selectionInterface.cpp

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//==============================================
//  copyright            : (C) 2003-2005 by Will Stokes
//==============================================
//  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.         
//==============================================
 
//Systemwide includes
#include <qsize.h>
#include <qapplication.h>
#include <qpainter.h>
#include <qevent.h>
#include <qpoint.h>
#include <q3accel.h>
#include <qcursor.h>
//Added by qt3to4:
#include <QPaintEvent>
#include <QResizeEvent>
#include <QPixmap>
#include <QMouseEvent>
#include <QKeyEvent>
#include <QDesktopWidget>
 
//Projectwide includes
#include "selectionInterface.h"
#include "../cursors.h"
#include "../../config.h"
#include "../../backend/tools/imageTools.h"
#include "../window.h"
#include "../../configuration/configuration.h"
 
#define MIN(x,y) ((x) < (y) ? (x) : (y))
#define MAX(x,y) ((x) > (y) ? (x) : (y))
 
//a mouse press within DRAG_THRESHOLD will move corners or sides
//if mouse press is not within DRAG_THRESHOLD of any corner or side of
//current selection a new selection will be started and both press and drag points will be reset
#define DRAG_THRESHOLD 8
 
//a mouse press within MOVE_THRESHOLD of the center along both x and y axis will
//move the entier selection
#define MOVE_THRESHOLD 150
 
//minimum size of a valid selection
#define MINIMUM_SELECTION_SIZE 3
 
//==============================================
SelectionInterface::SelectionInterface(QWidget *parent, const char* name ) : QWidget(parent,name)
{ 
  //avoid flicker when repainting
  setWindowFlags(Qt::WNoAutoErase);
 
  //set default selection off screen
  mousePressPoint = QPoint(-1,-1);
  mouseDragPoint = QPoint(-1,-1);
  
  //by default mouse movement does not effect the current selection
  currentDragMode = NO_EFFECT;
  currentMouseShape = NO_EFFECT;
    
  Q3Accel *keyAccel = new Q3Accel( this );
  keyAccel->connectItem( keyAccel->insertItem( Qt::CTRL + Qt::Key_A),
                         this, SLOT(selectAll()) );
  keyAccel->connectItem( keyAccel->insertItem( Qt::CTRL + Qt::SHIFT + Qt::Key_A ),
                         this, SLOT(selectNone()) );
  
  //watch mouse movements in order to change mouse cursor
  setMouseTracking(true);
 
  //accept focus when clicked on
  setFocusPolicy( Qt::ClickFocus );
  
  //initialize cached mouse position to be offscreen by default
  cachedMousePosition = QPoint(-1,-1);  
 
  //no crop size by default
  cropMaxDimen = -1.0;
}
//==============================================
SelectionInterface::~SelectionInterface() { }
//==============================================
void SelectionInterface::setPhoto(QString imageFilename, bool resetSelection)
{  
  //store original image filename
  origImageFilename = imageFilename;
 
  //store original image dimensions
  getImageSize( origImageFilename, origImageSize );
    
  //resize image to current screen size for faster
  //scaling during resize events
  QRect screenSize = qApp->desktop()->availableGeometry();
  scaleImage( origImageFilename, fullScreenImage, screenSize.width(), screenSize.height() );
 
  //construct display images  
  constructDisplayImages();
  
  //reset selection area to nothing
  if(resetSelection)
  {
    mousePressPoint = QPoint(-1,-1);
    mouseDragPoint  = QPoint(-1,-1);
    cropMaxDimen = -1.0;
    SHIFT_Pressed = false;
    CTRL_Pressed = false;
    emit selectionChanged();
  }
 
  //repaint widget
  //if we are resetting the selection then aspect ratio may have changed
  //so a full repaint (with erase) is necessary
  repaint(resetSelection);
}
//==============================================
void SelectionInterface::resizeEvent( QResizeEvent * )
{  
  //if image has yet to be set return
  if( fullScreenImage.isNull() ) return;
  
  //construct new images for painting
  constructDisplayImages();
}
//==============================================
void SelectionInterface::constructDisplayImages()
{  
  //rescale image to fit on screen
  scaledImage = fullScreenImage.scaled( width(), height(), Qt::KeepAspectRatio );     
  
  //construct an unselected scaled image
  unselectedScaledImage = scaledImage.copy();  
  int x, y;
  QRgb* rgb;
  uchar* scanLine;
  for( y=0; y<unselectedScaledImage.height(); y++)
  {   
    //iterate over each selected pixel in scanline
    scanLine = unselectedScaledImage.scanLine(y);
    for( x=0; x<unselectedScaledImage.width(); x++)
    {
      //compress dynamic range to 25% of original
      rgb = ((QRgb*)scanLine+x);
      
      double r = ((double)qRed(*rgb)   )/255.0;
      double g = ((double)qGreen(*rgb) )/255.0;
      double b = ((double)qBlue(*rgb)  )/255.0;
      
      //convert to hsv
      double h,s,v;
      RGBtoHSV(r,g,b,&h,&s,&v);
      
