allow parsing of projection definition object

src/expression/types/projection_definition.test.ts

@@ -36,4 +36,16 @@ describe('Projection class', () => {
         expect(projection.to).toBe('vertical-perspective');
         expect(projection.transition).toBe(0.5);
     });
+
+    test('should parse projection object', () => {
+        const projection = ProjectionDefinition.parse({from: 'mercator', to: 'vertical-perspective', transition: 0.5});
+        expect(projection.from).toBe('mercator');
+        expect(projection.to).toBe('vertical-perspective');
+        expect(projection.transition).toBe(0.5);
+    });
+
+    test('should serialize projection', () => {
+        const projection = ProjectionDefinition.parse(['mercator', 'vertical-perspective', 0.5]);
+        expect(JSON.stringify(projection)).toBe('{\"from\":\"mercator\",\"to\":\"vertical-perspective\",\"transition\":0.5}');
+    });
 });

src/expression/types/projection_definition.ts

@@ -20,6 +20,11 @@ export class ProjectionDefinition {
         if (Array.isArray(input) && input.length === 3 && typeof input[0] === 'string' && typeof input[1] === 'string' && typeof input[2] === 'number') {
             return new ProjectionDefinition(input[0], input[1], input[2]);
         }
+
+        if (typeof input === 'object' && typeof input.from === 'string' && typeof input.to === 'string' && typeof input.transition === 'number') {
+            return new ProjectionDefinition(input.from, input.to, input.transition);
+        }
+
         if (typeof input === 'string') {
             return new ProjectionDefinition(input, input, 1);
         }