NEW: you can provide a custom draw functor to barcharts to completely customize their look

doc/CMakeLists.txt

@@ -144,6 +144,7 @@ if(JKQtPlotter_BUILD_EXAMPLES)
         barchart_twocolor/barchart_twocolor,barchart_twocolor_hor
         barchart_errorbars/barchart_errorbars,barchart_errorbars_hor
         barchart_functorfill/barchart_functorfill,barchart_functorfill_hor
+        barchart_customdrawfunctor/barchart_customdrawfunctor,barchart_customdrawfunctor_hor
         wiggleplots/wiggleplot_x,wiggleplot_y
         advplotstyling/advancedlineandfillstyling
         boxplot
@@ -196,6 +197,7 @@ if(JKQtPlotter_BUILD_EXAMPLES)
         barchart_twocolor/JKQTPBarVerticalGraphTwoColorFilling,JKQTPBarHorizontalGraphTwoColorFilling/--smallscreenshotplot
         barchart_errorbars/JKQTPBarVerticalErrorGraph,JKQTPBarHorizontalErrorGraph/--smallscreenshotplot
         barchart_functorfill/JKQTPBarVerticalGraphFunctorFilling,JKQTPBarHorizontalGraphFunctorFilling/--smallscreenshotplot
+        barchart_customdrawfunctor/JKQTPBarVerticalGraphCustomDrawFunctor,JKQTPBarHorizontalGraphCustomDrawFunctor/--smallscreenshotplot
         wiggleplots/JKQTPFilledCurveXGraph_wiggle,JKQTPFilledCurveYGraph_wiggle
         contourplot/JKQTPColumnContourPlot/--smallscreenshotplot
         filledgraphs/JKQTPFilledCurveXGraph,JKQTPFilledCurveYGraph/--smallscreenshotplot

doc/dox/examples_and_tutorials.dox

@@ -46,9 +46,12 @@ All test-projects are Qt-projects that use qmake to build. You can load them int
 <tr><td> \image html barchart_twocolor_small.png
     <td> \subpage JKQTPlotterBarchartsTwoColorFilling
     <td> `JKQTPBarVerticalGraph` <br> JKQTPDatastore::addColumnCalculatedFromColumn()
-<tr><td> \image html barchart_functorfill_small.png
+<tr><td> \image html barchart_customdrawfunctor_small.png
     <td> \subpage JKQTPlotterBarchartsFunctorFilling
     <td> `JKQTPBarVerticalGraph` <br> JKQTPDatastore::addColumnCalculatedFromColumn()
+<tr><td> \image html barchart_functorfill_small.png
+    <td> \subpage JKQTPlotterBarchartsCustomDrawFunctor
+    <td> `JKQTPBarVerticalGraph` <br> JKQTPDatastore::addColumnCalculatedFromColumn()
 <tr><td> \image html stackedbars_small.png
     <td> \subpage JKQTPlotterStackedBarChart
     <td> `JKQTPBarVerticalStackableGraph`, `JKQTPBarHorizontalStackableGraph` <br> C++-style vectors of data 

doc/dox/todo.dox

@@ -26,7 +26,7 @@ This page lists several todos and wishes for future version of JKQTPlotter
     <li>plot: elongated grid to left of tick labels</li>
     <li>plot: legend positioning as combination of 3 values: inside|outside + left|center|right + top|vcenter|bottom</li>
     <li>plot: refactor print preview/export preview code </li>
-    <li>plot: reqork layouting of legends: there are some inconsistencies/too large gaps ...</li>
+    <li>plot: rework layouting of legends: there are some inconsistencies/too large gaps ...</li>
     <li>plot: secondary axes: independent and dependent (i.e. with transformation function from primary axis)</li>
     <li>sryling: better styling/more styling options for data-tooltips</li>
     <li>styling: color gradients as fill-styles in style-INIs</li>

doc/dox/whatsnew.dox

@@ -64,6 +64,7 @@ Changes, compared to  \ref page_whatsnew_V4_0_0 "v4.0.0" include:
     <li>NEW: barcharts (derived from JKQTPBarGraphBase) can be configured to use different fill styles above and below the baseline, see JKQTPBarGraphBase::FillMode </li>
     <li>NEW: barcharts may have rounded corners now, via JKQTPBarGraphBase::setRectRadius()</li>
     <li>NEW: barcharts can be colored by a user-specified functor</li>
+    <li>NEW: you can provide a custom draw functor to barcharts to completely customize their look</li>
   </ul></li>
   
