added y-range-plot JKQTPfilledVerticalRangeGraph and example for it + date/time axes

README.md

@@ -20,6 +20,7 @@ All test-projects are Qt-projects that use qmake to build. You can load them int
 | [![](https://raw.githubusercontent.com/jkriege2/JKQtPlotter/master/screenshots/jkqtplotter_simpletest1_small.png)](https://github.com/jkriege2/JKQtPlotter/tree/master/test/jkqtplotter_simpletest) | [Very Basic Example (Line Graph)](https://github.com/jkriege2/JKQtPlotter/tree/master/test/jkqtplotter_simpletest) | `JKQTPxyLineGraph`<br/>C-style arrays of data |
 | [![](https://raw.githubusercontent.com/jkriege2/JKQtPlotter/master/screenshots/jkqtplotter_simpletest_symbols_and_styles_small.png)](https://github.com/jkriege2/JKQtPlotter/tree/master/test/jkqtplotter_simpletest_symbols_and_styles) | [Line Graph with Different Symbols and Line Styles](https://github.com/jkriege2/JKQtPlotter/tree/master/test/jkqtplotter_simpletest_symbols_and_styles) | `JKQTPxyLineGraph`<br/>C++ vector of data<br/>setting line styles and symbol styles<br/>automatic graph coloring |
 | [![](https://raw.githubusercontent.com/jkriege2/JKQtPlotter/master/screenshots/jkqtplotter_simpletest_logaxes_small.png)](https://github.com/jkriege2/JKQtPlotter/tree/master/test/jkqtplotter_simpletest_logaxes) | [logarithmic axes](https://github.com/jkriege2/JKQtPlotter/tree/master/test/jkqtplotter_simpletest_logaxes) | `JKQTPxyLineGraph` and `JKQTPgeoText`<br/>C++ vector of data<br/>logarithmic axes<br/>plot line styles<br/>internal LaTeX parser<br/>add commenting text to a graph |
+| [![](https://raw.githubusercontent.com/jkriege2/JKQtPlotter/master/screenshots/jkqtplotter_simpletest_dateaxes_small.png)](https://github.com/jkriege2/JKQtPlotter/tree/master/test/jkqtplotter_simpletest_dateaxes) | [date/time axes](https://github.com/jkriege2/JKQtPlotter/tree/master/test/jkqtplotter_simpletest_dateaxes) | `JKQTPxyLineGraph` and ``<br/>C++ vector of data<br/>date/time axes<br/>plot min/max range graph<br/>internal LaTeX parser<br/>data from CSV files |
 | [![](https://raw.githubusercontent.com/jkriege2/JKQtPlotter/master/screenshots/jkqtplotter_simpletest_symbols_and_errors_small.png)](https://github.com/jkriege2/JKQtPlotter/tree/master/test/jkqtplotter_simpletest_symbols_and_errors) | [Simple Line/Symbol Graph With Errorbars](https://github.com/jkriege2/JKQtPlotter/tree/master/test/jkqtplotter_simpletest_symbols_and_errors) | `JKQTPxyLineErrorGraph`<br/>C-style arrays of data |
 | [![](https://raw.githubusercontent.com/jkriege2/JKQtPlotter/master/screenshots/jkqtplotter_simpletest_barchart_small.png)](https://github.com/jkriege2/JKQtPlotter/tree/master/test/jkqtplotter_simpletest_barchart) | [Simple Bar Charts](https://github.com/jkriege2/JKQtPlotter/tree/master/test/jkqtplotter_simpletest_barchart) | `JKQTPbarVerticalGraph`<br/>C-style arrays of data |
 | [![](https://raw.githubusercontent.com/jkriege2/JKQtPlotter/master/screenshots/JKQTPbarVerticalGraphStacked_small.png)](https://github.com/jkriege2/JKQtPlotter/tree/master/test/jkqtplotter_simpletest_stackedbars) | [Stacked Bar Charts](https://github.com/jkriege2/JKQtPlotter/tree/master/test/jkqtplotter_simpletest_stackedbars) | `JKQTPbarVerticalStackableGraph`, `JKQTPbarHorizontalStackableGraph`<br/>C++-style vectors of data |

lib/jkqtplotter/jkqtpbaseelements.cpp

@@ -255,9 +255,9 @@ void JKQTPcoordinateAxis::loadSettings(QSettings& settings, QString group) {
     JKQTPPROPERTYload(settings, group+axisPrefix, minorTickLabelFontSize, "minor_tick_label_font_size", toDouble());
     JKQTPPROPERTYload(settings, group+axisPrefix, minorTickLabelFullNumber, "minor_tick_label_full_number", toBool());
 
-    JKQTPPROPERTYload(settings, group+axisPrefix, tickTimeFormat, "tick_time_format", toDouble());
+    JKQTPPROPERTYload(settings, group+axisPrefix, tickTimeFormat, "tick_time_format", toString());
-    JKQTPPROPERTYload(settings, group+axisPrefix, tickDateFormat, "tick_date_format", toDouble());
+    JKQTPPROPERTYload(settings, group+axisPrefix, tickDateFormat, "tick_date_format", toString());
-    JKQTPPROPERTYload(settings, group+axisPrefix, tickDateTimeFormat, "tick_datetime_format", toDouble());
+    JKQTPPROPERTYload(settings, group+axisPrefix, tickDateTimeFormat, "tick_datetime_format", toString());
 
