When fitBounds() is called with nonzero bearing, rotate padding

src/ui/camera.js

@@ -480,6 +480,7 @@ class Camera extends Evented {
      *      in the viewport. LngLatBounds represent a box that is always axis-aligned with bearing 0.
      * @param options Options object
      * @param {number | PaddingOptions} [options.padding] The amount of padding in pixels to add to the given bounds.
+     * @param {number} [options.bearing=0] Desired map bearing at end of animation, in degrees.
      * @param {PointLike} [options.offset=[0, 0]] The center of the given bounds relative to the map's center, measured in pixels.
      * @param {number} [options.maxZoom] The maximum zoom level to allow when the camera would transition to the specified bounds.
      * @returns {CameraOptions | void} If map is able to fit to provided bounds, returns `CameraOptions` with
@@ -492,7 +493,8 @@ class Camera extends Evented {
      */
     cameraForBounds(bounds: LngLatBoundsLike, options?: CameraOptions): void | CameraOptions & AnimationOptions {
         bounds = LngLatBounds.convert(bounds);
-        return this._cameraForBoxAndBearing(bounds.getNorthWest(), bounds.getSouthEast(), 0, options);
+        const bearing = options && options.bearing || 0;
+        return this._cameraForBoxAndBearing(bounds.getNorthWest(), bounds.getSouthEast(), bearing, options);
     }
 
     /**
@@ -570,10 +572,12 @@ class Camera extends Evented {
         const zoom = Math.min(tr.scaleZoom(tr.scale * Math.min(scaleX, scaleY)), options.maxZoom);
 
         // Calculate center: apply the zoom, the configured offset, as well as offset that exists as a result of padding.
-        const offset = Point.convert(options.offset);
+        const offset = (typeof options.offset.x === 'number') ? new Point(options.offset.x, options.offset.y) : Point.convert(options.offset);
         const paddingOffsetX = (options.padding.left - options.padding.right) / 2;
         const paddingOffsetY = (options.padding.top - options.padding.bottom) / 2;
-        const offsetAtInitialZoom = new Point(offset.x + paddingOffsetX, offset.y + paddingOffsetY);
+        const paddingOffset = new Point(paddingOffsetX, paddingOffsetY);
+        const rotatedPaddingOffset = paddingOffset.rotate(bearing * Math.PI / 180);
+        const offsetAtInitialZoom = offset.add(rotatedPaddingOffset);
         const offsetAtFinalZoom = offsetAtInitialZoom.mult(tr.scale / tr.zoomScale(zoom));
 
         const center =  tr.unproject(p0world.add(p1world).div(2).sub(offsetAtFinalZoom));

test/unit/ui/camera.test.js

@@ -1797,7 +1797,7 @@ test('camera', (t) => {
     });
 
     t.test('#cameraForBounds', (t) => {
-        t.test('no padding passed', (t) => {
+        t.test('no options passed', (t) => {
             const camera = createCamera();
             const bb = [[-133, 16], [-68, 50]];
 
@@ -1807,6 +1807,28 @@ test('camera', (t) => {
             t.end();
         });
 
+        t.test('bearing positive number', (t) => {
+            const camera = createCamera();
+            const bb = [[-133, 16], [-68, 50]];
+
+            const transform = camera.cameraForBounds(bb, {bearing: 175});
+            t.deepEqual(fixedLngLat(transform.center, 4), {lng: -100.5, lat: 34.7171}, 'correctly calculates coordinates for new bounds');
+            t.equal(fixedNum(transform.zoom, 3), 2.558);
+            t.equal(transform.bearing, 175);
+            t.end();
+        });
+
+        t.test('bearing negative number', (t) => {
+            const camera = createCamera();
+            const bb = [[-133, 16], [-68, 50]];
+
+            const transform = camera.cameraForBounds(bb, {bearing: -30});
+            t.deepEqual(fixedLngLat(transform.center, 4), {lng: -100.5, lat: 34.7171}, 'correctly calculates coordinates for new bounds');
+            t.equal(fixedNum(transform.zoom, 3), 2.392);
+            t.equal(transform.bearing, -30);
+            t.end();
+        });
+
         t.test('padding number', (t) => {
             const camera = createCamera();
             const bb = [[-133, 16], [-68, 50]];
@@ -1826,7 +1848,7 @@ test('camera', (t) => {
             t.end();
         });
 
-        t.test('asymetrical padding', (t) => {
+        t.test('asymmetrical padding', (t) => {
             const camera = createCamera();
             const bb = [[-133, 16], [-68, 50]];
 
@@ -1835,6 +1857,15 @@ test('camera', (t) => {
             t.end();
         });
 
+        t.test('bearing and asymmetrical padding', (t) => {
+            const camera = createCamera();
+            const bb = [[-133, 16], [-68, 50]];
+
+            const transform = camera.cameraForBounds(bb, {bearing: 90, padding: {top: 10, right: 75, bottom: 50, left: 25}, duration: 0});
+            t.deepEqual(fixedLngLat(transform.center, 4), {lng: -103.3761, lat: 31.7099}, 'correctly calculates coordinates for bounds with bearing and padding option as object applied');
+            t.end();
+        });
+
         t.test('offset', (t) => {
             const camera = createCamera();
             const bb = [[-133, 16], [-68, 50]];
@@ -1862,6 +1893,15 @@ test('camera', (t) => {
             t.end();
         });
 
+        t.test('bearing, asymmetrical padding, and offset', (t) => {
+            const camera = createCamera();
+            const bb = [[-133, 16], [-68, 50]];
+
+            const transform = camera.cameraForBounds(bb, {bearing: 90, padding: {top: 10, right: 75, bottom: 50, left: 25}, offset: [0, 100], duration: 0});
+            t.deepEqual(fixedLngLat(transform.center, 4), {lng: -103.3761, lat: 43.0929}, 'correctly calculates coordinates for bounds with bearing, padding option as object, and offset applied');
+            t.end();
+        });
+
         t.end();
     });