   <li>JKQTMathText:<ul>

examples/CMakeLists.txt

@@ -51,6 +51,7 @@ add_subdirectory(boxplot)
 add_subdirectory(barchart_errorbars)
 add_subdirectory(barchart_functorfill)
 add_subdirectory(barchart_twocolor)
+add_subdirectory(barchart_customdrawfunctor)
 add_subdirectory(contourplot)
 add_subdirectory(datastore)
 add_subdirectory(datastore_groupedstat)

examples/barchart_customdrawfunctor/CMakeLists.txt

@@ -0,0 +1,34 @@
+cmake_minimum_required(VERSION 3.16)
+
+set(EXAMPLE_NAME barchart_customdrawfunctor)
+set(EXENAME jkqtptest_${EXAMPLE_NAME})
+
+message( STATUS "..   Building Example ${EXAMPLE_NAME}" )
+
+
+# Set up source files
+set(SOURCES barchart_customdrawfunctor.cpp )
+set(HEADERS  )
+set(RESOURCES  )
+set(UIS  )
+
+add_executable(${EXENAME} WIN32 ${SOURCES} ${HEADERS} ${RESOURCES} ${UIS})
+target_link_libraries(${EXENAME} JKQTPExampleToolsLib)
+target_include_directories(${EXENAME} PRIVATE ../../lib)
+if(JKQtPlotter_BUILD_STATIC_LIBS)
+    target_link_libraries(${EXENAME} JKQTPlotterLib)
+elseif(JKQtPlotter_BUILD_SHARED_LIBS)
+    target_link_libraries(${EXENAME} JKQTPlotterSharedLib)
+endif()
+
+# precomiled headers to speed up compilation
+if (JKQtPlotter_BUILD_WITH_PRECOMPILED_HEADERS)
+  target_precompile_headers(${EXENAME} REUSE_FROM jkqtptest_simpletest)
+endif (JKQtPlotter_BUILD_WITH_PRECOMPILED_HEADERS)
+
+
+# Installation
+install(TARGETS ${EXENAME} RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR})
+
+#Installation of Qt DLLs on Windows
+jkqtplotter_deployqt(${EXENAME})

