feat: basic lyrics support

lyricsmanager.cpp

@@ -0,0 +1,143 @@
+// SPDX-FileCopyrightText: 2024 Gary Wang <git@blumia.net>
+//
+// SPDX-License-Identifier: MIT
+
+#include "lyricsmanager.h"
+
+#include <QDir>
+#include <QFileInfo>
+#include <QRegularExpression>
+
+LyricsManager::LyricsManager(QObject *parent)
+    : QObject(parent)
+{
+
+}
+
+LyricsManager::~LyricsManager()
+{
+
+}
+
+bool LyricsManager::loadLyrics(QString filepath)
+{
+    // reset state
+    reset();
+
+    // check and load file
+    QFileInfo fileInfo(filepath);
+    if (!filepath.endsWith(".lrc", Qt::CaseInsensitive)) {
+        fileInfo.setFile(fileInfo.dir().filePath(fileInfo.completeBaseName() + ".lrc"));
+    }
+    if (!fileInfo.exists()) return false;
+
+    QFile file(fileInfo.absoluteFilePath());
+    if (!file.open(QIODevice::ReadOnly | QIODevice::Text)) {
+        return false;
+    }
+    QTextStream stream(&file);
+    QStringList lines = QString(stream.readAll()).split('\n');
+    file.close();
+
+    // parse lyrics timestamp
+    QRegularExpression tagRegex(R"regex(\[(ti|ar|al|au|length|by|offset|tool|re|ve|#):\s?([^\]]*)\]$)regex");
+    QRegularExpression lrcRegex(R"regex(\[(\d{2,3}:\d{2}\.\d{2})\](.*))regex");
+    bool tagSectionPassed = false;
+
+    for (QString line : std::as_const(lines)) {
+        line = line.trimmed();
+        if (line.isEmpty()) continue;
+
+        if (!tagSectionPassed) {
+            QRegularExpressionMatch tagMatch = tagRegex.match(line);
+            if (tagMatch.hasMatch()) {
+                QString tag(tagMatch.captured(1));
+                if (tag == QLatin1String("offset")) {
+                    // The value is prefixed with either + or -, with + causing lyrics to appear sooner
+                    m_timeOffset = -tagMatch.captured(2).toInt();
+                    qDebug() << m_timeOffset;
+                }
+                qDebug() << "[tag]" << tagMatch.captured(1) << tagMatch.captured(2);
+                continue;
+            }
+        }
+
+        QRegularExpressionMatch match = lrcRegex.match(line);
+        if (match.hasMatch()) {
+            tagSectionPassed = true;
+            QTime timestamp(QTime::fromString(match.captured(1), "m:s.zz"));
+            m_lyricsMap.insert(timestamp.msecsSinceStartOfDay(), match.captured(2));
+            qDebug() << "[lrc]" << match.captured(1) << match.captured(2);
+        }
+    }
+    if (!m_lyricsMap.isEmpty()) {
+        m_timestampList = m_lyricsMap.keys();
+        std::sort(m_timestampList.begin(), m_timestampList.end());
+        return true;
+    }
+
+    return false;
+}
+
+bool LyricsManager::hasLyrics() const
+{
+    return !m_lyricsMap.isEmpty();
+}
+
+void LyricsManager::updateCurrentTimeMs(int curTimeMs, int totalTimeMs)
+{
+    if (!hasLyrics()) return;
+
+    // TODO: we don't need to find from the top everytime the time is updated
+    auto iter = std::find_if(m_timestampList.begin(), m_timestampList.end() + 1, [&curTimeMs, this](int timestamp) -> bool {
+        return (timestamp + m_timeOffset) > curTimeMs;
+    });
+
+    m_nextLyricsTime = (iter == m_timestampList.end() + 1) ? totalTimeMs : *iter;
+    if (iter != m_timestampList.begin() && iter != (m_timestampList.end() + 1)) {
+        iter--;
+    }
+    m_currentLyricsTime = *iter;
+}
+
+QString LyricsManager::lyrics(int lineOffset) const
+{
+    if (!hasLyrics()) return QString();
+
+    int index = m_timestampList.indexOf(m_currentLyricsTime) + lineOffset;
+    if (index >= 0 && index < m_timestampList.count()) {
+        int timestamp = m_timestampList.at(index);
+        return m_lyricsMap.value(timestamp);
+    } else {
+        return QString();
+    }
+}
+
+double LyricsManager::maskPercent(int curTimeMs)
+{
+    if (!hasLyrics()) return 0;
+    if (curTimeMs <= currentLyricsTime()) return 0;
+    if (curTimeMs >= nextLyricsTime()) return 1;
+    if (m_nextLyricsTime == currentLyricsTime()) return 1;
+
+    return (double)(curTimeMs - currentLyricsTime()) / (m_nextLyricsTime - m_currentLyricsTime);
+}
+
+void LyricsManager::reset()
+{
+    m_currentLyricsTime = 0;
+    m_nextLyricsTime = 0;
+    m_timeOffset = 0;
+    m_lyricsMap.clear();
+    m_timestampList.clear();
+}
+
+int LyricsManager::currentLyricsTime() const
+{
+    return m_currentLyricsTime + m_timeOffset;
+}
+
+int LyricsManager::nextLyricsTime() const
+{
+    return m_nextLyricsTime + m_timeOffset;
+}