Dez dicas de Delphi - parte 3

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Veja mais dez dicas de Delphi

Dez dicas de Delphi

1. Fazendo uma janela filha de outra sem usar MDI                                                                    

procedure TForm2.CreateParams(var Params: TCreateParams);
begin
  inherited CreateParams(Params); { call the inherited first }
  with Params do
  begin
    Style := Style or WS_CHILD; { add a style flag }
    WndParent := Application.MainForm.Handle;
  end;
end;                                                                                                                         

2. Abrindo e Fechando a bandeja do drive de CD-ROM                                                                     

Para Abrir:
mciSendString('Set cdaudio door open wait', nil, 0, handle);

Para Fechar:
mciSendString('Set cdaudio door open wait', nil, 0, handle);
                                                                                                                            

3. Obtendo a Data e a Hora de um Arquivo                                                                                     

function GetFileDate(Arquivo: String): String;
var FHandle: integer;
begin
  FHandle := FileOpen(Arquivo, 0);
  try
    Result := DateTimeToStr(FileDateToDateTime(FileGetDate(FHandle)));
  finally
    FileClose(FHandle);
  end;
end;
                                                                                                                             

4. Testando a impressora se está OnLine                                                                                      

function PrinterOnLine : Boolean;
Const
  PrnStInt : Byte = $17;
  StRq : Byte = $02;
  PrnNum : Word = 0; { 0 para LPT1, 1 para LPT2, etc. }
Var nResult : byte;
Begin (* PrinterOnLine*)
  Asm
    mov ah,StRq;
    mov dx,PrnNum;
    Int $17;
    mov nResult,ah;
  end;
  PrinterOnLine := (nResult and $80) = $80;
End;
                                                                                                                             

5. Obtendo a letra do drive de CD-ROM                                                                                        

function FindFirstCDROMDrive: Char;
var
  drivemap, mask: DWORD;
  i: Integer;
  root: String;
begin
  Result := #0;
  root := 'A:\';
  drivemap := GetLogicalDrives;
  mask := 1;
  for i:= 1 To 32 Do
  begin
    if (mask and drivemap) <> 0 Then
      if GetDriveType( PChar(root) ) = DRIVE_CDROM Then
      begin
        Result := root[1];
        Break;
      end;
    mask := mask shl 1;
    Inc( root[1] );
  End;
End;

6. Obtendo o número serial do HD                                                                                             

function SerialNumber(FDrive:String) :String;
var
  Serial:DWord;
  DirLen,Flags: DWord;
  DLabel : Array[0..11] of Char;
begin
  Try
    GetVolumeInformation(PChar(FDrive+':\'),dLabel,12,@Serial,DirLen,Flags,nil,0);
    Result := IntToHex(Serial,8);
  Except
    Result :='';
  end;
end;
                                                                                                                             

7. Converte um número binário para inteiro                

function BinToInt(Value: String): LongInt;
{Converte um numero binário em Inteiro}
var i,Size: Integer;
begin
  Result := 0;
  Size := Length(Value);
  for i:=Size downto 0 do
    if Copy(Value,i,1)='1' then
      Result := Result+(1 shl i);
end;

8. Alterar atributos de um arquivo                

var Attrib: integer;
begin
  Attrib:=FileGetAttr('C:\ARQUIVO.XYZ');
  if Attrib<>-1 then
  begin
    Attrib:=Attrib and not faReadOnly;
    if FileSetAttr('C:\ARQUIVO.XYZ', Attrib)=0 then
      Alteração Efetuada
    else Windows code error;
  end;
end;

9. Carregando um cursor animado                

procedure TForm1.Button2Click(Sender: TObject);
const cnCursorID = 1;
begin
  Screen.Cursors[cnCursorID]:=LoadCursorFromFile('drive:\caminho\arquivo.ani' );
  Cursor := cnCursorID;
end;

10. Definindo o tamanho Mínimo e Máximo de um Formulário                


procedure TForm1.WMGetMinMaxInfo(var MSG: TMessage);
begin
  inherited;
  with PMinMaxInfo(MSG.lparam)^ do
  begin
    ptMinTRackSize.X := 300;
    ptMinTRackSize.Y := 150;
    ptMaxTRackSize.X := 350;
    ptMaxTRackSize.Y := 250;
  end;
end;

 
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