KDChartTernaryGrid.cpp

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/****************************************************************************
**
** This file is part of the KD Chart library.
**
** SPDX-FileCopyrightText: 2001 Klarälvdalens Datakonsult AB, a KDAB Group company <info@kdab.com>
**
** SPDX-License-Identifier: MIT
**
****************************************************************************/
 
#include "KDChartTernaryGrid.h"
 
#include <cmath>
 
#include <algorithm>
#include <limits>
 
#include <QApplication>
#include <QtDebug>
 
#include "KDChartPaintContext.h"
#include "KDChartPainterSaver_p.h"
#include "KDChartPrintingParameters.h"
#include "KDChartTernaryCoordinatePlane.h"
#include "TernaryConstants.h"
#include "TernaryPoint.h"
 
using namespace KDChart;
 
TickInfo::TickInfo(qreal _percentage, int _depth)
    : percentage(_percentage)
    , depth(_depth)
{
}
 
bool KDChart::operator==(const TickInfo &left, const TickInfo &right)
{
    return fabs(left.percentage - right.percentage)
        <= std::numeric_limits<qreal>::epsilon()
        && left.depth == right.depth;
}
 
TernaryGrid::TernaryGrid()
    : AbstractGrid()
{
}
 
TernaryGrid::~TernaryGrid()
{
}
 
void TernaryGrid::drawGrid(PaintContext *context)
{
    static const int GridLineDistanceTreshold = 20; // <Threshold> pixels between each grid line
 
    QPainter &painter = *context->painter(); // recover from pointer madness
    PainterSaver s(&painter); // can i have a reference based version of that?
    auto *plane = dynamic_cast<TernaryCoordinatePlane *>(context->coordinatePlane());
    Q_ASSERT_X(plane, "TernaryGrid::drawGrid",
               "Bad function call: PaintContext::coodinatePlane() NOT a ternary plane.");
 
    // translate the points and see how many grid lines we can draw:
    const int MaxDepth = 3;
    qreal xPixels = plane->translate(TriangleBottomRight).x() - plane->translate(TriangleBottomLeft).x();
    int granularity = 20;
    if (xPixels > 10 * GridLineDistanceTreshold)
        granularity = 10;
    if (xPixels > 20 * GridLineDistanceTreshold)
        granularity = 5;
 
    m_tickInfo.clear();
    for (int i = granularity; i < 100; i += granularity) {
        TickInfo tick((1.0 * i) / 100.0, 2);
        if (i % 10 == 0)
            tick.depth = 1;
        if (i % 20 == 0)
            tick.depth = 0;
        m_tickInfo.append(tick);
    }
 
    QVector<QLineF> lines[MaxDepth];
    {
        for (const TickInfo &tick : qAsConst(m_tickInfo)) {
            const qreal &percent = tick.percentage;
            { // draw parallels to B
                TernaryPoint ternaryStart(percent, 1.0 - percent);
                TernaryPoint ternaryEnd(0.0, 1.0 - percent);
                QPointF start(translate(ternaryStart));
                QPointF end(translate(ternaryEnd));
                lines[tick.depth].append(QLineF(plane->translate(start),
                                                plane->translate(end)));
            }
            { // draw parallels to C
                TernaryPoint ternaryStart(percent, 0.0);
                TernaryPoint ternaryEnd(0.0, percent);
                QPointF start(translate(ternaryStart));
                QPointF end(translate(ternaryEnd));
                lines[tick.depth].append(QLineF(plane->translate(start),
                                                plane->translate(end)));
            }
            { // draw parallels to A
                TernaryPoint ternaryStart(percent, 1.0 - percent);
                TernaryPoint ternaryEnd(percent, 0.0);
                QPointF start(translate(ternaryStart));
                QPointF end(translate(ternaryEnd));
                lines[tick.depth].append(QLineF(plane->translate(start),
                                                plane->translate(end)));
            }
        }
    }
 
