ROOT » HIST » HISTPAINTER » TGraphPainter

class TGraphPainter: public TVirtualGraphPainter


The graph painter class

Introduction

Graphs are drawn via the painter TGraphPainter class. This class implements techniques needed to display the various kind of graphs i.e.: TGraph, TGraphErrors, TGraphBentErrors and TGraphAsymmErrors.

To draw a graph "graph" it's enough to do:

   graph->Draw("AL");

The option "AL" in the Draw() method means:

  1. The axis should be drawn (option "A"),
  2. The graph should be drawn as a simple line (option "L").
By default a graph is drawn in the current pad in the current coordinate system. To define a suitable coordinate system and draw the axis the option "A" must be specified.

TGraphPainter offers many options to paint the various kind of graphs.

It is separated from the graph classes so that one can have graphs without the graphics overhead, for example in a batch program.

When a displayed graph is modified, there is no need to call Draw() again; the image will be refreshed the next time the pad will be updated.

A pad is updated after one of these three actions:

  1. a carriage return on the ROOT command line,
  2. a click inside the pad,
  3. a call to TPad::Update.

Graphs' plotting options

Graphs can be drawn with the following options:

"A" Axis are drawn around the graph
"L" A simple polyline is drawn
"F" A fill area is drawn ('CF' draw a smoothed fill area)
"C" A smooth Curve is drawn
"*" A Star is plotted at each point
"P" The current marker is plotted at each point
"B" A Bar chart is drawn
"1" When a graph is drawn as a bar chart, this option makes the bars start from the bottom of the pad. By default they start at 0.
"X+" The X-axis is drawn on the top side of the plot.
"Y+" The Y-axis is drawn on the right side of the plot.

Drawing options can be combined. In the following example the graph is drawn as a smooth curve (option "C") with markers (option "P") and with axes (option "A").

output of htmldoc/MACRO_TGraphPainter_1.gif
{
   TCanvas *c1 = new TCanvas("c1","c1",200,10,600,400);

   c1->SetFillColor(42);
   c1->SetGrid();

   const Int_t n = 20;
   Double_t x[n], y[n];
   for (Int_t i=0;i<n;i++) {
      x[i] = i*0.1;
      y[i] = 10*sin(x[i]+0.2);
   }
   gr = new TGraph(n,x,y);
   gr->SetLineColor(2);
   gr->SetLineWidth(4);
   gr->SetMarkerColor(4);
   gr->SetMarkerSize(1.5);
   gr->SetMarkerStyle(21);
   gr->SetTitle("Option ACP example");
   gr->GetXaxis()->SetTitle("X title");
   gr->GetYaxis()->SetTitle("Y title");
   gr->Draw("ACP");

   // TCanvas::Update() draws the frame, after which one can change it
   c1->Update();
   c1->GetFrame()->SetFillColor(21);
   c1->GetFrame()->SetBorderSize(12);
   c1->Modified();
   return c1;
}

The following macro shows the option "B" usage. It can be combined with the option "1".

output of htmldoc/MACRO_TGraphPainter_3.gif
{
   TCanvas *c47 = new TCanvas("c47","c47",200,10,600,400);
   c47->Divide(1,2);
   const Int_t n = 20;
   Double_t x[n], y[n];
   for (Int_t i=0;i<n;i++) {
      x[i] = i*0.1;
      y[i] = 10*sin(x[i]+0.2)-6;
   }
   gr = new TGraph(n,x,y);
   gr->SetFillColor(38);
   c47->cd(1); gr->Draw("AB");
   c47->cd(2); gr->Draw("AB1");
 return c47;
}

Exclusion graphs

When a graph is painted with the option "C" or "L" it is possible to draw a filled area on one side of the line. This is useful to show exclusion zones.

