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Console in GUI app and DLLs

Tue, 27 Aug 2002 00:06:59 -0700

Is it possible to create and use console screen in a GUI app?
Also can you tell me how can I use DLLs in Delphi.

Thanks.

Re: Console in GUI app and DLLs

Tue, 27 Aug 2002 05:55:12 -0700

: Is it possible to create and use console screen in a GUI app?

You can create a component that acts like a console screen. There is one nice one available at www.torry.net written by Danny Thorpe (a guy who works on Delphi over at Borland). I personally didnt like any of the ones available so wrote my own...if you are interested in writing your own as well I can give you more information on where to begin.

Re: Console in GUI app and DLLs

Tue, 27 Aug 2002 10:16:28 -0700

I'm new to Delphi so I don't think I could handle it. Anyway you could help me to get started.

I still prefere to use standart Console, so if anybody else know a way to do it please help me.

Re: Console in GUI app and DLLs

Tue, 27 Aug 2002 16:33:05 -0700

: Is it possible to create and use console screen in a GUI app?
: Also can you tell me how can I use DLLs in Delphi.
:
: Thanks.
:

Linking to a DLL:

If you want to import a routine from a DLL, the easiest way is a static link. Here is an example of a static link from the Windows unit:

function Beep(dwFreq, dwDuration: DWORD): BOOL; stdcall; external 'kernel32.dll';

This will automatically load the DLL into the memory, and retrieve the address of the function.
A more complex way to link to a DLL is called dynamic linking. Below is the same function, but then dynamically linked.

type
  TBeep=function(dwFreq, dwDuration: DWORD): BOOL; stdcall;
var
  BeepFunc: TBeep = nil;
  KernelDLL: THandle;
begin
  KernelDLL := LoadLibrary('kernel32.dll'); // load the DLL into memory
  if KernelDLL>HINSTANCE_ERROR then begin
    BeepFunc := GetProcAddress(FHandle,'Beep'); // Retrieve the procedure address
    if BeepFunc=nil then
      ShowMessage('Error finding beep in kernel32.dll')
    else 
      Beep(44000, 1000); // Play a tone for 1 second
    FreeLibrary(KernelDLL); // Remove the DLL from memory
  end else
    ShowMessage('Error loading kernel32.dll');
end;

Writing DLLs:

Below is a very simple example of a DLL project. As you can see this DLL isn't very useful, but it shows several features of a DLL.

library MyDLL; // <<< Note the word "library" instead of "program"

uses
  SysUtils;

function MyIntToStr(i: integer): string;
begin
  Result := IntToStr(i);
end;

function MyStrToInt(s: string): integer;
begin
  Result := StrToInt(s);
end;

exports
  MyStrToInt,
  MyIntToStr; // list of exported procedures

begin
  // No program code
end.

The procedures and functions are written as if they are part of a program. The names of the procedures to be exported are listed in the exports clause. These procedures can be linked as described above.
If you search for the word "exports" in the help files, you will find much more information about calling and writing DLLs.

My solution

Wed, 28 Aug 2002 03:25:18 -0700

I've created that class and it's working. I had problems with ReadConsole so I didn't include it. Since I'm a beginner in Delphi programming and I only spended few hours on it, I will finish this class later (add Read, colors, GotoXY and more).

unit console;

interface

   type TConsoleWnd = class
      private
         isCaption:string; {Caption}
         ibConsole:boolean; {the console already created ?}
         iiHIn,iiHOut,iiHErr:integer; {default i/o and error handles}

         procedure SetCaption(Value:string);
      public
         function CreateCon():boolean;
         function DestroyCon():boolean;
         function Write(str:string):boolean;
         function WriteLn(str:string):boolean;
         function Read(var buff:string):boolean;
         property Caption:string read isCaption write SetCaption;
   end;

implementation
uses SysUtils;

   function AllocConsole():integer; stdcall; external 'kernel32.dll';
   function FreeConsole():integer; stdcall; external 'kernel32.dll';
   function GetStdHandle(nStdHandle:integer):integer; stdcall; external 'kernel32.dll';
   const STD_INPUT_HANDLE :integer =      -10;
   const STD_OUTPUT_HANDLE :integer =     -11;
   const STD_ERROR_HANDLE :integer =      -12;


   function WriteConsole(hConsoleOutput:integer; lpBuffer:pchar;
                         nNumberOfCharsToWrite:integer;
                         var lpNumberOfCharsWritten:integer;
                         lpReserved:integer
         ):integer; stdcall; external 'kernel32.dll' name 'WriteConsoleA';

   function SetConsoleTitle (lpConsoleTitle:string):integer; stdcall; external 'kernel32.dll' name 'SetConsoleTitleA'


function TConsoleWnd.CreateCon():boolean;
begin
   if ibConsole then
      CreateCon:=false
   else begin
      AllocConsole;
      iiHIn:=GetStdHandle(STD_INPUT_HANDLE);
      iiHOut:=GetStdHandle(STD_OUTPUT_HANDLE);
      iiHErr:=GetStdHandle(STD_ERROR_HANDLE);
      ibConsole:=true;
      CreateCon:=true;
   end;
end;

function TConsoleWnd.DestroyCon():boolean;
begin
   if ibConsole then begin
      FreeConsole;
      ibConsole:=false;
      DestroyCon:=true;
   end else DestroyCon:=false;
end;

function TConsoleWnd.Write(str:string):boolean;
var num,l:integer;
begin
   if ibConsole then begin
      l:=length(str);
      WriteConsole(iiHOut, pchar(str), l,num,0);
      if l<>num then
         Write:=false
      else
         Write:=true;
   end else
      Write:=false;
end;

function TConsoleWnd.WriteLn(str:string):boolean;
var num,l:integer;
begin
   if ibConsole then begin
      l:=length(str);
      WriteConsole(iiHOut, pchar(str+#13+#10), l+2,num,0);
      if l<>num then
         WriteLn:=false
      else
         WriteLn:=true;
   end else
      WriteLn:=false;
end;

function TConsoleWnd.Read(var buff:string):boolean;
begin

end;


procedure TConsoleWnd.SetCaption(Value:string);
begin
   if ibConsole then begin
      isCaption:=Value;
      SetConsoleTitle(Value);
   end;
end;

end.