Line Attributes class.

This class is used (in general by secondary inheritance) by many other classes (graphics, histograms). It holds all the line attributes.

Line attributes

Line attributes are:

Line Color
Line Width
Line Style

Line Color

The line color is a color index (integer) pointing in the ROOT color table. The line color of any class inheriting from TAttLine can be changed using the method SetLineColor and retrieved using the method GetLineColor. The following table shows the first 50 default colors.

Color transparency

SetLineColorAlpha(), allows to set a transparent color. In the following example the line color of the histogram histo is set to blue with a transparency of 35%. The color kBlue itself remains fully opaque.

histo->SetLineColorAlpha(kBlue, 0.35);

The transparency is available on all platforms when the flagOpenGL.CanvasPreferGL is set to 1 in $ROOTSYS/etc/system.rootrc, or on Mac with the Cocoa backend. On the file output it is visible with PDF, PNG, Gif, JPEG, SVG ... but not PostScript.

Line Width

The line width is expressed in pixel units. The line width of any class inheriting from TAttLine can be changed using the method SetLineWidth and retrieved using the method GetLineWidth. The following picture shows the line widths from 1 to 10 pixels.

Line Style

Line styles are identified via integer numbers. The line style of any class inheriting from TAttLine can be changed using the method SetLineStyle and retrieved using the method GetLineStyle.

The first 10 line styles are predefined as shown on the following picture:

Additional line styles can be defined using TStyle::SetLineStyleString. For example the line style number 11 can be defined as follow:

gStyle->SetLineStyleString(11,"400 200");

Existing line styles (1 to 10) can be redefined using the same method.

Definition at line 32 of file TAttLine.h.

Public Member Functions
	TAttLine ()
	AttLine default constructor. More...

	TAttLine (Color_t lcolor, Style_t lstyle, Width_t lwidth)
	AttLine normal constructor. More...

virtual	~TAttLine ()
	AttLine destructor. More...

void	Copy (TAttLine &attline) const
	Copy this line attributes to a new TAttLine. More...

Int_t	DistancetoLine (Int_t px, Int_t py, Double_t xp1, Double_t yp1, Double_t xp2, Double_t yp2)
	Compute distance from point px,py to a line. More...

virtual Color_t	GetLineColor () const

virtual Style_t	GetLineStyle () const

virtual Width_t	GetLineWidth () const

virtual void	Modify ()
	Change current line attributes if necessary. More...

virtual void	ResetAttLine (Option_t *option="")
	Reset this line attributes to default values. More...

virtual void	SaveLineAttributes (std::ostream &out, const char *name, Int_t coldef=1, Int_t stydef=1, Int_t widdef=1)
	Save line attributes as C++ statement(s) on output stream out. More...

virtual void	SetLineAttributes ()
	Invoke the DialogCanvas Line attributes. More...

virtual void	SetLineColor (Color_t lcolor)

virtual void	SetLineColorAlpha (Color_t lcolor, Float_t lalpha)
	Set a transparent line color. More...

virtual void	SetLineStyle (Style_t lstyle)

virtual void	SetLineWidth (Width_t lwidth)

	ClassDef (TAttLine, 2)

Protected Attributes
Color_t	fLineColor

Style_t	fLineStyle

Width_t	fLineWidth

#include <TAttLine.h>

Inheritance diagram for TAttLine:

Constructor & Destructor Documentation

TAttLine::TAttLine ( )

AttLine default constructor.

Definition at line 125 of file TAttLine.cxx.

TAttLine::TAttLine	(	Color_t	color,
		Style_t	style,
		Width_t	width
	)

AttLine normal constructor.

Line attributes are taking from the argument list

color : must be one of the valid color index
style : 1=solid, 2=dash, 3=dash-dot, 4=dot-dot. New styles can be defined using TStyle::SetLineStyleString.
width : expressed in pixel units

Definition at line 142 of file TAttLine.cxx.

TAttLine::~TAttLine ( )

virtual

AttLine destructor.

Definition at line 152 of file TAttLine.cxx.

Member Function Documentation

TAttLine::ClassDef	(	TAttLine	,
		2
	)

void TAttLine::Copy ( TAttLine & attline ) const

Copy this line attributes to a new TAttLine.

Definition at line 159 of file TAttLine.cxx.

Referenced by TLegendEntry::Copy(), TPolyLine3D::Copy(), TLine::Copy(), TPolyLine::Copy(), TEllipse::Copy(), TBox::Copy(), THelix::Copy(), TLatex::Copy(), TStyle::Copy(), TH1::Copy(), TF1::Copy(), TArc::DrawArc(), TArrow::DrawArrow(), TBox::DrawBox(), TCanvas::DrawClonePad(), TCrown::DrawCrown(), TEllipse::DrawEllipse(), TGraph::DrawGraph(), TLine::DrawLine(), TPolyLine3D::DrawPolyLine(), TPolyLine::DrawPolyLine(), TEfficiency::FillGraph(), and TEfficiency::FillHistogram().

Int_t TAttLine::DistancetoLine	(	Int_t	px,
		Int_t	py,
		Double_t	xp1,
		Double_t	yp1,
		Double_t	xp2,
		Double_t	yp2
	)

Compute distance from point px,py to a line.

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

Algorithm:

  A(x1,y1)         P                             B(x2,y2)
  -----------------+------------------------------
                   |
                   |
                   |
                   |
                  M(x,y)
Let us call  a = distance AM     A=a**2
             b = distance BM     B=b**2
             c = distance AB     C=c**2
             d = distance PM     D=d**2
             u = distance AP     U=u**2
             v = distance BP     V=v**2     c = u + v
D = A - U
D = B - V  = B -(c-u)**2
   ==> u = (A -B +C)/2c