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smart_scroll_area.cpp

/**
 * This file is a part of Qtpfsgui package.
 * ---------------------------------------------------------------------- 
 * Copyright (C) 2007 Giuseppe Rota
 * 
 *  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.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 * ---------------------------------------------------------------------- 
 *
 * @author Giuseppe Rota <grota@users.sourceforge.net>
 */

#include "smart_scroll_area.h"
#include <QPixmap>
00026 SmartScrollArea::SmartScrollArea( QWidget *parent, QLabel *imagelabel ) : QScrollArea(parent), imageLabel(imagelabel), scaleFactor(1.0), fittingwin(false) {
      setBackgroundRole(QPalette::Light);
      imageLabel->setBackgroundRole(QPalette::Base);
      //the label ignores the pixmap's size
      imageLabel->setSizePolicy(QSizePolicy::Ignored, QSizePolicy::Ignored);
      //the label will scale the image to fill all available space (to its -the label's- size)
      imageLabel->setScaledContents(true);
      //false (the default), the scroll area honors the size of its widget.
      //Regardless of this property, you can programmatically resize the widget using widget()->resize()
      //indeed, when I zoom in/out I call imageLabel->resize(...)
      setWidgetResizable(false);
      setWidget(imageLabel);
}

void SmartScrollArea::zoomIn() {
      scaleImage(1.25);
}
void SmartScrollArea::zoomOut() {
      scaleImage(0.8);
}
void SmartScrollArea::fitToWindow(bool checked) {
      fittingwin=checked;
      if (checked)
            scaleLabelToFit();
      else
            // restore to the previous zoom factor
            scaleImage(1);
}
void SmartScrollArea::normalSize() {
      //use the image size for the label
      imageLabel->adjustSize();
      scaleFactor = 1.0;
}
void SmartScrollArea::scaleLabelToFit() {
      int sa_width=this->size().width();
      int sa_height=this->size().height();
      float imageratio=float(imageLabel->pixmap()->size().width())/float(imageLabel->pixmap()->size().height());
      float factor=1;
      if (sa_width<imageratio*sa_height) {
            factor=float(sa_width)/float(imageLabel->pixmap()->size().width());
      } else {
            factor=float(sa_height)/float(imageLabel->pixmap()->size().height());
      }
      imageLabel->resize(factor * 0.99 * imageLabel->pixmap()->size());
}
void SmartScrollArea::scaleImage(double factor) {
      scaleFactor *= factor;
      imageLabel->resize(scaleFactor * imageLabel->pixmap()->size());
      adjustScrollBar(horizontalScrollBar(), factor);
      adjustScrollBar(verticalScrollBar(), factor);
}
void SmartScrollArea::adjustScrollBar(QScrollBar *scrollBar, double factor) {
      scrollBar->setValue(int(factor * scrollBar->value() + ((factor - 1) * scrollBar->pageStep()/2)));
}
void SmartScrollArea::resizeEvent ( QResizeEvent * e) {
      if (fittingwin) {
            scaleLabelToFit();
      } else {
            //this seems to be a bug in qt4
            imageLabel->resize(imageLabel->size()-QSize(0,1));
            imageLabel->resize(imageLabel->size()+QSize(0,1));
            
//          QScrollBar *h=horizontalScrollBar();
//          QScrollBar *v=verticalScrollBar();
//          int fixwidth=imageLabel->size().width()+v->size().width()-this->size().width();
//          if (fixwidth>0)
//                h->setMaximum(qMax(0,fixwidth));
//          else
//                h->setMaximum(0);
//          int fixheight=imageLabel->size().height()-this->size().height();
//          if (fixheight>0)
//                v->setMaximum(qMax(0,fixheight));
//          else
//                v->setMaximum(0);
      }
}

void SmartScrollArea::mouseMoveEvent(QMouseEvent *e) {
      if (e->buttons()==Qt::MidButton) {
            QPoint diff = e->pos() - mousePos;
            if (e->modifiers()==Qt::ShiftModifier)
                  diff*=5;
            mousePos = e->pos();
            verticalScrollBar()->setValue(verticalScrollBar()->value() + 
      diff.y());
            horizontalScrollBar()->setValue(horizontalScrollBar()->value() + 
      diff.x());
      }
}

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