path: root/examples/datavisualization/graphgallery/doc/src/graphgallery.qdoc

// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only

/*!
    \example graphgallery
    \meta tags {DataVisualization, Q3DBars, Bar Graph, Custom Proxy}
    \meta category {Graphics}
    \title Graph Gallery
    \ingroup qtdatavisualization_examples
    \brief Gallery of Bar, Scatter, and Surface graphs.

    \e {Graph Gallery} demonstrates all three graph types and some of their special features.
    The graphs have their own tabs in the application.

    \image qmlgraphgallery-example.png

    \include examples-run.qdocinc

    \section1 Bar Graph

    In the \uicontrol {Bar Graph} tab, create a 3D bar graph using Q3DBars and combine the use of
    widgets to adjust various bar graph qualities. The example shows how to:

    \list
        \li Create an application with Q3DBars and some widgets
        \li Use QBar3DSeries and QBarDataProxy to set data to the graph
        \li Adjust some graph and series properties using widget controls
        \li Select a row or a column by clicking an axis label
        \li Create a custom proxy to use with Q3DBars
    \endlist

    For information about interacting with the graph, see
    \l{Qt Data Visualization Interacting with Data}{this page}.

    \section2 Creating the Application

    First, in \c{bargraph.cpp}, instantiate Q3DBars and a window container for it:

    \snippet graphgallery/bargraph.cpp 0

    The call to QWidget::createWindowContainer is required, as all data visualization graph classes
    (Q3DBars, Q3DScatter, Q3DSurface) inherit QWindow. This is the only way to use a class that
    inherits QWindow as a widget.

    Then, create horizontal and vertical layouts. Add the graph and the vertical layout to the
    horizontal one:

    \snippet graphgallery/bargraph.cpp 1

    Next, create another class to handle the data addition and other interaction with the
    graph:

    \snippet graphgallery/bargraph.cpp 2

    \section2 Setting up the Graph

    Set up the graph in the constructor of the \c GraphModifier class:

    \snippet graphgallery/graphmodifier.cpp 0

    First, create the axes and the series into member variables to support changing them easily:

    \snippet graphgallery/graphmodifier.cpp 1

    Then, set some visual qualities for the graph:

    \snippet graphgallery/graphmodifier.cpp 2

    Set up the axes and make them the active axes of the graph:

    \snippet graphgallery/graphmodifier.cpp 3

    Give axis labels a small autorotation angle with setLabelAutoRotation() to make them orient
    slightly toward the camera. This improves axis label readability at extreme camera angles.

    Next, initialize the visual properties of the series. Note that the second series is initially
    not visible:

    \snippet graphgallery/graphmodifier.cpp 4

    Add the series to the graph:

    \snippet graphgallery/graphmodifier.cpp 5

    Finally, set the camera angle by calling the same method the camera angle change button
    in the UI uses to cycle through various camera angles:

    \snippet graphgallery/graphmodifier.cpp 6

    The camera is controlled via the scene object of the graph:

    \snippet graphgallery/graphmodifier.cpp 7

    For more information about using scene and cameras, see Q3DScene and Q3DCamera.

    \section2 Adding Data to the Graph

    At the end of the constructor, call a method that sets up the data:

    \snippet graphgallery/graphmodifier.cpp 8

    This method adds data to the proxies of the two series:

    \snippet graphgallery/graphmodifier.cpp 9a
    \dots 0
    \snippet graphgallery/graphmodifier.cpp 9b

    \section2 Using Widgets to Control the Graph

    Continue by adding some widgets in \c{bargraph.cpp}. Add a slider:

    \snippet graphgallery/bargraph.cpp 3

    Use the slider to rotate the graph instead of just using a mouse or touch. Add it to the
    vertical layout:

    \snippet graphgallery/bargraph.cpp 4

    Then, connect it to a method in \c GraphModifier:

    \snippet graphgallery/bargraph.cpp 5

    Create a slot in \c GraphModifier for the signal connection. The camera is controlled via the
    scene object. This time, specify the actual camera position along the orbit around the center
    point, instead of specifying a preset camera angle:

    \snippet graphgallery/graphmodifier.cpp 10

    You can now use the slider to rotate the graph.

    Add more widgets to the vertical layout to control:

    \list
        \li Graph rotation
        \li Label style
        \li Camera preset
        \li Background visibility
        \li Grid visibility
        \li Bar shading smoothness
        \li Visibility of the second bar series
        \li Value axis direction
        \li Axis title visibility and rotation
        \li Data range to be shown
        \li Bar style
        \li Selection mode
        \li Theme
        \li Shadow quality
        \li Font
        \li Font size
        \li Axis label rotation
        \li Data mode
    \endlist

    Some widget controls are intentionally disabled when in the \uicontrol {Custom Proxy Data}
    data mode.

