Fix for older versions of curses

Author: peterbrittain

asciimatics/event.py

@@ -46,6 +46,7 @@ class MouseEvent(Event):
     LEFT_CLICK = 1
     RIGHT_CLICK = 2
     DOUBLE_CLICK = 4
+    # Note: older versions of curses (e.g. in pypy) do not support up/down
     SCROLL_UP = 8
     SCROLL_DOWN = 16
 

asciimatics/screen.py

@@ -2599,10 +2599,11 @@ def get_event(self) -> Optional[Event]:
                         buttons |= MouseEvent.LEFT_CLICK
                     if (bstate & curses.BUTTON3_PRESSED != 0 or bstate & curses.BUTTON3_CLICKED != 0):
                         buttons |= MouseEvent.RIGHT_CLICK
-                    if (bstate & curses.BUTTON4_PRESSED != 0 or bstate & curses.BUTTON4_CLICKED != 0):
-                        buttons |= MouseEvent.SCROLL_UP
-                    if (bstate & curses.BUTTON5_PRESSED != 0 or bstate & curses.BUTTON5_CLICKED != 0):
-                        buttons |= MouseEvent.SCROLL_DOWN
+                    if hasattr(curses, "BUTTON5_PRESSED"):
+                        if (bstate & curses.BUTTON4_PRESSED != 0 or bstate & curses.BUTTON4_CLICKED != 0):
+                            buttons |= MouseEvent.SCROLL_UP
+                        if (bstate & curses.BUTTON5_PRESSED != 0 or bstate & curses.BUTTON5_CLICKED != 0):
+                            buttons |= MouseEvent.SCROLL_DOWN
                     if bstate & curses.BUTTON1_DOUBLE_CLICKED != 0:
                         buttons |= MouseEvent.DOUBLE_CLICK
                     return MouseEvent(x, y, buttons)

tests/test_screen.py

@@ -711,10 +711,11 @@ def _inject_mouse(screen, x, y, button):
                 bstate |= curses.BUTTON3_CLICKED
             if button & MouseEvent.DOUBLE_CLICK != 0:
                 bstate |= curses.BUTTON1_DOUBLE_CLICKED
-            if button & MouseEvent.SCROLL_UP != 0:
-                bstate |= curses.BUTTON4_CLICKED
-            if button & MouseEvent.SCROLL_DOWN != 0:
-                bstate |= curses.BUTTON5_CLICKED
+            if hasattr(curses, "BUTTON5_PRESSED"):
+                if button & MouseEvent.SCROLL_UP != 0:
+                    bstate |= curses.BUTTON4_CLICKED
+                if button & MouseEvent.SCROLL_DOWN != 0:
+                    bstate |= curses.BUTTON5_CLICKED
             curses.ungetmouse(0, x, y, 0, bstate)
 
     def test_key_input(self):
@@ -791,21 +792,23 @@ def internal_checks(screen):
             self.assertEqual(ev.buttons, MouseEvent.DOUBLE_CLICK)
             self.assertIsNone(screen.get_event())
 
-            # Check scroll up
-            self._inject_mouse(screen, 1, 1, MouseEvent.SCROLL_UP)
-            ev = screen.get_event()
-            self.assertEqual(ev.x, 1)
-            self.assertEqual(ev.y, 1)
-            self.assertEqual(ev.buttons, MouseEvent.SCROLL_UP)
-            self.assertIsNone(screen.get_event())
+            # Not all curses versions support scrolling...
+            if hasattr(curses, "BUTTON5_PRESSED"):
+                # Check scroll up
+                self._inject_mouse(screen, 1, 1, MouseEvent.SCROLL_UP)
+                ev = screen.get_event()
+                self.assertEqual(ev.x, 1)
+                self.assertEqual(ev.y, 1)
+                self.assertEqual(ev.buttons, MouseEvent.SCROLL_UP)
+                self.assertIsNone(screen.get_event())
 
-            # Check scroll up
-            self._inject_mouse(screen, 1, 1, MouseEvent.SCROLL_DOWN)
-            ev = screen.get_event()
-            self.assertEqual(ev.x, 1)
-            self.assertEqual(ev.y, 1)
-            self.assertEqual(ev.buttons, MouseEvent.SCROLL_DOWN)
-            self.assertIsNone(screen.get_event())
+                # Check scroll up
+                self._inject_mouse(screen, 1, 1, MouseEvent.SCROLL_DOWN)
+                ev = screen.get_event()
+                self.assertEqual(ev.x, 1)
+                self.assertEqual(ev.y, 1)
+                self.assertEqual(ev.buttons, MouseEvent.SCROLL_DOWN)
+                self.assertIsNone(screen.get_event())
 
         Screen.wrapper(internal_checks, height=15)