Improve album cover searching and cover manager, use HttpStatusCodeAttribute and QSslError for services

- Improve album cover manager
- Change art_automatic and art_manual to QUrl
- Refresh collection album covers when new album covers are fetched
- Fix automatic album cover searching for local files outside of the collection
- Make all Json services check HttpStatusCodeAttribute
- Show detailed SSL errors for Subsonic, Tidal and Qobuz

src/covermanager/currentalbumcoverloader.h

@@ -0,0 +1,73 @@
+/*
+ * Strawberry Music Player
+ * This file was part of Clementine.
+ * Copyright 2010, David Sansome <me@davidsansome.com>
+ *
+ * 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/>.
+ *
+ */
+
+#ifndef CURRENTALBUMCOVERLOADER_H
+#define CURRENTALBUMCOVERLOADER_H
+
+#include "config.h"
+
+#include <memory>
+
+#include <QtGlobal>
+#include <QObject>
+#include <QString>
+#include <QImage>
+#include <QTemporaryFile>
+
+#include "core/song.h"
+#include "albumcoverloaderoptions.h"
+
+class Application;
+
+class CurrentAlbumCoverLoader : public QObject {
+  Q_OBJECT
+
+ public:
+  explicit CurrentAlbumCoverLoader(Application *app, QObject *parent = nullptr);
+  ~CurrentAlbumCoverLoader();
+
+  const AlbumCoverLoaderOptions &options() const { return options_; }
+  const Song &last_song() const { return last_song_; }
+
+ public slots:
+  void LoadAlbumCover(const Song &song);
+
+ signals:
+  void AlbumCoverLoaded(const Song &song, const QUrl &cover_url, const QImage &image);
+  void ThumbnailLoaded(const Song &song, const QUrl &thumbnail_uri, const QImage &image);
+
+ private slots:
+  void TempAlbumCoverLoaded(const quint64 id, const QUrl &remote_url, const QImage &image);
+
+ private:
+  Application *app_;
+  AlbumCoverLoaderOptions options_;
+
+  QString temp_file_pattern_;
+
+  std::unique_ptr<QTemporaryFile> temp_cover_;
+  std::unique_ptr<QTemporaryFile> temp_cover_thumbnail_;
+  quint64 id_;
+
+  Song last_song_;
+
+};
+
+#endif  // CURRENTALBUMCOVERLOADER_H