QMediaPlaylist :: addMedia（）对不存在的文件返回true

本文介绍了QMediaPlaylist :: addMedia（）对不存在的文件返回true的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 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.