Add event handling test and demo program

This is intended to be used as
  (a) an example of event handling and
  (b) a test program to visualize many event related variables

This first version is compatible with FLTK 1.3.x but lacks the screen
scaling factor under 1.3.x (which is always assumed to be 100%).

Note: this does not reflect any system or monitor related settings.

1 files changed, 120 insertions, 0 deletions

diff --git a/test/handle_events.cxx b/test/handle_events.cxx
new file mode 100644
index 000000000..be7a1a6e8
--- /dev/null
+++ b/test/handle_events.cxx
@@ -0,0 +1,120 @@
+//
+// Event test program for the Fast Light Tool Kit (FLTK).
+//
+// Copyright 1998-2021 by Bill Spitzak and others.
+//
+// This library is free software. Distribution and use rights are outlined in
+// the file "COPYING" which should have been included with this file.  If this
+// file is missing or damaged, see the license at:
+//
+//     https://www.fltk.org/COPYING.php
+//
+// Please see the following page on how to report bugs and issues:
+//
+//     https://www.fltk.org/bugs.php
+//
+// compile as: fltk-config --compile handle_events.cxx
+
+#include <FL/Fl.H>
+#include <FL/Fl_Double_Window.H>
+#include <FL/Fl_Gl_Window.H>
+#include <FL/Fl_Button.H>
+#include <FL/names.h>
+#include <stdio.h>
+
+// define WINDOW_TYPE as either "Fl_Gl_Window" or "Fl_Double_Window"
+#define WINDOW_TYPE Fl_Double_Window
+
+// Class to handle events
+class app : public WINDOW_TYPE {
+protected:
+  int handle(int);
+public:
+  // storage for the last event
+  int eventnum, ex, ey;
+  const char *eventname;
+  app(int X, int Y, int W, int H, const char *L = 0)
+    : WINDOW_TYPE(X, Y, W, H, L) {
+    eventname = NULL;
+    eventnum = 0;
+  }
+  // evaluates and prints the current event
+  void print_event(int ev) {
+    eventnum++;
+    ex = Fl::event_x();
+    ey = Fl::event_y();
+    int screen_num = Fl::screen_num(x(), y(), w(), h());
+#if defined(FL_API_VERSION) && FL_API_VERSION >= 10400
+    int scale = int(Fl::screen_scale(screen_num) * 100. + 0.5);
+#else
+    int scale = 100;
+#endif
+    eventname = fl_eventnames[ev];
+    fprintf(stderr,
+            "[%3d, win(%d,%d,%d,%d), screen %d, scale %3d%%] %-18.18s at (%4d, %4d)",
+            eventnum, x(), y(), w(), h(), screen_num, scale, eventname, ex, ey);
+    eventnum %= 999;
+  }
+};
+
+// Event handling
+int app::handle(int ev) {
+  print_event(ev); // common for all events
+  int res = WINDOW_TYPE::handle(ev);
+  switch (ev) {
+    case FL_PUSH:
+      printf(", button %d down", Fl::event_button());
+      res = 1;
+      break;
+    case FL_RELEASE:
+      printf(", button %d up", Fl::event_button());
+      res = 1;
+      break;
+    case FL_MOUSEWHEEL:
+      printf(", dx = %d, dy = %d", Fl::event_dx(), Fl::event_dy());
+      res = 1;
+      break;
+    case FL_ENTER:
+    case FL_LEAVE:
+    case FL_MOVE:
+    case FL_DRAG:
+      res = 1;
+      break;
+    case FL_KEYBOARD:
+      if (Fl::event_text()[0] >= 'a' && Fl::event_text()[0] <= 'z') {
+        printf(", Text = '%s'", Fl::event_text());
+        res = 1;
+      } else { // "ignore" everything else
+        printf(", ignored '%s'", Fl::event_text());
+      }
+      break;
+    case FL_KEYUP:
+      res = 1;
+      break;
+    case FL_FOCUS:
+    case FL_UNFOCUS:
+      res = 1;
+      break;
+    default:
+      break;
+  }
+  printf("\n"); fflush(stdout);
+  return res;
+} /* end of handle() method */
+
+// Quit button callback (closes the window)
+void quit_cb(Fl_Button *b, void *) {
+  b->window()->hide();
+}
+
+// main program
+int main(int argc, char **argv) {
+  app *win = new app(10, 10, 240, 240);
+  Fl_Button *quit = new Fl_Button(90, 100, 60, 40, "Quit");
+  quit->box(FL_THIN_UP_BOX);
+  quit->callback((Fl_Callback *)quit_cb);
+  win->end();
+  win->resizable(win);
+  win->show(argc, argv);
+  return Fl::run();
+}