Writing a custom mouse driver

The mouse unit has support for adding a custom mouse driver. This can be used to add support for mouses not supported by the standard Free Pascal driver, but also to enhance an existing driver for instance to log mouse events or to implement a record and playback function.

The following unit shows how a mouse driver can be enhanced by adding some logging capabilities to the driver.

Example

unit logmouse;
interface
Procedure StartMouseLogging;
Procedure StopMouseLogging;
Function  IsMouseLogging : Boolean;
Procedure SetMouseLogFileName(FileName : String);
implementation
uses sysutils,Mouse;
var
  NewMouseDriver,
  OldMouseDriver : TMouseDriver;
  Active,Logging : Boolean;
  LogFileName : String;
  MouseLog : Text;
Function TimeStamp : String;
begin
  TimeStamp:=FormatDateTime('hh:nn:ss',Time());
end;
Procedure StartMouseLogging;
begin
  Logging:=True;
  Writeln(MouseLog,'Start logging mouse events at: ',TimeStamp);
end;
Procedure StopMouseLogging;
begin
  Writeln(MouseLog,'Stop logging mouse events at: ',TimeStamp);
  Logging:=False;
end;
Function IsMouseLogging : Boolean;
begin
  IsMouseLogging:=Logging;
end;
Procedure LogGetMouseEvent(Var Event : TMouseEvent);
Var
  M : TMouseEvent;
begin
  OldMouseDriver.GetMouseEvent(M);
  If Logging then
    begin
    Write(MouseLog,TimeStamp,': Mouse ');
    With M do
      begin
      Case Action of
        MouseActionDown : Write(MouseLog,'down');
        MouseActionUp   : Write(MouseLog,'up');
        MouseActionMove : Write(MouseLog,'move');
      end;
      Write(MouseLog,' event at ',X,',',Y);
      If (Buttons<>0) then
        begin
        Write(MouseLog,' for buttons: ');
        If (Buttons and MouseLeftbutton)<>0 then
          Write(MouseLog,'Left ');
        If (Buttons and MouseRightbutton)<>0 then
          Write(MouseLog,'Right ');
        If (Buttons and MouseMiddlebutton)<>0 then
          Write(MouseLog,'Middle ');
        end;
      Writeln(MouseLog);
      end;
    end;
end;
Procedure LogInitMouse;
begin
  OldMouseDriver.InitDriver();
  Assign(MouseLog,logFileName);
  Rewrite(MouseLog);
  Active:=True;
  StartMouseLogging;
end;
Procedure LogDoneMouse;
begin
  StopMouseLogging;
  Close(MouseLog);
  Active:=False;
  OldMouseDriver.DoneDriver();
end;
Procedure SetMouseLogFileName(FileName : String);
begin
  If Not Active then
    LogFileName:=FileName;
end;
Initialization
  GetMouseDriver(OldMouseDriver);
  NewMouseDriver:=OldMouseDriver;
  NewMouseDriver.GetMouseEvent:=@LogGetMouseEvent;
  NewMouseDriver.InitDriver:=@LogInitMouse;
  NewMouseDriver.DoneDriver:=@LogDoneMouse;
  LogFileName:='Mouse.log';
  Logging:=False;
  SetMouseDriver(NewMouseDriver);
end.