Send thumbnails when uploading videos

NeoChat will now generate thumbnails from the first frame of the video,
since we are loading it anyway. This makes the experience of exchanging
videos in NeoChat much nicer!

src/libneochat/neochatroom.cpp

@@ -8,6 +8,8 @@
 #include <QMediaPlayer>
 #include <QMimeDatabase>
 #include <QTemporaryFile>
+#include <QVideoFrame>
+#include <QVideoSink>
 
 #include <Quotient/events/eventcontent.h>
 #include <Quotient/events/eventrelation.h>
@@ -245,11 +247,37 @@ QCoro::Task<void> NeoChatRoom::doUploadFile(QUrl url, QString body, std::optiona
     } else if (mime.name().startsWith("audio/"_L1)) {
         content = new EventContent::AudioContent(url, fileInfo.size(), mime, fileInfo.fileName());
     } else if (mime.name().startsWith("video/"_L1)) {
+        QVideoSink sink;
+
         QMediaPlayer player;
         player.setSource(url);
+        player.setVideoSink(&sink);
         co_await qCoro(&player, &QMediaPlayer::mediaStatusChanged);
-        auto resolution = player.metaData().value(QMediaMetaData::Resolution).toSize();
+
+        // Get the first video frame to use as a thumbnail.
+        player.play();
+        co_await qCoro(&player, &QMediaPlayer::positionChanged);
+
+        QTemporaryFile file;
+        file.setFileTemplate(QStringLiteral("XXXXXX.jpg"));
+        file.open();
+
+        const auto thumbnailImage = sink.videoFrame().toImage();
+        Q_UNUSED(thumbnailImage.save(file.fileName()))
+        player.stop(); // We have to delay the stop() because it will invalidate our image
+
+        const auto thumbnailFileInfo = QFileInfo(file.fileName());
+
+        // Upload the thumbnail
+        const auto job = connection()->uploadFile(thumbnailFileInfo.absoluteFilePath());
+        co_await qCoro(job.get(), &BaseJob::finished);
+
+        const auto resolution = player.metaData().value(QMediaMetaData::Resolution).toSize();
         content = new EventContent::VideoContent(url, fileInfo.size(), mime, resolution, fileInfo.fileName());
+        content->thumbnail = EventContent::Thumbnail(job->contentUri(),
+                                                     thumbnailFileInfo.size(),
+                                                     QMimeDatabase().mimeTypeForName(QStringLiteral("image/jpeg")),
+                                                     thumbnailImage.size());
     } else {
         content = new EventContent::FileContent(url, fileInfo.size(), mime, fileInfo.fileName());
     }