file.py

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#
# This macro displays the physical ROOT file structure
#

from ROOT import TCanvas, TPaveLabel, TPave, TLine, TArrow, TText, TPaveText
from ROOT import gROOT



c1 = TCanvas( 'c1', 'ROOT File description', 200, 10, 700, 550 )

c1.Range( 0, -0.25, 21, 14 )
title = TPaveLabel( 5, 12, 15, 13.7, c1.GetTitle() )
title.SetFillColor( 16 )
title.Draw()

# horizonthal file layout
file = TPave( 1, 8.5, 20, 11 )
file.SetFillColor( 11 )
file.Draw()
fileh = TPave( 1, 8.5, 2.5, 11 )
fileh.SetFillColor( 44 )
fileh.Draw()
lrh = TPave( 2.5, 8.5, 3.3, 11, 1 )
lrh.SetFillColor( 33 )
lrh.Draw()
lrh.DrawPave( 6.9, 8.5, 7.7, 11, 1 )
lrh.DrawPave( 10.5, 8.5, 11.3, 11, 1 )
lrh.DrawPave( 14.5, 8.5, 15.3, 11, 1 )
ldot = TLine( 1, 8.5, 0.5, 6.5 )
ldot.SetLineStyle( 2 )
ldot.Draw()
ldot.DrawLine( 2.5, 8.5, 9.4, 6.5 )
ldot.DrawLine( 10.5, 8.5, 10, 6.5 )
ldot.DrawLine( 11.3, 8.5, 19.5, 6.5 )
line = TLine( 2.6, 11, 2.6, 11.5 )
line.Draw()
line.DrawLine( 2.6, 11.5, 7, 11.5 )
arrow = TArrow( 7, 11.5, 7, 11.1, 0.01, '|>' )
arrow.SetFillStyle( 1001 )
arrow.Draw()
line.DrawLine( 7, 8.5, 7, 8.0 )
line.DrawLine( 7, 8.0, 10.6, 8 )
arrow.DrawArrow( 10.6,8, 10.6, 8.4, 0.01, '|>' )
line.DrawLine( 10.6, 11, 10.6, 11.5 )
line.DrawLine( 10.6, 11.5, 14.6, 11.5 )
arrow.DrawArrow( 14.6, 11.5, 14.6, 11.1, 0.01, '|>' )
line.DrawLine( 14.6, 8.5, 14.6, 8.0 )
line.DrawLine( 14.6, 8.0, 16, 8 )
ldot.DrawLine( 16, 8, 19, 8 )
vert = TText( 1.5, 9.75, 'File' )
vert.SetTextAlign( 21 )
vert.SetTextAngle( 90 )
vert.SetTextSize( 0.025 )
vert.Draw()
vert.DrawText(  2.0, 9.75, 'Header' )
vert.DrawText(  2.9, 9.75, 'Logical Record' )
vert.DrawText(  3.2, 9.75, 'Header' )
vert.DrawText(  7.3, 9.75, 'Logical Record' )
vert.DrawText(  7.6, 9.75, 'Header' )
vert.DrawText( 10.9, 9.75, 'Logical Record' )
vert.DrawText( 11.2, 9.75, 'Header' )
vert.DrawText( 14.9, 9.75, 'Logical Record' )
vert.DrawText( 15.2, 9.75, 'Header' )
hori = TText( 4.75, 10, 'Object' )
hori.SetTextAlign( 22 )
hori.SetTextSize( 0.035 )
hori.Draw()
hori.DrawText( 4.75, 9.5, 'Data' )
hori.DrawText( 9.2, 10, 'Deleted' )
hori.DrawText( 9.2, 9.5, 'Object' )
line.DrawLine( 6.9, 8.5, 10.5, 11 )
line.DrawLine( 6.9, 11, 10.5, 8.5 )
tbig = TText( 17, 9.75, '............' )
tbig.SetTextAlign( 22 )
tbig.SetTextSize( 0.03 )
tbig.Draw()
tbig.DrawText( 2.6, 7, 'fBEGIN' )
tbig.DrawText( 20., 7, 'fEND' )
arrow.DrawArrow( 2.6, 7, 2.6, 8.4, 0.01, '|>' )
arrow.DrawArrow( 20, 7, 20, 8.4, 0.01, '|>' )

#file header
header = TPaveText( 0.5, .2, 9.4, 6.5 )
header.SetFillColor( 44 )
header.Draw()
fh = header.AddText( 'File Header' )
fh.SetTextAlign( 22 )
fh.SetTextSize( 0.04 )
header.SetTextSize( 0.027 )
header.SetTextAlign( 12 )
header.AddText( ' ' )
header.AddLine( 0, 0, 0, 0 )
header.AddText( '"root": Root File Identifier' )
header.AddText( 'fVersion: File version identifier' )
header.AddText( 'fBEGIN: Pointer to first data record' )
header.AddText( 'fEND: Pointer to first free word at EOF' )
header.AddText( 'fSeekFree: Pointer to FREE data record' )
header.AddText( 'fNbytesFree: Number of bytes in FREE' )
header.AddText( 'fNfree: Number of free data records' )
header.AddText( 'fNbytesName: Number of bytes in name/title' )
header.AddText( 'fUnits: Number of bytes for pointers' )
header.AddText( 'fCompress: Compression level' )

#logical record header
lrecord = TPaveText( 10, 0.2, 19.5, 6.5 )
lrecord.SetFillColor( 33 )
lrecord.Draw()
tlrh = lrecord.AddText( 'Logical Record Header (TKEY)' )
tlrh.SetTextAlign( 22 )
tlrh.SetTextSize( 0.04 )
lrecord.SetTextSize( 0.027 )
lrecord.SetTextAlign( 12 )
lrecord.AddText( ' ' )
lrecord.AddLine( 0, 0, 0, 0 )
lrecord.AddText( 'fNbytes: Length of compressed object' )
lrecord.AddText( 'fVersion: Key version identifier' )
lrecord.AddText( 'fObjLen: Length of uncompressed object' )
lrecord.AddText( 'fDatime: Date/Time when written to store' )
lrecord.AddText( 'fKeylen: Number of bytes for the key' )
lrecord.AddText( 'fCycle : Cycle number' )
lrecord.AddText( 'fSeekKey: Pointer to object on file' )
lrecord.AddText( 'fSeekPdir: Pointer to directory on file' )
lrecord.AddText( 'fClassName: class name of the object' )
lrecord.AddText( 'fName: name of the object' )
lrecord.AddText( 'fTitle: title of the object' )

c1.Update()