windows 使用 SYSTEMTIME、FILETIME 和 ULARGE_INTEGER 修改日期和时间值
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Modifying the date and time values using SYSTEMTIME, FILETIME, and ULARGE_INTEGER
提问by Seb
I am making a program, in C++ using Visual Studio 2005, that needs to create a watermark with the time on a set of images.
我正在使用 Visual Studio 2005 在 C++ 中制作一个程序，该程序需要在一组图像上创建带有时间的水印。
These images are taken from a video that were processed at certain time intervals. What I am trying to do is to modify the time on each image through SYSTEMTIME. I looked at the MSDN and it says not to modify the values within SYSTEMTIME itself, but to convert it into a FILETIME and then an ULARGE_INTEGER. My question is how is the ULARGE_INTEGER split up? Is the HighPart the date and the Low Part the time and if that's the case how to I take into account rollover? Like if a image shows up at 11:58pm on 2/25/2011 and goes through until 12:11 2/26/2011? Would just adding the specified value automatically be taken into account and shown when I convert it back into a SYSTEMTIME variable?
这些图像取自以特定时间间隔处理的视频。我想要做的是通过SYSTEMTIME修改每个图像上的时间。我查看了 MSDN，它说不要修改 SYSTEMTIME 本身内的值，而是将其转换为 FILETIME，然后是 ULARGE_INTEGER。我的问题是 ULARGE_INTEGER 是如何拆分的？HighPart 是日期，Low Part 是时间，如果是这种情况，我该如何考虑翻转？就像图像在 2/25/2011 的晚上 11:58 显示并一直显示到 2/26/2011 的 12:11 一样？当我将其转换回 SYSTEMTIME 变量时，是否会自动考虑并显示添加指定的值？
Thanks in advance for your help.
在此先感谢您的帮助。
采纳答案by xtofl
They suggest converting SYSTEMTIMEto FILETIME, which is a number of ticks since an epoch. You can then add the required number of 'ticks' (i.e. 100ns intervals) to indicate yourtime, and convert back to SYSTEMTIME.
他们建议转换SYSTEMTIME为FILETIME，这是一个纪元以来的刻度数。然后，您可以添加所需数量的“滴答”（即 100ns 间隔）以指示您的时间，然后转换回SYSTEMTIME.
The ULARGE_INTEGERstruct is a union with a QuadPartmember, which is a 64bit number, that can be directly added to (on recent hardware).
该ULARGE_INTEGER结构是具有一个联盟QuadPart成员，这是一个64位的数，即可以直接加入到（最近的硬件）。
SYSTEMTIME add( SYSTEMTIME s, double seconds ) {
FILETIME f;
SystemTimeToFileTime( &s, &f );
ULARGE_INTEGER u ;
memcpy( &u , &f , sizeof( u ) );
const double c_dSecondsPer100nsInterval = 100.*1.e-9;
const double c_dNumberOf100nsIntervals =
seconds / c_dSecondsPer100nsInterval;
// note: you may want to round the number of intervals.
u.QuadPart += c_dNumberOf100nsIntervals;
memcpy( &f, &u, sizeof( f ) );
FileTimeToSystemTime( &f, &s );
return s;
}
