KDChartTextLabelCache.h

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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
**
****************************************************************************/
 
#ifndef KDCHARTTEXTLABELCACHE_H
#define KDCHARTTEXTLABELCACHE_H
 
#include <QBrush>
#include <QFont>
#include <QPen>
#include <QPixmap>
 
#include "KDChartEnums.h"
 
class PrerenderedElement
{
public:
    PrerenderedElement();
    virtual ~PrerenderedElement()
    {
    }
 
    virtual const QPixmap &pixmap() const = 0;
 
    virtual QPointF referencePointLocation(KDChartEnums::PositionValue) const = 0;
 
    void setPosition(const QPointF &position);
    const QPointF &position() const;
 
    void setReferencePoint(KDChartEnums::PositionValue);
    KDChartEnums::PositionValue referencePoint() const;
 
protected:
    virtual void invalidate() const = 0;
 
private:
    QPointF m_position;
    KDChartEnums::PositionValue m_referencePoint = KDChartEnums::PositionNorthWest;
};
 
// FIXME this is merely a prototype
// FIXME caching could be done by a second layer that can be used to,
// e.g., query for a prerendered element by id or name, or by changing
// the pixmap() method to do lazy evaluation.
class PrerenderedLabel : public PrerenderedElement
{
public:
    PrerenderedLabel();
    ~PrerenderedLabel() override;
 
    void setFont(const QFont &font);
    const QFont &font() const;
 
    void setText(const QString &text);
    const QString &text() const;
 
    void setBrush(const QBrush &brush);
    const QBrush &brush() const;
 
    void setPen(const QPen &);
    const QPen &pen() const;
 
    void setAngle(qreal angle);
    qreal angle() const;
 
    // reimp PrerenderedElement:
    const QPixmap &pixmap() const override;
    QPointF referencePointLocation(KDChartEnums::PositionValue position) const override;
    // overload: return location of referencePoint():
    QPointF referencePointLocation() const;
 
protected:
    void invalidate() const override;
 
private:
    void paint() const;
 
    // store the settings (these are used for the painting):
    mutable bool m_dirty = true;
    QFont m_font;
    QString m_text;
    QBrush m_brush;
    QPen m_pen;
    qreal m_angle = 0.0;
 
    // these are valid once the label has been rendered:
    mutable QPixmap m_pixmap;
    mutable QPointF m_referenceBottomLeft;
    mutable QPointF m_textBaseLineVector;
    mutable QPointF m_textAscendVector;
};
 
#endif