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### 15.3 Writing a custom mouse driver

The mouse 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.

Listing: mouseex/logmouse.pp

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.

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