limit number of items in plot history

Author: pfitzseb

lib/plots/pane.js

@@ -7,6 +7,7 @@ import PaneItem from '../util/pane-item'
 import { toView, Toolbar, Button, Icon, BackgroundMessage } from '../util/etch'
 
 let defaultPane
+const MAX_SIZE = 50
 
 export default class PlotPane extends PaneItem {
   static activate() {
@@ -119,6 +120,7 @@ export default class PlotPane extends PaneItem {
     if (view) {
       this.ids.push(this.counter += 1)
       this.items.push(view)
+      this.prune()
       this.activateItem(this.items.length - 1)
     }
     etch.update(this, false)
@@ -137,6 +139,21 @@ export default class PlotPane extends PaneItem {
     }
   }
 
+  prune () {
+    const numItems = this.items.length
+    if (numItems <= MAX_SIZE) return
+
+    const startInd = numItems - MAX_SIZE
+    this.items.forEach((item, ind) => {
+      if (ind < startInd && item.teardown) {
+        item.teardown()
+      }
+    })
+
+    this.ids = this.ids.slice(startInd, numItems)
+    this.items = this.items.slice(startInd, numItems)
+  }
+
   clearAll () {
     this.items.forEach(item => item.teardown && item.teardown())
     this.ids = []