How to Create Custom Video Editing Experiences in FlutterFlow

1// Custom Widget: VideoTrimEditor (simplified)
2// Requires: video_editor: ^3.0.1
3import 'package:flutter/material.dart';
4import 'package:video_editor/video_editor.dart';
5import 'dart:io';
6
7class VideoTrimEditor extends StatefulWidget {
8  final String videoPath;
9  final Function(String) onExported;
10  const VideoTrimEditor({Key? key, required this.videoPath, required this.onExported}) : super(key: key);
11
12  @override
13  State<VideoTrimEditor> createState() => _VideoTrimEditorState();
14}
15
16class _VideoTrimEditorState extends State<VideoTrimEditor> {
17  late VideoEditorController _controller;
18  bool _isExporting = false;
19
20  @override
21  void initState() {
22    super.initState();
23    _controller = VideoEditorController.file(
24      File(widget.videoPath),
25      minDuration: const Duration(seconds: 1),
26      maxDuration: const Duration(minutes: 3),
27    );
28    _controller.initialize().then((_) => setState(() {}));
29  }
30
31  @override
32  void dispose() {
33    _controller.dispose();
34    super.dispose();
35  }
36
37  Future<void> _exportTrimmed() async {
38    setState(() => _isExporting = true);
39    await _controller.exportVideo(
40      onCompleted: (file) {
41        widget.onExported(file.path);
42        setState(() => _isExporting = false);
43      },
44    );
45  }
46
47  @override
48  Widget build(BuildContext context) {
49    if (!_controller.initialized) return const CircularProgressIndicator();
50    return Column(
51      children: [
52        AspectRatio(aspectRatio: _controller.video.value.aspectRatio,
53          child: CropGridViewer.preview(controller: _controller)),
54        TrimSlider(controller: _controller, height: 60),
55        ElevatedButton(
56          onPressed: _isExporting ? null : _exportTrimmed,
57          child: _isExporting ? const CircularProgressIndicator() : const Text('Export Trimmed Video'),
58        ),
59      ],
60    );
61  }
62}

1// Cloud Run service handler (Node.js + Express)
2// Dockerfile: FROM node:18, RUN apt-get install -y ffmpeg
3const express = require('express');
4const { execSync } = require('child_process');
5const fs = require('fs');
6const path = require('path');
7const fetch = require('node-fetch');
8
9const app = express();
10app.use(express.json());
11
12app.post('/merge', async (req, res) => {
13  const { clipUrls, outputName } = req.body;
14  const tmpDir = '/tmp/' + Date.now();
15  fs.mkdirSync(tmpDir);
16
17  // Download all clips
18  const localPaths = [];
19  for (let i = 0; i < clipUrls.length; i++) {
20    const filePath = path.join(tmpDir, `clip_${i}.mp4`);
21    const response = await fetch(clipUrls[i]);
22    const buffer = await response.buffer();
23    fs.writeFileSync(filePath, buffer);
24    localPaths.push(filePath);
25  }
26
27  // Write concat list
28  const listPath = path.join(tmpDir, 'list.txt');
29  fs.writeFileSync(listPath, localPaths.map(p => `file '${p}'`).join('\n'));
30
31  // Run FFmpeg concat
32  const outputPath = path.join(tmpDir, outputName || 'merged.mp4');
33  execSync(`ffmpeg -f concat -safe 0 -i ${listPath} -c:v libx264 -c:a aac -movflags +faststart ${outputPath}`);
34
35  // Upload to Firebase Storage and return URL (implementation omitted for brevity)
36  res.json({ success: true, outputPath });
37});
38
39app.listen(8080);

1// Brightness + contrast ColorFilter computation
2ColorFilter buildColorFilter(double brightness, double contrast) {
3  // contrast: scale factor around 0.5 midpoint
4  // brightness: additive offset to all channels
5  final b = brightness;
6  final c = contrast;
7  final t = (1.0 - c) / 2.0 + b; // translation term
8
9  return ColorFilter.matrix([
10    c, 0, 0, 0, t * 255,
11    0, c, 0, 0, t * 255,
12    0, 0, c, 0, t * 255,
13    0, 0, 0, 1, 0,
14  ]);
15}