New context with albums and lyrics +++ much more

* Added new lyrics provider with lyrics from AudD and API Seeds
* New improved context widget with albums and lyrics
* Fixed playing and context widget getting stuck in play mode when there was an error
* Changed icons for artists in collection, tidal and cover manager
* Removed "search" icon from "Search automatically" checkbox (right click) that looked ugly
* Removed some unused widgets from the src/widgets directory
* Fixed initial size of window and side panel
* Fixed saving window size correctly

src/lyrics/lyricsfetcher.cpp

@@ -0,0 +1,124 @@
+/*
+ * Strawberry Music Player
+ * Copyright 2018, Jonas Kvinge <jonas@jkvinge.net>
+ *
+ * Strawberry is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Strawberry is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Strawberry.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "config.h"
+
+#include <QtGlobal>
+#include <QObject>
+#include <QTimer>
+#include <QString>
+
+#include "core/logging.h"
+#include "lyricsfetcher.h"
+#include "lyricsfetchersearch.h"
+
+const int LyricsFetcher::kMaxConcurrentRequests = 5;
+const QRegExp LyricsFetcher::kRemoveNonAlpha("[^a-zA-Z0-9\\d\\s]");
+const QRegExp LyricsFetcher::kRemoveFromTitle(" ?-? ((\\(|\\[)?)(Remastered|Live) ?((\\)|\\])?)$");
+
+LyricsFetcher::LyricsFetcher(LyricsProviders *lyrics_providers, QObject *parent)
+    : QObject(parent),
+      lyrics_providers_(lyrics_providers),
+      next_id_(0),
+      request_starter_(new QTimer(this))
+  {
+
+  request_starter_->setInterval(500);
+  connect(request_starter_, SIGNAL(timeout()), SLOT(StartRequests()));
+
+}
+
+quint64 LyricsFetcher::Search(const QString &artist, const QString &album, const QString &title) {
+
+  LyricsSearchRequest request;
+  request.artist = artist;
+  request.album = album;
+  request.album.remove(kRemoveNonAlpha);
+  request.album.remove(kRemoveFromTitle);
+  request.title = title;
+  request.title.remove(kRemoveNonAlpha);
+  request.title.remove(kRemoveFromTitle);
+  request.id = next_id_++;
+  AddRequest(request);
+
+  return request.id;
+
+}
+
+void LyricsFetcher::AddRequest(const LyricsSearchRequest &req) {
+
+  queued_requests_.enqueue(req);
+
+  if (!request_starter_->isActive()) request_starter_->start();
+
+  if (active_requests_.size() < kMaxConcurrentRequests) StartRequests();
+
+}
+
+void LyricsFetcher::Clear() {
+
+  queued_requests_.clear();
+
+  for (LyricsFetcherSearch *search : active_requests_.values()) {
+    search->Cancel();
+    search->deleteLater();
+  }
+  active_requests_.clear();
+
+}
+
+void LyricsFetcher::StartRequests() {
+
+  if (queued_requests_.isEmpty()) {
+    request_starter_->stop();
+    return;
+  }
+
+  while (!queued_requests_.isEmpty() && active_requests_.size() < kMaxConcurrentRequests) {
+
+    LyricsSearchRequest request = queued_requests_.dequeue();
+
+    LyricsFetcherSearch *search = new LyricsFetcherSearch(request, this);
+    active_requests_.insert(request.id, search);
+
+    connect(search, SIGNAL(SearchFinished(quint64, LyricsSearchResults)), SLOT(SingleSearchFinished(quint64, LyricsSearchResults)));
+    connect(search, SIGNAL(LyricsFetched(quint64, const QString&)), SLOT(SingleLyricsFetched(quint64, const QString&)));
+
+    search->Start(lyrics_providers_);
+  }
+
+}
+
+void LyricsFetcher::SingleSearchFinished(quint64 request_id, LyricsSearchResults results) {
+
+  LyricsFetcherSearch *search = active_requests_.take(request_id);
+  if (!search) return;
+  search->deleteLater();
+  emit SearchFinished(request_id, results);
+
+}
+
+void LyricsFetcher::SingleLyricsFetched(quint64 request_id, const QString &lyrics) {
+
+  LyricsFetcherSearch *search = active_requests_.take(request_id);
+  if (!search) return;
+  search->deleteLater();
+  emit LyricsFetched(request_id, lyrics);
+
+}