public static IEnumerable<TextRunLine> ToLines( Paragraph para, int maxwidth )
{
int length = para.Length;
var start = new ParagraphIterator() { Paragraph = para };
if ( !start.TryFindAdvance((ch)=>ch!=' ') ) yield break;
var end = start;
end.TryFindAdvance((ch)=>ch==' ');
start.Rewind();
for (;;) {
bool createline = false;
if ( end.Run >= para.Runs ) createline = true;
if (!createline) {
var possibleend = end;
possibleend.TryFindAdvance((ch)=>ch!=' ');
possibleend.TryFindAdvance((ch)=>ch==' ');
if ( MeasureLine(start,possibleend).Bounds.Width > maxwidth ) {
createline = true;
} else {
end = possibleend;
continue;
}
}
if (createline) {
yield return new TextRunLine(start,end);
if ( end.Run >= para.Runs ) yield break;
start = end;
start.TryFindAdvance((ch)=>ch!=' ');
if ( start.Run >= para.Runs ) yield break;
end = start;
end.TryFindAdvance((ch)=>ch==' ');
}
}
}