This drawing mode is activated when the absolute value of the graph line width (set by SetLineWidth()) is greater than 99. In that case the line width number is interpreted as:

      100*ff+ll = ffll
  • The two digits number "ll" represent the normal line width
  • The two digits number "ff" represent the filled area width.
  • The sign of "ffll" allows to flip the filled area from one side of the line to the other.
The current fill area attributes are used to draw the hatched zone.
output of htmldoc/MACRO_TGraphPainter_5.gif
TCanvas *exclusiongraph() {
   // Draw three graphs with an exclusion zone.
   //Author: Olivier Couet

   TCanvas *c1 = new TCanvas("c1","Exclusion graphs examples",200,10,600,400);
   c1->SetGrid();

   TMultiGraph *mg = new TMultiGraph();
   mg->SetTitle("Exclusion graphs");

   const Int_t n = 35;
   Double_t x1[n], x2[n], x3[n], y1[n], y2[n], y3[n];
   for (Int_t i=0;i<n;i++) {
     x1[i]  = i*0.1;
     x2[i]  = x1[i];
     x3[i]  = x1[i]+.5;
     y1[i] = 10*sin(x1[i]);
     y2[i] = 10*cos(x1[i]);
     y3[i] = 10*sin(x1[i])-2;
   }

   TGraph *gr1 = new TGraph(n,x1,y1);
   gr1->SetLineColor(2);
   gr1->SetLineWidth(1504);
   gr1->SetFillStyle(3005);

   TGraph *gr2 = new TGraph(n,x2,y2);
   gr2->SetLineColor(4);
   gr2->SetLineWidth(-2002);
   gr2->SetFillStyle(3004);
   gr2->SetFillColor(9);

   TGraph *gr3 = new TGraph(n,x3,y3);
   gr3->SetLineColor(5);
   gr3->SetLineWidth(-802);
   gr3->SetFillStyle(3002);
   gr3->SetFillColor(2);

   mg->Add(gr1);
   mg->Add(gr2);
   mg->Add(gr3);
   mg->Draw("AC");

   return c1;
}

Graphs with error bars

Three classes are available to handle graphs with error bars: TGraphErrors, TGraphAsymmErrors and TGraphBentErrors. The following drawing options are specific to graphs with error bars:

"Z" Do not draw small horizontal and vertical lines the end of the error bars. Without "Z", the default is to draw these.
">" An arrow is drawn at the end of the error bars. The size of the arrow is set to 2/3 of the marker size.
"|>" A filled arrow is drawn at the end of the error bars. The size of the arrow is set to 2/3 of the marker size.
"X" Do not draw error bars. By default, graph classes that have errors are drawn with the errors (TGraph itself has no errors, and so this option has no effect.)
"||" Draw only the small vertical/horizontal lines at the ends of the error bars, without drawing the bars themselves. This option is interesting to superimpose statistical-only errors on top of a graph with statistical+systematic errors.
"[]" Does the same as option "||" except that it draws additional marks at the ends of the small vertical/horizontal lines. It makes plots less ambiguous in case several graphs are drawn on the same picture.
"0" By default, when a data point is outside the visible range along the Y axis, the error bars are not drawn. This option forces error bars' drawing for the data points outside the visible range along the Y axis (see example below).
"2" Error rectangles are drawn.
"3" A filled area is drawn through the end points of the vertical error bars.
"4" A smoothed filled area is drawn through the end points of the vertical error bars.
"5" Error rectangles are drawn like option "2". In addition the contour line around the boxes is drawn. This can be useful when boxes' fill colors are very light or in gray scale mode.

gStyle->SetErrorX(dx) controls the size of the error along x. dx = 0 removes the error along x.

gStyle->SetEndErrorSize(np) controls the size of the lines at the end of the error bars (when option 1 is used). By default np=1. (np represents the number of pixels).

TGraphErrors

A TGraphErrors is a TGraph with error bars. The errors are defined along X and Y and are symmetric: The left and right errors are the same along X and the bottom and up errors are the same along Y.
output of htmldoc/MACRO_TGraphPainter_7.gif
{
   TCanvas *c4 = new TCanvas("c4","c4",200,10,600,400);
   double x[] = {0, 1, 2, 3, 4};
   double y[] = {0, 2, 4, 1, 3};
   double ex[] = {0.1, 0.2, 0.3, 0.4, 0.5};
   double ey[] = {1, 0.5, 1, 0.5, 1};
   TGraphErrors* ge = new TGraphErrors(5, x, y, ex, ey);
   ge->Draw("ap");
   return c4;
}

The option "0" shows the error bars for data points outside range.

output of htmldoc/MACRO_TGraphPainter_9.gif
{
   TCanvas *c48 = new TCanvas("c48","c48",200,10,600,400);
   float x[]     = {1,2,3};
   float err_x[] = {0,0,0};
   float err_y[] = {5,5,5};
   float y[]     = {1,4,9};
   TGraphErrors tg(3,x,y,err_x,err_y);
   c48->Divide(2,1);
   c48->cd(1); gPad->DrawFrame(0,0,4,8); tg.Draw("PC");
   c48->cd(2); gPad->DrawFrame(0,0,4,8); tg.Draw("0PC");
   return c48;
}

