER (object);
+
+  remove_switch_timer (self);
+  gtk_hdy_view_switcher_set_stack (self, NULL);
+
+  G_OBJECT_CLASS (gtk_hdy_view_switcher_parent_class)->dispose (object);
+}
+
+static void
+gtk_hdy_view_switcher_finalize (GObject *object)
+{
+  GtkHdyViewSwitcher *self = GTK_HDY_VIEW_SWITCHER (object);
+
+  g_hash_table_destroy (self->buttons);
+
+  G_OBJECT_CLASS (gtk_hdy_view_switcher_parent_class)->finalize (object);
+}
+
+static void
+gtk_hdy_view_switcher_get_preferred_width (GtkWidget *widget,
+                                           gint      *min,
+                                           gint      *nat)
+{
+  GtkHdyViewSwitcher *self = GTK_HDY_VIEW_SWITCHER (widget);
+  g_autoptr (GList) children = gtk_container_get_children (GTK_CONTAINER (self->box));
+  gint max_h_min = 0, max_h_nat = 0, max_v_min = 0, max_v_nat = 0;
+  gint n_children = 0;
+
+  for (GList *l = children; l != NULL; l = g_list_next (l)) {
+    gint h_min = 0, h_nat = 0, v_min = 0, v_nat = 0;
+
+    if (!gtk_widget_get_visible (l->data))
+      continue;
+
+    gtk_hdy_view_switcher_button_get_size (GTK_HDY_VIEW_SWITCHER_BUTTON (l->data), &h_min, &h_nat, &v_min, &v_nat);
+    max_h_min = MAX (h_min, max_h_min);
+    max_h_nat = MAX (h_nat, max_h_nat);
+    max_v_min = MAX (v_min, max_v_min);
+    max_v_nat = MAX (v_nat, max_v_nat);
+
+    n_children++;
+  }
+
+  /* Make the buttons ask at least a minimum arbitrary size for their natural
+   * width. This prevents them from looking terribly narrow in a very wide bar.
+   */
+  max_h_nat = MAX (max_h_nat, MIN_NAT_BUTTON_WIDTH);
+  max_v_nat = MAX (max_v_nat, MIN_NAT_BUTTON_WIDTH);
+
+  switch (self->policy) {
+  case GTK_HDY_VIEW_SWITCHER_POLICY_NARROW:
+    *min = max_v_min * n_children;
+    *nat = max_v_nat * n_children;
+    break;
+  case GTK_HDY_VIEW_SWITCHER_POLICY_WIDE:
+    *min = max_h_min * n_children;
+    *nat = max_h_nat * n_children;
+    break;
+  case GTK_HDY_VIEW_SWITCHER_POLICY_AUTO:
+  default:
+    *min = max_v_min * n_children;
+    *nat = max_h_nat * n_children;
+    break;
+  }
+
+  gtk_hdy_css_measure (widget, GTK_ORIENTATION_HORIZONTAL, min, nat);
+}
+
+static gint
+is_narrow (GtkHdyViewSwitcher *self,
+           gint             width)
+{
+  g_autoptr (GList) children = gtk_container_get_children (GTK_CONTAINER (self->box));
+  gint max_h_min = 0;
+  gint n_children = 0;
+
+  if (self->policy == GTK_HDY_VIEW_SWITCHER_POLICY_NARROW)
+    return TRUE;
+
+  if (self->policy == GTK_HDY_VIEW_SWITCHER_POLICY_WIDE)
+    return FALSE;
+
+  for (GList *l = children; l != NULL; l = g_list_next (l)) {
+    gint h_min = 0;
+
+    if (!gtk_widget_get_visible (l->data))
+      continue;
+
+    gtk_hdy_view_switcher_button_get_size (GTK_HDY_VIEW_SWITCHER_BUTTON (l->data), &h_min, NULL, NULL, NULL);
+    max_h_min = MAX (max_h_min, h_min);
+
+    n_children++;
+  }
+
+  return (max_h_min * n_children) > width;
+}
+
+static void
+gtk_hdy_view_switcher_size_allocate (GtkWidget     *widget,
+                                     GtkAllocation *allocation)
+{
+  GtkHdyViewSwitcher *self = GTK_HDY_VIEW_SWITCHER (widget);
+
+  g_autoptr (GList) children = gtk_container_get_children (GTK_CONTAINER (self->box));
+  GtkOrientation orientation;
+
+  gtk_hdy_css_size_allocate (widget, allocation);
+
+  orientation = is_narrow (GTK_HDY_VIEW_SWITCHER (widget), allocation->width) ?
