[hist] Add SetRefPad for consistent axis scaling

graf2d/graf/inc/TGaxis.h

@@ -47,6 +47,7 @@ class TGaxis : public TLine, public TAttText {
    TF1       *fFunction;            ///<! Pointer to function computing axis values
    TAxis     *fAxis;                ///<! Pointer to original TAxis axis (if any)
    TList     *fModLabs;             ///<  List of modified labels.
+   Float_t    fRefLength;           ///<! Reference length for automatic scaling (not saved to file)
 
    TGaxis(const TGaxis&);
    TGaxis& operator=(const TGaxis&);
@@ -137,6 +138,9 @@ class TGaxis : public TLine, public TAttText {
 
    void SetLabelColor(TColorNumber lcolor);
 
+   void SetRefLength(Float_t len) { fRefLength = len; }
+   Float_t GetRefLength() const { return fRefLength; }
+
    ClassDefOverride(TGaxis,6)  //Graphics axis
 };
 

graf2d/graf/src/TGaxis.cxx

@@ -690,7 +690,7 @@ End_Macro
 ////////////////////////////////////////////////////////////////////////////////
 /// TGaxis default constructor.
 
-TGaxis::TGaxis(): TLine(), TAttText(11,0,1,62,0.040)
+TGaxis::TGaxis(): TLine(), TAttText(11,0,1,62,0.040), fRefLength(0)
 {
 
    fGridLength  = 0.;
@@ -721,7 +721,7 @@ TGaxis::TGaxis(): TLine(), TAttText(11,0,1,62,0.040)
 TGaxis::TGaxis(Double_t xmin, Double_t ymin, Double_t xmax, Double_t ymax,
                Double_t wmin, Double_t wmax, Int_t ndiv,   Option_t *chopt,
                Double_t gridlength)
-       : TLine(xmin,ymin,xmax,ymax), TAttText(11,0,1,62,0.040)
+       : TLine(xmin,ymin,xmax,ymax), TAttText(11,0,1,62,0.040), fRefLength(0)
 {
 
    fWmin        = wmin;
@@ -758,7 +758,7 @@ TGaxis::TGaxis(Double_t xmin, Double_t ymin, Double_t xmax, Double_t ymax,
 TGaxis::TGaxis(Double_t xmin, Double_t ymin, Double_t xmax, Double_t ymax,
                const char *funcname, Int_t ndiv,   Option_t *chopt,
                Double_t gridlength)
-       : TLine(xmin,ymin,xmax,ymax), TAttText(11,0,1,62,0.040)
+       : TLine(xmin,ymin,xmax,ymax), TAttText(11,0,1,62,0.040), fRefLength(0)
 {
 
    fFunction = (TF1*)gROOT->GetFunction(funcname);
@@ -795,6 +795,7 @@ TGaxis::TGaxis(Double_t xmin, Double_t ymin, Double_t xmax, Double_t ymax,
 TGaxis::TGaxis(const TGaxis& ax) :
   TLine(ax),
   TAttText(ax),
+  fRefLength(ax.fRefLength),
   fWmin(ax.fWmin),
   fWmax(ax.fWmax),
   fGridLength(ax.fGridLength),
@@ -830,6 +831,7 @@ TGaxis& TGaxis::operator=(const TGaxis& ax)
    if(this!=&ax) {
       TLine::operator=(ax);
       TAttText::operator=(ax);
+      fRefLength = ax.fRefLength;
       fWmin=ax.fWmin;
       fWmax=ax.fWmax;
       fGridLength=ax.fGridLength;
@@ -977,6 +979,7 @@ void TGaxis::ImportAxisAttributes(TAxis *axis)
    SetBit(TAxis::kMoreLogLabels, axis->TestBit(TAxis::kMoreLogLabels));
    if (axis->GetDecimals())      SetBit(TAxis::kDecimals); //the bit is in TAxis::fAxis2
    SetTimeFormat(axis->GetTimeFormat());
+   SetRefLength(axis->GetRefLength());
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -1082,6 +1085,43 @@ void TGaxis::PaintAxis(Double_t xmin, Double_t ymin, Double_t xmax, Double_t yma
 
