Add pen/stylus/tablet API and driver for macOS (#1326)

* define the pen/tablet support API
* add pen event handler stub as a fallback
* add pen device test "penpal".
* Add macOS pen/stylus/tablet driver.
* Add Oxygen documentation.

1 files changed, 13 insertions, 2 deletions

diff --git a/FL/Fl_Widget_Tracker.H b/FL/Fl_Widget_Tracker.H
index d0aad86c0..fb2182e5f 100644
--- a/FL/Fl_Widget_Tracker.H
+++ b/FL/Fl_Widget_Tracker.H
@@ -76,9 +76,20 @@ class FL_EXPORT Fl_Widget_Tracker {
 public:
 
   Fl_Widget_Tracker(Fl_Widget *wi);
+  // Rule of five. Note that we *can* implement these when we refactor widget
+  // tracking with a C++11 map or unordered_map, for example.
+  Fl_Widget_Tracker(const Fl_Widget_Tracker&) = delete;
+  Fl_Widget_Tracker(Fl_Widget_Tracker&&) = delete;
+  Fl_Widget_Tracker& operator=(const Fl_Widget_Tracker&) = delete;
+  Fl_Widget_Tracker& operator=(Fl_Widget_Tracker&&) = delete;
   ~Fl_Widget_Tracker();
 
   /**
+   Clear the widget pointer.
+   */
+  void clear() { wp_ = nullptr; }
+
+  /**
     Returns a pointer to the watched widget.
     \return nullptr if the widget was deleted.
   */
@@ -88,13 +99,13 @@ public:
     Check if the widget was deleted since the tracker was created.
     \return 1 if the watched widget has been deleted, otherwise 0
   */
-  int deleted() {return wp_ == 0;}
+  int deleted() {return wp_ == nullptr;}
 
   /**
     Check if the widget exists and was not deleted since the tracker was created.
     \return 1 if the watched widget exists, otherwise 0
   */
-  int exists() { return wp_ != 0; }
+  int exists() { return wp_ != nullptr; }
 
 };