      //scale and clamp v
      v*=0.25;
      
      //convert adjusted color back to rgb colorspace and clamp
      HSVtoRGB( &r,&g,&b, h,s,v);         
      int rp = (int) MIN( MAX((r*255), 0), 255 );
      int gp = (int) MIN( MAX((g*255), 0), 255 );
      int bp = (int) MIN( MAX((b*255), 0), 255 );
      
      //set adjusted color value
      *rgb = qRgb(rp,gp,bp);          
    }
  }  
  
  
}
//==============================================
void SelectionInterface::paintEvent(QPaintEvent *e)
{  
    //if no scaled image just return
  if(scaledImage.isNull()) { return; }
    
  //create buffer to draw in
  QRect rct = rect();
  rct.moveBy(-x(), -y());
  QPixmap buffer( size() );
  
  //create a painter pointing to the buffer
  QPainter bufferPainter( &buffer );
 
  //turn off clipping to make painting operations faster
  bufferPainter.setClipping(false);
  
  //initialize buffer with background brush
  bufferPainter.fillRect( buffer.rect(), backgroundBrush() );
  
  //paint the image
  int xOffset = (width() - scaledImage.width()) / 2;
  int yOffset = (height() - scaledImage.height()) / 2;
 
  //if in draw line mode paint the image normall and then the currently selected line
  //if the two points are set
  if(currentDragMode == DRAW_LINE)
  {
    //paint entire image normally
    bufferPainter.drawImage( QPoint(xOffset, yOffset), scaledImage );       
 
    //if the first and 2nd points have been set draw the line as well
    if( mousePressPoint.x() != -1 &&
        mouseDragPoint.x() != -1 )
    {
      //get points in display space
      QPoint p1, p2;
      p1 = ConvertImageToDisplayCoordinate( mousePressPoint );
      p2 = ConvertImageToDisplayCoordinate( mouseDragPoint  );
 
      //setup painter to use green color
      QPen pen;
      pen.setStyle( Qt::SolidLine );
      pen.setCapStyle( Qt::RoundCap );
      pen.setWidth( 2 );
      pen.setColor( Qt::green );
      bufferPainter.setPen( pen);
      
      //draw line
      bufferPainter.drawLine( p1.x(), p1.y(), p2.x(), p2.y() );
    }
  }
  //else we're in normal selection mode
  else
  {  
    //if selected region is empty paint entire image in color
    if( mousePressPoint.x() == -1 ||
        (
         currentDragMode == NO_EFFECT &&
         (
          mousePressPoint.x() - mouseDragPoint.x() == 0 ||
          mousePressPoint.y() - mouseDragPoint.y() == 0 
          )
         ))
    {
      bufferPainter.drawImage( QPoint(xOffset, yOffset), scaledImage );       
    }
    //otherwise paint using a two-pass approach,
    //first in monochrome and then the selected region in color
    else
    {
      //first paint using unselected coloring
      bufferPainter.drawImage( QPoint(xOffset, yOffset), unselectedScaledImage );
      
      //construct topLeft and bottomRight points to make logic easier
      QPoint topLeft( MIN(mousePressPoint.x(), mouseDragPoint.x()),
                      MIN(mousePressPoint.y(), mouseDragPoint.y()) );
      QPoint bottomRight( MAX(mousePressPoint.x(), mouseDragPoint.x()),
                          MAX(mousePressPoint.y(), mouseDragPoint.y()) );  
      
      //convert coordinates from original image space to display space
      topLeft = ConvertImageToDisplayCoordinate( topLeft );
      bottomRight = ConvertImageToDisplayCoordinate( bottomRight );
      
      //now paint selected region in color
      bufferPainter.drawImage( topLeft.x(), 
                               topLeft.y(),
                               scaledImage,
                               topLeft.x()-xOffset, topLeft.y()-yOffset,
                               bottomRight.x() - topLeft.x(),
                               bottomRight.y() - topLeft.y() );                                   
      
      //determine color for painting selection rectangle and dimensions
      //use gray/white if cropping to a custom size (and thus real world dimensions
      //are not known). If the crop size is known (eg 5"x7") use green if above
      //resolution is great enough, otherwise use red to indicate that cropping to
      //the specified size will result in pixelation during printing
      QPen pen;
      QColor selectionColor = Qt::gray;
      QColor textColor = Qt::white;
      int selectedWidth = QABS( mouseDragPoint.x() - mousePressPoint.x() ) + 1;
      int selectedHeight = QABS( mouseDragPoint.y() - mousePressPoint.y() ) + 1;
      if(selectedWidth == 1) selectedWidth = 0;
      if(selectedHeight == 1) selectedHeight = 0;
      
      int DPI = -1;
      int minDPI = -1;
      if( cropMaxDimen != -1.0 )
      {
        //compute DPI that will be used in dominant direction
        int maxDimen = QMAX( selectedWidth, selectedHeight );
        DPI = (int) (maxDimen / cropMaxDimen);          
        
