TLatex

Class Description

   TLatex : to draw Mathematical Formula

   This class has been implemented by 

Nicolas Brun

.
   ========================================================

   TLatex's purpose is to write mathematical equations
   The syntax is very similar to the Latex one :

   ** Subscripts and Superscripts
   ------------------------------
   Subscripts and superscripts are made with the _ and ^ commands.  These commands
   can be combined to make complicated subscript and superscript expressions.
   You may choose how to display subscripts and superscripts using the 2 functions
   SetindiceSize(Double_t) and SetLimitindiceSize(Int_t).

/*p */

   ** Fractions
   ------------
   Fractions denoted by the / symbol are made in the obvious way.
   The #frac command is used for large fractions in displayed formula; it has
   two arguments: the numerator and the denominator.

/* */

   ** splitting a line in two lines
   --------------------------------
   A text can be split in two lines via the command #splitline
   For example #splitline{"21 April 2003}{14:02:30}

   ** Roots
   --------
   The #sqrt command produces the square root of its argument; it has an optional
   first argument for other roots.
   ex: #sqrt{10}  #sqrt[3]{10}

   ** Mathematical Symbols
   -----------------------
   TLatex can make dozens of special mathematical symbols. A few of them, such as
   + and > , are produced by typing the corresponding keyboard character.  Others
   are obtained with the commands in the following table :

/* */

    #Box       draw a square
    #perp      draw the perpendicular symbol
    #odot      draw odot
    #hbar      draw h-bar (Planck constant divided by 2*Pi)
    #parallel  draw the parallel symbol

   ** Delimiters
   -------------
   You can produce 4 kinds of proportional delimiters.
   #[]{....} or "a la" Latex #left[.....#right] : big square brackets
   #{}{....} or              #left{.....#right} : big curly brackets
   #||{....} or              #left|.....#right| : big absolute value symbol
   #(){....} or              #left(.....#right) : big parenthesis

   ** Greek Letters
   ----------------
   The command to produce a lowercase Greek letter is obtained by adding a # to
   the name of the letter. For an uppercase Greek letter, just capitalize the first
   letter of the command name. Some letter have two representations. The name of the
   second one (the "variation") starts with "var".
   #alpha #beta #chi #delta #varepsilon #phi #gamma #eta #iota #varphi #kappa #lambda
   #mu #nu #omicron #pi #theta #rho #sigma #tau #upsilon #varomega #omega #xi #psi #zeta
   #Alpha #Beta #Chi #Delta #Epsilon #Phi #Gamma #Eta #Iota #vartheta
   #Kappa #Lambda #Mu #Nu #Omicron #Pi #Theta #Rho #Sigma #Tau
   #Upsilon #varsigma #Omega #Xi #Psi #Zeta #varUpsilon #epsilon

/* */

   ** Putting One Thing Above Another
   ----------------------------------
   Symbols in a formula are sometimes placed on above another. TLatex provides
   special commands for doing this.

   ** Accents
   ----------
    #hat{a} = hat
    #check  = inversed hat
    #acute  = acute
    #grave  = agrave
    #dot    = derivative
    #ddot   = double derivative
    #tilde  = tilde

    #slash special sign. Draw a slash on top of the text between brackets
   for example #slash{E}_{T}  generates "Missing ET"

/* */

   #dot  #ddot  #hat  #check  #acute  #grave  #tilde

   ** Changing Style in Math Mode
   ------------------------------
   You can change the font and the text color at any moment using :
   #font[font-number]{...} and #color[color-number]{...}

   ** Example1
   -----------
     The following macro (tutorials/graphics/latex.C) produces the following picture:
  {
     gROOT->Reset();
     TCanvas c1("c1","Latex",600,700);
     TLatex l;
     l.SetTextAlign(12);
     l.SetTextSize(0.04);
     l.DrawLatex(0.1,0.8,"1)   C(x) = d #sqrt{#frac{2}{#lambdaD}}  #int^{x}_{0}cos(#frac{#pi}{2}t^{2})dt");
     l.DrawLatex(0.1,0.6,"2)   C(x) = d #sqrt{#frac{2}{#lambdaD}}  #int^{x}cos(#frac{#pi}{2}t^{2})dt");
     l.DrawLatex(0.1,0.4,"3)   R = |A|^{2} = #frac{1}{2}(#[]{#frac{1}{2}+C(V)}^{2}+#[]{#frac{1}{2}+S(V)}^{2})");
     l.DrawLatex(0.1,0.2,"4)   F(t) = #sum_{i=-#infty}^{#infty}A(i)cos#[]{#frac{i}{t+i}}");
  }

/* */

   ** Example2
   -----------
     The following macro (tutorials/graphics/latex2.C) produces the following picture:
  {
     gROOT->Reset();
     TCanvas c1("c1","Latex",600,700);
     TLatex l;
     l.SetTextAlign(23);
     l.SetTextSize(0.1);
     l.DrawLatex(0.5,0.95,"e^{+}e^{-}#rightarrowZ^{0}#rightarrowI#bar{I}, q#bar{q}");
     l.DrawLatex(0.5,0.75,"|#vec{a}#bullet#vec{b}|=#Sigmaa^{i}_{jk}+b^{bj}_{i}");
     l.DrawLatex(0.5,0.5,"i(#partial_{#mu}#bar{#psi}#gamma^{#mu}+m#bar{#psi}=0#Leftrightarrow(#Box+m^{2})#psi=0");
     l.DrawLatex(0.5,0.3,"L_{em}=eJ^{#mu}_{em}A_{#mu} , J^{#mu}_{em}=#bar{I}#gamma_{#mu}I , M^{j}_{i}=#SigmaA_{#alpha}#tau^{#alphaj}_{i}");
  }

