qgspainteffect.h

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/***************************************************************************
                             qgspainteffect.h
                             ----------------
    begin                : December 2014
    copyright            : (C) 2014 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 QGSPAINTEFFECT_H
#define QGSPAINTEFFECT_H

#include "qgis.h"
#include "qgsrendercontext.h"
#include <QPainter>
#include <QDomDocument>
#include <QDomElement>

class CORE_EXPORT QgsPaintEffect
{

  public:

    enum DrawMode
    {
      Modifier, 
      Render, 
      ModifyAndRender 
    };

    QgsPaintEffect();
    QgsPaintEffect( const QgsPaintEffect& other );
    virtual ~QgsPaintEffect();

    virtual QString type() const = 0;

    virtual QgsPaintEffect* clone() const = 0;

    virtual QgsStringMap properties() const = 0;

    virtual void readProperties( const QgsStringMap& props ) = 0;

    virtual bool saveProperties( QDomDocument& doc, QDomElement& element ) const;

    virtual bool readProperties( const QDomElement& element );

    virtual void render( QPicture& picture, QgsRenderContext& context );

    virtual void begin( QgsRenderContext& context );

    virtual void end( QgsRenderContext& context );

    bool enabled() const { return mEnabled; }

    void setEnabled( const bool enabled );

    DrawMode drawMode() const { return mDrawMode; }

    void setDrawMode( const DrawMode drawMode );

  protected:

    bool mEnabled;
    DrawMode mDrawMode;
    bool requiresQPainterDpiFix;

    virtual void draw( QgsRenderContext& context ) = 0;

    void drawSource( QPainter& painter );

    const QPicture* source() const { return mPicture; }

    QImage* sourceAsImage( QgsRenderContext &context );

    QPointF imageOffset( const QgsRenderContext& context ) const;

    virtual QRectF boundingRect( const QRectF& rect, const QgsRenderContext& context ) const;

    void fixQPictureDpi( QPainter* painter ) const;

  private:

    const QPicture* mPicture;
    QImage* mSourceImage;
    bool mOwnsImage;

    QPainter* mPrevPainter;
    QPainter* mEffectPainter;
    QPicture* mTempPicture;

    QRectF imageBoundingRect( const QgsRenderContext& context ) const;

    friend class QgsEffectStack;

};

class CORE_EXPORT QgsDrawSourceEffect : public QgsPaintEffect
{
  public:

    QgsDrawSourceEffect();
    virtual ~QgsDrawSourceEffect();

    static QgsPaintEffect* create( const QgsStringMap& map );

    virtual QString type() const override { return QString( "drawSource" ); }
    virtual QgsDrawSourceEffect* clone() const override;
    virtual QgsStringMap properties() const override;
    virtual void readProperties( const QgsStringMap& props ) override;

    void setTransparency( const double transparency ) { mTransparency = transparency; }

    double transparency() const { return mTransparency; }

    void setBlendMode( const QPainter::CompositionMode mode ) { mBlendMode = mode; }

    QPainter::CompositionMode blendMode() const { return mBlendMode; }

  protected:

    virtual void draw( QgsRenderContext& context ) override;

  private:

    double mTransparency;
    QPainter::CompositionMode mBlendMode;
};

#endif // QGSPAINTEFFECT_H