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Sometimes we need a quick and easy way to download a file from the Internet, and these days HTTPS is the way to go.
Unfortunately, most tools for Lazarus require OpenSSL (Indy, Synapse, etc), which means you'd have to distribute OpenSSL DLL's with your application, something I'd like to avoid for simple downloads.
The fix is using Windows Internet (WinINet) application programming interface (API), with the following code using the wininet unit (source):
Uses ... wininet ...
... function GetWebPage(const Url: string): string;
var
NetHandle: HINTERNET;
UrlHandle: HINTERNET;
Buffer: array[0..1023] of Byte;
BytesRead: dWord;
StrBuffer: UTF8String;
begin
Result := '';
BytesRead := Default(dWord);
NetHandle := InternetOpen('Mozilla/5.0(compatible; WinInet)', INTERNET_OPEN_TYPE_PRECONFIG, nil, nil, 0);
// NetHandle valid?
if Assigned(NetHandle) then
Try
UrlHandle := InternetOpenUrl(NetHandle, PChar(Url), nil, 0, INTERNET_FLAG_RELOAD, 0);
// UrlHandle valid?
if Assigned(UrlHandle) then
Try
repeat
InternetReadFile(UrlHandle, @Buffer, SizeOf(Buffer), BytesRead);
SetString(StrBuffer, PAnsiChar(@Buffer[0]), BytesRead);
Result := Result + StrBuffer;
until BytesRead = 0;
Finally
InternetCloseHandle(UrlHandle);
end
// o/w UrlHandle invalid
else
ShowMessage('Cannot open URL: ' + Url);
Finally
InternetCloseHandle(NetHandle);
end
// NetHandle invalid
else
raise Exception.Create('Unable to initialize WinInet');
end;
{$ENDIF}
