C++ ProgramInfo::GetBookmarkUpdate方法代码示例

/** \brief Generate a preview image for the specified program.
 *
 * This function will find an existing preview image for a program, or
 * schedules the generation of a preview image if it doesn't exist.
 * If any of the arguments that could affect the generated image
 * (size, outputfile, time offset) have been specified, then a new
 * image will always be generated.
 *
 * \param pginfo Generate the image for this program.
 * \param size Generate a preview image of these dimensions.  If this
 *        is not specified the generated image will be the same size
 *        as the program.
 * \param outputfile Use this specific filename for the preview
 *        image. If empty, a default name will be created based on the
 *        program information.
 * \param time An offset from the start of the program. This can be
 *        seconds or frames. (See the next argument.)
 * \param in_seconds If true, the 'time' offset is in seconds. If
 *        false, the offset is in frames.
 * \param token An arbitrary string value used to match up this
 *        request with the response from the backend, and as a key for
 *        some indexing.  A token isn't required, but is strongly
 *        suggested.
 * \return The filename of the preview images. This will be null if
 *         the preview does not yet or will never exist.
 *
 * \note This function will always send one of three events.  If the
 * program has been marked for deletion, this function will send a
 * PREVIEW_FAILED event.  If a preview already exists, the function
 * sends a PREVIEW_SUCCESS event.  Otherwise it sends a PREVIEW_QUEUED
 * event.
 *
 * \warning This function should only be called from the preview
 * generation thread.
 */
QString PreviewGeneratorQueue::GeneratePreviewImage(
    ProgramInfo &pginfo,
    const QSize &size,
    const QString &outputfile,
    long long time, bool in_seconds,
    QString token)
{
    QString key = QString("%1_%2x%3_%4%5")
        .arg(pginfo.GetBasename()).arg(size.width()).arg(size.height())
        .arg(time).arg(in_seconds?"s":"f");

    if (pginfo.GetAvailableStatus() == asPendingDelete)
    {
        SendEvent(pginfo, "PREVIEW_FAILED", key, token,
                  "Pending Delete", QDateTime());
        return QString();
    }

    // keep in sync with default filename in PreviewGenerator::RunReal
    QString filename = (outputfile.isEmpty()) ?
        pginfo.GetPathname() + ".png" : outputfile;
    QString ret_file = filename;
    QString ret;

    bool is_special = !outputfile.isEmpty() || time >= 0 ||
        size.width() || size.height();

    bool needs_gen = true;
    if (!is_special)
    {
        QDateTime previewLastModified;
        bool streaming = !filename.startsWith("/");
        bool locally_accessible = false;
        bool bookmark_updated = false;

        QDateTime bookmark_ts = pginfo.GetBookmarkUpdate();
        QDateTime cmp_ts;
        if (bookmark_ts.isValid())
            cmp_ts = bookmark_ts;
        else if (MythDate::current() >= pginfo.GetRecordingEndTime())
            cmp_ts = pginfo.GetLastModifiedTime();
        else
            cmp_ts = pginfo.GetRecordingStartTime();

        if (streaming)
        {
            ret_file = QString("%1/%2")
                .arg(GetRemoteCacheDir()).arg(filename.section('/', -1));

            QFileInfo finfo(ret_file);
            if (finfo.isReadable() && finfo.lastModified() >= cmp_ts)
            {
                // This is just an optimization to avoid
                // hitting the backend if our cached copy
                // is newer than the bookmark, or if we have
                // a preview and do not update it when the
                // bookmark changes.
                previewLastModified = finfo.lastModified();
            }
            else if (!IsGeneratingPreview(key))
            {
                previewLastModified =
                    RemoteGetPreviewIfModified(pginfo, ret_file);
            }
        }
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