 
     JKQTPPROPERTYload(settings, group+axisPrefix, minTicks, "min_ticks", toUInt());
@@ -577,17 +577,17 @@ QString JKQTPcoordinateAxis::floattolabel(double data) {
             }; break;
         case JKQTPCALTdate: {
                 QDateTime dt;
-                dt.setMSecsSinceEpoch(uint(data));
+                dt.setMSecsSinceEpoch(uint64_t(data));
                 return dt.toString(tickDateFormat);
             }; break;
         case JKQTPCALTtime: {
                 QDateTime dt;
-                dt.setMSecsSinceEpoch(uint(data));
+                dt.setMSecsSinceEpoch(uint64_t(data));
                 return dt.toString(tickTimeFormat);
             }; break;
         case JKQTPCALTdatetime: {
                 QDateTime dt;
-                dt.setMSecsSinceEpoch(uint(data));
+                dt.setMSecsSinceEpoch(uint64_t(data));
                 return dt.toString(tickDateTimeFormat);
             }; break;
         default:

lib/jkqtplotter/jkqtpbaseelements.h

@@ -650,11 +650,11 @@ class LIB_EXPORT JKQTPcoordinateAxis: public QObject {
         JKQTPPROPERTY(double, lineWidthZeroAxis)
 
 
-        /** \brief format string for time tick labels */
+        /** \brief format string for time tick labels, see see QDateTime::toString() documentation for details on format strings */
         JKQTPPROPERTY(QString, tickTimeFormat)
-        /** \brief format string for date tick labels */
+        /** \brief format string for date tick labels, see see QDateTime::toString() documentation for details on format strings */
         JKQTPPROPERTY(QString, tickDateFormat)
-        /** \brief format string for datetime tick labels */
+        /** \brief format string for datetime tick labels, see see QDateTime::toString() documentation for details on format strings */
         JKQTPPROPERTY(QString, tickDateTimeFormat)
 
         /** \brief calculates the tick spacing for a linear axis that spans \a awidth and that should

lib/jkqtplotter/jkqtpelements.cpp

@@ -2388,3 +2388,241 @@ bool JKQTPxyParametrizedErrorScatterGraph::intPlotXYErrorIndicatorsGetColor(JKQT
 }
 