    Double_t rwmi = wmin;
    Double_t rwma = wmax;
+
+   struct AttributeRestorer {
+      TGaxis *fAxis;
+      Float_t fLabelSize, fTitleSize, fTickSize, fLabelOffset, fTitleOffset;
+      AttributeRestorer(TGaxis *ax) : fAxis(ax), 
+         fLabelSize(ax->GetLabelSize()), fTitleSize(ax->GetTitleSize()),
+         fTickSize(ax->GetTickSize()), fLabelOffset(ax->GetLabelOffset()),
+         fTitleOffset(ax->GetTitleOffset()) {}
+      ~AttributeRestorer() {
+         fAxis->SetLabelSize(fLabelSize);
+         fAxis->SetTitleSize(fTitleSize);
+         fAxis->SetTickSize(fTickSize);
+         fAxis->SetLabelOffset(fLabelOffset);
+         fAxis->SetTitleOffset(fTitleOffset);
+      }
+   };
+   AttributeRestorer restorer(this);
+
+   Double_t scale = 1.0;
+
+   if (fRefLength > 0 && gPad) {
+      Double_t curH = gPad->GetWh() * gPad->GetAbsHNDC();
+      if (curH > 0) scale = fRefLength / curH;
+   }
+
+   if (scale != 1.0) {
+      // Only scale if precision is 2 (relative sizing). Precision 3 (pixels) ignores this.
+      if (GetLabelFont()%10 < 3) fLabelSize *= scale;
+      if (GetTextFont()%10 < 3)  fTitleSize *= scale;
+
+      fTickSize    *= scale;
+      fLabelOffset *= scale;
+      // fTitleOffset *= scale; // REVERTED: Causes quadratic scaling, pushing title off pad
+   }
+
+
+
    chtemp = &kchtemp[0];
    label  = &chlabel[0];
 

hist/hist/inc/TAxis.h

@@ -26,6 +26,7 @@
 #include "TArrayD.h"
 #include <vector>
 
+class TVirtualPad;
 class THashList;
 class TAxisModLab;
 
@@ -44,6 +45,7 @@ class TAxis : public TNamed, public TAttAxis {
    TObject     *fParent = nullptr;  ///<! Object owning this axis
    THashList   *fLabels = nullptr;  ///<  List of labels
    TList       *fModLabs = nullptr; ///<  List of modified labels
+   Float_t      fRefLength = 0;     ///<! Reference length for automatic scaling (not saved to file)
 
    /// TAxis extra status bits (stored in fBits2)
    enum {
@@ -176,6 +178,9 @@ class TAxis : public TNamed, public TAttAxis {
    virtual void       UnZoom();  // *MENU*
    virtual void       ZoomOut(Double_t factor=0, Double_t offset=0);  // *MENU*
 
+   void               SetRefPad(TVirtualPad *pad);
+   Float_t            GetRefLength() const { return fRefLength; }
+
    ClassDefOverride(TAxis,10)  //Axis class
 };
 

hist/hist/src/TAxis.cxx

@@ -56,6 +56,7 @@ TAxis::TAxis()
    fLast    = 0;
    fBits2   = 0;
    fTimeDisplay = false;
+   fRefLength = 0;
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -103,6 +104,7 @@ TAxis::TAxis(const TAxis &axis) : TNamed(axis), TAttAxis(axis)
    fParent  = nullptr;
    fLabels  = nullptr;
    fModLabs = nullptr;
+   fRefLength = 0;
 
    axis.TAxis::Copy(*this);
 }
@@ -117,6 +119,21 @@ TAxis& TAxis::operator=(const TAxis &axis)
    return *this;
 }
 
+////////////////////////////////////////////////////////////////////////////////
+/// Set the reference pad for automatic axis sizing.
+/// The axis will store the absolute pixel height of this pad and use it
+/// to scale its attributes when drawn in other pads.
+
+void TAxis::SetRefPad(TVirtualPad *pad)
+{
+   if (!pad) {
+      fRefLength = 0;
+      return;
+   }
+   fRefLength = pad->GetWh() * pad->GetAbsHNDC();
+}
+
+
 
 ////////////////////////////////////////////////////////////////////////////////
 /// Choose a reasonable time format from the coordinates in the active pad
@@ -223,6 +240,7 @@ void TAxis::Copy(TObject &obj) const
    axis.fTimeFormat   = fTimeFormat;
    axis.fTimeDisplay  = fTimeDisplay;
    axis.fParent       = fParent;
+   axis.fRefLength    = fRefLength;
    if (axis.fLabels) {
       axis.fLabels->Delete();
       delete axis.fLabels;