Subversion Repositories bw_tiff_compression

/*

 * Thanks to the autor of http://www.qtcentre.org/wiki/index.php?title=QGraphicsView:_Smooth_Panning_and_Zooming

 */

//Our includes

#include "CMyGraphicsView.h"

#include "stddefs.h"

//Qt includes

#include <QGraphicsTextItem>

#include <QTextStream>

#include <QScrollBar>

#include <QMouseEvent>

#include <QWheelEvent>

#include <QDebug>

#include <QBrush>

/**

* Sets up the subclassed QGraphicsView

*/

CMyGraphicsView::CMyGraphicsView(QWidget* parent) : QGraphicsView(parent) {

        setRenderHints(QPainter::Antialiasing | QPainter::SmoothPixmapTransform);

        //Set-up the scene

        Scene = new QGraphicsScene(this);

    QBrush oBrush;

    oBrush.setColor(Qt::lightGray);

    oBrush.setStyle(Qt::SolidPattern);

    Scene->setBackgroundBrush(oBrush);

        setScene(Scene);

        setCursor(Qt::OpenHandCursor);

//    setBackgroundBrush();

}

/**

  * Sets the current centerpoint.  Also updates the scene's center point.

  * Unlike centerOn, which has no way of getting the floating point center

  * back, SetCenter() stores the center point.  It also handles the special

  * sidebar case.  This function will claim the centerPoint to sceneRec ie.

  * the centerPoint must be within the sceneRec.

  */

//Set the current centerpoint in the

void CMyGraphicsView::SetCenter(const QPointF& centerPoint) {

        //Get the rectangle of the visible area in scene coords

        QRectF visibleArea = mapToScene(rect()).boundingRect();

        //Get the scene area

        QRectF sceneBounds = sceneRect();

        double boundX = visibleArea.width() / 2.0;

        double boundY = visibleArea.height() / 2.0;

        double boundWidth = sceneBounds.width() - 2.0 * boundX;

        double boundHeight = sceneBounds.height() - 2.0 * boundY;

        //The max boundary that the centerPoint can be to

        QRectF bounds(boundX, boundY, boundWidth, boundHeight);

        if(bounds.contains(centerPoint)) {

                //We are within the bounds

                CurrentCenterPoint = centerPoint;

        } else {

                //We need to clamp or use the center of the screen

                if(visibleArea.contains(sceneBounds)) {

                        //Use the center of scene ie. we can see the whole scene

                        CurrentCenterPoint = sceneBounds.center();

                } else {

                        CurrentCenterPoint = centerPoint;

                        //We need to clamp the center. The centerPoint is too large

                        if(centerPoint.x() > bounds.x() + bounds.width()) {

                                CurrentCenterPoint.setX(bounds.x() + bounds.width());

                        } else if(centerPoint.x() < bounds.x()) {

                                CurrentCenterPoint.setX(bounds.x());

                        }

                        if(centerPoint.y() > bounds.y() + bounds.height()) {

                                CurrentCenterPoint.setY(bounds.y() + bounds.height());

                        } else if(centerPoint.y() < bounds.y()) {

                                CurrentCenterPoint.setY(bounds.y());

                        }

                }

        }

        //Update the scrollbars

        centerOn(CurrentCenterPoint);

}

/**

  * Handles when the mouse button is pressed

  */

void CMyGraphicsView::mousePressEvent(QMouseEvent* event) {

        //For panning the view

        LastPanPoint = event->pos();

        setCursor(Qt::ClosedHandCursor);

}

/**

  * Handles when the mouse button is released

  */

void CMyGraphicsView::mouseReleaseEvent(QMouseEvent* event)

{

        REFER(event);

        setCursor(Qt::OpenHandCursor);

        LastPanPoint = QPoint();

}

/**

*Handles the mouse move event

*/

void CMyGraphicsView::mouseMoveEvent(QMouseEvent* event) {

        if(!LastPanPoint.isNull()) {

                //Get how much we panned

                QPointF delta = mapToScene(LastPanPoint) - mapToScene(event->pos());

                LastPanPoint = event->pos();

                //Update the center ie. do the pan

                SetCenter(GetCenter() + delta);

        }

}

/**

  * Zoom the view in and out.

  */

void CMyGraphicsView::wheelEvent(QWheelEvent* event) {

        //Get the position of the mouse before scaling, in scene coords

        QPointF pointBeforeScale(mapToScene(event->pos()));

        //Get the original screen centerpoint

        QPointF screenCenter = GetCenter(); //CurrentCenterPoint; //(visRect.center());

        //Scale the view ie. do the zoom

        double scaleFactor = 1.15; //How fast we zoom

        if(event->delta() > 0) {

                //Zoom in

                scale(scaleFactor, scaleFactor);

        } else {

                //Zooming out

                scale(1.0 / scaleFactor, 1.0 / scaleFactor);

        }

        //Get the position after scaling, in scene coords

        QPointF pointAfterScale(mapToScene(event->pos()));

        //Get the offset of how the screen moved

        QPointF offset = pointBeforeScale - pointAfterScale;

        //Adjust to the new center for correct zooming

        QPointF newCenter = screenCenter + offset;

        SetCenter(newCenter);

}

/**

  * Need to update the center so there is no jolt in the

  * interaction after resizing the widget.

  */

void CMyGraphicsView::resizeEvent(QResizeEvent* event) {

        //Get the rectangle of the visible area in scene coords

        QRectF visibleArea = mapToScene(rect()).boundingRect();

        SetCenter(visibleArea.center());

        //Call the subclass resize so the scrollbars are updated correctly

        QGraphicsView::resizeEvent(event);

}