The option "3" shows the errors as a band.

output of htmldoc/MACRO_TGraphPainter_11.gif
{
   TCanvas *c41 = new TCanvas("c41","c41",200,10,600,400);
   double x[] = {0, 1, 2, 3, 4};
   double y[] = {0, 2, 4, 1, 3};
   double ex[] = {0.1, 0.2, 0.3, 0.4, 0.5};
   double ey[] = {1, 0.5, 1, 0.5, 1};
   TGraphErrors* ge = new TGraphErrors(5, x, y, ex, ey);
   ge->SetFillColor(4);
   ge->SetFillStyle(3010);
   ge->Draw("a3");
   return c41;
}

The option "4" is similar to the option "3" except that the band is smoothed. As the following picture shows, this option should be used carefully because the smoothing algorithm may show some (huge) "bouncing" effects. In some cases it looks nicer than option "3" (because it is smooth) but it can be misleading.

output of htmldoc/MACRO_TGraphPainter_13.gif
{
   TCanvas *c42 = new TCanvas("c42","c42",200,10,600,400);
   double x[] = {0, 1, 2, 3, 4};
   double y[] = {0, 2, 4, 1, 3};
   double ex[] = {0.1, 0.2, 0.3, 0.4, 0.5};
   double ey[] = {1, 0.5, 1, 0.5, 1};
   TGraphErrors* ge = new TGraphErrors(5, x, y, ex, ey);
   ge->SetFillColor(6);
   ge->SetFillStyle(3005);
   ge->Draw("a4");
   return c42;
}

The following example shows how the option "[]" can be used to superimpose systematic errors on top of a graph with statistical errors.

output of htmldoc/MACRO_TGraphPainter_15.gif
{
   TCanvas *c43 = new TCanvas("c43","c43",200,10,600,400);
   c43->DrawFrame(0., -0.5, 6., 2);

   double x[5]    = {1, 2, 3, 4, 5};
   double zero[5] = {0, 0, 0, 0, 0};

   // data set (1) with stat and sys errors
   double py1[5]      = {1.2, 1.15, 1.19, 0.9, 1.4};
   double ey_stat1[5] = {0.2, 0.18, 0.17, 0.2, 0.4};
   double ey_sys1[5]  = {0.5, 0.71, 0.76, 0.5, 0.45};

   // data set (2) with stat and sys errors
   double y2[5]       = {0.25, 0.18, 0.29, 0.2, 0.21};
   double ey_stat2[5] = {0.2, 0.18, 0.17, 0.2, 0.4};
   double ey_sys2[5]  = {0.63, 0.19, 0.7, 0.2, 0.7};

   // Now draw data set (1)

   // We first have to draw it only with the stat errors
   TGraphErrors *graph1 = new TGraphErrors(5, x, py1, zero, ey_stat1);
   graph1->SetMarkerStyle(20);
   graph1->Draw("P");

   // Now we have to somehow depict the sys errors

   TGraphErrors *graph1_sys = new TGraphErrors(5, x, py1, zero, ey_sys1);
   graph1_sys->Draw("[]");

   // Now draw data set (2)

   // We first have to draw it only with the stat errors
   TGraphErrors *graph2 = new TGraphErrors(5, x, y2, zero, ey_stat2);
   graph2->SetMarkerStyle(24);
   graph2->Draw("P");

   // Now we have to somehow depict the sys errors

   TGraphErrors *graph2_sys = new TGraphErrors(5, x, y2, zero, ey_sys2);
   graph2_sys->Draw("[]");
   return c43;
}

TGraphAsymmErrors

A TGraphAsymmErrors is like a TGraphErrors but the errors defined along X and Y are not symmetric: The left and right errors are different along X and the bottom and up errors are different along Y.
output of htmldoc/MACRO_TGraphPainter_17.gif
{
   TCanvas *c44 = new TCanvas("c44","c44",200,10,600,400);
   double ax[] = {0, 1, 2, 3, 4};
   double ay[] = {0, 2, 4, 1, 3};
   double aexl[] = {0.1, 0.2, 0.3, 0.4, 0.5};
   double aexh[] = {0.5, 0.4, 0.3, 0.2, 0.1};
   double aeyl[] = {1, 0.5, 1, 0.5, 1};
   double aeyh[] = {0.5, 1, 0.5, 1, 0.5};
   TGraphAsymmErrors* gae = new TGraphAsymmErrors(5, ax, ay, aexl, aexh, aeyl, aeyh);
   gae->SetFillColor(2);
   gae->SetFillStyle(3001);
   gae->Draw("a2");
   gae->Draw("p");
   return c44;
}