examples/barchart_customdrawfunctor/README.md

@@ -0,0 +1,89 @@
+# Example (JKQTPlotter): Barchart With Custom Draw Functor {#JKQTPlotterBarchartsCustomDrawFunctor}
+This project (see [`barchart_customdrawfunctor`](https://github.com/jkriege2/JKQtPlotter/tree/master/examples/barchart_customdrawfunctor) shows how to draw customized barcharts, with a custom draw functor.
+
+The source code of the main application is (see [`barchart_customdrawfunctor.cpp`](https://github.com/jkriege2/JKQtPlotter/tree/master/examples/barchart_customdrawfunctor/barchart_customdrawfunctor.cpp):
+```.cpp
+    // 1. create a plotter window and get a pointer to the internal datastore (for convenience)
+    JKQTPDatastore* ds=plot.getDatastore();
+
+    // 2. now we create two columns for key and value
+    size_t columnK=ds->addLinearColumn(7, 0, 6, "k");
+    size_t columnV=ds->addColumnCalculatedFromColumn(columnK, [](double x) { return jkqtp_sign(2.0*x-2.5)*qMax(2.0,fabs(2.0*x-2.5)); }, "v");
+
+    // 3. load a stylesheet
+    plot.loadCurrentPlotterStyle(QSettings(":/JKQTPlotter/styles/seaborn.ini", QSettings::IniFormat));
+
+    // 4. create graph in the plot, which plots the dataset:
+    JKQTPBarVerticalGraph* graph=new JKQTPBarVerticalGraph(&plot);
+    graph->setKeyColumn(columnK);
+    graph->setValueColumn(columnV);
+    // this is the custom draw functor
+    graph->setCustomDrawingFunctor(
+    [](JKQTPEnhancedPainter& painter, const QRectF& bar_px, const QPointF& datapoint, Qt::Orientation orientation, JKQTPBarGraphBase* graph) {
+        painter.save();
+        painter.setPen(Qt::NoPen);
+        QBrush b=painter.brush();
+        QBrush bDeco=b;
+        bDeco.setColor(b.color().lighter());
+        // we draw the bar with a rounded end and add a lightly colored circle near the top
+        if (orientation==Qt::Vertical) {
+            // for vertical barcharts
+            const double dx=bar_px.width()/2.0;
+            const double r=dx*0.85;
+            // depending in whether the bar elongates above or below the baseline,
+            // we have to align the circle wrt the top or the bottom of the rectangle bar_px
+            if (datapoint.y()>=graph->getBaseline()) {
+                painter.drawComplexRoundedRect(bar_px, dx, dx, 0, 0, Qt::AbsoluteSize);
+                painter.setBrush(bDeco);
+                painter.drawEllipse(QPointF(bar_px.center().x(), bar_px.top()+dx), r,r);
+            } else {
+                painter.drawComplexRoundedRect(bar_px, 0, 0, dx, dx, Qt::AbsoluteSize);
+                painter.setBrush(bDeco);
+                painter.drawEllipse(QPointF(bar_px.center().x(), bar_px.bottom()-dx), r,r);
+            }
+        } else {
+            // for horizontal barcharts
+            const double dx=bar_px.height()/2.0;
+            const double r=dx*0.85;
+            if (datapoint.x()>=graph->getBaseline()) {
+                painter.drawComplexRoundedRect(bar_px, 0, dx, 0, dx, Qt::AbsoluteSize);
+                painter.setBrush(bDeco);
+                painter.drawEllipse(QPointF(bar_px.right()-dx, bar_px.center().y()), r,r);
+            } else {
+                painter.drawComplexRoundedRect(bar_px, dx,0,dx,0, Qt::AbsoluteSize);
+                painter.setBrush(bDeco);
+                painter.drawEllipse(QPointF(bar_px.left()+dx, bar_px.center().y()), r,r);
+            }
+        }
+        painter.restore();
+    }
+    );
+    // enable usage of cutom draw functor
+    graph->setUseCustomDrawFunctor(true);
+    // set graph color
+    graph->setColor(QColor("blue"));
+    plot.addGraph(graph);
+
+
+    // 5. autoscale the plot so the graph is contained
+    plot.zoomToFit();
+
+    // 6. show plotter and make it a decent size
+    plot.setWindowTitle(title);
+    plot.show();
+    plot.resize(400,400);
+```
+
+
+
+The result looks like this:
+
+![barchart_customdrawfunctor](https://raw.githubusercontent.com/jkriege2/JKQtPlotter/master/screenshots/barchart_customdrawfunctor.png)
+
+
+
+In order to draw horizontal error bars, you have to use `JKQTPBarHorizontalGraph` instead of `JKQTPBarVerticalGraph`. The functor given above also covers that case by checking the parameter `orientation`:
+
+![barchart_customdrawfunctor_hor](https://raw.githubusercontent.com/jkriege2/JKQtPlotter/master/screenshots/barchart_customdrawfunctor_hor.png)
+
+

