[SOLVED] Correct way to pass ordinary String to WinAPI Unicode
functions
lazarus / 34-Windows

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flowCRANE · 2021-04-05 15:21

There are at least few ways to convert standard String variable and
pass the result as a PWideChar to Windows API functions with postfix
W. But I am looking for a solution that is, above all, correct, short
and will work without any problems on modern Windows (especially
Windows 10) and using the OBJFPC mode.

So, in my program I store all strings as a standard String type. Now I
need to pass two such strings to the ShellExecuteW function. These
strings are to include the directory path and the file name. The
function is to open a given directory in the file explorer and
highlight the given file (setting lpOperation to explore). What is the
correct way to pass such a strings to ShellExecuteW function?

Thanks for any suggestions.

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ASerge · 2021-04-05 15:59

Quote from: furious programming on April 05, 2021, 05:21:00 pmThere
are at least few ways to convert standard String variable and pass the
result as a PWideChar to Windows API functions with postfix W. But I
am looking for a solution that is, above all, correct, short and will
work without any problems on modern Windows (especially Windows 10)
and using the OBJFPC mode.

So, in my program I store all strings as a standard String type. Now I
need to pass two such strings to the ShellExecuteW function. These
strings are to include the directory path and the file name. The
function is to open a given directory in the file explorer and
highlight the given file (setting lpOperation to explore). What is the
correct way to pass such a strings to ShellExecuteW function?
Use UnicodeString:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i {$MODE
OBJFPC} uses Windows, ActiveX, ShellApi; procedure
SelectFileInExplorer(const FileName: string);var  Params:
UnicodeString;begin  Params := ' /select, ' + UTF8Decode(FileName); 
ShellExecuteW(0, nil, 'explorer.exe', PWideChar(Params), nil,
SW_SHOW);end; begin  SetMultiByteConversionCodePage(CP_UTF8); //
Lazarus compatible  CoInitializeEx(nil, COINIT_APARTMENTTHREADED or
COINIT_DISABLE_OLE1DDE); 
SelectFileInExplorer('c:\Windows\system.ini');end.

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Aidex · 2021-04-05 16:10

I use this line ...
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i SysUtils.Ex
ecuteProcess(UnicodeString('explorer.exe'),UnicodeString('/select,"'+f
n+'"'),[]);

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Remy Lebeau · 2021-04-05 17:45

Quote from: Aidex on April 05, 2021, 06:10:04 pmI use this line ...
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i SysUtils.Ex
ecuteProcess(UnicodeString('explorer.exe'),UnicodeString('/select,"'+f
n+'"'),[]); 
Are the typecasts really necessary?  ExecuteProcess() is overloaded
for RawByteString and UnicodeString, so if the type-casts are removed:

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i
SysUtils.ExecuteProcess('explorer.exe', '/select,"'+fn+'"', []); 
Then, if String is a (UTF-8 encoded) AnsiString then the RawByteString
overload will be called, otherwise String will be UnicodeString so the
UnicodeString overload will be called instead.

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Aidex · 2021-04-05 18:00

The Unicode typecast is not necessary.
I only use it because I saw in the Windows specific sourcecodes of
FreePascal that there is always a typecast to Unicode done internally.
Therefore I got used to use UnicodeString for paths and filenames if
possible. At least under Windows it is no disadvantage, I think.
Since in my other source codes the filename is already defined as
UnicodeString, I did so.

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flowCRANE · 2021-04-05 18:51

To this day, I have used two ways to convert — one was:

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i
PWideChar(UnicodeString(MyString))
and the other was:

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i
PWideChar(UTF8ToUTF16(MyString))
Both worked, without any extra things. But I found it strange that the
same conversion (regular String to PWideChar) could be solved in
different ways. It seemed to me that they are not unambiguous. And now
@ASerge gave another one, this time using the UTF8Decode function and
UnicodeString as a temp variable (and other initialization functions,
which is more complex that simple casting/converting).

Actually all these ways are correct?

Ultimately, I used ExecuteProcess because it allows me to skip the
conversion (there is a version for RawByteString), and secondly, I can
open the directory in the file explorer and additionally select the
file, if it should be selected. The only problem is that I can't
select multiple files this way — I tried various ways to use the
/select parameter, but it didn't do anything.

Anyone have an idea how to open a directory in the system file
explorer and highlight a few files? Is such a thing possible?

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ASerge · 2021-04-05 18:59

Quote from: furious programming on April 05, 2021, 08:51:55 pmAnyone
have an idea how to open a directory in the system file explorer and
highlight a few files? Is such a thing possible?
See SHOpenFolderAndSelectItems.

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flowCRANE · 2021-04-05 19:08

Ok, thanks for the reply. But in my project this is additional
feature, so I will consider its implementation. Thank you all for
help, problems solved.