 
+
+JKQTPfilledVerticalRangeGraph::JKQTPfilledVerticalRangeGraph(JKQtBasePlotter *parent):
+    JKQTPxyGraph(parent)
+{
+    drawSelectionLine=false;
+    selectionLineColor=Qt::transparent;
+    color=QColor("red");
+    fillColor=color.lighter();
+    style=Qt::SolidLine;
+    lineWidth=2;
+    parentPlotStyle=-1;
+    drawLine=true;
+    fillStyle=Qt::SolidPattern;
+
+    if (parent) { // get style settings from parent object
+        parentPlotStyle=parent->getNextStyle();
+        //std::cout<<"got style settings from parent: "<<parentPlotStyle<<std::endl;
+        color=parent->getPlotStyle(parentPlotStyle).color();
+        style=parent->getPlotStyle(parentPlotStyle).style();
+        fillColor=color.lighter();
+    }
+}
+
+JKQTPfilledVerticalRangeGraph::JKQTPfilledVerticalRangeGraph(JKQtPlotter *parent):
+    JKQTPxyGraph(parent)
+{
+    drawSelectionLine=false;
+    selectionLineColor=Qt::transparent;
+    color=QColor("red");
+    fillColor=color.lighter();
+    style=Qt::SolidLine;
+    lineWidth=2;
+    parentPlotStyle=-1;
+    drawLine=true;
+    fillStyle=Qt::SolidPattern;
+
+    if (parent) { // get style settings from parent object
+        parentPlotStyle=parent->getNextStyle();
+        //std::cout<<"got style settings from parent: "<<parentPlotStyle<<std::endl;
+        color=parent->getPlotStyle(parentPlotStyle).color();
+        style=parent->getPlotStyle(parentPlotStyle).style();
+        fillColor=color.lighter();
+    }
+}
+
+bool JKQTPfilledVerticalRangeGraph::getYMinMax(double &miny, double &maxy, double &smallestGreaterZero)
+{
+    bool start=true;
+    miny=0;
+    maxy=0;
+    smallestGreaterZero=0;
+
+    if (parent==nullptr) return false;
+
+    JKQTPdatastore* datastore=parent->getDatastore();
+    int imin=0;
+    int imax=qMin(qMin(datastore->getColumn(static_cast<size_t>(xColumn)).getRows(), datastore->getColumn(static_cast<size_t>(yColumn)).getRows()), datastore->getColumn(static_cast<size_t>(yColumn2)).getRows());
+    // interpret data ranges
+    if (datarange_start>-1) {
+        imin=qMin(datarange_start, static_cast<long long>(imax));
+    }
+    if (datarange_end>-1) {
+        imax=qMin(datarange_end, static_cast<long long>(imax));
+    }
+    if (imax<imin) {
+        int h=imin;
+        imin=imax;
+        imax=h;
+    }
+    if (imin<0) imin=0;
+    if (imax<0) imax=0;
+
+    for (int i=imin; i<imax; i++) {
+        double yv=datastore->get(static_cast<size_t>(yColumn),static_cast<size_t>(i));
+        double yv2=datastore->get(static_cast<size_t>(yColumn2),static_cast<size_t>(i));
+        if (JKQTPIsOKFloat(yv)) {
+            if (start || yv>maxy) maxy=yv;
+            if (start || yv<miny) miny=yv;
+            double xvsgz;
+            xvsgz=yv; SmallestGreaterZeroCompare_xvsgz();
+            start=false;
+        }
+        if (JKQTPIsOKFloat(yv2)) {
+            if (start || yv2>maxy) maxy=yv2;
+            if (start || yv2<miny) miny=yv2;
+            double xvsgz;
+            xvsgz=yv2; SmallestGreaterZeroCompare_xvsgz();
+            start=false;
+        }
+    }
+    return !start;
+}
+
+bool JKQTPfilledVerticalRangeGraph::usesColumn(int column)
+{
+    return JKQTPxyGraph::usesColumn(column)||(column==yColumn2);
+}
+
+void JKQTPfilledVerticalRangeGraph::draw(JKQTPEnhancedPainter &painter)
+{
+#ifdef JKQTBP_AUTOTIMER
+    JKQTPAutoOutputTimer jkaaot("JKQTPfilledCurveXGraph::draw");
+#endif
+    if (parent==nullptr) return;
+    JKQTPdatastore* datastore=parent->getDatastore();
+    if (datastore==nullptr) return;
+
+    drawErrorsBefore(painter);
+
+    painter.save();
+
+    QPen p=painter.pen();
+    p.setColor(color);
+    p.setWidthF(qMax(JKQTPLOTTER_ABS_MIN_LINEWIDTH, parent->pt2px(painter, lineWidth*parent->get_lineWidthMultiplier())));
+    p.setStyle(style);
+    p.setJoinStyle(Qt::RoundJoin);
+    p.setCapStyle(Qt::RoundCap);
+    QPen np(Qt::NoPen);
+
+    QBrush b=painter.brush();
+    b.setColor(fillColor);
+    b.setStyle(fillStyle);
+
+    int imax=qMin(qMin(datastore->getColumn(static_cast<size_t>(xColumn)).getRows(), datastore->getColumn(static_cast<size_t>(yColumn)).getRows()), datastore->getColumn(static_cast<size_t>(yColumn2)).getRows());
+    int imin=0;
+    // interpret data ranges
+    if (datarange_start>-1) {
+        imin=qMin(datarange_start, static_cast<long long>(imax));
+    }
+    if (datarange_end>-1) {
+        imax=qMin(datarange_end, static_cast<long long>(imax));
+    }
+    if (imax<imin) {
+        int h=imin;
+        imin=imax;
+        imax=h;
+    }
+    if (imin<0) imin=0;
+    if (imax<0) imax=0;
+
+    // upper points are added to poly_all, lower points to plow
+    // then plow points are added to poly_all in vewerse order
+    // then the whole thing is drawn
+    QPolygonF poly_all, phigh, plow;
+
+    double xold=-1;
+
+    bool first=true;
+    intSortData();
+    for (int iii=imin; iii<imax; iii++) {
+        int i=qBound(imin, getDataIndex(iii), imax);
+        double xv=datastore->get(static_cast<size_t>(xColumn),static_cast<size_t>(i));
+        double yv=datastore->get(static_cast<size_t>(yColumn),static_cast<size_t>(i));
+        double yv2=datastore->get(static_cast<size_t>(yColumn2),static_cast<size_t>(i));
+        //std::cout<<"(xv, yv) =    ( "<<xv<<", "<<yv<<" )\n";
+        if (JKQTPIsOKFloat(xv)) {
+            double x=xAxis->x2p(xv); bool xok=JKQTPIsOKFloat(x);
+            double y=yAxis->x2p(yv); bool yok=JKQTPIsOKFloat(y);
+            double y2=yAxis->x2p(yv2); bool y2ok=JKQTPIsOKFloat(y2);
+
+            if (xok&&yok) phigh.append(QPointF(x,y));
+            if (xok&&yok) poly_all.append(QPointF(x,y));
+            if (xok&&y2ok) plow.append(QPointF(x,y2));
+        }
+    }
+
+    if (plow.size()>0) {
+        for (int i=plow.size()-1; i>=0; i--) {
+            poly_all.append(plow[i]);
+        }
+    }
+    painter.setBrush(b);
+    painter.setPen(np);
+    painter.drawPolygon(poly_all);
+
+    painter.restore();
+    if (drawLine) {
+        painter.save();
+
+        if (drawSelectionLine) {
+            QPen penSelection=p; penSelection.setStyle(Qt::SolidLine);
+            QColor selcol=penSelection.color(); selcol.setAlphaF(0.5); penSelection.setColor(selcol);
+            if (selectionLineColor!=Qt::transparent) {
+                penSelection.setColor(selectionLineColor);
+            }
+            penSelection.setWidthF(penSelection.widthF()*3.0);
+            painter.setPen(penSelection);
+            painter.drawPolyline(phigh);
+            painter.drawPolyline(plow);
+        }
+
+
+        painter.setPen(p);
+        painter.drawPolyline(phigh);
+        painter.drawPolyline(plow);
+        painter.restore();
+    }
+
+    drawErrorsAfter(painter);
+}
+
+void JKQTPfilledVerticalRangeGraph::drawKeyMarker(JKQTPEnhancedPainter &painter, QRectF &rect)
+{
+    painter.save();
+    QRectF r=rect;
+    r.setHeight(r.height()/2.0);
+    r.moveTo(r.x(), r.y()+r.height()-1);
+    painter.fillRect(r, getBrush(painter));
+    if (drawLine) {
+        painter.setPen(getLinePen(painter));
+        painter.drawLine(QLineF(r.topLeft(), r.topRight()));
+    }
+    painter.restore();
+}
+
+QColor JKQTPfilledVerticalRangeGraph::getKeyLabelColor()
+{
+    return color;
+}
+
+QBrush JKQTPfilledVerticalRangeGraph::getBrush(JKQTPEnhancedPainter &painter) const
+{
+    QBrush b;
+    b.setColor(fillColor);
+    b.setStyle(fillStyle);
+    return b;
+}
+
+QPen JKQTPfilledVerticalRangeGraph::getLinePen(JKQTPEnhancedPainter &painter) const
+{
+    QPen p;
+    p.setColor(color);
+    p.setWidthF(qMax(JKQTPLOTTER_ABS_MIN_LINEWIDTH, parent->pt2px(painter, lineWidth*parent->get_lineWidthMultiplier())));
+    p.setStyle(style);
+    p.setJoinStyle(Qt::RoundJoin);
+    p.setCapStyle(Qt::RoundCap);
+    return p;
+}

lib/jkqtplotter/jkqtpelements.h

@@ -605,6 +605,84 @@ class LIB_EXPORT JKQTPfilledCurveYErrorGraph: public JKQTPfilledCurveYGraph, pub
 
 
 