examples/barchart_customdrawfunctor/barchart_customdrawfunctor.cpp

@@ -0,0 +1,102 @@
+/** \example barchart_functorfill.cpp
+ * Shows how to draw Barcharts with colors defined by a functor JKQTPlotter
+ *
+ * \ref JKQTPlotterBarchartsFunctorFilling
+ */
+
+#include "jkqtpexampleapplication.h"
+#include <QApplication>
+#include "jkqtplotter/jkqtplotter.h"
+#include "jkqtplotter/graphs/jkqtpbarchart.h"
+#include "jkqtcommon/jkqtpmathtools.h"
+#include "jkqtpexampleapplication.h"
+
+
+
+template <class TCHART>
+void doExample(JKQTPlotter& plot, const QString& title)
+{
+    // 1. create a plotter window and get a pointer to the internal datastore (for convenience)
+    JKQTPDatastore* ds=plot.getDatastore();
+
+    // 2. now we create two columns for key and value
+    size_t columnK=ds->addLinearColumn(7, 0, 6, "k");
+    size_t columnV=ds->addColumnCalculatedFromColumn(columnK, [](double x) { return jkqtp_sign(2.0*x-2.5)*qMax(2.0,fabs(2.0*x-2.5)); }, "v");
+
+    // 3. load a stylesheet
+    plot.loadCurrentPlotterStyle(QSettings(":/JKQTPlotter/styles/seaborn.ini", QSettings::IniFormat));
+
+    // 4. create graph in the plot, which plots the dataset:
+    JKQTPBarGraphBase* graph=new TCHART(&plot);
+    graph->setKeyColumn(columnK);
+    graph->setValueColumn(columnV);
+    // this is the custom draw functor
+    graph->setCustomDrawingFunctor(
+    [](JKQTPEnhancedPainter& painter, const QRectF& bar_px, const QPointF& datapoint, Qt::Orientation orientation, JKQTPBarGraphBase* graph) {
+        painter.save();
+        painter.setPen(Qt::NoPen);
+        QBrush b=painter.brush();
+        QBrush bDeco=b;
+        bDeco.setColor(b.color().lighter());
+        // we draw the bar with a rounded end and add a lightly colored circle near the top
+        if (orientation==Qt::Vertical) {
+            // for vertical barcharts
+            const double dx=bar_px.width()/2.0;
+            const double r=dx*0.85;
+            // depending in whether the bar elongates above or below the baseline,
+            // we have to align the circle wrt the top or the bottom of the rectangle bar_px
+            if (datapoint.y()>=graph->getBaseline()) {
+                painter.drawComplexRoundedRect(bar_px, dx, dx, 0, 0, Qt::AbsoluteSize);
+                painter.setBrush(bDeco);
+                painter.drawEllipse(QPointF(bar_px.center().x(), bar_px.top()+dx), r,r);
+            } else {
+                painter.drawComplexRoundedRect(bar_px, 0, 0, dx, dx, Qt::AbsoluteSize);
+                painter.setBrush(bDeco);
+                painter.drawEllipse(QPointF(bar_px.center().x(), bar_px.bottom()-dx), r,r);
+            }
+        } else {
+            // for horizontal barcharts
+            const double dx=bar_px.height()/2.0;
+            const double r=dx*0.85;
+            if (datapoint.x()>=graph->getBaseline()) {
+                painter.drawComplexRoundedRect(bar_px, 0, dx, 0, dx, Qt::AbsoluteSize);
+                painter.setBrush(bDeco);
+                painter.drawEllipse(QPointF(bar_px.right()-dx, bar_px.center().y()), r,r);
+            } else {
+                painter.drawComplexRoundedRect(bar_px, dx,0,dx,0, Qt::AbsoluteSize);
+                painter.setBrush(bDeco);
+                painter.drawEllipse(QPointF(bar_px.left()+dx, bar_px.center().y()), r,r);
+            }
+        }
+        painter.restore();
+    }
+    );
+    // enable usage of cutom draw functor
+    graph->setUseCustomDrawFunctor(true);
+    // set graph color
+    graph->setColor(QColor("blue"));
+    plot.addGraph(graph);
+
+
+    // 5. autoscale the plot so the graph is contained
+    plot.zoomToFit();
+
+    // 6. show plotter and make it a decent size
+    plot.setWindowTitle(title);
+    plot.show();
+    plot.resize(400,400);
+}
+
+int main(int argc, char* argv[])
+{
+
+    JKQTPAppSettingController highDPIController(argc,argv);
+    JKQTPExampleApplication app(argc, argv);
+
+
+    JKQTPlotter plotV, plotH;
+    doExample<JKQTPBarVerticalGraph>(plotV, "1: JKQTPBarVerticalGraph");
+    doExample<JKQTPBarHorizontalGraph>(plotH, "2: JKQTPBarHorizontalGraph");
+
+    return app.exec();
+}

examples/barchart_functorfill/README.md

@@ -11,7 +11,7 @@ The source code of the main application is (see [`barchart_functorfill.cpp`](htt
     size_t columnV=ds->addColumnCalculatedFromColumn(columnK, [](double x) { return 5.0+x; }, "v");
 
