Handle window and container resize events

Resizes metrics graph on window and sidebard width changes

app/assets/javascripts/lib/utils/common_utils.js

@@ -220,6 +220,22 @@ export const scrollToElement = element => {
   );
 };
 
+/**
+ * Returns a function that can only be invoked once between
+ * each browser screen repaint.
+ * @param {Function} fn
+ */
+export const debounceByAnimationFrame = fn => {
+  let requestId;
+
+  return function debounced(...args) {
+    if (requestId) {
+      window.cancelAnimationFrame(requestId);
+    }
+    requestId = window.requestAnimationFrame(() => fn.apply(this, args));
+  };
+};
+
 /**
   this will take in the `name` of the param you want to parse in the url
   if the name does not exist this function will return `null`

app/assets/javascripts/monitoring/components/charts/area.vue

 <script>
 import { GlAreaChart } from '@gitlab/ui';
 import dateFormat from 'dateformat';
+import { debounceByAnimationFrame } from '~/lib/utils/common_utils';
+
+let debouncedResize;
 
 export default {
   components: {
@@ -26,12 +29,22 @@ export default {
         );
       },
     },
+    containerWidth: {
+      type: Number,
+      required: true,
+    },
     alertData: {
       type: Object,
       required: false,
       default: () => ({}),
     },
   },
+  data() {
+    return {
+      width: 0,
+      height: 0,
+    };
+  },
   computed: {
     chartData() {
       return this.graphData.queries.reduce((accumulator, query) => {
@@ -76,11 +89,26 @@ export default {
       return `${this.graphData.y_label} (${query.unit})`;
     },
   },
+  watch: {
+    containerWidth: 'onResize',
+  },
+  beforeDestroy() {
+    window.removeEventListener('resize', debouncedResize);
+  },
+  created() {
+    debouncedResize = debounceByAnimationFrame(this.onResize);
+    window.addEventListener('resize', debouncedResize);
+  },
   methods: {
     formatTooltipText(params) {
       const [date, value] = params;
       return [dateFormat(date, 'dd mmm yyyy, h:MMtt'), value.toFixed(3)];
     },
+    onResize() {
+      const { width, height } = this.$refs.areaChart.$el.getBoundingClientRect();
+      this.width = width;
+      this.height = height;
+    },
   },
 };
 </script>
@@ -92,11 +120,14 @@ export default {
       <div class="prometheus-graph-widgets"><slot></slot></div>
     </div>
     <gl-area-chart
+      ref="areaChart"
       v-bind="$attrs"
       :data="chartData"
       :option="chartOptions"
       :format-tooltip-text="formatTooltipText"
       :thresholds="alertData"
+      :width="width"
+      :height="height"
     />
   </div>
 </template>

app/assets/javascripts/monitoring/components/dashboard.vue

@@ -2,7 +2,6 @@
 // ee-only
 import DashboardMixin from 'ee/monitoring/components/dashboard_mixin';
 
-import _ from 'underscore';
 import { s__ } from '~/locale';
 import Icon from '~/vue_shared/components/icon.vue';
 import Flash from '../../flash';
@@ -12,6 +11,9 @@ import GraphGroup from './graph_group.vue';
 import EmptyState from './empty_state.vue';
 import MonitoringStore from '../stores/monitoring_store';
 
+const sidebarAnimationDuration = 150;
+let sidebarMutationObserver;
+
 export default {
   components: {
     MonitorAreaChart,
@@ -101,29 +103,19 @@ export default {
       elWidth: 0,
     };
   },
-  computed: {
-    forceRedraw() {
-      return this.elWidth;
-    },
-  },
   created() {
     this.service = new MonitoringService({
       metricsEndpoint: this.metricsEndpoint,
       deploymentEndpoint: this.deploymentEndpoint,
       environmentsEndpoint: this.environmentsEndpoint,
     });
-    this.mutationObserverConfig = {
-      attributes: true,
-      childList: false,
-      subtree: false,
-    };
   },
   beforeDestroy() {
-    window.removeEventListener('resize', this.resizeThrottled, false);
-    this.sidebarMutationObserver.disconnect();
+    if (sidebarMutationObserver) {
+      sidebarMutationObserver.disconnect();
+    }
   },
   mounted() {
-    this.resizeThrottled = _.debounce(this.resize, 100);
     this.servicePromises = [
       this.service
         .getGraphsData()
@@ -148,12 +140,12 @@ export default {
         );
       }
       this.getGraphsData();
-      window.addEventListener('resize', this.resizeThrottled, false);
-
-      const sidebarEl = document.querySelector('.nav-sidebar');
-      // The sidebar listener
-      this.sidebarMutationObserver = new MutationObserver(this.resizeThrottled);
-      this.sidebarMutationObserver.observe(sidebarEl, this.mutationObserverConfig);
+      sidebarMutationObserver = new MutationObserver(this.onSidebarMutation);
+      sidebarMutationObserver.observe(document.querySelector('.layout-page'), {
+        attributes: true,
+        childList: false,
+        subtree: false,
+      });
     }
   },
   methods: {
@@ -171,20 +163,21 @@ export default {
 
