Handle window and container resize events

Resizes metrics graph on window and sidebard width changes

3 files changed, 65 insertions, 24 deletions

diff --git a/app/assets/javascripts/lib/utils/common_utils.js b/app/assets/javascripts/lib/utils/common_utils.js
index ae8b4b4d635..0ceff10a02a 100644
--- a/app/assets/javascripts/lib/utils/common_utils.js
+++ b/app/assets/javascripts/lib/utils/common_utils.js
@@ -221,6 +221,22 @@ 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`
   otherwise it will return the value of the param key provided
diff --git a/app/assets/javascripts/monitoring/components/charts/area.vue b/app/assets/javascripts/monitoring/components/charts/area.vue
index 5ca561259b6..91004ca54a9 100644
--- a/app/assets/javascripts/monitoring/components/charts/area.vue
+++ b/app/assets/javascripts/monitoring/components/charts/area.vue
@@ -1,6 +1,9 @@
 <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>
diff --git a/app/assets/javascripts/monitoring/components/dashboard.vue b/app/assets/javascripts/monitoring/components/dashboard.vue
index 0b4bb9cc686..76059cb602d 100644
--- a/app/assets/javascripts/monitoring/components/dashboard.vue
+++ b/app/assets/javascripts/monitoring/components/dashboard.vue
@@ -1,5 +1,4 @@
 <script>
-import _ from 'underscore';
 import { s__ } from '~/locale';
 import Icon from '~/vue_shared/components/icon.vue';
 import Flash from '../../flash';
@@ -9,6 +8,9 @@ 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,
@@ -89,39 +91,29 @@ 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);
     if (!this.hasMetrics) {
       this.state = 'gettingStarted';
     } else {
       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: {
@@ -149,20 +141,21 @@ 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 class="environments d-flex align-items-center">
       {{ s__('Metrics|Environment') }}
       <div class="dropdown prepend-left-10">
@@ -198,6 +191,7 @@ export default {
         :key="graphIndex"
         :graph-data="graphData"
         :alert-data="getGraphAlerts(graphData.id)"
+        :container-width="elWidth"
         group-id="monitor-area-chart"
       />
     </graph-group>