[gtk+/wip/overlay-scrollbar: 4/5] Add an experiment for overlay scrollbars

[Matthias Clasen <matthiasc src gnome org>]

commit 3a373eaad7ff0fe90b8d1ce42340c6b491b0a9c2
Author: Matthias Clasen <mclasen redhat com>
Date:   Sat Oct 4 23:37:11 2014 -0400

    Add an experiment for overlay scrollbars
    
    This is just meant as a prototype for how we can show a
    scroll position indicator for touch. This uses GTK_POLICY_EXTERNAL
    to hide the scrolled windows scrollbar while still allowing
    scrolling.

 tests/Makefile.am     |    1 +
 tests/overlayscroll.c |  217 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 218 insertions(+), 0 deletions(-)
---
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 78b9b29..aa2287a 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -25,6 +25,7 @@ testsocket_programs = testsocket testsocket_child
 endif
 
 noinst_PROGRAMS =  $(TEST_PROGS)       \
+       overlayscroll                   \
        syncscroll                      \
        subsurface                      \
        animated-resizing               \
diff --git a/tests/overlayscroll.c b/tests/overlayscroll.c
new file mode 100644
index 0000000..06a5675
--- /dev/null
+++ b/tests/overlayscroll.c
@@ -0,0 +1,217 @@
+/* simple.c
+ * Copyright (C) 1997  Red Hat, Inc
+ * Author: Elliot Lee
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library 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
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ */
+#include <gtk/gtk.h>
+
+typedef struct {
+  GtkWidget *rv;
+  gint64 last_scroll_time;
+  gboolean over;
+  gboolean dragging;
+} IndicatorData;
+
+IndicatorData *
+get_indicator_data (GtkWidget *sb)
+{
+  IndicatorData *data;
+
+  data = (IndicatorData *) g_object_get_data (G_OBJECT (sb), "indicator-data");
+
+  if (!data)
+    {
+      data = g_new0 (IndicatorData, 1);
+      g_object_set_data_full (G_OBJECT (sb), "indicator-data", data, g_free);
+    }
+
+  return data;
+}
+
+static gboolean
+conceil_scrollbar (gpointer data)
+{
+  GtkWidget *sb = data;
+  IndicatorData *id = get_indicator_data (sb);
+
+  if (g_get_monotonic_time () - id->last_scroll_time >= 1000000 &&
+      !id->over &&
+      !id->dragging)
+    {
+      if (gtk_revealer_get_reveal_child (GTK_REVEALER (id->rv)))
+        gtk_revealer_set_reveal_child (GTK_REVEALER (id->rv), FALSE);
+    }
+
+  return G_SOURCE_CONTINUE;
+}
+
+static void
+value_changed (GtkAdjustment *adj, GtkWidget *sb)
+{
+  IndicatorData *id = get_indicator_data (sb);
+
+  if (!gtk_revealer_get_reveal_child (GTK_REVEALER (id->rv)))
+    gtk_revealer_set_reveal_child (GTK_REVEALER (id->rv), TRUE);
+
+  id->last_scroll_time = g_get_monotonic_time ();  
+}
+
+static gboolean
+enter_notify (GtkWidget *sb, GdkEventCrossing *event)
+{
+  GtkStyleContext *context = gtk_widget_get_style_context (sb);
+  IndicatorData *id = get_indicator_data (sb);
+
+  gtk_style_context_add_class (context, "locked");
+  gtk_widget_queue_resize (sb);
+  id->over = TRUE;
+
+  return G_SOURCE_CONTINUE;
+}
+
+static gboolean
+leave_notify (GtkWidget *sb, GdkEventCrossing *event)
+{
+  GtkStyleContext *context = gtk_widget_get_style_context (sb);
+  IndicatorData *id = get_indicator_data (sb);
+
+  gtk_style_context_remove_class (context, "locked");
+  gtk_widget_queue_resize (sb);
+  id->over = FALSE;
+
+  return G_SOURCE_CONTINUE;
+}
+
+static void
+style_changed (GtkStyleContext *context, GtkWidget *sb)
+{
+  IndicatorData *id = get_indicator_data (sb);
+
+  if (gtk_style_context_has_class (context, "dragging"))