     // 3. create graph in the plot, which plots the dataset:
-    JKQTPBarGraphBase* graph=new TCHART(&plot);
+    JKQTPBarVerticalGraph* graph=new JKQTPBarVerticalGraph(&plot);
     graph->setKeyColumn(columnK);
     graph->setValueColumn(columnV);
     // set FunctorFilling fill Mode

lib/jkqtplotter/graphs/jkqtpbarchart.cpp

@@ -121,21 +121,26 @@ void JKQTPBarVerticalGraph::draw(JKQTPEnhancedPainter& painter) {
                         painter.setPen(p);
                     }
                     const QRectF r(QPointF(x, y), QPointF(xx, yy));
-                    const double rAtBaseline=parent->pt2px(painter, rectRadiusAtBaseline);
+                    if (usesCustomDrawFunctor()) {
-                    const double rAtValue=parent->pt2px(painter, rectRadiusAtValue);
+                        if (m_customDrawFunctor) {
-                    //qDebug()<<"r="<<r<<", rectRadiusAtBaseline="<<rectRadiusAtBaseline<<", rectRadiusAtValue="<<rectRadiusAtValue<<", rAtBaseline="<<rAtBaseline<<", rAtValue="<<rAtValue;
+                            m_customDrawFunctor(painter, r, QPointF(xv,yv), Qt::Vertical, this);
-                    if (rAtBaseline+rAtValue>=r.height()+2) {
+                        }
-                        //qDebug()<<"drawRect";
-                        painter.drawRect(r);
                     } else {
-                        //qDebug()<<"drawRoundRect swapped="<<swapped;
+                        const double rAtBaseline=parent->pt2px(painter, rectRadiusAtBaseline);
-                        if (swapped) {
+                        const double rAtValue=parent->pt2px(painter, rectRadiusAtValue);
-                            painter.drawComplexRoundedRect(r,rAtBaseline,rAtBaseline,rAtValue,rAtValue,Qt::AbsoluteSize);
+                        //qDebug()<<"r="<<r<<", rectRadiusAtBaseline="<<rectRadiusAtBaseline<<", rectRadiusAtValue="<<rectRadiusAtValue<<", rAtBaseline="<<rAtBaseline<<", rAtValue="<<rAtValue;
+                        if (rAtBaseline+rAtValue>=r.height()+2) {
+                            //qDebug()<<"drawRect";
+                            painter.drawRect(r);
                         } else {
-                            painter.drawComplexRoundedRect(r,rAtValue,rAtValue,rAtBaseline,rAtBaseline,Qt::AbsoluteSize);
+                            //qDebug()<<"drawRoundRect swapped="<<swapped;
+                            if (swapped) {
+                                painter.drawComplexRoundedRect(r,rAtBaseline,rAtBaseline,rAtValue,rAtValue,Qt::AbsoluteSize);
+                            } else {
+                                painter.drawComplexRoundedRect(r,rAtValue,rAtValue,rAtBaseline,rAtBaseline,Qt::AbsoluteSize);
+                            }
                         }
                     }
-
                 }
             }
         }
@@ -283,17 +288,24 @@ void JKQTPBarHorizontalGraph::draw(JKQTPEnhancedPainter& painter) {
                             painter.setPen(p);
                         }
                         const QRectF r(QPointF(x, y), QPointF(xx, yy));
-                        const double rAtBaseline=parent->pt2px(painter, rectRadiusAtBaseline);
+                        if (usesCustomDrawFunctor()) {
-                        const double rAtValue=parent->pt2px(painter, rectRadiusAtBaseline);
+                            if (m_customDrawFunctor) {
-                        if (rAtBaseline+rAtValue>r.width()+2) {
+                                m_customDrawFunctor(painter, r, QPointF(xv,yv), Qt::Horizontal, this);
-                            painter.drawRect(r);
-                        } else {
-                            if (swapped) {
-                                painter.drawComplexRoundedRect(r,rAtBaseline,rAtValue,rAtBaseline,rAtValue,Qt::AbsoluteSize);
-                            } else {
-                                painter.drawComplexRoundedRect(r,rAtValue,rAtBaseline,rAtValue,rAtBaseline,Qt::AbsoluteSize);
                             }
-                        }                    }
+                        } else {
+                            const double rAtBaseline=parent->pt2px(painter, rectRadiusAtBaseline);
+                            const double rAtValue=parent->pt2px(painter, rectRadiusAtBaseline);
+                            if (rAtBaseline+rAtValue>r.width()+2) {
+                                painter.drawRect(r);
+                            } else {
+                                if (swapped) {
+                                    painter.drawComplexRoundedRect(r,rAtBaseline,rAtValue,rAtBaseline,rAtValue,Qt::AbsoluteSize);
+                                } else {
+                                    painter.drawComplexRoundedRect(r,rAtValue,rAtBaseline,rAtValue,rAtBaseline,Qt::AbsoluteSize);
+                                }
+                            }
+                        }
+                    }
                 }
             }
         }

