Progress Spinner: Replace SVG+CSS with Canvas

src/components/ui/ProgressSpinner.scss

@@ -50,38 +50,17 @@
     width: 3.25rem;
     height: 3.25rem;
 
-    svg {
-      width: 3rem;
-      height: 3rem;
+    &_canvas {
       margin: 0.125rem;
     }
-
-    circle {
-      stroke-width: 3px;
-    }
   }
 
   &.transparent {
     background-color: transparent !important;
   }
 
-  svg {
+  &_canvas {
     display: block;
-    transform: rotate(-90deg);
-    transform-origin: 50% 50%;
-    animation: 4s linear 0s infinite ProgressSpinnerAnimation;
-  }
-
-  circle {
-    transition: stroke-dashoffset 0.5s;
-  }
-}
-
-@keyframes ProgressSpinnerAnimation {
-  from {
-    transform: rotate(0deg);
-  }
-  to {
-    transform: rotate(360deg);
+    background-color: transparent !important;
   }
 }

src/components/ui/ProgressSpinner.tsx

@@ -1,16 +1,24 @@
-import React, { memo } from '../../lib/teact/teact';
 import type { FC } from '../../lib/teact/teact';
+import React, { memo, useEffect, useRef } from '../../lib/teact/teact';
 
+import { DPR } from '../../util/windowEnvironment';
 import buildClassName from '../../util/buildClassName';
 
 import './ProgressSpinner.scss';
+import { animate, timingFunctions } from '../../util/animation';
+import { requestMutation } from '../../lib/fasterdom/fasterdom';
+import { useStateRef } from '../../hooks/useStateRef';
 
-const RADIUSES = {
-  s: 22, m: 25, l: 28, xl: 20,
+const SIZES = {
+  s: 42, m: 48, l: 54, xl: 52,
 };
-const STROKE_WIDTH = 2;
+const STROKE_WIDTH = 2 * DPR;
+const STROKE_WIDTH_XL = 3 * DPR;
+const PADDING = 2 * DPR;
 const MIN_PROGRESS = 0.05;
 const MAX_PROGRESS = 1;
+const GROW_DURATION = 600; // 0.6 s
+const ROTATE_DURATION = 2000; // 2 s
 
 const ProgressSpinner: FC<{
   progress?: number;
@@ -27,11 +35,47 @@ const ProgressSpinner: FC<{
   noCross,
   onClick,
 }) => {
-  const radius = RADIUSES[size];
-  const circleRadius = radius - STROKE_WIDTH * 2;
-  const borderRadius = radius - 1;
-  const circumference = circleRadius * 2 * Math.PI;
-  const strokeDashOffset = circumference - Math.min(Math.max(MIN_PROGRESS, progress), MAX_PROGRESS) * circumference;
+  // eslint-disable-next-line no-null/no-null
+  const canvasRef = useRef<HTMLCanvasElement>(null);
+  const width = SIZES[size];
+  const progressRef = useStateRef(progress);
+
+  useEffect(() => {
+    let isFirst = true;
+    let growFrom = MIN_PROGRESS;
+    let growStartedAt: number | undefined;
+    let prevProgress: number | undefined;
+
+    animate(() => {
+      if (!canvasRef.current) {
+        return false;
+      }
+
+      if (progressRef.current !== prevProgress) {
+        growFrom = Math.min(Math.max(MIN_PROGRESS, prevProgress || 0), MAX_PROGRESS);
+        growStartedAt = Date.now();
+        prevProgress = progressRef.current;
+      }
+
+      const targetProgress = Math.min(Math.max(MIN_PROGRESS, progressRef.current), MAX_PROGRESS);
+      const t = Math.min(1, (Date.now() - growStartedAt!) / GROW_DURATION);
+      const animationFactor = timingFunctions.easeOutQuad(t);
+      const currentProgress = growFrom + (targetProgress - growFrom) * animationFactor;
+
+      drawSpinnerArc(
+        canvasRef.current,
+        width * DPR,
+        size === 'xl' ? STROKE_WIDTH_XL : STROKE_WIDTH,
+        'white',
+        currentProgress,
+        isFirst,
+      );
+
+      isFirst = false;
+
+      return currentProgress < 1;
+    }, requestMutation);
+  }, [progressRef, size, width]);
 
   const className = buildClassName(
     `ProgressSpinner size-${size}`,
@@ -45,25 +89,39 @@ const ProgressSpinner: FC<{
       className={className}
       onClick={onClick}
     >
-      <svg
-        viewBox={`0 0 ${borderRadius * 2} ${borderRadius * 2}`}
-        height={borderRadius * 2}
-        width={borderRadius * 2}
-      >
-        <circle
-          stroke="white"
-          fill="transparent"
-          stroke-width={STROKE_WIDTH}
-          stroke-dasharray={`${circumference} ${circumference}`}
-          stroke-dashoffset={strokeDashOffset}
-          stroke-linecap="round"
-          r={circleRadius}
-          cx={borderRadius}
-          cy={borderRadius}
-        />
-      </svg>
+      <canvas ref={canvasRef} className="ProgressSpinner_canvas" style={`width: ${width}; height: ${width}px;`} />
     </div>
   );
 };
 
+function drawSpinnerArc(
+  canvas: HTMLCanvasElement,
+  size: number,
+  strokeWidth: number,
+  color: string,
+  progress: number,
+  shouldInit = false,
+) {
+  const centerCoordinate = size / 2;
+  const radius = (size - strokeWidth) / 2 - PADDING;
+  const rotationOffset = (Date.now() % ROTATE_DURATION) / ROTATE_DURATION;
+  const startAngle = (2 * Math.PI) * rotationOffset;
+  const endAngle = startAngle + (2 * Math.PI) * progress;
+  const ctx = canvas.getContext('2d')!;
+
+  if (shouldInit) {
+    canvas.width = size;
+    canvas.height = size;
+
+    ctx.lineCap = 'round';
+    ctx.strokeStyle = color;
+    ctx.lineWidth = strokeWidth;
+  }
+
+  ctx.clearRect(0, 0, size, size);
+  ctx.beginPath();
+  ctx.arc(centerCoordinate, centerCoordinate, radius, startAngle, endAngle);
+  ctx.stroke();
+}
+
 export default memo(ProgressSpinner);