    // now draw the lines:
    painter.setPen(PrintingParameters::scalePen(QPen(QColor("lightgray"), 1)));
    painter.setBrush(QColor("lightgray"));
    painter.drawLines(lines[2]);
    painter.setPen(PrintingParameters::scalePen(QPen(QColor("gray"), 1)));
    painter.setBrush(QColor("gray"));
    painter.drawLines(lines[1]);
    painter.setPen(PrintingParameters::scalePen(QPen(QColor("darkslategray"), 1)));
    painter.setBrush(QColor("darkslategray"));
    painter.drawLines(lines[0]);
 
    // now draw the triangle (this could be part of the axis, in fact):
    painter.setPen(PrintingParameters::scalePen(QPen(Qt::black, 1)));
    // make sure this does not fill, otherwise it wipes the contents
    // of the triangle (doh!):
    painter.setBrush(Qt::NoBrush);
    QPolygonF points;
    points << plane->translate(TriangleBottomLeft)
           << plane->translate(TriangleBottomRight)
           << plane->translate(TriangleTop);
    painter.drawPolygon(points);
 
    // now draw the ticks:
    painter.setPen(PrintingParameters::scalePen(QPen(Qt::black)));
    painter.setBrush(Qt::black);
 
    QVector<QLineF> ticks;
    // prepare list of percentages, then calculate lines:
    QVector<TickInfo> percentages(m_tickInfo);
    // I have commented those out, I think it looks ugly if they are
    // enabled:
    // percentages.prepend( 0.0 );
    // percentages.append( 1.0 );
 
    // FIXME this may need a predicate that takes eplison into account
    // (but it does not hurt, since it will not make the painter
    // paint two lines):
    percentages.erase(std::unique(percentages.begin(), percentages.end()),
                      percentages.end());
 
    {
        for (const TickInfo &tick : percentages) {
            const qreal &percent = tick.percentage;
            { // BC axis markers:
                const QPointF markerDistance(FullMarkerDistanceBC
                                             / (tick.depth + 1));
                QPointF start(percent, 0.0);
                ticks.append(QLineF(plane->translate(start),
                                    plane->translate(start - markerDistance)));
            }
            { // AC axis markers:
                const QPointF markerDistance(FullMarkerDistanceAC
                                             / (tick.depth + 1));
                const QPointF start(TriangleBottomRight + percent * AxisVector_C_A);
                const QPointF end(start + markerDistance);
                ticks.append(QLineF(plane->translate(start),
                                    plane->translate(end)));
            }
            {
                // AB axis markers:
                const QPointF markerDistance(FullMarkerDistanceBA
                                             / (tick.depth + 1));
                const QPointF start(percent * AxisVector_B_A);
                const QPointF end(start + markerDistance);
                ticks.append(QLineF(plane->translate(start),
                                    plane->translate(end)));
            }
        }
    }
    painter.drawLines(ticks);
}
 
DataDimensionsList TernaryGrid::calculateGrid(const DataDimensionsList &) const
{
    return DataDimensionsList();
}
 
QPair<QSizeF, QSizeF> TernaryGrid::requiredMargins() const
{
    //    qreal topMargin = ( FullMarkerDistanceBA * RelMarkerLength ).x();
    qreal topMargin = 0.0; // no markers on tip of triangle
    qreal leftMargin = fabs(FullMarkerDistanceBA.x());
    qreal bottomMargin = fabs(FullMarkerDistanceBC.y());
    //     qDebug() << "TernaryGrid::requiredMargins: leftMargin:" << leftMargin
    //              << ", bottomMargin:" << bottomMargin
    //              << ", topMargin:" << topMargin
    //              << ", FullMarkerDistanceBC:" << FullMarkerDistanceBC
    //              << ", FullMarkerDistanceBA:" << FullMarkerDistanceBA
    //              << ", FullMarkerDistanceAC:" << FullMarkerDistanceAC
    //              << ", RelMarkerLength:" << RelMarkerLength;
    return QPair<QSizeF, QSizeF>(QSizeF(leftMargin, topMargin),
                                 QSizeF(leftMargin, bottomMargin));
}
 
const QVector<TickInfo> &TernaryGrid::tickInfo() const
{
    return m_tickInfo;
}