refactor: Use ResizeObserver for responsive charts

draftlogs/8017_change.md

@@ -0,0 +1 @@
+Use `ResizeObserver` for responsive chart resizing instead of listening for window resize events [[#8017](https://github.com/plotly/plotly.js/pull/8017)], with thanks to @Lexachoc for the contribution!

src/lib/clear_responsive.js

@@ -6,8 +6,8 @@
  * @param {DOM node or object} gd : graph div object
  */
 module.exports = function clearResponsive(gd) {
-    if(gd._responsiveChartHandler) {
-        window.removeEventListener('resize', gd._responsiveChartHandler);
-        delete gd._responsiveChartHandler;
+    if (gd._clearResponsive) {
+        gd._clearResponsive();
+        delete gd._clearResponsive;
     }
 };

src/plot_api/plot_api.js

@@ -165,16 +165,34 @@ function _doPlot(gd, data, layout, config) {
         gd.calcdata[i][0].trace = gd._fullData[i];
     }
 
-    // make the figure responsive
+    // Make the figure responsive. We need to save the callback that clears the
+    // listener for proper teardown.
     if (gd._context.responsive) {
-        if (!gd._responsiveChartHandler) {
-            // Keep a reference to the resize handler to purge it down the road
-            gd._responsiveChartHandler = function () {
+        if (!gd._clearResponsive) {
+            const resizeIfShown = () => {
                 if (!Lib.isHidden(gd)) Plots.resize(gd);
             };
-
-            // Listen to window resize
-            window.addEventListener('resize', gd._responsiveChartHandler);
+            // We still need the window resize listener for `fillFrame` and an
+            // escape hatch for browser-like users that don't support `ResizeObserver` (like jsdom)
+            if (gd._context.fillFrame || typeof ResizeObserver === 'undefined') {
+                window.addEventListener('resize', resizeIfShown);
+                gd._clearResponsive = () => window.removeEventListener('resize', resizeIfShown);
+            } else {
+                let previousWidth = gd.offsetWidth;
+                let previousHeight = gd.offsetHeight;
+                const observer = new ResizeObserver(() => {
+                    const width = gd.offsetWidth;
+                    const height = gd.offsetHeight;
+                    // Ignore size changes of one pixel or less (the same as plotAutoSize)
+                    const changed = Math.abs(width - previousWidth) > 1 || Math.abs(height - previousHeight) > 1;
+                    previousWidth = width;
+                    previousHeight = height;
+                    // Only resize plot if it changed and is visible (width and height > 0)
+                    if (changed && width && height) resizeIfShown();
+                });
+                observer.observe(gd);
+                gd._clearResponsive = () => observer.disconnect();
+            }
         }
     } else {
         Lib.clearResponsive(gd);

src/plot_api/plot_config.js

@@ -128,8 +128,8 @@ var configAttributes = {
         valType: 'boolean',
         dflt: false,
         description: [
-            'Determines whether to change the layout size when window is resized.',
-            'In v3, this option will be removed and will always be true.'
+            'Determines whether to change the layout size when the graph container is resized.',
+            'In v5, this option will be removed and will always be true.'
         ].join(' ')
     },
     fillFrame: {

src/types/generated/schema.d.ts

@@ -16809,7 +16809,7 @@ export interface ConfigBase {
      */
     queueLength?: number;
     /**
-     * Determines whether to change the layout size when window is resized. In v3, this option will be removed and will always be true.
+     * Determines whether to change the layout size when the graph container is resized. In v5, this option will be removed and will always be true.
      * @default false
      */
     responsive?: boolean;

test/plot-schema.json

@@ -279,7 +279,7 @@
       "valType": "integer"
     },
     "responsive": {
-      "description": "Determines whether to change the layout size when window is resized. In v3, this option will be removed and will always be true.",
+      "description": "Determines whether to change the layout size when the graph container is resized. In v5, this option will be removed and will always be true.",
       "dflt": false,
       "valType": "boolean"
     },