+    id->dragging = TRUE;
+  else
+    id->dragging = FALSE;
+}
+
+static gchar *
+get_content (void)
+{
+  GString *s;
+  gint i;
+
+  s = g_string_new ("");
+  for (i = 1; i <= 150; i++)
+    g_string_append_printf (s, "Line %d\n", i);
+
+  return g_string_free (s, FALSE);
+}
+
+static const gchar data[] =
+  ".scrollbar.overlay-indicator.dragging,"
+  ".scrollbar.overlay-indicator.locked {"
+  "   -GtkRange-slider-width: 15;"
+  "}"
+  ".scrollbar.overlay-indicator.dragging.trough,"
+  ".scrollbar.overlay-indicator.locked.trough {"
+  "   background-color: alpha(black,0.1);"
+  "}"
+  ".scrollbar.overlay-indicator {"
+  "   -GtkRange-slider-width: 10;"
+  "}"
+  ".scrollbar.overlay-indicator.trough {"
+  "   background-color: transparent;"
+  "}";
+
+int
+main (int argc, char *argv[])
+{
+  GtkWidget *window;
+  gchar *content;
+  GtkWidget *box;
+  GtkWidget *sw;
+  GtkWidget *tv;
+  GtkWidget *ov;
+  GtkWidget *sb;
+  GtkWidget *rv;
+  GtkAdjustment *adj;
+  GtkCssProvider *provider;
+  IndicatorData *id;
+
+  gtk_init (&argc, &argv);
+
+  provider = gtk_css_provider_new ();
+  gtk_css_provider_load_from_data (provider, data, -1, NULL);
+  gtk_style_context_add_provider_for_screen (gdk_screen_get_default (),
+                                             GTK_STYLE_PROVIDER (provider),
+                                             GTK_STYLE_PROVIDER_PRIORITY_APPLICATION);
+
+  window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
+  gtk_window_set_default_size (GTK_WINDOW (window), 640, 480);
+
+  box = gtk_box_new (GTK_ORIENTATION_HORIZONTAL, 20);
+  gtk_container_add (GTK_CONTAINER (window), box);
+
+  ov = gtk_overlay_new ();
+  gtk_box_pack_start (GTK_BOX (box), ov, TRUE, TRUE, 0);
+
+  sw = gtk_scrolled_window_new (NULL, NULL);
+  gtk_scrolled_window_set_policy (GTK_SCROLLED_WINDOW (sw),
+                                  GTK_POLICY_NEVER,
+                                  GTK_POLICY_EXTERNAL);
+
+  gtk_container_add (GTK_CONTAINER (ov), sw);
+
+  content = get_content ();
+
+  tv = gtk_text_view_new ();
+  gtk_text_view_set_wrap_mode (GTK_TEXT_VIEW (tv), GTK_WRAP_WORD);
+  gtk_container_add (GTK_CONTAINER (sw), tv);
+  gtk_text_buffer_set_text (gtk_text_view_get_buffer (GTK_TEXT_VIEW (tv)),
+                            content, -1);
+  g_free (content);
+
+  adj = gtk_scrollable_get_vadjustment (GTK_SCROLLABLE (tv));
+
+  sb = gtk_scrollbar_new (GTK_ORIENTATION_VERTICAL, adj);
+
+  rv = gtk_revealer_new ();
+  gtk_revealer_set_transition_type (GTK_REVEALER (rv), GTK_REVEALER_TRANSITION_TYPE_CROSSFADE);
+  gtk_revealer_set_transition_duration (GTK_REVEALER (rv), 750);
+  gtk_container_add (GTK_CONTAINER (rv), sb);
+  gtk_overlay_add_overlay (GTK_OVERLAY (ov), rv);
+  gtk_widget_set_halign (rv, GTK_ALIGN_END);
+  gtk_widget_set_valign (rv, GTK_ALIGN_FILL);
+
+  id = get_indicator_data (sb);
+  id->rv = rv;
+
+  gtk_style_context_add_class (gtk_widget_get_style_context (sb), "overlay-indicator");
+  g_signal_connect (sb, "enter-notify-event", G_CALLBACK (enter_notify), NULL);
+  g_signal_connect (sb, "leave-notify-event", G_CALLBACK (leave_notify), NULL);
+  g_signal_connect (gtk_widget_get_style_context (sb), "changed", G_CALLBACK (style_changed), sb);
+  g_signal_connect (adj, "value-changed", G_CALLBACK (value_changed), sb);
+  g_timeout_add (500, conceil_scrollbar, sb);
+
+#if 1
+  sb = gtk_scrollbar_new (GTK_ORIENTATION_VERTICAL, adj);
+  gtk_container_add (GTK_CONTAINER (box), sb);
+#endif
+
+  gtk_widget_show_all (window);
+
+  gtk_main ();
+
+  return 0;
+}