qgsgeometrypaintdevice.h

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/***************************************************************************
  qgsgeometrypaintdevice.h
  --------------------------------------
  Date                 : May 2024
  Copyright            : (C) 2024 by Nyall Dawson
  Email                : nyall dot dawson at gmail dot com
 ***************************************************************************
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/
 
#ifndef QGSGEOMETRYPAINTDEVICE_H
#define QGSGEOMETRYPAINTDEVICE_H
 
#include <memory>
 
#include "qgis_core.h"
#include "qgis_sip.h"
#include "qgsgeometry.h"
#include "qgsgeometrycollection.h"
 
#include <QPaintDevice>
#include <QPaintEngine>
#include <QPainterPath>
 
class QgsLineString;
 
#ifndef SIP_RUN

class QgsGeometryPaintEngine : public QPaintEngine
{
  public:
    QgsGeometryPaintEngine( bool usePathStroker = false );

    void setStrokedPathSegments( int segments );

    void setSimplificationTolerance( double tolerance );
 
    bool begin( QPaintDevice * ) final;
    bool end() final;
    QPaintEngine::Type type() const final;
    void updateState( const QPaintEngineState & ) final;
 
    // no-op drawing methods. We don't want the base class methods to be called and unnecessary work performed
    void drawImage( const QRectF &rectangle, const QImage &image, const QRectF &sr, Qt::ImageConversionFlags flags = Qt::AutoColor ) final;
    void drawPixmap( const QRectF &, const QPixmap &, const QRectF & ) final;
    void drawTiledPixmap( const QRectF &rect, const QPixmap &pixmap, const QPointF &p ) final;
 
    // supported drawing operations. While we could rely on the base class methods to convert these operations
    // to paths and then only implement drawPath, we instead want this class to be as FAST as possible
    // and accordingly we implement the most optimised geometry conversion for each drawing primitive
    void drawLines( const QLineF *lines, int lineCount ) final;
    void drawLines( const QLine *lines, int lineCount ) final;
    void drawPoints( const QPointF *points, int pointCount ) final;
    void drawPoints( const QPoint *points, int pointCount ) final;
    void drawPolygon( const QPointF *points, int pointCount, QPaintEngine::PolygonDrawMode mode ) final;
    void drawPolygon( const QPoint *points, int pointCount, QPaintEngine::PolygonDrawMode mode ) final;
    void drawRects( const QRectF *rects, int rectCount ) final;
    void drawRects( const QRect *rects, int rectCount ) final;
    void drawPath( const QPainterPath &path ) final;
 
    // We can't represent an ellipse as a curved geometry, so let QPaintEngine base class convert this to a segmentized
    // shape instead
    // void drawEllipse(const QRectF &rect) final;
 
    // We want Qt to handle text -> path conversion
    // void drawTextItem(const QPointF &p, const QTextItem &textItem) final;

    const QgsAbstractGeometry &geometry() const { return mGeometry; }
 
  private:
    void addSubpathGeometries( const QPainterPath &path, const QTransform &matrix );
    void addStrokedLine( const QgsLineString *line, double penWidth, Qgis::EndCapStyle endCapStyle, Qgis::JoinStyle joinStyle, double miterLimit, const QTransform *matrix );
 
    bool mUsePathStroker = false;
    QPen mPen;
    QgsGeometryCollection mGeometry;
    int mStrokedPathsSegments = 8;
    double mSimplifyTolerance = 0;
};
 
#endif
 

class CORE_EXPORT QgsGeometryPaintDevice : public QPaintDevice
{
  public:
    QgsGeometryPaintDevice( bool usePathStroker = false );

    void setStrokedPathSegments( int segments );

    void setSimplificationTolerance( double tolerance );
 
    QPaintEngine *paintEngine() const override;
 
    int metric( PaintDeviceMetric metric ) const override;

    const QgsAbstractGeometry &geometry() const;

    static QgsGeometry painterPathToGeometry( const QPainterPath &path );
 
  private:
    std::unique_ptr<QgsGeometryPaintEngine> mPaintEngine;
 
    QSize mSize;
};
 
 
#endif // QGSGEOMETRYPAINTDEVICE_H