Handle scrollwheel event. For wheel up, event.delta = 120*n on Windows, -1*n on darwin, where n can be > 1 if one scrolls fast. Flicking the wheel generates up to maybe 20 events with n up to 10 or more 1. Macs use wheel down (delta = 1*n) to scroll up, so positive delta means
(event, widget=None)
| 57 | root.images = images |
| 58 | |
| 59 | def wheel_event(event, widget=None): |
| 60 | """Handle scrollwheel event. |
| 61 | |
| 62 | For wheel up, event.delta = 120*n on Windows, -1*n on darwin, |
| 63 | where n can be > 1 if one scrolls fast. Flicking the wheel |
| 64 | generates up to maybe 20 events with n up to 10 or more 1. |
| 65 | Macs use wheel down (delta = 1*n) to scroll up, so positive |
| 66 | delta means to scroll up on both systems. |
| 67 | |
| 68 | X-11 sends Control-Button-4,5 events instead. |
| 69 | |
| 70 | The widget parameter is needed so browser label bindings can pass |
| 71 | the underlying canvas. |
| 72 | |
| 73 | This function depends on widget.yview to not be overridden by |
| 74 | a subclass. |
| 75 | """ |
| 76 | up = {EventType.MouseWheel: event.delta > 0, |
| 77 | EventType.ButtonPress: event.num == 4} |
| 78 | lines = -5 if up[event.type] else 5 |
| 79 | widget = event.widget if widget is None else widget |
| 80 | widget.yview(SCROLL, lines, 'units') |
| 81 | return 'break' |
| 82 | |
| 83 | |
| 84 | class TreeNode: |