/* */

   ** Example3
   -----------
     The following macro (tutorials/graphics/latex3.C) produces the following picture:
  {
     gROOT->Reset();
   TCanvas c1("c1");
   TPaveText pt(.1,.5,.9,.9);
   pt.AddText("#frac{2s}{#pi#alpha^{2}}  #frac{d#sigma}{dcos#theta} (e^{+}e^{-} #rightarrow f#bar{f} ) = ");
   pt.AddText("#left| #frac{1}{1 - #Delta#alpha} #right|^{2} (1+cos^{2}#theta");
   pt.AddText("+ 4 Re #left{ #frac{2}{1 - #Delta#alpha} #chi(s) #[]{#hat{g}_{#nu}^{e}#hat{g}_{#nu}^{f}
    (1 + cos^{2}#theta) + 2 #hat{g}_{a}^{e}#hat{g}_{a}^{f} cos#theta) } #right}");
   pt.SetLabel("Born equation");
   pt.Draw();
  }

/* */

   ** Alignment rules
   ------------------
  The TText alignment rules apply to the TLatex objects with one exception
  concerning the vertical alignment:
  If the vertical alignment = 1 , subscripts are not taken into account
  if the vertical alignment = 0 , the text is aligned to the box surrounding
                                  the full text with sub and superscripts
  This is illustrated in the following example:

{
  gROOT->Reset();
  TCanvas c1("c1","c1",600,500);
  c1.SetGrid();
  c1.DrawFrame(0,0,1,1);
  const char *longstring = "K_{S}... K^{*0}... #frac{2s}{#pi#alpha^{2}}
 #frac{d#sigma}{dcos#theta} (e^{+}e^{-} #rightarrow f#bar{f} ) =
 #left| #frac{1}{1 - #Delta#alpha} #right|^{2} (1+cos^{2}#theta)";

  TLatex latex;
  latex.SetTextSize(0.033);
  latex.SetTextAlign(13);  //align at top
  latex.DrawLatex(.2,.9,"K_{S}");
  latex.DrawLatex(.3,.9,"K^{*0}");
  latex.DrawLatex(.2,.8,longstring);

  latex.SetTextAlign(12);  //centered
  latex.DrawLatex(.2,.6,"K_{S}");
  latex.DrawLatex(.3,.6,"K^{*0}");
  latex.DrawLatex(.2,.5,longstring);

  latex.SetTextAlign(11);  //default bottom alignment
  latex.DrawLatex(.2,.4,"K_{S}");
  latex.DrawLatex(.3,.4,"K^{*0}");
  latex.DrawLatex(.2,.3,longstring);

  latex.SetTextAlign(10);  //special bottom alignment
  latex.DrawLatex(.2,.2,"K_{S}");
  latex.DrawLatex(.3,.2,"K^{*0}");
  latex.DrawLatex(.2,.1,longstring);

  latex.SetTextAlign(12);
  latex->SetTextFont(72);
  latex->DrawLatex(.1,.80,"13");
  latex->DrawLatex(.1,.55,"12");
  latex->DrawLatex(.1,.35,"11");
  latex->DrawLatex(.1,.18,"10");
}

/* */

______________________________________________________________________________

 Default constructor.

 Normal constructor.

 Destructor.

 Copy constructor.

assignment operator

 Copy this TLatex object to another TLatex.

 Analyse function.

  Analyse and paint the TLatex formula

  It is called twice : first for calculating the size of
  each portion of the formula, then to paint the formula.
  When analyse finds an operator or separator, it calls
  itself recursively to analyse the arguments of the operator.
  when the argument is an atom (normal text), it calculates
  the size of it and return it as the result.
  for example : if the operator #frac{arg1}{arg2} is found :
  Analyse(arg1) return the size of arg1 (width, up, down)
  Analyse(arg2) return the size of arg2
  now, we know the size of #frac{arg1}{arg2}  :
  width = max(width_arg1, width_arg2)
  up = up_arg1 + down_arg1
  down = up_arg2 + down_arg2
  so, when the user wants to paint a fraction at position (x,y),
  the rect used for the formula is : (x,y-up,x+width,y+down)

 return size of zone occupied by the text/formula
 t : chain to be analyzed
 length : number of chars in t.

 Make a copy of this object with the new parameters
 And copy object attributes

 Draw a line in a Latex formula

 Draw an arc of ellipse in a Latex formula (right or left parenthesis)

 Draw an arc of ellipse in a Latex formula (right or left parenthesis)

 Paint.

 Main drawing function

 Warning: Unlike most others "XYZ::PaintXYZ" methods, PaintLatex modifies
          the TLatex data members.

 Check if the Latex syntax is correct

 First parsing of the analyse sequence

 Return height of current pad in pixels

 Return size of the formula along X in pad coordinates

 Return text size in pixels

 Return size of the formula along Y in pad coordinates

 Read fs in fTabSize

 Save fs values in array fTabSize

 Save primitive as a C++ statement(s) on output stream out

 Set relative size of subscripts and superscripts

 Set limit for text resizing of subscipts and superscripts