+
+/*! \brief This implements filled curve plots where the area is filled between two data columns for each x-value
+    \ingroup jkqtplotter_plots
+
+    With set_drawlines(false):
+    \image html JKQTPfilledVerticalRangeGraph.png
+
+    With set_drawlines(true):
+    \image html JKQTPfilledVerticalRangeGraph_WithLines.png
+ */
+class LIB_EXPORT JKQTPfilledVerticalRangeGraph: public JKQTPxyGraph {
+        Q_OBJECT
+    public:
+        /** \brief class constructor */
+        JKQTPfilledVerticalRangeGraph(JKQtBasePlotter* parent=nullptr);
+        /** \brief class constructor */
+        JKQTPfilledVerticalRangeGraph(JKQtPlotter* parent);
+        /** \brief get the maximum and minimum y-value of the graph
+         *
+         * The result is given in the two parameters which are call-by-reference parameters!
+         */
+        virtual bool getYMinMax(double& miny, double& maxy, double& smallestGreaterZero);
+
+        /** \copydoc JKQTPgraph::usesColumn() */
+        virtual bool usesColumn(int column);
+
+        /** \brief plots the graph to the plotter object specified as parent */
+        virtual void draw(JKQTPEnhancedPainter& painter);
+        /** \brief plots a key marker inside the specified rectangle \a rect */
+        virtual void drawKeyMarker(JKQTPEnhancedPainter& painter, QRectF& rect);
+        /** \brief returns the color to be used for the key label */
+        virtual QColor getKeyLabelColor();
+
+        JKQTPGET_SET_MACRO(int, yColumn2)
+        JKQTPSET_CAST_MACRO(size_t, int, yColumn2)
+
+        JKQTPGET_SET_MACRO(QColor, color)
+        JKQTPGET_SET_MACRO(QColor, fillColor)
+        JKQTPGET_SET_MACRO(Qt::PenStyle, style)
+        JKQTPGET_SET_MACRO(bool, drawLine)
+        JKQTPGET_SET_MACRO(Qt::BrushStyle, fillStyle)
+
+        JKQTPGET_SET_MACRO(bool, drawSelectionLine)
+        JKQTPGET_SET_MACRO(QColor, selectionLineColor)
+
+    protected:
+
+        /** \brief the column that contains the second y-component of the range */
+        int yColumn2;
+        /** \brief if \c true, draws a thick shadow around the line*/
+        bool drawSelectionLine;
+        /** \brief color for the shadow, or a lighter version of the line color, if transparent (default) */
+        QColor selectionLineColor;
+
+        /** \brief which plot style to use from the parent plotter (via JKQtPlotterBase::getPlotStyle() and JKQtPlotterBase::getNextStyle() ) */
+        int parentPlotStyle;
+
+        /** \brief color of the graph */
+        QColor color;
+        /** \brief color of the graph fill */
+        QColor fillColor;
+        /** \brief fill styl for the curve */
+        Qt::BrushStyle fillStyle;
+        /** \brief linestyle of the graph lines */
+        Qt::PenStyle style;
+        /** \brief width (pixels) of the graph */
+        double lineWidth;
+        /** \brief indicates whether to draw a line or not */
+        bool drawLine;
+
+        QBrush getBrush(JKQTPEnhancedPainter& painter) const;
+        QPen getLinePen(JKQTPEnhancedPainter& painter) const;
+};
+
+
+
+
+
 /*! \brief This implements a step plot with values \f$ \left(x, f(x) \right) \f$
     \ingroup jkqtplotter_plots
 

