private static IEnumerable <AssLine> CreateFrameLines(AssDocument document, AssLine originalLine, TimeRange timeRange, List <AnimationWithSectionIndex> animations)
{
int rangeStartFrame = TimeUtil.StartTimeToFrame(timeRange.Start);
int rangeEndFrame = TimeUtil.EndTimeToFrame(timeRange.End);
const int frameStepSize = 2;
int subStepFrames = (rangeEndFrame + 1 - rangeStartFrame) % frameStepSize;
int lastIterationFrame = rangeEndFrame + 1 - subStepFrames - frameStepSize;
bool needTextReset = animations.Any(a => a.Animation.AffectsText);
AssLine frameLine = originalLine;
for (int frame = rangeStartFrame; frame <= lastIterationFrame; frame += frameStepSize)
{
frameLine = (AssLine)frameLine.Clone();
frameLine.Start = TimeUtil.FrameToStartTime(frame);
frameLine.End = frame < lastIterationFrame?TimeUtil.FrameToEndTime(frame + frameStepSize - 1) : timeRange.End;
frameLine.Position = originalLine.Position ?? document.GetDefaultPosition(originalLine.AnchorPoint);
if (needTextReset)
{
ResetText(frameLine, originalLine);
}
float interpFrame = frame + (frameStepSize - 1) / 2.0f;
foreach (AnimationWithSectionIndex animWithSection in animations)
{
int animStartFrame = TimeUtil.StartTimeToFrame(animWithSection.Animation.StartTime);
int animEndFrame = TimeUtil.EndTimeToFrame(animWithSection.Animation.EndTime);
if (interpFrame >= animStartFrame && interpFrame < animEndFrame)
{
float t = (interpFrame - animStartFrame) / (animEndFrame - animStartFrame);
ApplyAnimation(frameLine, animWithSection, t);
}
else if (interpFrame >= animEndFrame && interpFrame < animEndFrame + frameStepSize)
{
ApplyAnimation(frameLine, animWithSection, 1);
}
}
yield return(frameLine);
}
}