TGraphBentErrors

A TGraphBentErrors is like a TGraphAsymmErrors. An extra parameter allows to bend the error bars to better see them when several graphs are drawn on the same plot.
output of htmldoc/MACRO_TGraphPainter_19.gif
{
   TCanvas *c45 = new TCanvas("c45","c45",200,10,600,400);
   const Int_t n = 10;
   Double_t x[n]  = {-0.22, 0.05, 0.25, 0.35, 0.5, 0.61,0.7,0.85,0.89,0.95};
   Double_t y[n]  = {1,2.9,5.6,7.4,9,9.6,8.7,6.3,4.5,1};
   Double_t exl[n] = {.05,.1,.07,.07,.04,.05,.06,.07,.08,.05};
   Double_t eyl[n] = {.8,.7,.6,.5,.4,.4,.5,.6,.7,.8};
   Double_t exh[n] = {.02,.08,.05,.05,.03,.03,.04,.05,.06,.03};
   Double_t eyh[n] = {.6,.5,.4,.3,.2,.2,.3,.4,.5,.6};
   Double_t exld[n] = {.0,.0,.0,.0,.0,.0,.0,.0,.0,.0};
   Double_t eyld[n] = {.0,.0,.05,.0,.0,.0,.0,.0,.0,.0};
   Double_t exhd[n] = {.0,.0,.0,.0,.0,.0,.0,.0,.0,.0};
   Double_t eyhd[n] = {.0,.0,.0,.0,.0,.0,.0,.0,.05,.0};
   TGraphBentErrors *gr = new TGraphBentErrors(n,x,y,exl,exh,eyl,eyh,exld,exhd,eyld,eyhd);
   gr->SetTitle("TGraphBentErrors Example");
   gr->SetMarkerColor(4);
   gr->SetMarkerStyle(21);
   gr->Draw("ALP");
   return c45;
}

TGraphPolar options

The drawing options for the polar graphs are the following:
"O" Polar labels are drawn orthogonally to the polargram radius.
"P" Polymarker are drawn at each point position.
"E" Draw error bars.
"F" Draw fill area (closed polygon).
"A" Force axis redrawing even if a polargram already exists.
"N" Disable the display of the polar labels.
output of htmldoc/MACRO_TGraphPainter_21.gif
{
   TCanvas *c46 = new TCanvas("c46","c46",500,500);
   TGraphPolar * grP1 = new TGraphPolar();
   grP1->SetTitle("TGraphPolar example");

   grP1->SetPoint(0, (1*TMath::Pi())/4., 0.05);
   grP1->SetPoint(1, (2*TMath::Pi())/4., 0.10);
   grP1->SetPoint(2, (3*TMath::Pi())/4., 0.15);
   grP1->SetPoint(3, (4*TMath::Pi())/4., 0.20);
   grP1->SetPoint(4, (5*TMath::Pi())/4., 0.25);
   grP1->SetPoint(5, (6*TMath::Pi())/4., 0.30);
   grP1->SetPoint(6, (7*TMath::Pi())/4., 0.35);
   grP1->SetPoint(7, (8*TMath::Pi())/4., 0.40);

   grP1->SetMarkerStyle(20);
   grP1->SetMarkerSize(1.);
   grP1->SetMarkerColor(4);
   grP1->SetLineColor(4);
   grP1->Draw("ALP");