test/jkqtplotter_simpletest_dateaxes/README.md

@@ -0,0 +1,171 @@
+[Back to JKQTPlotter main page](https://github.com/jkriege2/JKQtPlotter/)
+
+# JKQtPlotter
+
+## Date/Time Axes
+
+### Date Axis
+This project (see `./test/jkqtplotter_simpletest_dateaxes/`) simply creates a JKQtPlotter widget (as a new window) with the X-axis showing time or date(-time) values, formated as such. 
+
+The source code of the main application can be found in  [`jkqtplotter_simpletest_dateaxes.cpp`](https://github.com/jkriege2/JKQtPlotter/blob/master/test/jkqtplotter_simpletest_dateaxes/jkqtplotter_simpletest_dateaxes.cpp). 
+
+First some data is parsed from a CSV-file (added as ressource to the example). Note that the Time/date or Date+Time data is internally stored as milliseconds since epoc (Jan 1st 1970, 00:00:00), therefore data has to be converted accordingly before beeing added to the graph.
+
+```c++
+	QVector<double> date;
+    QVector<double> temperature, temperature_min, temperature_max;
+    // parse a textfile with comments on the first line and the
+    // semicolon separated data. The first column is a date and time
+    // the second to fourth columns contain a floating-point number
+    // with temperature average, min and max
+    QFile file(":/weatherdata_gelsenkirchen.csv");
+    file.open(QFile::ReadOnly|QFile::Text);
+    file.readLine(); // eat comment
+    while (!file.atEnd()) {
+        QString line=file.readLine();
+        QTextStream in(&line);
+        QStringList items=line.split(";");
+        // date/time values are stored as doubles representing the corresponding number of milliseconds sind epoch
+        date<<QDateTime::fromString(items[0], Qt::ISODate).toUTC().toMSecsSinceEpoch();
+        // store Heidelbergs daily temperature
+        temperature<<items[1].toDouble();
+        temperature_min<<items[2].toDouble();
+        temperature_max<<items[3].toDouble();
+    }
+```
+
+The parsed data looks like this:
+```
+	ISO-Date+Time;Temp_mean[degC];Temp_min[degC];Temp_max[degC]; data from http://wetter.mpg-ge.de/NOAA/NOAA-2018.txt and http://wetter.mpg-ge.de/NOAA/NOAA-2017.txt
+	2017-01-15T12:00; 1.2; -1.2; 3.7
+	2017-02-15T12:00; 5.6; 3.2; 8.1
+	2017-03-15T12:00; 9.6; 6.2; 13.5
+	...
+```
+
+Then two graphs are added. One of type `JKQTPfilledVerticalRangeGraph` plots the range of min+max temperature for each month:
+```c++
+   // 3. add a plot for the data mean line (graphTemperature) and range (graphTemperatureRange)
+    JKQTPfilledVerticalRangeGraph* graphTemperatureRange=new JKQTPfilledVerticalRangeGraph(&plot);
+
+    // 4. copy data into datastore and immediately set the yColumn
+    size_t colDate=ds->addCopiedColumn(date, "date");
+    graphTemperatureRange->set_xColumn(colDate);
+    graphTemperatureRange->set_yColumn(ds->addCopiedColumn(temperature_min, "temperature_min"));
+    graphTemperatureRange->set_yColumn2(ds->addCopiedColumn(temperature_max, "temperature_max"));
+
+
+    // 5. min/max range data
+    // graph fill color is a lighter shade of the average graph
+    graphTemperatureRange->set_fillColor(graphTemperature->get_color().lighter());
+    // don't draw lines of the data
+    graphTemperatureRange->set_drawLine(false);
+    // plot label in key
+    graphTemperatureRange->set_title("Min/Max Temperature");
+    // add the graph to the plot, so it is actually displayed
+    plot.addGraph(graphTemperatureRange);
+```
+
+On top of that plot, a second plot is added, which draws the average temperatures of each month as a line:
+
+```c++
+   // 3. add a plot for the data mean line (graphTemperature) and range (graphTemperatureRange)
+    JKQTPxyLineErrorGraph* graphTemperature=new JKQTPxyLineErrorGraph(&plot);
+
+    // 4. copy data into datastore and immediately set the yColumn
+    size_t colDate=ds->addCopiedColumn(date, "date");
+    graphTemperature->set_xColumn(colDate);
+    graphTemperature->set_yColumn(ds->addCopiedColumn(temperature, "temperature"));
+
+
+    // 5. min/max range data
+    // .... see above
+
+    // 6. average data
+    // don't use symbols
+    graphTemperature->set_symbol(JKQTPnoSymbol);
+    // set the line width
+    graphTemperature->set_lineWidth(1);
+    // draw small symbols
+    graphTemperature->set_symbolSize(6);
+    // graph title
+    graphTemperature->set_title("Average Temperature");
+    // add the graph to the plot, so it is actually displayed
+    plot.addGraph(graphTemperature);
+```
+
+Finally the x-axis is formatted to display dates (see [Qt-Documentation of `QDateTime::toString()`](http://doc.qt.io/qt-5/qdatetime.html#toString) for details on the formating strings):
+```c++
+    // 7. format the plot
+    // set the title above the plot, use LaTeX instructions to make text bold
+    plot.get_plotter()->set_plotLabel("\\textbf{Weather in Gelsenkirchen, 2017-2018}");
+    // set x-axis date-time-axis
+    plot.getXAxis()->set_labelType(JKQTPCALTdatetime);
+    plot.getXAxis()->set_axisLabel("Date");
+    // set format string for date axis (e.g. Jan '18), see Documentation of QDateTime::toString()
+    plot.getXAxis()->set_tickDateTimeFormat("MMM ''yy");
+    // set y-axis temperature axis
+    plot.getYAxis()->set_axisLabel("Average Daily Temperature [{\\degree}C]");
+```
+
+The result looks like this:
+
+![jkqtplotter_simpletest_symbols_and_styles](https://raw.githubusercontent.com/jkriege2/JKQtPlotter/master/screenshots/jkqtplotter_simpletest_dateaxes.png)
+
+
+### Time Axis
+A second variant (see the example CPP-file) displays data with a time-axis:
+
+![jkqtplotter_simpletest_symbols_and_styles](https://raw.githubusercontent.com/jkriege2/JKQtPlotter/master/screenshots/jkqtplotter_simpletest_dateaxes_timeaxis.png)
+
+
+For that example data-pasring is a bit different, because the file only contains times and no dates:
+```c++
+    // 2. now we create data vectors with data parsed from a CSV-file
+    QVector<double> time;
+    QVector<double> temperature;
+    // parse a textfile with comments on the first line and the
+    // semicolon separated data. The first column is a time
+    // the second contain a floating-point number with temperatures
+    QFile file(":/weatherdata_heidelberg_2018-10-14.csv");
+    file.open(QFile::ReadOnly|QFile::Text);
+    file.readLine(); // eat comment
+    while (!file.atEnd()) {
+        QString line=file.readLine();
+        QTextStream in(&line);
+        QStringList items=line.split(";");
+        // date/time values are stored as doubles representing the corresponding
+        // number of milliseconds sind epoch. Since the data is time only, we have to use an arbitrary
+        // date as basis
+        time<<QDateTime::fromString("1970-01-01T"+items[0], Qt::ISODate).toUTC().toMSecsSinceEpoch();
+        // store Heidelbergs daily temperature
+        temperature<<items[1].toDouble();
+    }
+```
+
+The parsed data looks like this:
+```
+	Time;     Temperature [degC]
+	00:00:00; 24.2
+	00:10:00; 24.2
+	00:20:00; 24.1
+	00:30:00; 24.1
+	...
+```
+
+Axis formating for this example is done like this:
+```c++
+    // 7. format the plot
+    // set the title above the plot, use LaTeX instructions to make text bold
+    plot.get_plotter()->set_plotLabel("\\textbf{Weather in Heidelberg, 14^{th} Oct 2018}");
+    // set x-axis date-time-axis
+    plot.getXAxis()->set_labelType(JKQTPCALTtime);
+    plot.getXAxis()->set_axisLabel("Time of Day");
+    // set format string for time axis with 24-hour and minute only,
+    // see QDateTime::toString() documentation for details on format strings
+    plot.getXAxis()->set_tickTimeFormat("HH:mm");
+    // set y-axis temperature axis
+    plot.getYAxis()->set_axisLabel("Temperature [{\\degree}C]");
+```
+
+[Back to JKQTPlotter main page](https://github.com/jkriege2/JKQtPlotter/)

