Optimizing work with an array of records - arrays

Question

I have the following object with an array of a record type:
type
TTimeMark = record
// many fields here
end;
TTimeMarks = array of TTimeMark;
TUserProfile = class(TObject)
TimeLine: TTimeMarks;
....
end;
In this list TUserProfile.TimeLine will be inserted items at run time. I don't know a method of inserting items other than increasing the lenghth of the array with one and then moving all the items a place down until I reach the desired possition. But in this array, the items are records with many fields, so, if I do TimeLine[I]:= TimeLine[I-1], all the data in the memory will be copied from one place to another (am I right ?), and this will take some time. Do you think should I use an array of pointers of that record, instead ? Or is there other fast method to do this ?

Answer 1

This is how I've done.. I used an array of pointers and I make some procedures to easy add, delete and move items:
TPointerArray = array of Pointer;
procedure PArrayInsert(var AArray: TPointerArray; Position: Integer; Count: Integer = 1);
var L, CTail: Integer;
begin
L:= Length(AArray);
if (Count = 0) or (Position > L) then Exit;
SetLength(AArray, L + Count);
CTail:= L - Position;
if CTail > 0 then
Move(AArray[Position], AArray[Position+Count], CTail * SizeOf(Pointer));
end;
procedure PArrayDelete(var AArray: TPointerArray; Position: Integer; Count: Integer = 1);
var L, CTail: Integer;
begin
L:= Length(AArray);
if (L = 0) or (Count = 0) or (Position >= L) or ((Position+Count) > L) then Exit;
CTail:= L - (Position + Count);
if CTail > 0 then
Move(AArray[Position+Count], AArray[Position], CTail * SizeOf(Pointer));
SetLength(AArray, L - Count);
end;
function PArrayMove(var AArray: TPointerArray; FromIndex, ToIndex: Integer; Count: Integer = 1): Boolean;
var L, Size, CT: Integer;
Buff: Pointer;
begin
Result:= False;
L:= High(AArray);
if (FromIndex > L) or (ToIndex > L+1) or
((ToIndex >= FromIndex) and (ToIndex <= (FromIndex+Count))) then Exit;
Size:= Count * SizeOf(Pointer);
GetMem(Buff, Size);
Move(AArray[FromIndex], Buff^, Size);
if FromIndex > ToIndex then begin
CT:= FromIndex - ToIndex;
Move(AArray[ToIndex], AArray[FromIndex+Count-CT], CT * SizeOf(Pointer));
Move(Buff^, AArray[ToIndex], Size);
end
else begin
CT:= ToIndex - FromIndex - Count;
Move(AArray[FromIndex+Count], AArray[FromIndex], CT * SizeOf(Pointer));
Move(Buff^, AArray[FromIndex+CT], Size);
end;
FreeMem(Buff);
Result:= True;
end;