Operations related to the Delphi and Inno Setup files

Procedure tform1.button1click (Sender: tobject );
VaR
Reg: Tregistry;
Begin
Reg: = Tregistry. Create;
Reg. rootkey: = hkey_classes_root;

{Add our virtual. TST format in the registry, and specify the default value as testfile}
Reg. openkey ('. tst', true );
Reg. writestring ('', 'testfile ');
Reg. closekey;

{File opening Association}
Reg. openkey ('testfile \ shell \ open \ command', true );
Reg. writestring ('', paramstr (0) + '% 1 ');
Reg. closekey;

{File icon Association}
Reg. openkey ('testfile \ defaulticon ', true );
Reg. writestring ('', paramstr (0) + ', 0 ');
Reg. closekey;

Reg. Free;

{Refresh icon display}
Shchangenovel (shcn_assocchanged, shcnf_idlist, nil, nil );
End;

{Clear settings above}
Procedure tform1.button2click (Sender: tobject );
VaR
Reg: Tregistry;
Begin
Reg: = Tregistry. Create;
Reg. rootkey: = hkey_classes_root;
Reg. deletekey ('. tst ');
Reg. deletekey ('testfile ');
Reg. Free;
Shchangenovel (shcn_assocchanged, shcnf_idlist, nil, nil );
End;

You can also manually set file associations by opening a folder-tools-Folder Options-"file type" tab-and clicking "advanced ".

It is very convenient to use Inno. Instead of writing code, simply use the [registry] segment. For example:
[Registry]
Root: hkcr; subkey: "Real Media File"; valuetype: string; valuedata: "Real Media File"; flags: uninsdeletekey
Root: hkcr; subkey: "Real Media file \ defaulticon"; valuetype: string; valuedata: "{app} \ ABC. ICO"; flags: uninsdeletekey
Root: hkcr; subkey: "Real Media file \ shell \ open \ command"; valuetype: string; valuedata: "{app} \ myplayer.exe % 1"; flags: uninsdeletekey
Root: hkcr; subkey: "Real Media file \ shell \ open (& O) \ command" with my player; valuetype: string; valuedata: "{app} \ myplayer.exe % 1"; flags: uninsdeletekey
Root: hkcr; subkey: "*. rmvb"; valuetype: string; valuedata: "Real Media File"; flags: uninsdeletekey
Root: hkcr; subkey: "*. rm"; valuetype: string; valuedata: "Real Media File"; flags: uninsdeletekey
Root: hkcr; subkey: "*. Ra"; valuetype: string; valuedata: "Real Media File"; flags: uninsdeletekey