test/jkqtplotter_simpletest_dateaxes/jkqtplotter_simpletest_dateaxes.cpp

@@ -0,0 +1,172 @@
+#include <QApplication>
+#include <QDateTime>
+#include <QTime>
+#include <QFile>
+#include <QTextStream>
+#include "jkqtplotter/jkqtplotter.h"
+#include "jkqtplotter/jkqtpgeoelements.h"
+#include "jkqtplottertools/jkqtptools.h"
+
+void drawWithDateAxis(JKQtPlotter& plot) {
+
+    // 1. create a plotter window and get a pointer to the internal datastore (for convenience)
+    JKQTPdatastore* ds=plot.getDatastore();
+
+    // 2. now we create data vectors with data parsed from a CSV-file
+    QVector<double> date;
+    QVector<double> temperature, temperature_min, temperature_max;
+    // parse a textfile with comments on the first line and the
+    // semicolon separated data. The first column is a date and time
+    // the second to fourth columns contain a floating-point number
+    // with temperature average, min and max
+    QFile file(":/weatherdata_gelsenkirchen.csv");
+    file.open(QFile::ReadOnly|QFile::Text);
+    file.readLine(); // eat comment
+    while (!file.atEnd()) {
+        QString line=file.readLine();
+        QTextStream in(&line);
+        QStringList items=line.split(";");
+        // date/time values are stored as doubles representing the corresponding number of milliseconds sind epoch
+        date<<QDateTime::fromString(items[0], Qt::ISODate).toUTC().toMSecsSinceEpoch();
+        // store Heidelbergs daily temperature
+        temperature<<items[1].toDouble();
+        temperature_min<<items[2].toDouble();
+        temperature_max<<items[3].toDouble();
+    }
+
+    // 3. add a plot for the data mean line (graphTemperature) and range (graphTemperatureRange)
+    JKQTPfilledVerticalRangeGraph* graphTemperatureRange=new JKQTPfilledVerticalRangeGraph(&plot);
+    JKQTPxyLineErrorGraph* graphTemperature=new JKQTPxyLineErrorGraph(&plot);
+
+    // 4. copy data into datastore and immediately set the yColumn
+    size_t colDate=ds->addCopiedColumn(date, "date");
+    graphTemperature->set_xColumn(colDate);
+    graphTemperature->set_yColumn(ds->addCopiedColumn(temperature, "temperature"));
+    graphTemperatureRange->set_xColumn(colDate);
+    graphTemperatureRange->set_yColumn(ds->addCopiedColumn(temperature_min, "temperature_min"));
+    graphTemperatureRange->set_yColumn2(ds->addCopiedColumn(temperature_max, "temperature_max"));
+
+
+    // 5. min/max range data
+    // graph fill color is a lighter shade of the average graph
+    graphTemperatureRange->set_fillColor(graphTemperature->get_color().lighter());
+    // don't draw lines of the data
+    graphTemperatureRange->set_drawLine(false);
+    // plot label in key
+    graphTemperatureRange->set_title("Min/Max Temperature");
+    // add the graph to the plot, so it is actually displayed
+    plot.addGraph(graphTemperatureRange);
+
+    // 6. average data
+    // don't use symbols
+    graphTemperature->set_symbol(JKQTPnoSymbol);
+    // set the line width
+    graphTemperature->set_lineWidth(1);
+    // draw small symbols
+    graphTemperature->set_symbolSize(6);
+    // graph title
+    graphTemperature->set_title("Average Temperature");
+    // add the graph to the plot, so it is actually displayed
+    plot.addGraph(graphTemperature);
+
+
+    // 7. format the plot
+    // set the title above the plot, use LaTeX instructions to make text bold
+    plot.get_plotter()->set_plotLabel("\\textbf{Weather in Gelsenkirchen, 2017-2018}");
+    // set x-axis date-time-axis
+    plot.getXAxis()->set_labelType(JKQTPCALTdatetime);
+    plot.getXAxis()->set_axisLabel("Date");
+    // set format string for date axis (e.g. Jan '18), see Documentation of QDateTime::toString()
+    plot.getXAxis()->set_tickDateTimeFormat("MMM ''yy");
+    // set y-axis temperature axis
+    plot.getYAxis()->set_axisLabel("Average Daily Temperature [{\\degree}C]");
+
+    // 8. autoscale the plot so the graph is contained
+    plot.zoomToFit();
+
+    // 9. show plotter and make it a decent size
+    plot.show();
+    plot.resize(600,400);
+    plot.setWindowTitle("Date Axis");
+}
+
+void drawWithTimeAxis(JKQtPlotter& plot) {
+    // 1. create a plotter window and get a pointer to the internal datastore (for convenience)
+    JKQTPdatastore* ds=plot.getDatastore();
+
+    // 2. now we create data vectors with data parsed from a CSV-file
+    QVector<double> time;
+    QVector<double> temperature;
+    // parse a textfile with comments on the first line and the
+    // semicolon separated data. The first column is a time
+    // the second contain a floating-point number with temperatures
+    QFile file(":/weatherdata_heidelberg_2018-10-14.csv");
+    file.open(QFile::ReadOnly|QFile::Text);
+    file.readLine(); // eat comment
+    while (!file.atEnd()) {
+        QString line=file.readLine();
+        QTextStream in(&line);
+        QStringList items=line.split(";");
+        // date/time values are stored as doubles representing the corresponding
+        // number of milliseconds sind epoch. Since the data is time only, we have to use an arbitrary
+        // date as basis
+        time<<QDateTime::fromString("1970-01-01T"+items[0], Qt::ISODate).toMSecsSinceEpoch();
+        // store Heidelbergs daily temperature
+        temperature<<items[1].toDouble();
+    }
+
+    // 3. add a plot for the data mean line (graphTemperature) and range (graphTemperatureRange)
+    JKQTPxyLineErrorGraph* graphTemperature=new JKQTPxyLineErrorGraph(&plot);
+
+    // 4. copy data into datastore and immediately set the yColumn
+    size_t colDate=ds->addCopiedColumn(time, "time");
+    graphTemperature->set_xColumn(colDate);
+    graphTemperature->set_yColumn(ds->addCopiedColumn(temperature, "temperature"));
+
+
+    // 6. average data
+    // don't use symbols
+    graphTemperature->set_symbol(JKQTPcross);
+    // set the line width
+    graphTemperature->set_lineWidth(1);
+    // draw small symbols
+    graphTemperature->set_symbolSize(6);
+    // graph title
+    graphTemperature->set_title("Average Temperature");
+    // add the graph to the plot, so it is actually displayed
+    plot.addGraph(graphTemperature);
+
+
+    // 7. format the plot
+    // set the title above the plot, use LaTeX instructions to make text bold
+    plot.get_plotter()->set_plotLabel("\\textbf{Weather in Heidelberg, 14^{th} Oct 2018}");
+    // set x-axis date-time-axis
+    plot.getXAxis()->set_labelType(JKQTPCALTtime);
+    plot.getXAxis()->set_axisLabel("Time of Day");
+    // set format string for time axis with 24-hour and minute only,
+    // see QDateTime::toString() documentation for details on format strings
+    plot.getXAxis()->set_tickTimeFormat("HH:mm");
+    // set y-axis temperature axis
+    plot.getYAxis()->set_axisLabel("Temperature [{\\degree}C]");
+
+    // 8. autoscale the plot so the graph is contained
+    plot.zoomToFit();
+
+    // 9. show plotter and make it a decent size
+    plot.show();
+    plot.resize(600,400);
+    plot.setWindowTitle("Time Axis");
+}
+
+int main(int argc, char* argv[])
+{
+    QApplication app(argc, argv);
+    JKQtPlotter plotDate;
+    drawWithDateAxis(plotDate);
+    plotDate.move(100,100);
+    JKQtPlotter plotTime;
+    drawWithTimeAxis(plotTime);
+    plotTime.move(100,550);
+
+    return app.exec();
+}