lib/jkqtplotter/graphs/jkqtpbarchart.h

@@ -71,6 +71,26 @@
 
    \image html JKQTPBarVerticalGraphFunctorFilling.png
 
+
+   You can also completely customize the drawing by defining a custom draw functor:
+   \code
+     graph->setCustomDrawingFunctor(
+       [](JKQTPEnhancedPainter& painter, const QRectF& bar_px, const QPointF& datapoint, Qt::Orientation orientation, JKQTPBarGraphBase* graph) {
+         // draw the bar (if required), pen and brush are already set properly
+         painter.drawRect(bar_px);
+         // now we can add some decoration or replace the instruction above:
+         // ........
+       }
+     );
+     // enable usage of cutom draw functor
+     graph->setUseCustomDrawFunctor(true);
+   \endcode
+
+   See \ref JKQTPlotterBarchartsCustomDrawFunctor for a detailed example.
+   The result may look like this:
+
+   \image html JKQTPBarVerticalGraphCustomDrawFunctor.png
+
    \see JKQTPBarHorizontalGraph, \ref JKQTPlotterBarcharts, jkqtpstatAddHHistogram1D(), jkqtpstatAddHHistogram1DAutoranged()
  */
 class JKQTPLOTTER_LIB_EXPORT JKQTPBarVerticalGraph: public JKQTPBarGraphBase {
@@ -190,6 +210,24 @@ class JKQTPLOTTER_LIB_EXPORT JKQTPBarVerticalErrorGraph: public JKQTPBarVertical
 
    \image html JKQTPBarHorizontalGraphFunctorFilling.png
 
+   You can also completely customize the drawing by defining a custom draw functor:
+   \code
+     graph->setCustomDrawingFunctor(
+       [](JKQTPEnhancedPainter& painter, const QRectF& bar_px, const QPointF& datapoint, Qt::Orientation orientation, JKQTPBarGraphBase* graph) {
+         // draw the bar (if required), pen and brush are already set properly
+         painter.drawRect(bar_px);
+         // now we can add some decoration or replace the instruction above:
+         // ........
+       }
+     );
+     // enable usage of cutom draw functor
+     graph->setUseCustomDrawFunctor(true);
+   \endcode
+
+   See \ref JKQTPlotterBarchartsCustomDrawFunctor for a detailed example.
+   The result may look like this:
+
+   \image html JKQTPBarHorizontalGraphCustomDrawFunctor.png
 
