[gtk+/wip/carlosg/stylus-gesture: 1/2] gtk: Add GtkGestureStylus

[Carlos Garnacho <carlosg src gnome org>]

commit 1e52541c22c91e0204cfeb7f1b2aa0a4fc2288d8
Author: Carlos Garnacho <carlosg gnome org>
Date:   Thu Feb 1 17:52:40 2018 +0100

    gtk: Add GtkGestureStylus
    
    This is a GtkGesture done to deal with stylus events from drawing tablets.
    Those have a special number of characteristics that extend a regular
    pointer, so it makes sense to wrap that.

 gtk/gtk.h                     |    1 +
 gtk/gtkgesturestylus.c        |  330 +++++++++++++++++++++++++++++++++++++++++
 gtk/gtkgesturestylus.h        |   63 ++++++++
 gtk/gtkgesturestylusprivate.h |   51 +++++++
 gtk/meson.build               |    2 +
 5 files changed, 447 insertions(+), 0 deletions(-)
---
diff --git a/gtk/gtk.h b/gtk/gtk.h
index acd5b76..0eef26d 100644
--- a/gtk/gtk.h
+++ b/gtk/gtk.h
@@ -116,6 +116,7 @@
 #include <gtk/gtkgesturepan.h>
 #include <gtk/gtkgesturerotate.h>
 #include <gtk/gtkgesturesingle.h>
+#include <gtk/gtkgesturestylus.h>
 #include <gtk/gtkgestureswipe.h>
 #include <gtk/gtkgesturezoom.h>
 #include <gtk/gtkglarea.h>
diff --git a/gtk/gtkgesturestylus.c b/gtk/gtkgesturestylus.c
new file mode 100644
index 0000000..e2ed86d
--- /dev/null
+++ b/gtk/gtkgesturestylus.c
@@ -0,0 +1,330 @@
+/* GTK - The GIMP Toolkit
+ * Copyright (C) 2017-2018, Red Hat, Inc.
+ *
+ * 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/>.
+ *
+ * Author(s): Carlos Garnacho <carlosg gnome org>
+ */
+
+/**
+ * SECTION:gtkgesturestylus
+ * @Short_description: Gesture for stylus input
+ * @Title: GtkGestureStylus
+ * @See_also: #GtkGesture, #GtkGestureSingle
+ *
+ * #GtkGestureStylus is a #GtkGesture implementation specific to stylus
+ * input. The provided signals just provide the basic information
+ */
+
+#include "config.h"
+#include "gtkgesturestylus.h"
+#include "gtkgesturestylusprivate.h"
+#include "gtkprivate.h"
+#include "gtkintl.h"
+
+G_DEFINE_TYPE (GtkGestureStylus, gtk_gesture_stylus, GTK_TYPE_GESTURE_SINGLE)
+
+enum {
+  PROXIMITY,
+  DOWN,
+  MOTION,
+  UP,
+  N_SIGNALS
+};
+
+static guint signals[N_SIGNALS] = { 0, };
+
+static gboolean
+gtk_gesture_stylus_handle_event (GtkEventController *controller,
+                                 const GdkEvent     *event)
+{
+  GdkModifierType modifiers;
+  guint n_signal;
+  gdouble x, y;
+
+  GTK_EVENT_CONTROLLER_CLASS (gtk_gesture_stylus_parent_class)->handle_event (controller, event);
+
+  if (!gdk_event_get_device_tool (event))
+    return FALSE;
+  if (!gdk_event_get_coords (event, &x, &y))
+    return FALSE;
+
+  switch ((guint) gdk_event_get_event_type (event))
+    {
+    case GDK_BUTTON_PRESS:
+      n_signal = DOWN;
+      break;
+    case GDK_BUTTON_RELEASE:
+      n_signal = UP;
+      break;
+    case GDK_MOTION_NOTIFY:
+      gdk_event_get_state (event, &modifiers);
+
+      if (modifiers & GDK_BUTTON1_MASK)
+        n_signal = MOTION;
+      else
+        n_signal = PROXIMITY;
+      break;
+    default:
+      return FALSE;
+    }
+
+  g_signal_emit (controller, signals[n_signal], 0, x, y);
+
+  return TRUE;
+}
+
+static void
+gtk_gesture_stylus_class_init (GtkGestureStylusClass *klass)
+{
+  GObjectClass *object_class;
+  GtkEventControllerClass *event_controller_class;
+
+  object_class = G_OBJECT_CLASS (klass);
+  event_controller_class = GTK_EVENT_CONTROLLER_CLASS (klass);