   // Update, otherwise GetPolargram returns 0
   c46->Update();
   grP1->GetPolargram()->SetToRadian();

   return c46;
}
 

Function Members (Methods)

public:
virtual~TGraphPainter()
voidTObject::AbstractMethod(const char* method) const
virtual voidTObject::AppendPad(Option_t* option = "")
virtual voidTObject::Browse(TBrowser* b)
static TClass*Class()
virtual const char*TObject::ClassName() const
virtual voidTObject::Clear(Option_t* = "")
virtual TObject*TObject::Clone(const char* newname = "") const
virtual Int_tTObject::Compare(const TObject* obj) const
voidComputeLogs(Int_t npoints, Int_t opt)
virtual voidTObject::Copy(TObject& object) const
virtual voidTObject::Delete(Option_t* option = "")MENU
virtual Int_tTObject::DistancetoPrimitive(Int_t px, Int_t py)
virtual Int_tDistancetoPrimitiveHelper(TGraph* theGraph, Int_t px, Int_t py)
virtual voidTObject::Draw(Option_t* option = "")
virtual voidTObject::DrawClass() constMENU
virtual TObject*TObject::DrawClone(Option_t* option = "") constMENU
virtual voidDrawPanelHelper(TGraph* theGraph)
virtual voidTObject::Dump() constMENU
virtual voidTObject::Error(const char* method, const char* msgfmt) const
virtual voidTObject::Execute(const char* method, const char* params, Int_t* error = 0)
virtual voidTObject::Execute(TMethod* method, TObjArray* params, Int_t* error = 0)
virtual voidTObject::ExecuteEvent(Int_t event, Int_t px, Int_t py)
virtual voidExecuteEventHelper(TGraph* theGraph, Int_t event, Int_t px, Int_t py)
virtual voidTObject::Fatal(const char* method, const char* msgfmt) const
virtual TObject*TObject::FindObject(const char* name) const
virtual TObject*TObject::FindObject(const TObject* obj) const
virtual Option_t*TObject::GetDrawOption() const
static Long_tTObject::GetDtorOnly()
virtual const char*TObject::GetIconName() const
virtual const char*TObject::GetName() const
virtual char*TObject::GetObjectInfo(Int_t px, Int_t py) const
virtual char*GetObjectInfoHelper(TGraph* theGraph, Int_t px, Int_t py) const
static Bool_tTObject::GetObjectStat()
virtual Option_t*TObject::GetOption() const
static TVirtualGraphPainter*TVirtualGraphPainter::GetPainter()
virtual const char*TObject::GetTitle() const
virtual UInt_tTObject::GetUniqueID() const
virtual Bool_tTObject::HandleTimer(TTimer* timer)
virtual ULong_tTObject::Hash() const
virtual voidTObject::Info(const char* method, const char* msgfmt) const
virtual Bool_tTObject::InheritsFrom(const char* classname) const
virtual Bool_tTObject::InheritsFrom(const TClass* cl) const
virtual voidTObject::Inspect() constMENU
voidTObject::InvertBit(UInt_t f)
virtual TClass*IsA() const
virtual Bool_tTObject::IsEqual(const TObject* obj) const
virtual Bool_tTObject::IsFolder() const
Bool_tTObject::IsOnHeap() const
virtual Bool_tTObject::IsSortable() const
Bool_tTObject::IsZombie() const
virtual voidTObject::ls(Option_t* option = "") const
voidTObject::MayNotUse(const char* method) const
virtual Bool_tTObject::Notify()
voidTObject::Obsolete(const char* method, const char* asOfVers, const char* removedFromVers) const
voidTObject::operator delete(void* ptr)
voidTObject::operator delete(void* ptr, void* vp)
voidTObject::operator delete[](void* ptr)
voidTObject::operator delete[](void* ptr, void* vp)
void*TObject::operator new(size_t sz)
void*TObject::operator new(size_t sz, void* vp)
void*TObject::operator new[](size_t sz)
void*TObject::operator new[](size_t sz, void* vp)
TGraphPainter&operator=(const TGraphPainter&)
virtual voidTObject::Paint(Option_t* option = "")
virtual voidPaintGraph(TGraph* theGraph, Int_t npoints, const Double_t* x, const Double_t* y, Option_t* chopt)
voidPaintGraphAsymmErrors(TGraph* theGraph, Option_t* option)
voidPaintGraphBentErrors(TGraph* theGraph, Option_t* option)
voidPaintGraphErrors(TGraph* theGraph, Option_t* option)
virtual voidPaintGrapHist(TGraph* theGraph, Int_t npoints, const Double_t* x, const Double_t* y, Option_t* chopt)
voidPaintGraphPolar(TGraph* theGraph, Option_t* option)
voidPaintGraphQQ(TGraph* theGraph, Option_t* option)
voidPaintGraphSimple(TGraph* theGraph, Option_t* option)
virtual voidPaintHelper(TGraph* theGraph, Option_t* option)
voidPaintPolyLineHatches(TGraph* theGraph, Int_t n, const Double_t* x, const Double_t* y)
virtual voidPaintStats(TGraph* theGraph, TF1* fit)
virtual voidTObject::Pop()
virtual voidTObject::Print(Option_t* option = "") const
virtual Int_tTObject::Read(const char* name)
virtual voidTObject::RecursiveRemove(TObject* obj)
voidTObject::ResetBit(UInt_t f)
virtual voidTObject::SaveAs(const char* filename = "", Option_t* option = "") constMENU
virtual voidTObject::SavePrimitive(ostream& out, Option_t* option = "")
voidTObject::SetBit(UInt_t f)
voidTObject::SetBit(UInt_t f, Bool_t set)
virtual voidTObject::SetDrawOption(Option_t* option = "")MENU
static voidTObject::SetDtorOnly(void* obj)
static voidTObject::SetObjectStat(Bool_t stat)
static voidTVirtualGraphPainter::SetPainter(TVirtualGraphPainter* painter)
virtual voidTObject::SetUniqueID(UInt_t uid)
virtual voidShowMembers(TMemberInspector& insp) const
voidSmooth(TGraph* theGraph, Int_t npoints, Double_t* x, Double_t* y, Int_t drawtype)
virtual voidStreamer(TBuffer&)
voidStreamerNVirtual(TBuffer& ClassDef_StreamerNVirtual_b)
virtual voidTObject::SysError(const char* method, const char* msgfmt) const
Bool_tTObject::TestBit(UInt_t f) const
Int_tTObject::TestBits(UInt_t f) const
TGraphPainter()
TGraphPainter(const TGraphPainter&)
virtual voidTObject::UseCurrentStyle()
virtual voidTObject::Warning(const char* method, const char* msgfmt) const
virtual Int_tTObject::Write(const char* name = 0, Int_t option = 0, Int_t bufsize = 0)
virtual Int_tTObject::Write(const char* name = 0, Int_t option = 0, Int_t bufsize = 0) const
protected:
virtual voidTObject::DoError(int level, const char* location, const char* fmt, va_list va) const
voidTObject::MakeZombie()