    \section2 Selecting a Row or Column by Clicking an Axis Label

    Selection by axis label is default functionality for bar graphs. As an example, you can select
    rows by clicking an axis label in the following way:

    \list 1
        \li Change selection mode to \c SelectionRow
        \li Click a year label
        \li The row with the clicked year is selected
    \endlist

    The same method works with \c SelectionSlice and \c SelectionItem flags, as long as
    either \c SelectionRow or \c SelectionColumn is set as well.

    \section2 Zooming to Selection

    As an example of adjusting the camera target, implement an animation of zooming to
    selection via a button press. Animation initializations are done in the constructor:

    \snippet graphgallery/graphmodifier.cpp 11

    Function \c{GraphModifier::zoomToSelectedBar()} contains the zooming functionality.
    QPropertyAnimation \c m_animationCameraTarget targets Q3DCamera::target property,
    which takes a value normalized to the range (-1, 1).

    Figure out where the selected bar is relative to axes, and use that as the end value for
    \c{m_animationCameraTarget}:

    \snippet graphgallery/graphmodifier.cpp 12
    \dots 0
    \snippet graphgallery/graphmodifier.cpp 13

    Then, rotate the camera so that it always points approximately to the center of
    the graph at the end of the animation:

    \snippet graphgallery/graphmodifier.cpp 14

    \section2 Custom Proxy for Data

    By toggling \uicontrol {Custom Proxy Data} data mode on, a custom dataset and the corresponding
    proxy are taken into use.

    Define a simple flexible data set, \c{VariantDataSet}, where each data item is
    a variant list. Each item can have multiple values, identified by their index in
    the list. In this case, the data set is storing monthly rainfall data, where the value in
    index zero is the year, the value in index one is the month, and the value in index two is
    the amount of rainfall in that month.

    The custom proxy is similar to itemmodel-based proxies provided by Qt Data Visualization, and
    it requires mapping to interpret the data.

    \section3 VariantDataSet

    Define the data items as QVariantList objects. Add functionality for clearing the data set and
    querying for a reference to the data contained in the set. Also, add signals to be emitted when
    data is added or the set is cleared:

    \snippet graphgallery/variantdataset.h 0
    \dots 0
    \codeline
    \snippet graphgallery/variantdataset.h 1

    \section3 VariantBarDataProxy

    Subclass \c VariantBarDataProxy from QBarDataProxy and provide a simple API of getters and
    setters for the data set and the mapping:

    \snippet graphgallery/variantbardataproxy.h 0
    \dots 0
    \codeline
    \snippet graphgallery/variantbardataproxy.h 1

    The proxy listens for the changes in the data set and the mapping, and resolves the data set
    if any changes are detected. This is not a particularly efficient implementation, as any change
    will cause re-resolving of the entire data set, but that is not an issue for this example.

    In \c resolveDataSet() method, sort the variant data values into rows and columns based on the
    mapping. This is very similar to how QItemModelBarDataProxy handles mapping, except you use
    list indexes instead of item model roles here. Once the values are sorted, generate
    \c QBarDataArray out of them, and call the \c resetArray() method in the parent class:

    \snippet graphgallery/variantbardataproxy.cpp 0

    \section3 VariantBarDataMapping

    Store the mapping information between \c VariantDataSet data item indexes and rows, columns,
    and values of \c QBarDataArray in \c VariantBarDataMapping. It contains the lists of rows and
    columns to be included in the resolved data:

    \snippet graphgallery/variantbardatamapping.h 0
    \dots 0
    \codeline
    \snippet graphgallery/variantbardatamapping.h 1
    \dots 0
    \codeline
    \snippet graphgallery/variantbardatamapping.h 2
    \dots 0
    \codeline
    \snippet graphgallery/variantbardatamapping.h 3

    The primary way to use a \c VariantBarDataMapping object is to give the mappings in the
    constructor, though you can use the \c remap() method to set them later, either individually or
    all together. Emit a signal if mapping changes. The outcome is a simplified version of the
    mapping functionality of QItemModelBarDataProxy, adapted to work with variant lists instead of
    item models.

    \section3 RainfallData

    Handle the setup of QBar3DSeries with the custom proxy in the \c RainfallData class:

    \snippet graphgallery/rainfalldata.cpp 0

    Populate the variant data set in the \c addDataSet() method:

    \snippet graphgallery/rainfalldata.cpp 1
    \dots

    Add the data set to the custom proxy and set the mapping:

    \snippet graphgallery/rainfalldata.cpp 2

    Finally, add a function for getting the created series for displaying:

    \snippet graphgallery/rainfalldata.h 0

*/