test/jkqtplotter_simpletest_dateaxes/jkqtplotter_simpletest_dateaxes.pro

@@ -0,0 +1,20 @@
+# source code for this simple demo
+SOURCES = jkqtplotter_simpletest_dateaxes.cpp 
+
+# configure Qt
+CONFIG += qt
+QT += core gui svg
+greaterThan(QT_MAJOR_VERSION, 4): QT += widgets printsupport
+
+# output executable name
+TARGET = jkqtplotter_simpletest_dateaxes
+
+# include JKQtPlotter source code
+include(../../lib/jkqtplotter.pri)
+
+# here you can activate some debug options
+#DEFINES += SHOW_JKQTPLOTTER_DEBUG
+#DEFINES += JKQTBP_AUTOTIMER
+
+RESOURCES += \
+    jkqtplotter_simpletest_dateaxes.qrc

test/jkqtplotter_simpletest_dateaxes/jkqtplotter_simpletest_dateaxes.qrc

@@ -0,0 +1,7 @@
+<RCC>
+    <qresource prefix="/">
+        <file>weatherdata_gelsenkirchen.csv</file>
+        <file>weatherdata_heidelberg_2018-10-14.csv</file>
+        <file>weatherdata_heidelberg.csv</file>
+    </qresource>
+</RCC>

test/jkqtplotter_simpletest_dateaxes/weatherdata_gelsenkirchen.csv

@@ -0,0 +1,24 @@
+Datum;Zeit;Temp_mean[degC];Temp_min[degC];Temp_max[degC]; data from http://wetter.mpg-ge.de/NOAA/NOAA-2018.txt and http://wetter.mpg-ge.de/NOAA/NOAA-2017.txt
+2017-01-15T12:00; 1.2; -1.2; 3.7
+2017-02-15T12:00; 5.6; 3.2; 8.1
+2017-03-15T12:00; 9.6; 6.2; 13.5
+2017-04-15T12:00; 8.9; 5.1; 12.9
+2017-05-15T12:00; 16.0; 11.4; 20.8
+2017-06-15T12:00; 19.2; 15.0; 23.5
+2017-07-15T12:00; 19.1; 15.2; 23.4
+2017-08-15T12:00; 18.5; 14.7; 22.5
+2017-09-15T12:00; 14.4; 11.4; 18.3
+2017-10-15T12:00; 13.1; 10.8; 16.0
+2017-11-15T12:00; 7.5; 5.6; 9.7
+2017-12-15T12:00; 4.2; 2.6; 5.9
+2018-01-15T12:00; 5.7; 3.7; 7.8
+2018-02-15T12:00; 0.4; -1.9; 3.2
+2018-03-15T12:00; 5.0; 1.5; 8.5
+2018-04-15T12:00; 14.3; 9.8; 18.9
+2018-05-15T12:00; 16.7; 12.3; 21.2
+2018-06-15T12:00; 18.3; 14.5; 22.7
+2018-07-15T12:00; 22.2; 16.4; 27.9
+2018-08-15T12:00; 20.5; 15.9; 25.6
+2018-09-15T12:00; 16.2; 12.1; 20.8
+2018-10-15T12:00; 13.0; 9.6; 17.0
+2018-11-15T12:00; 7.2; 4.8; 10.0

