Logo ROOT   6.21/01
Reference Guide
file.C File Reference

Detailed Description

View in nbviewer Open in SWAN This macro displays the physical ROOT file structure

pict1_file.C.png
void file(){
TCanvas *c1 = new TCanvas("c1","ROOT File description",200,10,700,550);
c1->Range(0,-0.25,21,14);
TPaveLabel *title = new TPaveLabel(5,12,15,13.7,c1->GetTitle());
title->SetFillColor(16);
title->Draw();
// horizonthal file layout
TPave *file = new TPave(1,8.5,20,11);
file->SetFillColor(11);
file->Draw();
TPave *fileh = new TPave(1,8.5,2.5,11);
fileh->SetFillColor(44);
fileh->Draw();
TPave *lrh = new 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);
TLine *ldot = new 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);
TLine *line = new TLine(2.6,11,2.6,11.5);
line->Draw();
line->DrawLine(2.6,11.5,7,11.5);
TArrow *arrow = new 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);
TText *vert = new 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");
TText *hori = new 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);
TText *tbig = new 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
TPaveText *header = new TPaveText(0.5,.2,9.4,6.5);
header->SetFillColor(44);
header->Draw();
TText *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
TPaveText *lrecord = new TPaveText(10,0.2,19.5,6.5);
lrecord->SetFillColor(33);
lrecord->Draw();
TText *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();
c1->Print("file.png");
}
Author
Rene Brun

Definition in file file.C.