     \see \ref JKQTPlotterBarcharts, jkqtpstatAddVHistogram1D(), jkqtpstatAddVHistogram1DAutoranged()
  */

lib/jkqtplotter/graphs/jkqtpbarchartbase.cpp

@@ -38,6 +38,7 @@ JKQTPBarGraphBase::JKQTPBarGraphBase(JKQTBasePlotter* parent):
     JKQTPXYBaselineGraph(parent),
     width(0.9), shift(0),
     m_fillMode(FillMode::SingleFilling),
+    m_useCustomDrawFunctor(false),
     m_lineColorDerivationModeForSpecialFill(parent->getCurrentPlotterStyle().graphsStyle.barchartStyle.graphColorDerivationMode),
     rectRadiusAtBaseline(0),rectRadiusAtValue(0)
 {
@@ -57,7 +58,6 @@ JKQTPBarGraphBase::JKQTPBarGraphBase(JKQTPlotter* parent):
 void JKQTPBarGraphBase::drawKeyMarker(JKQTPEnhancedPainter& painter, QRectF& rect) {
     painter.save(); auto __finalpaint=JKQTPFinally([&painter]() {painter.restore();});
     QPen p=getLinePenForRects(painter, parent);
-    QPen np(Qt::NoPen);
     QBrush b=getFillBrush(painter, parent);
     //int y=rect.top()+rect.height()/2.0;
     painter.setPen(p);
@@ -242,6 +242,21 @@ void JKQTPBarGraphBase::setFillBrushFunctor(SimpleFillBrushFunctor &&f) {
     m_fillBrushFunctor=SimpleFillBrushFunctorAdaptor(std::forward<SimpleFillBrushFunctor>(f));
 }
 
+void JKQTPBarGraphBase::setCustomDrawingFunctor(CustomDrawingFunctor &&f)
+{
+    m_customDrawFunctor=std::forward<CustomDrawingFunctor>(f);
+}
+
+void JKQTPBarGraphBase::setCustomDrawingFunctor(const CustomDrawingFunctor &f)
+{
+    m_customDrawFunctor=f;
+}
+
+void JKQTPBarGraphBase::setUseCustomDrawFunctor(bool enabled)
+{
+    m_useCustomDrawFunctor=enabled;
+}
+
 double JKQTPBarGraphBase::getParentStackedMax(int /*index*/) const
 {
     return getBaseline();
@@ -383,3 +398,8 @@ JKQTPColorDerivationMode JKQTPBarGraphBase::getLineColorDerivationModeForSpecial
 {
     return m_lineColorDerivationModeForSpecialFill;
 }
+
+bool JKQTPBarGraphBase::usesCustomDrawFunctor() const
+{
+    return m_useCustomDrawFunctor;
+}

lib/jkqtplotter/graphs/jkqtpbarchartbase.h

@@ -67,6 +67,27 @@
  *  The result may look like this:
  *
  *  \image html JKQTPBarVerticalGraphFunctorFilling.png
+ *
+ *  You can also completely customize the drawing by defining a custom draw functor:
+ *  \code
+ *    graph->setCustomDrawingFunctor(
+ *      [](JKQTPEnhancedPainter& painter, const QRectF& bar_px, const QPointF& datapoint, Qt::Orientation orientation, JKQTPBarGraphBase* graph) {
+ *        // draw the bar (if required), pen and brush are already set properly
+ *        painter.drawRect(bar_px);
+ *        // now we can add some decoration or replace the instruction above:
+ *        // ........
+ *      }
+ *    );
+ *    // enable usage of cutom draw functor
+ *    graph->setUseCustomDrawFunctor(true);
+ *  \endcode
+ *
+ *  See \ref JKQTPlotterBarchartsCustomDrawFunctor for a detailed example.
+ *
+ *  The result may look like this:
+ *
+ *  \image html JKQTPBarVerticalGraphCustomDrawFunctor.png
+
  *
  *  \see JKQTPBarHorizontalGraph, JKQTPBarVerticalGraph
  */
@@ -83,6 +104,9 @@ class JKQTPLOTTER_LIB_EXPORT JKQTPBarGraphBase: public JKQTPXYBaselineGraph, pub
          *  \see setFillBrushFunctor(), getFillBrushFunctor()
          */
         typedef std::function<QBrush(double key, double value)> SimpleFillBrushFunctor;
+
+        /** \brief functor for custom drawing of bars */
+        typedef std::function<void(JKQTPEnhancedPainter& painter, const QRectF& bar_px, const QPointF& datapoint, Qt::Orientation orientation, JKQTPBarGraphBase* graph)> CustomDrawingFunctor;
         /** \brief specifies how the area below the graph is filled
          *
          *  \see setFillMode(), getFillMode(), fillStyleBelow(), \ref JKQTPlotterWigglePlots
@@ -137,6 +161,8 @@ class JKQTPLOTTER_LIB_EXPORT JKQTPBarGraphBase: public JKQTPXYBaselineGraph, pub
         const FillBrushFunctor& getFillBrushFunctor() const;
         /** \copydoc m_lineColorDerivationModeForSpecialFill */
         JKQTPColorDerivationMode getLineColorDerivationModeForSpecialFill() const;
+        /** \copydoc m_useCustomDrawFunctor */
+        bool usesCustomDrawFunctor() const;
 
