Bearing Dial - msupino/NavigationApp GitHub Wiki

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Bearing dial (map rotation)

The bearing dial rotates the map, so you can fly track-up instead of north-up.

Where it is

Bottom-right of the map, above the zoom buttons. The red needle is a north arrow: it points where north is on the turned chart. The number field beside it shows the map's rotation, true: north up is 0, in flight too. Only while heading-up turns the chart with a live position (location, recording, simulator) does it show the heading at the top of the screen, magnetic like the strip. A value typed into it is read the way the number was shown. Dragging the dial moves the needle with your finger — north goes where you drop it.

Using it

Action Result
Drag the dial Rotate continuously to any bearing
Click the dial Step 90° per click: 0° → 90° → 180° → 270° → 0°, always true: 0 is the chart square with real north up, in flight too. From an off-axis angle the first click goes to 0. A click ends heading-up.
Type in the heading field Jump straight to that bearing
Two-finger twist Rotate on a touch screen — off by default, enable with the touchRotateGesture tuning key

From the keyboard

The dial takes focus (Tab to it) and behaves as a slider:

Key Result
↑ / → Turn 1°
↓ / ← Turn 1° the other way
Page Up / Page Down Turn 10°
Home North up
Space / Enter Step 90°, the same as a tap

Heading is a circle: one degree below north is 359°, not a floor to stop at. A key the dial acts on does not also reach the map, so an arrow turns the map without panning it.

A drag has to travel past a small threshold (rotDragPx, 8 px by default) before it counts as a rotation, so a slightly imprecise tap still reads as a click.

Why rotate

  • Track up — turn your course to point up the screen, the way a moving-map GPS shows it.
  • North up — the default (0°).
  • Anything between — align the map with a coastline or a road you are following.

What rotation affects

  • The map, the route overlay, and every marker rotate together.
  • PNG and print export match the screen, bearing included — tiles are fetched north-up and re-composited with the rotation applied, so what you print is what you saw.
  • The wind field overlay hides itself while the map is rotated and shows a north-up note; it returns at 0°.
  • The bearing persists across reloads (navaid.bearing).

See also