test/jkqtplotter_simpletest_dateaxes/weatherdata_heidelberg.csv

@@ -0,0 +1,289 @@
+2018-10-14T00:00:00; 24.2
+2018-10-14T00:10:00; 24.2
+2018-10-14T00:20:00; 24.1
+2018-10-14T00:30:00; 24.1
+2018-10-14T00:40:00; 24.1
+2018-10-14T00:50:00; 24.0
+2018-10-14T01:00:00; 24.0
+2018-10-14T01:10:00; 24.0
+2018-10-14T01:20:00; 24.0
+2018-10-14T01:30:00; 24.0
+2018-10-14T01:40:00; 23.9
+2018-10-14T01:50:00; 23.9
+2018-10-14T02:00:00; 23.8
+2018-10-14T02:10:00; 23.8
+2018-10-14T02:20:00; 23.8
+2018-10-14T02:30:00; 23.8
+2018-10-14T02:40:00; 23.8
+2018-10-14T02:50:00; 23.7
+2018-10-14T03:00:00; 23.7
+2018-10-14T03:10:00; 23.7
+2018-10-14T03:20:00; 23.6
+2018-10-14T03:30:00; 23.6
+2018-10-14T03:40:00; 23.6
+2018-10-14T03:50:00; 23.6
+2018-10-14T04:00:00; 23.6
+2018-10-14T04:10:00; 23.6
+2018-10-14T04:20:00; 23.6
+2018-10-14T04:30:00; 23.6
+2018-10-14T04:40:00; 23.6
+2018-10-14T04:50:00; 23.5
+2018-10-14T05:00:00; 23.5
+2018-10-14T05:10:00; 23.5
+2018-10-14T05:20:00; 23.4
+2018-10-14T05:30:00; 23.4
+2018-10-14T05:40:00; 23.4
+2018-10-14T05:50:00; 23.4
+2018-10-14T06:00:00; 23.4
+2018-10-14T06:10:00; 23.4
+2018-10-14T06:20:00; 23.4
+2018-10-14T06:30:00; 23.4
+2018-10-14T06:40:00; 23.4
+2018-10-14T06:50:00; 23.4
+2018-10-14T07:00:00; 23.4
+2018-10-14T07:10:00; 23.4
+2018-10-14T07:20:00; 23.4
+2018-10-14T07:30:00; 23.4
+2018-10-14T07:40:00; 23.4
+2018-10-14T07:50:00; 23.4
+2018-10-14T08:00:00; 23.4
+2018-10-14T08:10:00; 23.3
+2018-10-14T08:20:00; 23.3
+2018-10-14T08:30:00; 23.2
+2018-10-14T08:40:00; 23.2
+2018-10-14T08:50:00; 23.2
+2018-10-14T09:00:00; 23.1
+2018-10-14T09:10:00; 23.1
+2018-10-14T09:20:00; 23.0
+2018-10-14T09:30:00; 23.0
+2018-10-14T09:40:00; 23.0
+2018-10-14T09:50:00; 23.1
+2018-10-14T10:00:00; 23.1
+2018-10-14T10:10:00; 23.2
+2018-10-14T10:20:00; 23.2
+2018-10-14T10:30:00; 23.3
+2018-10-14T10:40:00; 23.4
+2018-10-14T10:50:00; 23.5
+2018-10-14T11:00:00; 23.6
+2018-10-14T11:10:00; 23.8
+2018-10-14T11:20:00; 24.0
+2018-10-14T11:30:00; 24.3
+2018-10-14T11:40:00; 24.6
+2018-10-14T11:50:00; 24.9
+2018-10-14T12:00:00; 25.3
+2018-10-14T12:10:00; 25.6
+2018-10-14T12:20:00; 25.8
+2018-10-14T12:30:00; 25.8
+2018-10-14T12:40:00; 25.8
+2018-10-14T12:50:00; 25.8
+2018-10-14T13:00:00; 25.8
+2018-10-14T13:10:00; 25.9
+2018-10-14T13:20:00; 26.1
+2018-10-14T13:30:00; 26.3
+2018-10-14T13:40:00; 26.5
+2018-10-14T13:50:00; 26.6
+2018-10-14T14:00:00; 26.8
+2018-10-14T14:10:00; 26.9
+2018-10-14T14:20:00; 27.0
+2018-10-14T14:30:00; 27.2
+2018-10-14T14:40:00; 27.2
+2018-10-14T14:50:00; 27.4
+2018-10-14T15:00:00; 27.4
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+2018-10-14T16:10:00; 27.4
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+2018-10-14T16:40:00; 26.8
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+2018-10-14T21:50:00; 25.9
+2018-10-14T22:00:00; 25.9
+2018-10-14T22:10:00; 26.0
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+2018-10-14T22:30:00; 26.0
+2018-10-14T22:40:00; 26.0
+2018-10-14T22:50:00; 26.0
+2018-10-14T23:00:00; 26.0
+2018-10-14T23:10:00; 26.0
+2018-10-14T23:20:00; 26.0
+2018-10-14T23:30:00; 26.0
+2018-10-14T23:40:00; 25.8
+2018-10-14T23:50:00; 25.6
+2018-10-15T00:00:00; 25.4
+2018-10-15T00:10:00; 25.2
+2018-10-15T00:20:00; 25.0
+2018-10-15T00:30:00; 24.9
+2018-10-15T00:40:00; 24.8
+2018-10-15T00:50:00; 24.6
+2018-10-15T01:00:00; 24.5
+2018-10-15T01:10:00; 24.4
+2018-10-15T01:20:00; 24.4
+2018-10-15T01:30:00; 24.3
+2018-10-15T01:40:00; 24.2
+2018-10-15T01:50:00; 24.2
+2018-10-15T02:00:00; 24.1
+2018-10-15T02:10:00; 24.0
+2018-10-15T02:20:00; 24.0
+2018-10-15T02:30:00; 23.9
+2018-10-15T02:40:00; 23.8
+2018-10-15T02:50:00; 23.8
+2018-10-15T03:00:00; 23.7
+2018-10-15T03:10:00; 23.7
+2018-10-15T03:20:00; 23.6
+2018-10-15T03:30:00; 23.6
+2018-10-15T03:40:00; 23.5
+2018-10-15T03:50:00; 23.5
+2018-10-15T04:00:00; 23.4
+2018-10-15T04:10:00; 23.4
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+2018-10-15T04:40:00; 23.2
+2018-10-15T04:50:00; 23.2
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+2018-10-15T05:39:00; 23.1
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+2018-10-15T07:30:00; 22.9
+2018-10-15T07:40:00; 22.9
+2018-10-15T07:50:00; 22.9
+2018-10-15T08:00:00; 22.9
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test/jkqtplotter_simpletest_dateaxes/weatherdata_heidelberg_2018-10-14.csv

@@ -0,0 +1,145 @@
+Time;     Temperature [degC]
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