KDChartTextLabelCache.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 "KDChartTextLabelCache.h"
 
#include <cmath>
 
#include <QApplication>
#include <QImage>
#include <QPainter>
#include <QPixmap>
#include <QtDebug>
 
#ifndef NDEBUG
int HitCount = 0;
int MissCount = 0;
#define INC_HIT_COUNT \
    {                 \
        ++HitCount;   \
    }
#define INC_MISS_COUNT \
    {                  \
        ++MissCount;   \
    }
#define DUMP_CACHE_STATS                                         \
    if (HitCount != 0 && MissCount != 0) {                       \
        int total = HitCount + MissCount;                        \
        qreal hitQuote = (1.0 * HitCount) / total;               \
        qDebug() << "PrerenderedLabel dtor: hits/misses/total:"  \
                 << HitCount << "/" << MissCount << "/" << total \
                 << "(" << 100 * hitQuote << "% hits)";          \
    }
#else
#define INC_HIT_COUNT
#define INC_MISS_COUNT
#define DUMP_CACHE_STATS
#endif
 
PrerenderedElement::PrerenderedElement()
{
}
 
void PrerenderedElement::setPosition(const QPointF &position)
{ // this does not invalidate the element
    m_position = position;
}
 
const QPointF &PrerenderedElement::position() const
{
    return m_position;
}
 
void PrerenderedElement::setReferencePoint(KDChartEnums::PositionValue point)
{ // this does not invalidate the element
    m_referencePoint = point;
}
 
KDChartEnums::PositionValue PrerenderedElement::referencePoint() const
{
    return m_referencePoint;
}
 
PrerenderedLabel::PrerenderedLabel()
    : PrerenderedElement()
    , m_font(qApp->font())
    , m_brush(Qt::black)
    , m_pen(Qt::black) // do not use anything invisible
{
}
 
PrerenderedLabel::~PrerenderedLabel()
{
    DUMP_CACHE_STATS;
}
 
void PrerenderedLabel::invalidate() const
{
    m_dirty = true;
}
 
void PrerenderedLabel::setFont(const QFont &font)
{
    m_font = font;
    invalidate();
}
 
const QFont &PrerenderedLabel::font() const
{
    return m_font;
}
 
void PrerenderedLabel::setText(const QString &text)
{
    m_text = text;
    invalidate();
}
 
const QString &PrerenderedLabel::text() const
{
    return m_text;
}
 
void PrerenderedLabel::setBrush(const QBrush &brush)
{
    m_brush = brush;
    invalidate();
}
 
const QBrush &PrerenderedLabel::brush() const
{
    return m_brush;
}
 
void PrerenderedLabel::setAngle(qreal angle)
{
    m_angle = angle;
    invalidate();
}
 
qreal PrerenderedLabel::angle() const
{
    return m_angle;
}
 
const QPixmap &PrerenderedLabel::pixmap() const
{
    if (m_dirty) {
        INC_MISS_COUNT;
        paint();
    } else {
        INC_HIT_COUNT;
    }
    return m_pixmap;
}
 
void PrerenderedLabel::paint() const
{
    // FIXME find a better value using font metrics of text (this
    // requires finding the diameter of the circle formed by rotating
    // the bounding rect around the center):
    const int Width = 1000;
    const int Height = Width;
 
    QRectF boundingRect;
    const QColor FullTransparent(255, 255, 255, 0);
#ifdef Q_WS_X11
    QImage pixmap(Width, Height, QImage::Format_ARGB32_Premultiplied);
    qWarning() << "PrerenderedLabel::paint: using QImage for prerendered labels "
               << "to work around XRender/Qt4 bug.";
#else
    QPixmap pixmap(Width, Height);
#endif
    // pixmap.fill( FullTransparent );
    {
        static const QPointF Center(0.0, 0.0);
        QPointF textBottomRight;
        QPainter painter(&pixmap);
        painter.setRenderHint(QPainter::TextAntialiasing, true);
        painter.setRenderHint(QPainter::Antialiasing, true);
 
        // QImage (X11 workaround) does not have fill():
        painter.setPen(FullTransparent);
        painter.setBrush(FullTransparent);
        QPainter::CompositionMode mode = painter.compositionMode();
        painter.setCompositionMode(QPainter::CompositionMode_Clear);
        painter.drawRect(0, 0, Width, Height);
        painter.setCompositionMode(mode);
 
