feat(fitView): add padding option

src/GraphView/index.js

@@ -62,7 +62,7 @@ const GraphView = memo((props) => {
       props.onLoad({
         nodes: state.nodes,
         edges: state.edges,
-        fitView: () => dispatch(fitView()),
+        fitView: opts => dispatch(fitView(opts)),
         zoomIn: () => dispatch(zoomIn()),
         zoomOut: () => dispatch(zoomOut())
       });

src/state/actions.js

@@ -54,8 +54,8 @@ export const initD3 = ({ zoom, selection }) => {
   };
 };
 
-export const fitView = () => {
-  return { type: FIT_VIEW };
+export const fitView = ({ padding = 0 }) => {
+  return { type: FIT_VIEW, payload: { padding } };
 };
 
 export const zoomIn = () => {

src/state/index.js

@@ -69,7 +69,8 @@ export const reducer = (state, action) => {
     }
     case FIT_VIEW: {
       const bounds = getBoundingBox(state.nodes);
-      const k = Math.min(state.width, state.height) / Math.max(bounds.width, bounds.height);
+      const maxBoundsSize = Math.max(bounds.width, bounds.height);
+      const k = Math.min(state.width, state.height) / (maxBoundsSize + (maxBoundsSize * action.payload.padding));
       const boundsCenterX = bounds.x + (bounds.width / 2);
       const boundsCenterY = bounds.y + (bounds.height / 2);
       const transform = [(state.width / 2) - (boundsCenterX * k), (state.height / 2) - (boundsCenterY * k)];