Add battery extension (#504)

extensions/battery.js

@@ -0,0 +1,136 @@
+(function (Scratch) {
+  'use strict';
+
+  /** @type {Promise<BatteryManager>|null} */
+  let getBatteryPromise = null;
+  /** @type {BatteryManager|null} */
+  let cachedBattery = null;
+  /** @type {boolean} */
+  let batteryError = false;
+  const withBattery = (callback) => {
+    // Getting the BatteryManager is async the first time. Usually it's very fast, but we shouldn't assume that it is.
+    // All the logic here lets us return values immediately when we have already got the battery instead of forcing
+    // a delay by returning a promise.
+    if (!navigator.getBattery || batteryError) {
+      return callback(null);
+    }
+    if (cachedBattery) {
+      return callback(cachedBattery);
+    }
+    if (!getBatteryPromise) {
+      getBatteryPromise = navigator.getBattery()
+        .then(battery => {
+          getBatteryPromise = null;
+          cachedBattery = battery;
+
+          cachedBattery.addEventListener('chargingchange', () => {
+            Scratch.vm.runtime.startHats('battery_chargingChanged');
+          });
+          cachedBattery.addEventListener('levelchange', () => {
+            Scratch.vm.runtime.startHats('battery_levelChanged');
+          });
+          cachedBattery.addEventListener('chargingtimechange', () => {
+            Scratch.vm.runtime.startHats('battery_chargeTimeChanged');
+          });
+          cachedBattery.addEventListener('dischargingtimechange', () => {
+            Scratch.vm.runtime.startHats('battery_dischargeTimeChanged');
+          });
+
+          return cachedBattery;
+        })
+        .catch(error => {
+          getBatteryPromise = null;
+          console.error('Could not get battery', error);
+          batteryError = true;
+          return null;
+        });
+    }
+    return getBatteryPromise.then(battery => {
+      return callback(battery);
+    });
+  };
+
+  // Try to get the battery immediately so that event blocks work.
+  withBattery(() => {});
+
+  class BatteryExtension {
+    getInfo () {
+      return {
+        name: 'Battery',
+        id: 'battery',
+        blocks: [
+          {
+            opcode: 'charging',
+            blockType: Scratch.BlockType.BOOLEAN,
+            text: 'charging?'
+          },
+          {
+            opcode: 'level',
+            blockType: Scratch.BlockType.REPORTER,
+            text: 'battery level'
+          },
+          {
+            opcode: 'chargeTime',
+            blockType: Scratch.BlockType.REPORTER,
+            text: 'seconds until charged'
+          },
+          {
+            opcode: 'dischargeTime',
+            blockType: Scratch.BlockType.REPORTER,
+            text: 'seconds until empty'
+          },
+          {
+            opcode: 'chargingChanged',
+            blockType: Scratch.BlockType.HAT,
+            text: 'when charging changed',
+            isEdgeActivated: false
+          },
+          {
+            opcode: 'levelChanged',
+            blockType: Scratch.BlockType.HAT,
+            text: 'when battery level changed',
+            isEdgeActivated: false
+          },
+          {
+            opcode: 'chargeTimeChanged',
+            blockType: Scratch.BlockType.HAT,
+            text: 'when time until charged changed',
+            isEdgeActivated: false
+          },
+          {
+            opcode: 'dischargeTimeChanged',
+            blockType: Scratch.BlockType.HAT,
+            text: 'when time until empty changed',
+            isEdgeActivated: false
+          },
+        ]
+      };
+    }
+    charging () {
+      return withBattery(battery => {
+        if (!battery) return true;
+        return battery.charging;
+      });
+    }
+    level () {
+      return withBattery(battery => {
+        if (!battery) return 100;
+        return battery.level * 100;
+      });
+    }
+    chargeTime () {
+      return withBattery(battery => {
+        if (!battery) return 0;
+        return battery.chargingTime;
+      });
+    }
+    dischargeTime () {
+      return withBattery(battery => {
+        if (!battery) return Infinity;
+        return battery.dischargingTime;
+      });
+    }
+  }
+
+  Scratch.extensions.register(new BatteryExtension());
+})(Scratch);

images/README.md

@@ -192,3 +192,6 @@ All images in this folder are licensed under the [GNU General Public License ver
  - Created by [@True-Fantom](https://scratch.mit.edu/users/TrueFantom/) in https://github.com/TurboWarp/extensions/pull/498.
  - File icons based on https://icon-icons.com/icon/file-pdf/153412 under [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/).
  - Background based on https://bgjar.com/contour-line under [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/).
+
+## battery.svg
+ - Created by [@Martinelplayz](https://github.com/Martinelplayz) in https://github.com/TurboWarp/extensions/pull/504#issuecomment-1574243161

website/index.ejs

@@ -476,6 +476,12 @@
           <p>Details about the user's browser and operating system.</p>
         </div>
 
+        <div class="extension">
+          <%- banner('battery') %>
+          <h3>Battery</h3>
+          <p>Access information about the battery of phones or laptops. May not work on all devices and browsers.</p>
+        </div>
+
         <div class="extension">
           <%- banner('mdwalters/notifications') %>
           <h3>Notifications</h3>