           this.showEmptyState = false;
         })
-        .then(this.resize)
         .catch(() => {
           this.state = 'unableToConnect';
         });
     },
-    resize() {
-      this.elWidth = this.$el.clientWidth;
+    onSidebarMutation() {
+      setTimeout(() => {
+        this.elWidth = this.$el.clientWidth;
+      }, sidebarAnimationDuration);
     },
   },
 };
 </script>
 
 <template>
-  <div v-if="!showEmptyState" :key="forceRedraw" class="prometheus-graphs prepend-top-default">
+  <div v-if="!showEmptyState" class="prometheus-graphs prepend-top-default">
     <div v-if="showEnvironmentDropdown" class="environments d-flex align-items-center">
       {{ s__('Metrics|Environment') }}
       <div class="dropdown prepend-left-10">
@@ -220,6 +213,7 @@ export default {
         :key="graphIndex"
         :graph-data="graphData"
         :alert-data="getGraphAlerts(graphData.id)"
+        :container-width="elWidth"
         group-id="monitor-area-chart"
       >
         <!-- EE content -->

spec/javascripts/lib/utils/common_utils_spec.js

@@ -232,6 +232,21 @@ describe('common_utils', () => {
     });
   });
 
+  describe('debounceByAnimationFrame', () => {
+    it('debounces a function to allow a maximum of one call per animation frame', done => {
+      const spy = jasmine.createSpy('spy');
+      const debouncedSpy = commonUtils.debounceByAnimationFrame(spy);
+      window.requestAnimationFrame(() => {
+        debouncedSpy();
+        debouncedSpy();
+        window.requestAnimationFrame(() => {
+          expect(spy).toHaveBeenCalledTimes(1);
+          done();
+        });
+      });
+    });
+  });
+
   describe('getParameterByName', () => {
     beforeEach(() => {
       window.history.pushState({}, null, '?scope=all&p=2');

spec/javascripts/monitoring/dashboard_spec.js

@@ -29,7 +29,7 @@ describe('Dashboard', () => {
   beforeEach(() => {
     setFixtures(`
       <div class="prometheus-graphs"></div>
-      <div class="nav-sidebar"></div>
+      <div class="layout-page"></div>
     `);
     DashboardComponent = Vue.extend(Dashboard);
   });
@@ -183,16 +183,16 @@ describe('Dashboard', () => {
       jasmine.clock().uninstall();
     });
 
-    it('rerenders the dashboard when the sidebar is resized', done => {
+    it('sets elWidth to page width when the sidebar is resized', done => {
       const component = new DashboardComponent({
         el: document.querySelector('.prometheus-graphs'),
         propsData: { ...propsData, hasMetrics: true, showPanels: false },
       });
 
-      expect(component.forceRedraw).toEqual(0);
+      expect(component.elWidth).toEqual(0);
 
-      const navSidebarEl = document.querySelector('.nav-sidebar');
-      navSidebarEl.classList.add('nav-sidebar-collapsed');
+      const pageLayoutEl = document.querySelector('.layout-page');
+      pageLayoutEl.classList.add('page-with-icon-sidebar');
 
       Vue.nextTick()
         .then(() => {
@@ -200,7 +200,7 @@ describe('Dashboard', () => {
           return Vue.nextTick();
         })
         .then(() => {
-          expect(component.forceRedraw).toEqual(component.elWidth);
+          expect(component.elWidth).toEqual(pageLayoutEl.clientWidth);
           done();
         })
         .catch(done.fail);