Data Members

public:
static TObject::(anonymous)TObject::kBitMask
static TObject::EStatusBitsTObject::kCanDelete
static TObject::EStatusBitsTObject::kCannotPick
static TObject::EStatusBitsTObject::kHasUUID
static TObject::EStatusBitsTObject::kInvalidObject
static TObject::(anonymous)TObject::kIsOnHeap
static TObject::EStatusBitsTObject::kIsReferenced
static TObject::EStatusBitsTObject::kMustCleanup
static TObject::EStatusBitsTObject::kNoContextMenu
static TObject::(anonymous)TObject::kNotDeleted
static TObject::EStatusBitsTObject::kObjInCanvas
static TObject::(anonymous)TObject::kOverwrite
static TObject::(anonymous)TObject::kSingleKey
static TObject::(anonymous)TObject::kWriteDelete
static TObject::(anonymous)TObject::kZombie

Class Charts

Inheritance Inherited Members Includes Libraries
Class Charts

Function documentation

TGraphPainter()
   Default constructor
   
 
~TGraphPainter()
   Destructor.
   
 
void ComputeLogs(Int_t npoints, Int_t opt)
   Compute the logarithm of global variables gxwork and gywork
   according to the value of Options and put the results in the global
   variables gxworkl and gyworkl.
   

npoints : Number of points in gxwork and in gywork.

  • opt = 1 ComputeLogs is called from PaintGrapHist
  • opt = 0 ComputeLogs is called from PaintGraph
 
Int_t DistancetoPrimitiveHelper(TGraph* theGraph, Int_t px, Int_t py)
   Compute distance from point px,py to a graph.
   

Compute the closest distance of approach from point px,py to this line. The distance is computed in pixels units.

 
void DrawPanelHelper(TGraph* theGraph)
   Display a panel with all histogram drawing options.
   
 
void ExecuteEventHelper(TGraph* theGraph, Int_t event, Int_t px, Int_t py)
   Execute action corresponding to one event.
   

This member function is called when a graph is clicked with the locator.

If the left mouse button is clicked on one of the line end points, this point follows the cursor until button is released.

