File access error programming in Delphi 7 using ReWrite(f) - delphi-7

Question

Spent 2 hours looking at similar issues and used IsFileInUse, and sure enough it is in use. It loads a jpg image using MapObjectsLt and though I do understand a little of file locking, this software worked perfectly under Windows 7, which we used at work. Now I have moved to Windows 10 on a new laptop, and it only now gives an error. Myself and windows explorer are the only users I am aware of so no one else has that small text file which positions the image when open. I think the difference lies in Windows. I used ProcExp.exe to look at the processes that might be locking/using that file and it could not find that small 6 line file. I changed my code and first unloaded the image before changing the jgw/text file, after which it reloads and is repositioned. If MapObjectsLt locked the file and Windows 7 allowed the change?? Do I change this in code somehow ie force the removal of a handle knowing no one that matters is using the file??
procedure SaveWorldFile(FileName:TFileName);
var f:TextFile; i:Integer; Ext:String[4]; ImageFile:TFileName;
begin
ImageFile:=FileName;
if Pos('.SID',UpperCase(FileName))<>0 then Ext:='.sdw' else
if Pos('.JPG',UpperCase(FileName))<>0 then Ext:='.jgw' else Ext:='.tfw';
FileName:=ChangeFileExt(FileName,Ext);
//tried to close the handle in this function..because
//I believe at this point I am the only one using this file.
//Did not work but was part of my hunt for a solution
//I used for a different reason but found on this site
IsFileInUse(FileName);
//This section worked before and last line reloads the image
//The image is "untouched" only its position changes
//This worked under Windows 7 now Windows 10 does not
AssignFile(f,FileName);
ReWrite(f); //error under Windows 10
for i:=1 to 6 do WriteLn(f,P[i]:0:8);
CloseFile(f);
//Now reload the image
frmWRM.AddImageLayer(ImageFile);
end;

Answer 1

I have found the solution on your site, after hours of following what I thought was a Windows 10 error. It was the permissions on files copied to a hard drive. Once changed my software was working as per normal. Thanks for the hint from your site.