+    GTK_ORIENTATION_VERTICAL :
+    GTK_ORIENTATION_HORIZONTAL;
+
+  for (GList *l = children; l != NULL; l = g_list_next (l))
+    gtk_orientable_set_orientation (GTK_ORIENTABLE (l->data), orientation);
+
+  GTK_WIDGET_CLASS (gtk_hdy_view_switcher_parent_class)->size_allocate (widget, allocation);
+}
+
+static void
+gtk_hdy_view_switcher_class_init (GtkHdyViewSwitcherClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+  GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);
+
+  object_class->get_property = gtk_hdy_view_switcher_get_property;
+  object_class->set_property = gtk_hdy_view_switcher_set_property;
+  object_class->dispose = gtk_hdy_view_switcher_dispose;
+  object_class->finalize = gtk_hdy_view_switcher_finalize;
+
+  widget_class->size_allocate = gtk_hdy_view_switcher_size_allocate;
+  widget_class->get_preferred_width = gtk_hdy_view_switcher_get_preferred_width;
+  widget_class->drag_motion = gtk_hdy_view_switcher_drag_motion;
+  widget_class->drag_leave = gtk_hdy_view_switcher_drag_leave;
+
+  /**
+   * GtkHdyViewSwitcher:policy:
+   *
+   * The #GtkHdyViewSwitcherPolicy the view switcher should use to determine which
+   * mode to use.
+   *
+   * Since: 0.0.10
+   */
+  props[PROP_POLICY] =
+    g_param_spec_enum ("policy",
+                       _("Policy"),
+                       _("The policy to determine the mode to use"),
+                       GTK_TYPE_HDY_VIEW_SWITCHER_POLICY, GTK_HDY_VIEW_SWITCHER_POLICY_AUTO,
+                       G_PARAM_EXPLICIT_NOTIFY | G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS);
+
+  /**
+   * GtkHdyViewSwitcher:narrow-ellipsize:
+   *
+   * The preferred place to ellipsize the string, if the narrow mode label does
+   * not have enough room to display the entire string, specified as a
+   * #PangoEllipsizeMode.
+   *
+   * Note that setting this property to a value other than %PANGO_ELLIPSIZE_NONE
+   * has the side-effect that the label requests only enough space to display
+   * the ellipsis.
+   *
+   * Since: 0.0.10
+   */
+  props[PROP_NARROW_ELLIPSIZE] =
+    g_param_spec_enum ("narrow-ellipsize",
+                       _("Narrow ellipsize"),
+                       _("The preferred place to ellipsize the string, if the narrow mode label does not have enough room to display the entire string"),
+                       PANGO_TYPE_ELLIPSIZE_MODE,
+                       PANGO_ELLIPSIZE_NONE,
+                       G_PARAM_READWRITE | G_PARAM_EXPLICIT_NOTIFY);
+
+  /**
+   * GtkHdyViewSwitcher:stack:
+   *
+   * The #GtkStack the view switcher controls.
