1 files changed, 33 insertions, 0 deletions
diff --git a/src/modules/pan-zoom.js b/src/modules/pan-zoom.js
new file mode 100644
index 0000000..86f6727
--- /dev/null
+++ b/src/modules/pan-zoom.js
@@ -0,0 +1,33 @@
+import { pan, zoom } from 'pan-zoom';
+
+const storageKey = 'pan-zoom',
+  zoomFactor = 0.25;
+
+function restorePanZoomVal(svg) {
+  const storedPanZoomVal = localStorage.getItem(storageKey);
+
+  if (storedPanZoomVal) {
+    svg.style.transform = storedPanZoomVal;
+  }
+}
+
+function addEventListeners(svg) {
+  svg.addEventListener('wheel', e => zoom(svg, e, zoomFactor), { passive: false });
+  svg.addEventListener('pointerdown', e => pan(svg, e), { passive: false });
+}
+
+function storePanZoomVal(transformMatrix) {
+  localStorage.setItem(storageKey, transformMatrix);
+}
+
+function observePanZoomChanges(svg) {
+  const observer = new MutationObserver(() => storePanZoomVal(svg.style.transform));
+
+  observer.observe(svg, { attributeFilter: ['style'] });
+}
+
+export function start(svg) {
+  restorePanZoomVal(svg);
+  addEventListeners(svg);
+  observePanZoomChanges(svg);
+}