strawberry-audio-player-windows-mac-linux/src/covermanager/albumcoverloader.cpp

/*
 * 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/>.
 * 
 */

#include "config.h"

#include "albumcoverloader.h"

#include <QCoreApplication>
#include <QStandardPaths>
#include <QString>
#include <QDir>
#include <QUrl>
#include <QNetworkReply>
#include <QImage>
#include <QPixmap>
#include <QPainter>
#include <QMutexLocker>

#include "config.h"
#include "core/closure.h"
#include "core/logging.h"
#include "core/network.h"
#include "core/tagreaderclient.h"

AlbumCoverLoader::AlbumCoverLoader(QObject *parent)
    : QObject(parent),
      stop_requested_(false),
      next_id_(1),
      network_(new NetworkAccessManager(this)){}

QString AlbumCoverLoader::ImageCacheDir() {
  return QStandardPaths::writableLocation(QStandardPaths::AppLocalDataLocation) + "/albumcovers";
}

void AlbumCoverLoader::CancelTask(quint64 id) {
    
  QMutexLocker l(&mutex_);
  for (QQueue<Task>::iterator it = tasks_.begin(); it != tasks_.end(); ++it) {
    if (it->id == id) {
      tasks_.erase(it);
      break;
    }
  }
}

void AlbumCoverLoader::CancelTasks(const QSet<quint64> &ids) {
    
  QMutexLocker l(&mutex_);
  for (QQueue<Task>::iterator it = tasks_.begin(); it != tasks_.end();) {
    if (ids.contains(it->id)) {
      it = tasks_.erase(it);
    }
    else {
      ++it;
    }
  }
}

quint64 AlbumCoverLoader::LoadImageAsync(const AlbumCoverLoaderOptions& options, const Song &song) {
  return LoadImageAsync(options, song.art_automatic(), song.art_manual(), song.url().toLocalFile(), song.image());
}

quint64 AlbumCoverLoader::LoadImageAsync(const AlbumCoverLoaderOptions &options, const QString &art_automatic, const QString &art_manual, const QString &song_filename, const QImage &embedded_image) {

  Task task;
  task.options = options;
  task.art_automatic = art_automatic;
  task.art_manual = art_manual;
  task.song_filename = song_filename;
  task.embedded_image = embedded_image;
  task.state = State_TryingManual;

  {
    QMutexLocker l(&mutex_);
    task.id = next_id_++;
    tasks_.enqueue(task);
  }

  metaObject()->invokeMethod(this, "ProcessTasks", Qt::QueuedConnection);

  return task.id;
}

void AlbumCoverLoader::ProcessTasks() {

  while (!stop_requested_) {
    // Get the next task
    Task task;
    {
      QMutexLocker l(&mutex_);
      if (tasks_.isEmpty()) return;
      task = tasks_.dequeue();
    }

    ProcessTask(&task);
  }
}

void AlbumCoverLoader::ProcessTask(Task *task) {

  TryLoadResult result = TryLoadImage(*task);
  if (result.started_async) {
    // The image is being loaded from a remote URL, we'll carry on later when it's done
    return;
  }

  if (result.loaded_success) {
    QImage scaled = ScaleAndPad(task->options, result.image);
    emit ImageLoaded(task->id, scaled);
    emit ImageLoaded(task->id, scaled, result.image);
    return;
  }

  NextState(task);
}

void AlbumCoverLoader::NextState(Task *task) {

  if (task->state == State_TryingManual) {
    // Try the automatic one next
    task->state = State_TryingAuto;
    ProcessTask(task);
  }
  else {
    // Give up
    emit ImageLoaded(task->id, task->options.default_output_image_);
    emit ImageLoaded(task->id, task->options.default_output_image_, task->options.default_output_image_);
  }

}

AlbumCoverLoader::TryLoadResult AlbumCoverLoader::TryLoadImage(const Task &task) {

  // An image embedded in the song itself takes priority
  if (!task.embedded_image.isNull())
    return TryLoadResult(false, true, ScaleAndPad(task.options, task.embedded_image));