+
+  event_controller_class->handle_event = gtk_gesture_stylus_handle_event;
+
+  signals[PROXIMITY] =
+    g_signal_new (I_("proximity"),
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_LAST,
+                  G_STRUCT_OFFSET (GtkGestureStylusClass, proximity),
+                  NULL, NULL, NULL,
+                  G_TYPE_NONE, 2, G_TYPE_DOUBLE, G_TYPE_DOUBLE);
+  signals[DOWN] =
+    g_signal_new (I_("down"),
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_LAST,
+                  G_STRUCT_OFFSET (GtkGestureStylusClass, down),
+                  NULL, NULL, NULL,
+                  G_TYPE_NONE, 2, G_TYPE_DOUBLE, G_TYPE_DOUBLE);
+  signals[MOTION] =
+    g_signal_new (I_("motion"),
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_LAST,
+                  G_STRUCT_OFFSET (GtkGestureStylusClass, motion),
+                  NULL, NULL, NULL,
+                  G_TYPE_NONE, 2, G_TYPE_DOUBLE, G_TYPE_DOUBLE);
+  signals[UP] =
+    g_signal_new (I_("up"),
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_LAST,
+                  G_STRUCT_OFFSET (GtkGestureStylusClass, up),
+                  NULL, NULL, NULL,
+                  G_TYPE_NONE, 2, G_TYPE_DOUBLE, G_TYPE_DOUBLE);
+}
+
+static void
+gtk_gesture_stylus_init (GtkGestureStylus *gesture)
+{
+}
+
+/**
+ * gtk_gesture_stylus_new:
+ * @widget: a #GtkWidget
+ *
+ * Creates a new #GtkGestureStylus.
+ *
+ * Returns: a newly created stylus gesture
+ *
+ * Since: 3.94
+ **/
+GtkGesture *
+gtk_gesture_stylus_new (GtkWidget *widget)
+{
+  return g_object_new (GTK_TYPE_GESTURE_STYLUS,
+                       "widget", widget,
+                       NULL);
+}
+
+static const GdkEvent *
+gesture_get_current_event (GtkGestureStylus *gesture)
+{
+  GdkEventSequence *sequence;
+
+  sequence = gtk_gesture_single_get_current_sequence (GTK_GESTURE_SINGLE (gesture));
+
+  return gtk_gesture_get_last_event (GTK_GESTURE (gesture), sequence);
+}
+
+/**
+ * gtk_gesture_stylus_get_axis:
+ * @gesture: a #GtkGestureStylus
+ * @axis: requested device axis
+ * @value: (out): return location for the axis value
+ *
+ * Returns the current value for the requested @axis. This function
+ * must be called from either the #GtkGestureStylus:down,
+ * #GtkGestureStylus:motion, #GtkGestureStylus:up or #GtkGestureStylus:proximity
+ * signals.
+ *
+ * Returns: #TRUE if there is a current value for the axis
+ *
+ * Since: 3.94
+ **/
+gboolean
+gtk_gesture_stylus_get_axis (GtkGestureStylus *gesture,
+                            GdkAxisUse        axis,
+                            gdouble          *value)
+{
+  const GdkEvent *event;
+
+  g_return_val_if_fail (GTK_IS_GESTURE_STYLUS (gesture), FALSE);
+  g_return_val_if_fail (axis < GDK_AXIS_LAST, FALSE);
+  g_return_val_if_fail (value != NULL, FALSE);
+
+  event = gesture_get_current_event (gesture);
+  if (!event)
+    return FALSE;
+
+  return gdk_event_get_axis (event, axis, value);
+}
+
+/**
+ * gtk_gesture_stylus_get_axes:
+ * @gesture: a GtkGestureStylus
+ * @axes: array of requested axes, terminated with #GDK_AXIS_IGNORE
+ * @values: (out): return location for the axis values
+ *
+ * Returns the current values for the requested @axes. This function
+ * must be called from either the #GtkGestureStylus:down,
+ * #GtkGestureStylus:motion, #GtkGestureStylus:up or #GtkGestureStylus:proximity
+ * signals.