        QTransform matrix;
        matrix.translate(0.5 * Width, 0.5 * Height);
        matrix.rotate(m_angle);
        painter.setWorldTransform(matrix);
 
        painter.setPen(m_pen);
        painter.setBrush(m_brush);
        painter.setFont(m_font);
        QRectF container(-0.5 * Width, -0.5 * Height, Width, 0.5 * Height);
        painter.drawText(container, Qt::AlignHCenter | Qt::AlignBottom,
                         m_text, &boundingRect);
        m_referenceBottomLeft = QPointF(boundingRect.bottomLeft().x(), 0.0);
        textBottomRight = QPointF(boundingRect.bottomRight().x(), 0.0);
        m_textAscendVector = boundingRect.topRight() - textBottomRight;
        m_textBaseLineVector = textBottomRight - m_referenceBottomLeft;
 
        // FIXME translate topright by char height
        boundingRect = matrix.mapRect(boundingRect);
        m_referenceBottomLeft = matrix.map(m_referenceBottomLeft)
            - boundingRect.topLeft();
        textBottomRight = matrix.map(textBottomRight)
            - boundingRect.topLeft();
        m_textAscendVector = matrix.map(m_textAscendVector)
            - matrix.map(Center);
        m_textBaseLineVector = matrix.map(m_textBaseLineVector)
            - matrix.map(Center);
    }
 
    m_dirty = false; // now all the calculation vectors are valid
 
    QPixmap temp(static_cast<int>(boundingRect.width()),
                 static_cast<int>(boundingRect.height()));
    {
        temp.fill(FullTransparent);
        QPainter painter(&temp);
#ifdef Q_WS_X11
        painter.drawImage(QPointF(0.0, 0.0), pixmap, boundingRect);
#else
        painter.drawPixmap(QPointF(0.0, 0.0), pixmap, boundingRect);
#endif
// #define PRERENDEREDLABEL_DEBUG
#ifdef PRERENDEREDLABEL_DEBUG
        painter.setPen(QPen(Qt::red, 2));
        painter.setBrush(Qt::red);
        // paint markers for the reference points
        const QList<KDChartEnums::PositionValue> positions = {
            KDChartEnums::PositionCenter,
            KDChartEnums::PositionNorthWest,
            KDChartEnums::PositionNorth,
            KDChartEnums::PositionNorthEast,
            KDChartEnums::PositionEast,
            KDChartEnums::PositionSouthEast,
            KDChartEnums::PositionSouth,
            KDChartEnums::PositionSouthWest,
            KDChartEnums::PositionWest,
        };
        for (KDChartEnums::PositionValue position : positions) {
            static const double Radius = 0.5;
            static const double Diameter = 2 * Radius;
 
            QPointF point(referencePointLocation(position));
            painter.drawEllipse(QRectF(point - QPointF(Radius, Radius),
                                       QSizeF(Diameter, Diameter)));
        }
#endif
    }
 
    m_pixmap = temp;
}
 
QPointF PrerenderedLabel::referencePointLocation() const
{
    return referencePointLocation(referencePoint());
}
 
QPointF PrerenderedLabel::referencePointLocation(KDChartEnums::PositionValue position) const
{
    if (m_dirty) {
        INC_MISS_COUNT;
        paint();
    } else {
        INC_HIT_COUNT;
    }
 
    switch (position) {
    case KDChartEnums::PositionCenter:
        return m_referenceBottomLeft + 0.5 * m_textBaseLineVector + 0.5 * m_textAscendVector;
    case KDChartEnums::PositionNorthWest:
        return m_referenceBottomLeft + m_textAscendVector;
    case KDChartEnums::PositionNorth:
        return m_referenceBottomLeft + 0.5 * m_textBaseLineVector + m_textAscendVector;
    case KDChartEnums::PositionNorthEast:
        return m_referenceBottomLeft + m_textBaseLineVector + m_textAscendVector;
    case KDChartEnums::PositionEast:
        return m_referenceBottomLeft + 0.5 * m_textAscendVector;
    case KDChartEnums::PositionSouthEast:
        return m_referenceBottomLeft + m_textBaseLineVector;
    case KDChartEnums::PositionSouth:
        return m_referenceBottomLeft + 0.5 * m_textBaseLineVector;
    case KDChartEnums::PositionSouthWest:
        return m_referenceBottomLeft;
    case KDChartEnums::PositionWest:
        return m_referenceBottomLeft + m_textBaseLineVector + 0.5 * m_textAscendVector;
 
    case KDChartEnums::PositionUnknown: // intentional fall-through
    case KDChartEnums::PositionFloating: // intentional fall-through
        return QPointF();
    }
 
    return QPointF();
}