Trouble with dynamic array of timage and tlabel in delphi - delphi

Question

I want to add an attachment, and have the form grow longer each time an attachment is added, to make room for a line that holds information about the attachment with a label and some 16X16 images. For this I chose to use a dynamic array (not sure whether that's best). each time an attachment is added, I want to create a new instance of these objects. My code doesn't seem to work. what's wrong with the follwing code?
procedure TVisionMail.AddAttachment(FileString: String);
var
I: Integer;
begin
AttCount := AttCount + 1; // increment attachment count
//set attachment file name
if (AttCount <> 0) and (edAttachment.Text <> '') then
edAttachment.text := edAttachment.text + ';';
edAttachment.text := edAttachment.text + FileString;
//move objects position down to allow space for attachment line
VisionMail.Height := VisionMail.Height + 25;
Panel1.Height := Panel1.Height + 25;
btnSend.Top := btnSend.Top + 25;
btnExit.Top := btnExit.Top + 25;
StatusMemo.Top := StatusMemo.Top + 25;
Memo1.Top := Memo1.Top + 25;
lblBody.Top := lblBody.Top + 25;
//Allocate memory for arrays
SetLength(newImg, AttCount);
SetLength(newlbl, AttCount);
SetLength(newDel, AttCount);
SetLength(newPin, AttCount);
//create new instance and set parents, positions, color, events
newImg[AttCount]:= TImage.Create(VisionMail);
with newImg[AttCount] do
begin
Parent := Panel1;
Top := Memo1.Top - 25;
Left := 408;
Height := 16;
Width := 16;
end;
newlbl[AttCount]:= TLabel.Create(VisionMail);
with newlbl[AttCount] do
begin
Parent := Panel1;
Top := newImg[I].Top + 2;
Left := 397;
Height := 3;
Width := 13;
BiDiMode := bdRightToLeft;
end;
newDel[AttCount] := TAdvToolButton.Create(VisionMail);
with newDel[AttCount] do
begin
Parent := Panel1;
Top := newImg[I].Top;
Left := 440;
Height := 16;
Width := 16;
color := clBtnFace;
colorChecked := clBtnFace;
colorDown := clBtnFace;
colorHot := clBtnFace;
OnClick := btnDelAttClick;
OnMouseEnter := btnDelAttMouseEnter;
OnMouseLeave := btnDelAttMouseLeave;
end;
newPin[AttCount] := TImage.Create(VisionMail);
with newDel[AttCount] do
begin
Parent := Panel1;
Top := newImg[I].Top;
Left := 425;
Height := 16;
Width := 16;
end;
//get Icon for extension of file
lstIcons.GetBitmap(GetIcon(ExtractFileExt
(OpenDialog1.FileName)),
newImg[AttCount].Picture.Bitmap);
newlbl[AttCount].Caption := ExtractFileName(FileString);
end;

Answer 1

The most obvious flaw is that you are writing off the end of all of your arrays. For example, you write
SetLength(newImg, AttCount);
and that means that the valid indices for newImg are 0 to AttCount-1 inclusive. But then you write
newImg[AttCount] := ...
and that is an out of bounds access because the last index is AttCount-1. You do the same for all your array access.
If you compile with range checking enabled, the compiler will generate a runtime error that explains what you have done wrong.
Personally I think you would be better using a record to hold your four components:
TAttachmentControls = record
Img: TImage;
Lbl: TLabel;
.. etc.
end;
And use a TList<TAttachmentControls> as your container.