+ *
+ * Returns: #TRUE if there is a current value for the axes
+ **/
+gboolean
+gtk_gesture_stylus_get_axes (GtkGestureStylus  *gesture,
+                            GdkAxisUse         axes[],
+                            gdouble          **values)
+{
+  const GdkEvent *event;
+  GArray *array;
+  gint i;
+
+  g_return_val_if_fail (GTK_IS_GESTURE_STYLUS (gesture), FALSE);
+  g_return_val_if_fail (values != NULL, FALSE);
+
+  event = gesture_get_current_event (gesture);
+  if (!event)
+    return FALSE;
+
+  while (axes[i] != GDK_AXIS_IGNORE)
+    {
+      gdouble value;
+
+      if (axes[i] >= GDK_AXIS_LAST)
+        {
+          g_warning ("Requesting unknown axis %d, did you "
+                     "forget to add a last GDK_AXIS_IGNORE axis?",
+                     axes[i]);
+          g_array_free (array, TRUE);
+          return FALSE;
+        }
+
+      gdk_event_get_axis (event, axes[i], &value);
+      g_array_append_val (array, value);
+      i++;
+    }
+
+  *values = g_array_free (array, FALSE);
+  return TRUE;
+}
+
+/**
+ * gtk_gesture_stylus_get_backlog:
+ * @gesture: a #GtkGestureStylus
+ * @backlog: (out): coordinates and times for the backlog events
+ * @n_elems: (out): return location for the number of elements
+ *
+ * By default, GTK+ will limit rate of input events. On stylus input where
+ * accuracy of strokes is paramount, this function returns the accumulated
+ * coordinate/timing state before the emission of the current
+ * #GtkGestureStylus:motion signal.
+ *
+ * This function may only be called within a #GtkGestureStylus::motion
+ * signal handler, the state given in this signal and obtainable through
+ * gtk_gesture_stylus_get_axis() call express the latest (most up-to-date)
+ * state in motion history.
+ *
+ * @backlog is provided in chronological order.
+ *
+ * Returns: #TRUE if there is a backlog to unfold in the current state.
+ **/
+gboolean
+gtk_gesture_stylus_get_backlog (GtkGestureStylus  *gesture,
+                               GdkTimeCoord     **backlog,
+                               guint             *n_elems)
+{
+  GdkEvent *event;
+  GArray *backlog_array;
+  GList *history, *l;
+  gint i;
+
+  g_return_val_if_fail (GTK_IS_GESTURE_STYLUS (gesture), FALSE);
+  g_return_val_if_fail (backlog != NULL && n_elems != NULL, FALSE);
+
+  event = gesture_get_current_event (gesture);
+
+  if (event)
+    history = gdk_event_get_history (event);
+  if (!history)
+    return FALSE;
+
+  backlog_array = g_array_new (FALSE, FALSE, sizeof (GdkTimeCoord));
+  for (l = history; l; l = l->next)
+    {
+      GdkTimeCoord time_coord;
+      GdkEvent *ev = l->data;
+
+      time_coord.time = gdk_event_get_time (ev);
+
+      for (i = 0; i < GDK_AXIS_LAST; i++)
+        gdk_event_get_axis (event, i, &time_coord.axes[i]);
+
+      g_array_append_val (backlog_array, time_coord);
+    }
+
+  *n_elems = backlog_array->len;
+  *backlog = g_array_free (backlog_array, FALSE);
+  g_list_free (history);
+
+  return TRUE;
+}
+
+/**
+ * gdk_gesture_stylus_get_device_tool:
+ * @gesture: a #GtkGestureStylus
+ *
+ * Returns the #GdkDeviceTool currently driving input through this gesture.
+ * This function must be called from either the #GtkGestureStylus:down,
+ * #GtkGestureStylus:motion, #GtkGestureStylus:up or #GtkGestureStylus:proximity
+ * signals.
+ *
+ * Returns: (transfer none): The current stylus tool
+ **/
+GdkDeviceTool *
+gtk_gesture_stylus_get_device_tool (GtkGestureStylus *gesture)
+{
+  const GdkEvent *event;
+
+  g_return_val_if_fail (GTK_IS_GESTURE_STYLUS (gesture), FALSE);
+
+  event = gesture_get_current_event (gesture);
+  if (!event)
+    return NULL;
+
+  return gdk_event_get_device_tool (event);
+}
diff --git a/gtk/gtkgesturestylus.h b/gtk/gtkgesturestylus.h
new file mode 100644
index 0000000..11ed827
--- /dev/null
+++ b/gtk/gtkgesturestylus.h
@@ -0,0 +1,63 @@
+/* GTK - The GIMP Toolkit
+ * Copyright (C) 2017-2018, Red Hat, Inc.
+ *
+ * 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/>.
+ *
+ * Author(s): Carlos Garnacho <carlosg gnome org>
+ */
+#ifndef __GTK_GESTURE_STYLUS_H__
+#define __GTK_GESTURE_STYLUS_H__
+
+#include <gtk/gtkgesture.h>
+
+#if !defined (__GTK_H_INSIDE__) && !defined (GTK_COMPILATION)
+#error "Only <gtk/gtk.h> can be included directly."
