Implement animations for progress bars

src/components/views/elements/ProgressBar.tsx

@@ -1,5 +1,5 @@
 /*
-Copyright 2020 The Matrix.org Foundation C.I.C.
+Copyright 2020,2022 The Matrix.org Foundation C.I.C.
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
@@ -16,13 +16,20 @@ limitations under the License.
 
 import React from "react";
 
+import { useSmoothAnimation } from "../../../hooks/useSmoothAnimation";
+
 interface IProps {
     value: number;
     max: number;
+    animated?: boolean;
 }
 
-const ProgressBar: React.FC<IProps> = ({ value, max }) => {
-    return <progress className="mx_ProgressBar" max={max} value={value} />;
+const PROGRESS_BAR_ANIMATION_DURATION = 300;
+const ProgressBar: React.FC<IProps> = ({ value, max, animated }) => {
+    // Animating progress bars via CSS transition isn’t possible in all of our supported browsers yet.
+    // As workaround, we’re using animations through JS requestAnimationFrame
+    const currentValue = useSmoothAnimation(0, value, PROGRESS_BAR_ANIMATION_DURATION, animated);
+    return <progress className="mx_ProgressBar" max={max} value={currentValue} />;
 };
 
 export default ProgressBar;

src/hooks/useAnimation.ts

@@ -0,0 +1,55 @@
+/*
+Copyright 2022 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import { logger } from "matrix-js-sdk/src/logger";
+import { useCallback, useEffect, useRef } from "react";
+
+import SettingsStore from "../settings/SettingsStore";
+
+const debuglog = (...args: any[]) => {
+    if (SettingsStore.getValue("debug_animation")) {
+        logger.log.call(console, "Animation debuglog:", ...args);
+    }
+};
+
+export function useAnimation(enabled: boolean, callback: (timestamp: DOMHighResTimeStamp) => boolean) {
+    const handle = useRef<number | null>(null);
+
+    const handler = useCallback(
+        (timestamp: DOMHighResTimeStamp) => {
+            if (callback(timestamp)) {
+                handle.current = requestAnimationFrame(handler);
+            } else {
+                debuglog("Finished animation!");
+            }
+        },
+        [callback],
+    );
+
+    useEffect(() => {
+        debuglog("Started animation!");
+        if (enabled) {
+            handle.current = requestAnimationFrame(handler);
+        }
+        return () => {
+            if (handle.current) {
+                debuglog("Aborted animation!");
+                cancelAnimationFrame(handle.current);
+                handle.current = null;
+            }
+        };
+    }, [enabled, handler]);
+}

src/hooks/useSmoothAnimation.ts

@@ -0,0 +1,85 @@
+/*
+Copyright 2022 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import { logger } from "matrix-js-sdk/src/logger";
+import { useCallback, useEffect, useRef, useState } from "react";
+
+import SettingsStore from "../settings/SettingsStore";
+import { useAnimation } from "./useAnimation";
+
+const debuglog = (...args: any[]) => {
+    if (SettingsStore.getValue("debug_animation")) {
+        logger.log.call(console, "Animation debuglog:", ...args);
+    }
+};
+
+/**
+ * Utility function to smoothly animate to a certain target value
+ * @param initialValue Initial value to be used as initial starting point
+ * @param targetValue Desired value to animate to (can be changed repeatedly to whatever is current at that time)
+ * @param duration Duration that each animation should take
+ * @param enabled Whether the animation should run or not
+ */
+export function useSmoothAnimation(
+    initialValue: number,
+    targetValue: number,
+    duration: number,
+    enabled: boolean,
+): number {
+    const state = useRef<{ timestamp: DOMHighResTimeStamp | null, value: number }>({
+        timestamp: null,
+        value: initialValue,
+    });
+    const [currentValue, setCurrentValue] = useState<number>(initialValue);
+    const [currentStepSize, setCurrentStepSize] = useState<number>(0);
+
+    useEffect(() => {
+        const totalDelta = targetValue - state.current.value;
+        setCurrentStepSize(totalDelta / duration);
+        state.current = { ...state.current, timestamp: null };
+    }, [duration, targetValue]);
+
+    const update = useCallback(
+        (timestamp: DOMHighResTimeStamp): boolean => {
+            if (!state.current.timestamp) {
+                state.current = { ...state.current, timestamp };
+                return true;
+            }
+
+            if (Math.abs(currentStepSize) < Number.EPSILON) {
+                return false;
+            }
+
+            const timeDelta = timestamp - state.current.timestamp;
+            const valueDelta = currentStepSize * timeDelta;
+            const maxValueDelta = targetValue - state.current.value;
+            const clampedValueDelta = Math.sign(valueDelta) * Math.min(Math.abs(maxValueDelta), Math.abs(valueDelta));
+            const value = state.current.value + clampedValueDelta;
+
+            debuglog(`Animating to ${targetValue} at ${value} timeDelta=${timeDelta}, valueDelta=${valueDelta}`);
+
+            setCurrentValue(value);
+            state.current = { value, timestamp };
+
+            return Math.abs(maxValueDelta) > Number.EPSILON;
+        },
+        [currentStepSize, targetValue],
+    );
+
+    useAnimation(enabled, update);
+
+    return currentValue;
+}

src/settings/Settings.tsx

@@ -952,6 +952,10 @@ export const SETTINGS: {[setting: string]: ISetting} = {
         supportedLevels: LEVELS_DEVICE_ONLY_SETTINGS,
         default: false,
     },
+    "debug_animation": {
+        supportedLevels: LEVELS_DEVICE_ONLY_SETTINGS,
+        default: false,
+    },
     "audioInputMuted": {
         supportedLevels: LEVELS_DEVICE_ONLY_SETTINGS,
         default: false,