public static PlayRange GetNativePlayRange(this IMediaSource mediaSource)
{
if (!mediaSource.HasNativeDuration())
{
throw new ArgumentException("没有原生时长。", "mediaSource");
}
return(new PlayRange(mediaSource.NativeDuration.Value));
}
public static PlayRange Adjust(this IMediaSource mediaSource, PlayRange playRange)
{
if (!mediaSource.HasNativeDuration())
{
playRange = new PlayRange(playRange.Duration);
}
mediaSource.ValidatePlayRange(playRange);
return(playRange);
}
private static bool IsValidPlayRange(this IMediaSource mediaSource, PlayRange playRange)
{
if (mediaSource.HasNativeDuration())
{
return(mediaSource.GetNativePlayRange().Include(playRange));
}
else
{
return(playRange.StartPosition == TimeSpan.Zero);
}
}
private static void ValidatePlayRange(this IMediaSource mediaSource, PlayRange playRange)
{
if (!mediaSource.IsValidPlayRange(playRange))
{
if (mediaSource.HasNativeDuration())
{
throw new ArgumentException(
string.Format("{0}无效，有效范围为：{1}。", playRange, mediaSource.GetNativePlayRange()),
"playRange");
}
else
{
throw new ArgumentException(
string.Format("{0}无效，起始位置必须为TimeSpan.Zero。", playRange),
"playRange");
}
}
}
internal static PlayRange Merge(this IMediaSource mediaSource, PlayRange first, PlayRange second)
{
if (!mediaSource.CanMerge(first, second))
{
throw new InvalidOperationException();
}
first = mediaSource.Adjust(first);
second = mediaSource.Adjust(second);
if (mediaSource.HasNativeDuration())
{
return(PlayRange.Merge(first, second));
}
else
{
return(new PlayRange(first.Duration + second.Duration));
}
}
internal static bool CanMerge(this IMediaSource mediaSource, PlayRange first, PlayRange second)
{
return(mediaSource.HasNativeDuration() ?
PlayRange.IsUnbroken(mediaSource.Adjust(first), mediaSource.Adjust(second)) : true);
}