fix(📼): add seek playback option (#2448)

Author: wcandillon

Diff for: docs/docs/video.md

@@ -5,8 +5,7 @@ sidebar_label: Video
 slug: /video
 ---
 
-React Native Skia provides a way to load video frames as images, enabling rich multimedia experiences within your applications.
-A video frame can be used anywhere a Skia image is accepted: `Image`, `ImageShader`, and `Atlas`.
+React Native Skia provides a way to load video frames as images, enabling rich multimedia experiences within your applications. A video frame can be used anywhere a Skia image is accepted: `Image`, `ImageShader`, and `Atlas`.
 
 ## Requirements
 
@@ -35,7 +34,7 @@ interface VideoExampleProps {
     localVideoFile: string;
 }
 
-// The URL needs to be a local path, we usually use expo-asset for that.
+// The URL needs to be a local path; we usually use expo-asset for that.
 export const VideoExample = ({ localVideoFile }: VideoExampleProps) => {
   const paused = useSharedValue(false);
   const { width, height } = useWindowDimensions();
@@ -75,7 +74,7 @@ export const VideoExample = ({ localVideoFile }: VideoExampleProps) => {
 
 ## Using expo-asset
 
-Below is an example where we use [expo-asset](https://docs.expo.dev/versions/latest/sdk/asset/) to load the video.
+Below is an example of how to use [expo-asset](https://docs.expo.dev/versions/latest/sdk/asset/) to load the video.
 
 ```tsx twoslash
 import { useVideo } from "@shopify/react-native-skia";
@@ -93,4 +92,68 @@ export const useVideoFromAsset = (
   }
   return useVideo(assets ? assets[0].localUri : null, options);
 };
+```
+
+## Playback Options
+
+You can seek a video via the `seek` playback option. By default, the seek option is null. If you set a value in milliseconds, it will seek to that point in the video and then set the option value to null again.
+
+There is also the `currentTime` option, which is a Reanimated value that contains the current playback time of the video.
+
+`looping` indicates whether the video should be looped or not.
+
+`playbackSpeed` indicates the playback speed of the video (default is 1).
+
+In the example below, every time we tap on the video, we set the video to 2 seconds.
+
+```tsx twoslash
+import React from "react";
+import {
+  Canvas,
+  Fill,
+  Image,
+  useVideo
+} from "@shopify/react-native-skia";
+import { Pressable, useWindowDimensions } from "react-native";
+import { useSharedValue } from "react-native-reanimated";
+
+interface VideoExampleProps {
+    localVideoFile: string;
+}
+
+export const VideoExample = ({ localVideoFile }: VideoExampleProps) => {
+  const seek = useSharedValue<null | number>(null);
+  // Set this value to true to pause the video
+  const paused = useSharedValue(false);
+  // Contains the current playback time of the video
+  const currentTime = useSharedValue(0);
+  const { width, height } = useWindowDimensions();
+  const video = useVideo(
+    require(localVideoFile),
+    {
+      seek,
+      paused,
+      currentTime,
+      looping: true,
+      playbackSpeed: 1
+    }
+  );
+  return (
+    <Pressable
+      style={{ flex: 1 }}
+      onPress={() => (seek.value = 2000)}
+    >
+      <Canvas style={{ flex: 1 }}>
+        <Image
+          image={video}
+          x={0}
+          y={0}
+          width={width}
+          height={height}
+          fit="cover"
+        />
+      </Canvas>
+    </Pressable>
+  );
+};
 ```

Diff for: package/src/external/reanimated/useVideo.ts

@@ -18,12 +18,16 @@ export interface PlaybackOptions {
   playbackSpeed: Animated<number>;
   looping: Animated<boolean>;
   paused: Animated<boolean>;
+  seek: Animated<number | null>;
+  currentTime: Animated<number>;
 }
 
 const defaultOptions = {
   playbackSpeed: 1,
   looping: true,
   paused: false,
+  seek: null,
+  currentTime: 0,
 };
 
 const useOption = <T>(value: Animated<T>) => {
@@ -42,6 +46,10 @@ export const useVideo = (
   const video = useMemo(() => (source ? Skia.Video(source) : null), [source]);
   const isPaused = useOption(userOptions?.paused ?? defaultOptions.paused);
   const looping = useOption(userOptions?.looping ?? defaultOptions.looping);
+  const seek = useOption(userOptions?.seek ?? defaultOptions.seek);
+  const currentTime = useOption(
+    userOptions?.currentTime ?? defaultOptions.currentTime
+  );
   const playbackSpeed = useOption(
     userOptions?.playbackSpeed ?? defaultOptions.playbackSpeed
   );
@@ -64,6 +72,12 @@ export const useVideo = (
     if (!video) {
       return;
     }
+    if (seek.value !== null) {
+      video.seek(seek.value);
+      seek.value = null;
+      lastTimestamp.value = -1;
+      startTimestamp.value = -1;
+    }
     if (isPaused.value && lastTimestamp.value !== -1) {
       return;
     }
@@ -76,6 +90,7 @@ export const useVideo = (
 
     // Calculate the current time in the video
     const currentTimestamp = timestamp - startTimestamp.value;
+    currentTime.value = currentTimestamp;
 
     // Handle looping
     if (currentTimestamp > duration && looping.value) {