File indexing completed on 2024-04-28 04:32:07

 /*
  * Copyright (C) 2015 by Stephen Allewell
  * steve.allewell@gmail.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.
  */
 
 /** @file
  * This file defines an extension to a QLabel that scales the associated QPixmap
  * to maintain the aspect ratio when scaling to fill the extents of the QLabel
  * area.
  */
 
 #ifndef ScaledPixmapLabel_H
 #define ScaledPixmapLabel_H
 
 // Qt includes
 #include <QLabel>
 #include <QPixmap>
 
 // Forward declaration of classes
 class QMouseEvent;
 
 /**
  * This class extends QLabel to scale the associated QPixmap to fill the QLabel
  * area whilst maintaining the aspect ratio of the pixmap.
  */
 class ScaledPixmapLabel : public QLabel
 {
     Q_OBJECT
 
 public:
     /**
      * Constructor to initialise the class as a child of the parent.
      *
      * @param parent is a pointer to the parent QWidget
      */
     explicit ScaledPixmapLabel(QWidget *parent);
 
     /**
      * This overrides the base class method to calculate the height required
      * to maintain the aspect ratio for the specified width.
      *
      * @param width is the required width
      *
      * @return an int representing the height required
      */
     virtual int heightForWidth(int width) const Q_DECL_OVERRIDE;
 
     /**
      * This overrides the base class method to calculate the size of the widget
      * required to fill the parent window and maintain the aspect ratio.
      *
      * @return a QSize representing the width and height
      */
     virtual QSize sizeHint() const Q_DECL_OVERRIDE;
 
     /**
      * Calculate the size and position occupied by the scaled pixmap.
      *
      * @return a QRect representing the area occupied by the pixmap
      */
     QRect pixmapRect() const;
 
 signals:
     /**
      * Emit a signal to notify a change in the crop area.
      * The value is scaled to relate to the modified image not the size of the QLabel.
      * A QRectF is used for accuracy to prevent rounding error with the various scaling
      * that occurs.
      *
      * @param rect a QRect defining the area of the image being cropped
      */
     void imageCropped(const QRectF &rectF);
 
 public slots:
     /**
      * Set the pixmap of the QLabel to a scaled version of the supplied pixmap.
      * The supplied pixmap is stored within the class to be reused when resizing.
      * This method hides the QLabel version which is then called from this one.
      *
      * @param pixmap a const reference to the QPixmap to be assigned to the QLabel
      */
     void setPixmap(const QPixmap &pixmap);
 
     /**
      * Enable cropping of the image
      *
      * @param checked is a bool enabling cropping of the image
      */
     void setCropping(bool checked);
 
 protected:
     /**
      * This overrides the base class method to resize the pixmap maintaining the
      * aspect ratio.  The widget has been resized at this point and the event
      * parameter is not used to determine the new size of the pixmap as the size
      * is taken from the widget size.
      *
      * @param event is a pointer to a QResizeEvent
      */
     virtual void resizeEvent(QResizeEvent *event) Q_DECL_OVERRIDE;
 
     /**
      * Override the paint event to allow drawing of a crop rectangle based on the
      * value of m_crop.
      *
      * @param event is a pointer to a QPaintEvent
      */
     virtual void paintEvent(QPaintEvent *event) Q_DECL_OVERRIDE;
 
     /**
      * Override the mousePressEvent to begin a crop operation of the image
      * defining the start position.
      *
      * @param event is a pointer to the QMouseEvent
      */
     virtual void mousePressEvent(QMouseEvent *event) Q_DECL_OVERRIDE;
 
     /**
      * Override the mouseMoveEvent to drag a selection rectangle across the
      * image to define the crop area.
      *
      * @param event is a pointer to the QMouseEvent
      */
     virtual void mouseMoveEvent(QMouseEvent *event) Q_DECL_OVERRIDE;
 
     /**
      * Override the mouseReleaseEvent to end the selection of a crop area.
      *
      * @param event is a pointer to the QMouseEvent
      */
     virtual void mouseReleaseEvent(QMouseEvent *event) Q_DECL_OVERRIDE;
 
     /**
      * When the mouse leaves the widget, update the view so that the
      * guides are removed.
      *
      * @param event is a pointer to the QEvent
      */
     virtual void leaveEvent(QEvent *event) Q_DECL_OVERRIDE;
 
 private:
     QPixmap m_pixmap; /**< copy of the pixmap which is scaled to fill the label */
     bool m_cropping; /**< true if cropping is enabled */
     QPoint m_start; /**< start position of the crop rectangle */
     QPoint m_end; /**< end position of the crop rectangle */
     QRect m_crop; /**< rectangle defining the crop area in normalized coordinates */
 };
 
 #endif // ScaledPixmapLabel_H