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An efficient implementation of a gantt chart library for qml. The library provides a custom View element which handles lazy loading of items according to its viewport. Items are loaded from a model which can easily be implemented according to custom specifications.

• Version: 0.1.0
• License: LPGL
• Library requirements: Qt5 or higher
• Sample project requirements: Qt5.3 or higher

A fully editable gantt chart element is provided in the associated sample project:

The project can be used as an externally linked library or by including the source files directly. (The first option would be the preferred one).

• Download the source code
• Run the following command within the project directory to generate the library:

    cd build
    qmake -r ..
    make (or nmake)

• The library will be available within the build directory. You can run the associated gantt example project from the sample directory:

	sample/./sample	

• Or you can link to the library from your own project and implement the model data:

    INCLUDEPATH += $$GANTTLIBPATH/include
	
    LIBS += -L$$GANTTLIBPATH/lib -lqmlgantt

• Download the source code
• Include the following files into your project:
  • qganttglobal
  • qabstractrangemodel.h
  • qabstractrangemodel.cpp
  • qrangeview.h
  • qrangeview.cpp
  • qganttmodel.h
  • qganttmodel.cpp
  • qganttmodelitem.h
  • qganttmodelitem.cpp
• Implement the model data and you're ready to go

There are two ways to add custom data through the model:

• Adding a QGanntModel item (the easy way)
• Implementing your own model by extending the QAbstractRangeModel (the custom way and also the bit more difficult one)

The QGanttModel class is an already implemented version of the QAbstractRangeModel class, therefore provides all the methods required to communicate with the RangeView element. It's child items contain 3 properites: the position and length, which are used by the model to keep items sorted for easy access, and the data property, which is a variant type customizable by the user. It can contain any qml value type, or a reference to a QObject subclass, which can further extend the number of properties available.

In the associated sample subproject, I've included the QGanttData class, which adds a color and label property to each gantt item. The QGanttModel class is assigned a QGanttData object whenever a new QGanttModelItem is created and inserted in the model. This is done internally by the model by calling a configured data factory function whenever an insertion is triggered. The function is configured by using the QGanttModelItem::setItemDataFactoryFunction setter. The factory function is defined in the sample/src/main.cpp file.

To assign a different data item:

class CustomData : public QObject{

    Q_OBJECT
    Q_PROPERTY(QString property1...)
    ...

}

we register the type to qml:

qmlRegisterType<CustomData>("Gantt", 1, 0, "CustomData");

then define the item factory function:

QVariant createModelData(){
    return QVariant::fromValue(new CustomData);
}

and register the function to our model:

QGanttModel* model = new QanttModel;
model->setItemDataFactoryFunction(&createModelData);

then, whenever we invoke a new insertion, a CustomData type object will be set in the data field:

model->insertItem(10, 10);

Which, in our delegate, can be accessed through the modelData property:

RangeView{
    ...
    delegate: Component{
        Text{ text: modelData.property1 }
    }
} 

The properties are set through simple assignments:

RangeView{
    ...
    delegate: Component{
        Rectangle{
            width: 200; height: 40;
            Text{ text: modelData.property1 }
            MouseArea{ anchors.fill: parent; onClicked: modelData.property1 = "new value"; }
        }
    }
} 

The sample/resource/GanttLine.qml file provides a full example on assignments and other item handling.

The QAbstractRangeModel and QAbstractRangeModelIterator provide the implementation requirements used by the QRangeView to work with the model data. The section is treated separately here.