  QString filename;
  switch (task.state) {
    case State_TryingAuto:   filename = task.art_automatic; break;
    case State_TryingManual: filename = task.art_manual;    break;
  }

  if (filename == Song::kManuallyUnsetCover)
    return TryLoadResult(false, true, task.options.default_output_image_);

  if (filename == Song::kEmbeddedCover && !task.song_filename.isEmpty()) {
    const QImage taglib_image = TagReaderClient::Instance()->LoadEmbeddedArtBlocking(task.song_filename);

    if (!taglib_image.isNull())
      return TryLoadResult(false, true, ScaleAndPad(task.options, taglib_image));
  }

  if (filename.toLower().startsWith("http://") || filename.toLower().startsWith("https://")) {

    QUrl url(filename);
    QNetworkReply* reply = network_->get(QNetworkRequest(url));
    NewClosure(reply, SIGNAL(finished()), this, SLOT(RemoteFetchFinished(QNetworkReply*)), reply);

    remote_tasks_.insert(reply, task);
    return TryLoadResult(true, false, QImage());
  }
  else if (filename.isEmpty()) {
    // Avoid "QFSFileEngine::open: No file name specified" messages if we know that the filename is empty
    return TryLoadResult(false, false, task.options.default_output_image_);
  }

  QImage image(filename);
  return TryLoadResult(false, !image.isNull(), image.isNull() ? task.options.default_output_image_ : image);

}

void AlbumCoverLoader::RemoteFetchFinished(QNetworkReply *reply) {

  reply->deleteLater();

  Task task = remote_tasks_.take(reply);

  // Handle redirects.
  QVariant redirect = reply->attribute(QNetworkRequest::RedirectionTargetAttribute);
  if (redirect.isValid()) {
    if (++task.redirects > kMaxRedirects) {
      return;  // Give up.
    }
    QNetworkRequest request = reply->request();
    request.setUrl(redirect.toUrl());
    QNetworkReply* redirected_reply = network_->get(request);
    NewClosure(redirected_reply, SIGNAL(finished()), this, SLOT(RemoteFetchFinished(QNetworkReply*)), redirected_reply);

    remote_tasks_.insert(redirected_reply, task);
    return;
  }

  if (reply->error() == QNetworkReply::NoError) {
    // Try to load the image
    QImage image;
    if (image.load(reply, 0)) {
      QImage scaled = ScaleAndPad(task.options, image);
      emit ImageLoaded(task.id, scaled);
      emit ImageLoaded(task.id, scaled, image);
      return;
    }
  }

  NextState(&task);
}

QImage AlbumCoverLoader::ScaleAndPad(const AlbumCoverLoaderOptions &options, const QImage &image) {

  if (image.isNull()) return image;

  // Scale the image down
  QImage copy;
  if (options.scale_output_image_) {
    copy = image.scaled(QSize(options.desired_height_, options.desired_height_), Qt::KeepAspectRatio, Qt::SmoothTransformation);
  }
  else {
    copy = image;
  }

  if (!options.pad_output_image_) return copy;

  // Pad the image to height_ x height_
  QImage padded_image(options.desired_height_, options.desired_height_, QImage::Format_ARGB32);
  padded_image.fill(0);

  QPainter p(&padded_image);
  p.drawImage((options.desired_height_ - copy.width()) / 2, (options.desired_height_ - copy.height()) / 2, copy);
  p.end();

  return padded_image;

}

QPixmap AlbumCoverLoader::TryLoadPixmap(const QString &automatic, const QString &manual, const QString &filename) {

  QPixmap ret;
  if (manual == Song::kManuallyUnsetCover) return ret;
  if (!manual.isEmpty()) ret.load(manual);
  if (ret.isNull()) {
    if (automatic == Song::kEmbeddedCover && !filename.isNull())
      ret = QPixmap::fromImage(TagReaderClient::Instance()->LoadEmbeddedArtBlocking(filename));
    else if (!automatic.isEmpty())
      ret.load(automatic);
  }
  return ret;

}