If the middle mouse button clicked, the line is moved parallel to itself until the button is released.

 
char * GetObjectInfoHelper(TGraph* theGraph, Int_t px, Int_t py) const
void PaintHelper(TGraph* theGraph, Option_t* option)
   Paint a any kind of TGraph
   
 
void PaintGraph(TGraph* theGraph, Int_t npoints, const Double_t* x, const Double_t* y, Option_t* chopt)
void PaintGrapHist(TGraph* theGraph, Int_t npoints, const Double_t* x, const Double_t* y, Option_t* chopt)
    This is a service method used by
    THistPainter
    to paint 1D histograms. It is not used to paint TGraph.
    

Input parameters:

  • npoints : Number of points in X or in Y.
  • x[npoints] or x[0] : x coordinates or (xmin,xmax).
  • y[npoints] or y[0] : y coordinates or (ymin,ymax).
  • chopt : Option.

The aspect of the histogram is done according to the value of the chopt.

"R" Graph is drawn horizontaly, parallel to X axis. (default is vertically, parallel to Y axis)
If option R is selected the user must give:
  • 2 values for Y (y[0]=YMIN and y[1]=YMAX)
  • N values for X, one for each channel.
Otherwise the user must give:
  • N values for Y, one for each channel.
  • 2 values for X (x[0]=XMIN and x[1]=XMAX)
"L" A simple polyline beetwen every points is drawn.
"H" An Histogram with equidistant bins is drawn as a polyline.
"F" An histogram with equidistant bins is drawn as a fill area. Contour is not drawn unless chopt='H' is also selected..
"N" Non equidistant bins (default is equidistant). If N is the number of channels array X and Y must be dimensionned as follow:
  • >If option R is not selected (default) then the user must give:
    • (N+1) values for X (limits of channels).
    • N values for Y, one for each channel.
      • Otherwise the user must give:
        • (N+1) values for Y (limits of channels).
        • N values for X, one for each channel.
"F1" Idem as 'F' except that fill area base line is the minimum of the pad instead of Y=0.
"F2" Draw a Fill area polyline connecting the center of bins
"C" A smooth Curve is drawn.
"*" A Star is plotted at the center of each bin.
"P" Idem with the current marker.
"P0" Idem with the current marker. Empty bins also drawn.
"B" A Bar chart with equidistant bins is drawn as fill areas (Contours are drawn).
"][" "Cutoff" style. When this option is selected together with H option, the first and last vertical lines of the histogram are not drawn.
 
void PaintGraphAsymmErrors(TGraph* theGraph, Option_t* option)
void PaintGraphBentErrors(TGraph* theGraph, Option_t* option)
void PaintGraphErrors(TGraph* theGraph, Option_t* option)
void PaintGraphPolar(TGraph* theGraph, Option_t* option)
void PaintGraphQQ(TGraph* theGraph, Option_t* option)
   Paint this graphQQ. No options for the time being.
   
 
void PaintGraphSimple(TGraph* theGraph, Option_t* option)
   Paint a simple graph, without errors bars.
   
 
void PaintPolyLineHatches(TGraph* theGraph, Int_t n, const Double_t* x, const Double_t* y)
   Paint a polyline with hatches on one side showing an exclusion zone. x and y
   are the the vectors holding the polyline and n the number of points in the
   polyline and w the width of the hatches. w can be negative.
   This method is not meant to be used directly. It is called automatically
   according to the line style convention.
   
 
void PaintStats(TGraph* theGraph, TF1* fit)
   Paint the statistics box with the fit info.
   
 
void Smooth(TGraph* theGraph, Int_t npoints, Double_t* x, Double_t* y, Int_t drawtype)
   Smooth a curve given by N points.
   

The original code is from an underlaying routine for Draw based on the CERN GD3 routine TVIPTE:

        Author - Marlow etc.   Modified by - P. Ward     Date -  3.10.1973
   
This method draws a smooth tangentially continuous curve through the sequence of data points P(I) I=1,N where P(I)=(X(I),Y(I)). The curve is approximated by a polygonal arc of short vectors. The data points can represent open curves, P(1) != P(N) or closed curves P(2) == P(N). If a tangential discontinuity at P(I) is required, then set P(I)=P(I+1). Loops are also allowed.

Reference Marlow and Powell, Harwell report No.R.7092.1972 MCCONALOGUE, Computer Journal VOL.13, NO4, NOV1970P p392 6

  • npoints : Number of data points.
  • x : Abscissa
  • y : Ordinate
 
TGraphPainter()