From 2bf84e79acb023014155dd6eb798e22c4c4ab147 Mon Sep 17 00:00:00 2001
From: wmayer <wmayer@users.sourceforge.net>
Date: Wed, 2 Feb 2022 21:12:59 +0100
Subject: [PATCH] App/Gui: make color bar to handle very small values

---
 src/App/ColorModel.cpp                  | 11 +++++++++--
 src/App/ColorModel.h                    |  2 --
 src/Gui/DlgSettingsColorGradientImp.cpp |  4 ++--
 src/Gui/SoFCColorGradient.cpp           | 17 ++++++++---------
 4 files changed, 19 insertions(+), 15 deletions(-)

diff --git a/src/App/ColorModel.cpp b/src/App/ColorModel.cpp
index 555e4a1510..4b6ff2e1b4 100644
--- a/src/App/ColorModel.cpp
+++ b/src/App/ColorModel.cpp
@@ -27,6 +27,7 @@
 #endif
 
 #include "ColorModel.h"
+#include <Base/Exception.h>
 
 using namespace App;
 
@@ -107,7 +108,10 @@ void ColorField::set (const ColorModel &rclModel, float fMin, float fMax, std::s
 {
     colorModel = rclModel;
     this->fMin = std::min<float>(fMin, fMax);
-    this->fMax = std::max<float>(this->fMin + CCR_EPS, fMax);
+    this->fMax = std::max<float>(fMin, fMax);
+    if (this->fMax <= this->fMin) {
+        throw Base::ValueError("Maximum must be higher than minimum");
+    }
     ctColors = std::max<std::size_t>(usCt, colorModel.getCountColors());
     rebuild();
 }
@@ -206,7 +210,10 @@ std::vector<std::string> ColorGradient::getColorModelNames() const
 void ColorGradient::set (float fMin, float fMax, std::size_t usCt, TStyle tS, bool bOG)
 {
     _fMin = std::min<float>(fMin, fMax);
-    _fMax = std::max<float>(_fMin + CCR_EPS, fMax);
+    _fMax = std::max<float>(fMin, fMax);
+    if (_fMax <= _fMin) {
+        throw Base::ValueError("Maximum must be higher than minimum");
+    }
     ctColors = std::max<std::size_t>(usCt, getMinColors());
     tStyle = tS;
     outsideGrayed = bOG;
diff --git a/src/App/ColorModel.h b/src/App/ColorModel.h
index 998b1154cb..4f1611fe40 100644
--- a/src/App/ColorModel.h
+++ b/src/App/ColorModel.h
@@ -31,8 +31,6 @@
 #include <string>
 #include <vector>
 
-#define CCR_EPS  1.0e-5f
-
 namespace App
 {
 
diff --git a/src/Gui/DlgSettingsColorGradientImp.cpp b/src/Gui/DlgSettingsColorGradientImp.cpp
index a7d320f421..eeb31312ff 100644
--- a/src/Gui/DlgSettingsColorGradientImp.cpp
+++ b/src/Gui/DlgSettingsColorGradientImp.cpp
@@ -122,10 +122,10 @@ bool DlgSettingsColorGradientImp::isOutInvisible() const
 void DlgSettingsColorGradientImp::setRange( float fMin, float fMax )
 {
     ui->floatLineEditMax->blockSignals(true);
-    ui->floatLineEditMax->setText(QLocale().toString(fMax, 'f', numberOfDecimals()));
+    ui->floatLineEditMax->setText(QLocale().toString(fMax, 'g', numberOfDecimals()));
     ui->floatLineEditMax->blockSignals(false);
     ui->floatLineEditMin->blockSignals(true);
-    ui->floatLineEditMin->setText(QLocale().toString(fMin, 'f', numberOfDecimals()));
+    ui->floatLineEditMin->setText(QLocale().toString(fMin, 'g', numberOfDecimals()));
     ui->floatLineEditMin->blockSignals(false);
 }
 
diff --git a/src/Gui/SoFCColorGradient.cpp b/src/Gui/SoFCColorGradient.cpp
index c0819cdf51..e851706884 100644
--- a/src/Gui/SoFCColorGradient.cpp
+++ b/src/Gui/SoFCColorGradient.cpp
@@ -175,25 +175,24 @@ void SoFCColorGradient::setViewportSize( const SbVec2s& size )
     }
 }
 
-void SoFCColorGradient::setRange( float fMin, float fMax, int prec )
+void SoFCColorGradient::setRange(float fMin, float fMax, int prec)
 {
     _cColGrad.setRange(fMin, fMax);
 
     SoMFString label;
 
-    float fFac = (float)pow(10.0, (double)prec);
+    float eps = std::pow(10.0f, static_cast<float>(-prec));
+    float value = std::min<float>(fabs(fMin), fabs(fMax));
+    std::ios::fmtflags flags = value < eps ? (std::ios::scientific | std::ios::showpoint | std::ios::showpos)
+                                           : (std::ios::fixed | std::ios::showpoint | std::ios::showpos);
 
     int i=0;
     std::vector<float> marks = getMarkerValues(fMin, fMax, _cColGrad.getCountColors());
-    for ( std::vector<float>::iterator it = marks.begin(); it != marks.end(); ++it )
-    {
+    for (const auto& it : marks) {
         std::stringstream s;
         s.precision(prec);
-        s.setf(std::ios::fixed | std::ios::showpoint | std::ios::showpos);
-        float fValue = *it;
-        if ( fabs(fValue*fFac) < 1.0 )
-            fValue = 0.0f;
-        s << fValue;
+        s.setf(flags);
+        s << it;
         label.set1Value(i++, s.str().c_str());
     }