QMediaPlaylist :: addMedia（）对不存在的文件返回true [英] QMediaPlaylist::addMedia() returns true for nonexistent files

问题描述

文档说如果QMediaPlaylist :: addMedia失败，则返回false：

bool QMediaPlaylist :: addMedia（const QMediaContent& content ）
将媒体内容附加到播放列表。
如果操作成功返回true，否则返回false。

但是这个代码将打印为true， 't exists：

  QMediaPlayer * player = new QMediaPlayer; 
 QMediaPlaylist * playlist = new QMediaPlaylist（player）; 
 qDebug（）<< playlist-> addMedia（QUrl（this file does not exist.mp4））; 
  

如果文件不存在，操作如何才能成功？

$ b在进入Qt源后，我看到QMediaPlaylist :: addMedia（）调用 QMediaNetworkPlaylistProvider :: addMedia（） code>，它总是返回true：

  bool QMediaPlaylist :: addMedia（const QMediaContent& content）
 {
 return d_func（） - > control-> playlistProvider（） - > addMedia（content）; 
} 
 
 bool QMediaNetworkPlaylistProvider :: addMedia（const QMediaContent& content）
 {
 Q_D（QMediaNetworkPlaylistProvider）; 
 
 int pos = d-> resources.count（）; 
 
 emit mediaAboutToBeInserted（pos，pos）; 
 d-> resources.append（content）; 
 emit mediaInserted（pos，pos）; 
 
 return true; 
} 
  

虽然为什么它需要返回一个总是真的bool是一个谜。

The docs say that QMediaPlaylist::addMedia returns false if it fails:

bool QMediaPlaylist::addMedia(const QMediaContent & content) Append the media content to the playlist. Returns true if the operation is successful, otherwise return false.

But this code will print true even though the file doesn't exist:

QMediaPlayer *player = new QMediaPlayer;
QMediaPlaylist *playlist = new QMediaPlaylist(player);
qDebug() << playlist->addMedia(QUrl("this file doesn't exist.mp4"));

If the file doesn't exist how can the operation be considered successful?

解决方案

After stepping into the Qt sources, I saw that QMediaPlaylist::addMedia() calls QMediaNetworkPlaylistProvider::addMedia(), which always returns true:

bool QMediaPlaylist::addMedia(const QMediaContent &content)
{
    return d_func()->control->playlistProvider()->addMedia(content);
}

bool QMediaNetworkPlaylistProvider::addMedia(const QMediaContent &content)
{
    Q_D(QMediaNetworkPlaylistProvider);

    int pos = d->resources.count();

    emit mediaAboutToBeInserted(pos, pos);
    d->resources.append(content);
    emit mediaInserted(pos, pos);

    return true;
}

Although why it needs to return a bool that's always true is a mystery to me.

这篇关于QMediaPlaylist :: addMedia（）对不存在的文件返回true的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！