+   *
+   * Since: 0.0.10
+   */
+  props[PROP_STACK] =
+    g_param_spec_object ("stack",
+                         _("Stack"),
+                         _("Stack"),
+                         GTK_TYPE_STACK,
+                         G_PARAM_EXPLICIT_NOTIFY | G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS);
+
+  g_object_class_install_properties (object_class, LAST_PROP, props);
+
+  gtk_widget_class_set_css_name (widget_class, "viewswitcher");
+}
+
+static void
+gtk_hdy_view_switcher_init (GtkHdyViewSwitcher *self)
+{
+  self->box = gtk_box_new (GTK_ORIENTATION_HORIZONTAL, 0);
+  gtk_widget_show (self->box);
+  gtk_box_set_homogeneous (GTK_BOX (self->box), TRUE);
+  gtk_container_add (GTK_CONTAINER (self), self->box);
+
+  self->buttons = g_hash_table_new (g_direct_hash, g_direct_equal);
+
+  gtk_widget_set_valign (GTK_WIDGET (self), GTK_ALIGN_FILL);
+
+  gtk_drag_dest_set (GTK_WIDGET (self), 0, NULL, 0, 0);
+  gtk_drag_dest_set_track_motion (GTK_WIDGET (self), TRUE);
+}
+
+/**
+ * gtk_hdy_view_switcher_new:
+ *
+ * Creates a new #GtkHdyViewSwitcher widget.
+ *
+ * Returns: a new #GtkHdyViewSwitcher
+ *
+ * Since: 0.0.10
+ */
+GtkWidget *
+gtk_hdy_view_switcher_new (void)
+{
+  return g_object_new (GTK_TYPE_HDY_VIEW_SWITCHER, NULL);
+}
+
+/**
+ * gtk_hdy_view_switcher_get_policy:
+ * @self: a #GtkHdyViewSwitcher
+ *
+ * Gets the policy of @self.
+ *
+ * Returns: the policy of @self
+ *
+ * Since: 0.0.10
+ */
+GtkHdyViewSwitcherPolicy
+gtk_hdy_view_switcher_get_policy (GtkHdyViewSwitcher *self)
+{
+  g_return_val_if_fail (GTK_IS_HDY_VIEW_SWITCHER (self), GTK_HDY_VIEW_SWITCHER_POLICY_AUTO);
+
+  return self->policy;
+}
+
+/**
+ * gtk_hdy_view_switcher_set_policy:
+ * @self: a #GtkHdyViewSwitcher
+ * @policy: the new policy
+ *
+ * Sets the policy of @self.
+ *
+ * Since: 0.0.10
+ */
+void
+gtk_hdy_view_switcher_set_policy (GtkHdyViewSwitcher       *self,
+                                  GtkHdyViewSwitcherPolicy  policy)
+{
+  g_return_if_fail (GTK_IS_HDY_VIEW_SWITCHER (self));
+
+  if (self->policy == policy)
+    return;
+
+  self->policy = policy;
+
+  g_object_notify_by_pspec (G_OBJECT (self), props[PROP_POLICY]);
+
+  gtk_widget_queue_resize (GTK_WIDGET (self));
+}
+
+/**
+ * gtk_hdy_view_switcher_get_narrow_ellipsize:
+ * @self: a #GtkHdyViewSwitcher
+ *
+ * Get the ellipsizing position of the narrow mode label. See
+ * gtk_hdy_view_switcher_set_narrow_ellipsize().
+ *
+ * Returns: #PangoEllipsizeMode
+ *
+ * Since: 0.0.10
+ **/
+PangoEllipsizeMode
+gtk_hdy_view_switcher_get_narrow_ellipsize (GtkHdyViewSwitcher *self)
+{
+  g_return_val_if_fail (GTK_IS_HDY_VIEW_SWITCHER (self), PANGO_ELLIPSIZE_NONE);
+
+  return self->narrow_ellipsize;
+}
+
+/**
+ * gtk_hdy_view_switcher_set_narrow_ellipsize:
+ * @self: a #GtkHdyViewSwitcher
+ * @mode: a #PangoEllipsizeMode
+ *
+ * Set the mode used to ellipsize the text in narrow mode if there is not
+ * enough space to render the entire string.
