canvas.C

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/// \file
/// \ingroup tutorial_graphics
/// \notebook -js
/// \preview Example of primitives in a canvas.
/// One of the first actions in a ROOT session is the creation of a Canvas.
/// Here we create a Canvas named "c1".
///
/// After having executed this macro, try now to point on any object on the
/// screen: pad, text, lines, etc.
///
/// When the cursor points to sensitive areas in an object, the cursor
/// shape changes and suggests the type of action that can be applied.
///
/// For example:
///  - One can move, grow,shrink a pad.
///  - A text can be moved.
///  - A line can be moved or its end points can be modified.
///  - One can move, grow and shrink PaveLabels and PavesText.
///
/// Point to an object and click the right mouse button to change attributes.
/// Try to change the canvas size.
///
/// In the canvas "File" menu, select the option "Print" to produce
/// a PostScript file with a copy of the canvas.
///
/// \macro_image
/// \macro_code
///
/// \author Rene Brun
 
void canvas()
{
   TCanvas *c1 = new TCanvas("c1", "Canvas Example", 200, 10, 600, 480);
 
   gBenchmark->Start("canvas");
 
   // Inside this canvas, we create two pads
   TPad *pad1 = new TPad("pad1", "This is pad1", 0.05, 0.52, 0.95, 0.97);
   TPad *pad2 = new TPad("pad2", "This is pad2", 0.05, 0.02, 0.95, 0.47);
   pad1->SetFillColor(11);
   pad2->SetFillColor(11);
   pad1->Draw();
   pad2->Draw();
 
   // A pad may contain other pads and graphics objects.
   // We set the current pad to pad2.
   // Note that the current pad is always highlighted.
   pad2->cd();
   TPad *pad21 = new TPad("pad21", "First subpad of pad2", 0.02, 0.05, 0.48, 0.95, 17, 3);
   TPad *pad22 = new TPad("pad22", "Second subpad of pad2", 0.52, 0.05, 0.98, 0.95, 17, 3);
   pad21->Draw();
   pad22->Draw();
 
   // We enter some primitives in the created pads and set some attributes
   pad1->cd();
   float xt1 = 0.5;
   float yt1 = 0.1;
   TText *t1 = new TText(0.5, yt1, "ROOT");
   t1->SetTextAlign(22);
   t1->SetTextSize(0.05);
   t1->Draw();
   TLine *line1 = new TLine(0.05, 0.05, 0.80, 0.70);
   line1->SetLineWidth(8);
   line1->SetLineColor(2);
   line1->Draw();
   line1->DrawLine(0.6, 0.1, 0.9, 0.9);
   TLine *line2 = new TLine(0.05, 0.70, 0.50, 0.10);
   line2->SetLineWidth(4);
   line2->SetLineColor(5);
   line2->Draw();
 
   pad21->cd();
   TText *t21 = new TText(0.05, 0.8, "This is pad21");
   t21->SetTextSize(0.1);
   t21->Draw();
   float xp2 = 0.5;
   float yp2 = 0.4;
   TPavesText *paves = new TPavesText(0.1, 0.1, xp2, yp2);
   paves->AddText("This is a PavesText");
   paves->AddText("You can add new lines");
   paves->AddText("Text formatting is automatic");
   paves->SetFillColor(43);
   paves->Draw();
   pad22->cd();
   TText *t22 = new TText(0.05, 0.8, "This is pad22");
   t22->SetTextSize(0.1);
   t22->Draw();
   float xlc = 0.01;
   float ylc = 0.01;
   TPaveLabel *label = new TPaveLabel(xlc, ylc, xlc + 0.8, ylc + 0.1, "This is a PaveLabel");
   label->SetFillColor(24);
   label->Draw();
 
   // Modify object attributes in a loop
   Int_t nloops = 50;
   float dxp2 = (0.9 - xp2) / nloops;
   float dyp2 = (0.7 - yp2) / nloops;
   float dxlc = (0.1 - xlc) / nloops;
   float dylc = (0.4 - xlc) / nloops;
   float dxt1 = (0.5 - xt1) / nloops;
   float dyt1 = (0.8 - yt1) / nloops;
   float t10 = t1->GetTextSize();
   float t1end = 0.3;
   float t1ds = (t1end - t10) / nloops;
   Int_t color = 0;
   for (int i = 0; i < nloops; i++) {
      color++;
      color %= 8;
      line1->SetLineColor(color);
      t1->SetTextSize(t10 + t1ds * i);
      t1->SetTextColor(color);
      t1->SetX(xt1 + dxt1 * i);
      t1->SetY(yt1 + dyt1 * i);
      pad1->Modified();
      paves->SetX2NDC(xp2 + dxp2 * i);
      paves->SetY2NDC(yp2 + dyp2 * i);
      pad21->Modified();
      label->SetX1NDC(xlc + dxlc * i);
      label->SetY1NDC(ylc + dylc * i);
      label->SetX2NDC(xlc + dxlc * i + 0.8);
      label->SetY2NDC(ylc + dylc * i + 0.2);
      pad22->Modified();
      c1->Update();
   }
   gBenchmark->Show("canvas");
}