+#endif
+
+G_BEGIN_DECLS
+
+#define GTK_TYPE_GESTURE_STYLUS         (gtk_gesture_stylus_get_type ())
+#define GTK_GESTURE_STYLUS(o)           (G_TYPE_CHECK_INSTANCE_CAST ((o), GTK_TYPE_GESTURE_STYLUS, 
GtkGestureStylus))
+#define GTK_GESTURE_STYLUS_CLASS(k)     (G_TYPE_CHECK_CLASS_CAST ((k), GTK_TYPE_GESTURE_STYLUS, 
GtkGestureStylusClass))
+#define GTK_IS_GESTURE_STYLUS(o)        (G_TYPE_CHECK_INSTANCE_TYPE ((o), GTK_TYPE_GESTURE_STYLUS))
+#define GTK_IS_GESTURE_STYLUS_CLASS(k)  (G_TYPE_CHECK_CLASS_TYPE ((k), GTK_TYPE_GESTURE_STYLUS))
+#define GTK_GESTURE_STYLUS_GET_CLASS(o) (G_TYPE_INSTANCE_GET_CLASS ((o), GTK_TYPE_GESTURE_STYLUS, 
GtkGestureStylusClass))
+
+typedef struct _GtkGestureStylus GtkGestureStylus;
+typedef struct _GtkGestureStylusClass GtkGestureStylusClass;
+
+GDK_AVAILABLE_IN_3_94
+GType             gtk_gesture_stylus_get_type (void) G_GNUC_CONST;
+
+GDK_AVAILABLE_IN_3_94
+GtkGesture *      gtk_gesture_stylus_new      (GtkWidget *widget);
+
+GDK_AVAILABLE_IN_3_94
+gboolean          gtk_gesture_stylus_get_axis (GtkGestureStylus *gesture,
+                                              GdkAxisUse        axis,
+                                              gdouble          *value);
+GDK_AVAILABLE_IN_3_94
+gboolean          gtk_gesture_stylus_get_axes (GtkGestureStylus  *gesture,
+                                              GdkAxisUse         axis[],
+                                              gdouble          **axes);
+GDK_AVAILABLE_IN_3_94
+gboolean          gtk_gesture_stylus_get_backlog (GtkGestureStylus  *gesture,
+                                                 GdkTimeCoord     **backlog,
+                                                 guint             *n_elems);
+GDK_AVAILABLE_IN_3_94
+GdkDeviceTool *   gtk_gesture_stylus_get_device_tool (GtkGestureStylus *gesture);
+
+G_END_DECLS
+
+#endif /* __GTK_GESTURE_STYLUS_H__ */
diff --git a/gtk/gtkgesturestylusprivate.h b/gtk/gtkgesturestylusprivate.h
new file mode 100644
index 0000000..9869b52
--- /dev/null
+++ b/gtk/gtkgesturestylusprivate.h
@@ -0,0 +1,51 @@
+/* GTK - The GIMP Toolkit
+ * Copyright (C) 2017-2018, Red Hat, Inc.
+ *
+ * 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/>.
+ *
+ * Author(s): Carlos Garnacho <carlosg gnome org>
+ */
+#ifndef __GTK_GESTURE_STYLUS_PRIVATE_H__
+#define __GTK_GESTURE_STYLUS_PRIVATE_H__
+
+#include "gtkgesturesingleprivate.h"
+#include "gtkgesturestylus.h"
+
+struct _GtkGestureStylus
+{
+  GtkGestureSingle parent_instance;
+};
+
+struct _GtkGestureStylusClass
+{
+  GtkGestureSingleClass parent_class;
+
+  void (*proximity) (GtkGestureStylus *gesture,
+                     gdouble           x,
+                     gdouble           y);
+  void (*down)      (GtkGestureStylus *gesture,
+                     gdouble           x,
+                     gdouble           y);
+  void (*motion)    (GtkGestureStylus *gesture,
+                     gdouble           x,
+                     gdouble           y);
+  void (*up)        (GtkGestureStylus *gesture,
+                     gdouble           x,
+                     gdouble           y);
+
+  /*< private >*/
+  gpointer padding[10];
+};
+
+#endif /* __GTK_GESTURE_STYLUS_PRIVATE_H__ */
diff --git a/gtk/meson.build b/gtk/meson.build
index ff6ebe7..c75964f 100644
--- a/gtk/meson.build
+++ b/gtk/meson.build
@@ -181,6 +181,7 @@ gtk_public_sources = files([
   'gtkgesturepan.c',
   'gtkgesturerotate.c',
   'gtkgesturesingle.c',
+  'gtkgesturestylus.c',
   'gtkgestureswipe.c',
   'gtkgesturezoom.c',
   'gtkgizmo.c',
@@ -463,6 +464,7 @@ gtk_public_headers = files([
   'gtkgesturepan.h',
   'gtkgesturerotate.h',
   'gtkgesturesingle.h',
+  'gtkgesturestylus.h',
   'gtkgestureswipe.h',
   'gtkgesturezoom.h',
   'gtkglarea.h',