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Reference Guide
TGeoGlobalMagField.cxx
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1 // @(#)root/geom:$Id$
2 
3 /*************************************************************************
4  * Copyright (C) 1995-2000, Rene Brun and Fons Rademakers. *
5  * All rights reserved. *
6  * *
7  * For the licensing terms see $ROOTSYS/LICENSE. *
8  * For the list of contributors see $ROOTSYS/README/CREDITS. *
9  *************************************************************************/
10 
11 #include "TROOT.h"
12 #include "TGeoGlobalMagField.h"
13 
14 /** \class TGeoGlobalMagField
15 \ingroup Geometry_classes
16 
17 Global magnetic field manager. Provides access to
18 and owns the actual magnetic field set via `SetField()`. The field is deleted
19 upon destruction of the field manager at the end of ROOT session or
20 by calling:
21 
22 ~~~ {.cpp}
23 TGeoGlobalMagField::Instance()->SetField(0).
24 ~~~
25 
26 The previous global field is deleted upon replacement with notification.
27 
28 The global field manager provides access to the global field via:
29 
30 ~~~ {.cpp}
31  TGeoGlobalMagField::Instance()->GetField()
32 ~~~
33 
34 One can directly call the Field() method of a field via the global field manager:
35 
36 ~~~ {.cpp}
37  TGeoGlobalMagField::Instance()->Field(x,B)
38 ~~~
39 */
40 
42 
44 
45 ////////////////////////////////////////////////////////////////////////////////
46 /// Global field default constructor.
47 
49 {
50  fField = NULL;
51  fLock = kFALSE;
52  if (fgInstance) {
54  if (field)
55  Fatal("TGeoGlobalMagField", "A global field manager already existing and containing a field. \
56  \n If you want a new global field please set it via: \
57  \n TGeoGlobalMagField::Instance()->SetField(myField).");
58  else
59  Warning("TGeoGlobalMagField", "A global field manager already existing. Please access via: \
60  \n TGeoGlobalMagField::Instance().");
61  delete fgInstance;
62  }
63  gROOT->GetListOfGeometries()->Add(this); // list of cleanups not deleted
64  fgInstance = this;
65 }
66 
67 ////////////////////////////////////////////////////////////////////////////////
68 /// Global field destructor.
69 
71 {
72  gROOT->GetListOfGeometries()->Remove(this);
73  if (fField) {
74  TVirtualMagField *field = fField;
75  fField = NULL;
76  delete field;
77  }
78  fgInstance = NULL;
79 }
80 
81 ////////////////////////////////////////////////////////////////////////////////
82 /// Field setter. Deletes previous field if any. Acts only if fLock=kFALSE.
83 
85 {
86  if (field==fField) return;
87  // Check if we are allowed to change the old field.
88  if (fField) {
89  if (fLock) {
90  Error("SetField", "Global field is already set to <%s> and locked", fField->GetName());
91  return;
92  }
93  // We delete the old global field and notify user.
94  Info("SetField", "Previous magnetic field <%s> will be deleted", fField->GetName());
95  TVirtualMagField *oldfield = fField;
96  fField = NULL;
97  delete oldfield;
98  }
99  fField = field;
100  if (fField) Info("SetField", "Global magnetic field set to <%s>", fField->GetName());
101 }
102 
103 ////////////////////////////////////////////////////////////////////////////////
104 /// Static getter that does not create the object.
105 
107 {
108  return fgInstance;
109 }
110 
111 ////////////////////////////////////////////////////////////////////////////////
112 /// Returns always a valid static pointer to the field manager.
113 
115 {
116  if (fgInstance) return fgInstance;
117  return new TGeoGlobalMagField();
118 }
119 
120 ////////////////////////////////////////////////////////////////////////////////
121 /// Locks the global magnetic field if this is set. Cannot be unlocked.
122 
124 {
125  if (!fField) {
126  Warning("Lock", "Cannot lock global magnetic field since this was not set yet");
127  return;
128  }
129  fLock = kTRUE;
130  Info("Lock", "Global magnetic field <%s> is now locked", fField->GetName());
131 }
virtual const char * GetName() const
Returns name of object.
Definition: TNamed.h:47
virtual void Info(const char *method, const char *msgfmt,...) const
Issue info message.
Definition: TObject.cxx:854
TVirtualMagField * GetField() const
static TGeoGlobalMagField * Instance()
Returns always a valid static pointer to the field manager.
#define gROOT
Definition: TROOT.h:415
TGeoGlobalMagField()
Global field default constructor.
virtual ~TGeoGlobalMagField()
Global field destructor.
virtual void Error(const char *method, const char *msgfmt,...) const
Issue error message.
Definition: TObject.cxx:880
Global magnetic field manager.
static TGeoGlobalMagField * GetInstance()
Static getter that does not create the object.
static TGeoGlobalMagField * fgInstance
const Bool_t kFALSE
Definition: RtypesCore.h:88
#define ClassImp(name)
Definition: Rtypes.h:365
Abstract class for magnetic field.
TVirtualMagField * fField
void Lock()
Locks the global magnetic field if this is set. Cannot be unlocked.
virtual void Fatal(const char *method, const char *msgfmt,...) const
Issue fatal error message.
Definition: TObject.cxx:908
const Bool_t kTRUE
Definition: RtypesCore.h:87
virtual void Warning(const char *method, const char *msgfmt,...) const
Issue warning message.
Definition: TObject.cxx:866
void SetField(TVirtualMagField *field)
Field setter. Deletes previous field if any. Acts only if fLock=kFALSE.