     public slots:
         /** \copydoc m_fillMode */
@@ -152,6 +178,13 @@ class JKQTPLOTTER_LIB_EXPORT JKQTPBarGraphBase: public JKQTPXYBaselineGraph, pub
         /** \copydoc m_fillBrushFunctor */
         void setFillBrushFunctor(JKQTPBarGraphBase::SimpleFillBrushFunctor&& f);
 
+        /** \copydoc m_customDrawFunctor */
+        void setCustomDrawingFunctor(JKQTPBarGraphBase::CustomDrawingFunctor&& f);
+        /** \copydoc m_customDrawFunctor */
+        void setCustomDrawingFunctor(const JKQTPBarGraphBase::CustomDrawingFunctor& f);
+        /** \copydoc m_useCustomDrawFunctor */
+        void setUseCustomDrawFunctor(bool enabled);
+
         /** \brief finds all bar charts of the same orientation and determines width and shift, so they stand side by side
          *
          *  \param maxWidth the maximum (relative) width, that all bars will span of the (doubled) inter-bar distance
@@ -263,6 +296,36 @@ class JKQTPLOTTER_LIB_EXPORT JKQTPBarGraphBase: public JKQTPXYBaselineGraph, pub
          *  \see setFillBrushFunctor(), getFillBrushFunctor(), m_fillMode
          */
         FillBrushFunctor m_fillBrushFunctor;
+        /** \brief this allows to provide custom drawing code for the bars.
+         *         It is called for every visible bar if activated by \c setUseCustomDrawFunctor(true) .
+         *
+         *  Here is an example for a custom draw functor:
+         *  \code
+         *    graph->setCustomDrawingFunctor(
+         *      [](JKQTPEnhancedPainter& painter, const QRectF& bar_px, const QPointF& datapoint, Qt::Orientation orientation, JKQTPBarGraphBase* graph) {
+         *        // draw the bar (if required), pen and brush are already set properly
+         *        painter.drawRect(bar_px);
+         *        // now we can add some decoration or replace the instruction above:
+         *        // ........
+         *      }
+         *    );
+         *    // enable usage of cutom draw functor
+         *    graph->setUseCustomDrawFunctor(true);
+         *  \endcode
+         *
+         *
+         *  The result may look like this:
+         *
+         *  \image html JKQTPBarVerticalGraphCustomDrawFunctor.png
+         *
+         *  \see CustomDrawingFunctor, m_useCustomDrawFunctor, setUseCustomDrawFunctor(), \ref JKQTPlotterBarchartsCustomDrawFunctor for a detailed example
+         */
+        CustomDrawingFunctor m_customDrawFunctor;
+        /** \brief enabled custom drawing by m_customDrawFunctor
+         *
+         *  \see m_customDrawFunctor
+         */
+        bool m_useCustomDrawFunctor;
 
         /** \brief returns a FillBrushFunctor that is appropriate for the currently selected m_fillMode */
         virtual FillBrushFunctor constructFillBrushFunctor() const;