+ *
+ * Since: 0.0.10
+ **/
+void
+gtk_hdy_view_switcher_set_narrow_ellipsize (GtkHdyViewSwitcher *self,
+                                            PangoEllipsizeMode  mode)
+{
+  GHashTableIter iter;
+  gpointer button;
+
+  g_return_if_fail (GTK_IS_HDY_VIEW_SWITCHER (self));
+  g_return_if_fail (mode >= PANGO_ELLIPSIZE_NONE && mode <= PANGO_ELLIPSIZE_END);
+
+  if ((PangoEllipsizeMode) self->narrow_ellipsize == mode)
+    return;
+
+  self->narrow_ellipsize = mode;
+
+  g_hash_table_iter_init (&iter, self->buttons);
+  while (g_hash_table_iter_next (&iter, NULL, &button))
+    gtk_hdy_view_switcher_button_set_narrow_ellipsize (GTK_HDY_VIEW_SWITCHER_BUTTON (button), mode);
+
+  g_object_notify_by_pspec (G_OBJECT (self), props[PROP_NARROW_ELLIPSIZE]);
+}
+
+/**
+ * gtk_hdy_view_switcher_get_stack:
+ * @self: a #GtkHdyViewSwitcher
+ *
+ * Get the #GtkStack being controlled by the #GtkHdyViewSwitcher.
+ *
+ * See: gtk_hdy_view_switcher_set_stack()
+ *
+ * Returns: (nullable) (transfer none): the #GtkStack, or %NULL if none has been set
+ *
+ * Since: 0.0.10
+ */
+GtkStack *
+gtk_hdy_view_switcher_get_stack (GtkHdyViewSwitcher *self)
+{
+  g_return_val_if_fail (GTK_IS_HDY_VIEW_SWITCHER (self), NULL);
+
+  return self->stack;
+}
+
+/**
+ * gtk_hdy_view_switcher_set_stack:
+ * @self: a #GtkHdyViewSwitcher
+ * @stack: (nullable): a #GtkStack
+ *
+ * Sets the #GtkStack to control.
+ *
+ * Since: 0.0.10
+ */
+void
+gtk_hdy_view_switcher_set_stack (GtkHdyViewSwitcher *self,
+                                 GtkStack           *stack)
+{
+  g_return_if_fail (GTK_IS_HDY_VIEW_SWITCHER (self));
+  g_return_if_fail (stack == NULL || GTK_IS_STACK (stack));
+
+  if (self->stack == stack)
+    return;
+
+  if (self->stack) {
+    disconnect_stack_signals (self);
+    gtk_container_foreach (GTK_CONTAINER (self->stack), (GtkCallback) remove_button_for_stack_child_cb, self);
+  }
+
+  g_set_object (&self->stack, stack);
+
+  if (self->stack) {
+    gtk_container_foreach (GTK_CONTAINER (self->stack), (GtkCallback) add_button_for_stack_child_cb, self);
+    update_active_button_for_visible_stack_child (self);
+    connect_stack_signals (self);
+  }
+
+  gtk_widget_queue_resize (GTK_WIDGET (self));
+
+  g_object_notify_by_pspec (G_OBJECT (self), props[PROP_STACK]);
+}
diff --git a/gtk/meson.build b/gtk/meson.build
index e538327..45b26cf 100644
--- a/gtk/meson.build
+++ b/gtk/meson.build
@@ -383,7 +383,9 @@ gtk_sources = files(
   'gtkwin32draw.c',
   'gtkwin32theme.c',
   'gdkpixbufutils.c',
+  'hdy-css.c',
   'hdy-view-switcher-button.c',
+  'hdy-view-switcher.c',
   'language-names.c',
   'script-names.c',
 )
@@ -391,7 +393,9 @@ gtk_sources = files(
 gtk_private_type_headers = files(
   'gtkcsstypesprivate.h',
   'gtktexthandleprivate.h',
+  'hdy-css-private.h',
   'hdy-view-switcher-button-private.h',
+  'hdy-view-switcher-private.h',
 )
 
 gtk_gir_public_headers = files(
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