        //if DPI is below minimum use red color for selection rectangle to indicate pixalation may occur
        minDPI = ((Window*)qApp->mainWidget())->getConfig()->getInt( "misc", "minDPI" );      
        if( DPI < minDPI ) 
        { selectionColor = QColor( 200, 0, 0 ); }
        //otherwise use green to signal cropping to this size is safe
        else { selectionColor = QColor( 0, 200, 0 ); }
      } 
      pen.setStyle( Qt::SolidLine );
      pen.setWidth( 2 );
      bufferPainter.setPen( pen);
      
      //paint selection size in lower right corner of selected area
      QString selectionText;
      if( cropMaxDimen != -1.0 &&
          DPI < minDPI )
        selectionText = QString("%1 x %2 (DPI: %3!)").arg(selectedWidth).arg(selectedHeight).arg(DPI);
      else
        selectionText = QString("%1 x %2").arg(selectedWidth).arg(selectedHeight);
      
      QFontMetrics fm( this->font() );
      int stringWidth = fm.width(selectionText);
      int stringHeight = fm.ascent();
      
      int textX = 0;
      int textY = 0;
      const int TEXT_MARGIN = 4;
      if( mouseDragPoint.x() > mousePressPoint.x() )
      { 
        textX = MIN( xOffset + unselectedScaledImage.width() - TEXT_MARGIN - stringWidth,
                      bottomRight.x() + TEXT_MARGIN ); 
      }
      else
      { 
        textX = MAX( xOffset + TEXT_MARGIN, 
                      topLeft.x() - TEXT_MARGIN - stringWidth ); 
      }
      
      if( mouseDragPoint.y() > mousePressPoint.y() )
      { 
        textY = MIN( yOffset + unselectedScaledImage.height() - TEXT_MARGIN,
                      bottomRight.y() + TEXT_MARGIN + stringHeight); 
      }
      else
      { 
        textY = MAX( yOffset + TEXT_MARGIN + stringHeight, 
                      topLeft.y() - TEXT_MARGIN ); 
      }
      
      //paint a thin outline around the selection
      pen.setColor( selectionColor );
      bufferPainter.setPen( pen);
      QRect selection( topLeft, bottomRight );
      bufferPainter.drawRect(selection);       
      
      //paint image under selected dimension using selected coloring to help make it more visible
      bufferPainter.drawImage( textX, textY-stringHeight,
                               unselectedScaledImage,
                               textX - xOffset, textY-stringHeight-yOffset,
                               stringWidth, fm.height() );
      
      
      //paint selected dimensions    
      pen.setColor( textColor );
      bufferPainter.setPen( pen);
      bufferPainter.drawText( textX, textY, selectionText );
    }        
  }
  
  bufferPainter.end();
  
  //blit buffer to screen
  bitBlt( this,
          e->rect().x(), e->rect().y(),
          &buffer, 
          e->rect().x(), e->rect().y(),
          e->rect().width(), e->rect().height() );
}
//==============================================
DRAG_MODE SelectionInterface::mouseActionByPosition(QPoint p)
{   
  //If SHIFT_Pressed is set then scaling a selection
  if(SHIFT_Pressed) { return SCALE_SELECTION; }
  
  //construct topLeft and bottomRight points to make logic easier
  QPoint topLeft( MIN(mousePressPoint.x(), mouseDragPoint.x()),
                  MIN(mousePressPoint.y(), mouseDragPoint.y()) );
  QPoint bottomRight( MAX(mousePressPoint.x(), mouseDragPoint.x()),
                      MAX(mousePressPoint.y(), mouseDragPoint.y()) );  
   
  //convert selelection bounary to display space since thresholds are all in display space
  topLeft = ConvertImageToDisplayCoordinate( topLeft );
  bottomRight = ConvertImageToDisplayCoordinate( bottomRight );
    
  //compute selection center
  QPoint center( (topLeft.x() + bottomRight.x()) / 2,
                 (topLeft.y() + bottomRight.y()) / 2);
  
  //if pointer is not over image no effect will occur when clicking
  int xOffset = (width() - scaledImage.width()   ) / 2;
  int yOffset = (height() - scaledImage.height() ) / 2;  
  if(p.x() < xOffset || p.x() >= scaledImage.width() + xOffset ||
     p.y() < yOffset || p.y() >= scaledImage.height() + yOffset )
  { return NO_EFFECT; }
    
  //if either there is no selection or the entire image is selected, new
  //mouse clicks are interpreted as being for selecting new regions
  if( mousePressPoint.x() == -1 ||
      ( bottomRight.x() - topLeft.x() == origImageSize.width() - 1 &&
        bottomRight.y() - topLeft.y() == origImageSize.height() - 1 )
      )
  { return DRAW_SELECTION; }
  //move entire selection
  //mouse is within MOVE_THRESH of center and outside
  //DRAG_THRESH of any side
  else if( p.x() >= MAX( center.x() - MOVE_THRESHOLD, topLeft.x() ) &&
           p.x() <= MIN( center.x() + MOVE_THRESHOLD, bottomRight.x() ) &&
           p.y() >= MAX( center.y() - MOVE_THRESHOLD, topLeft.y() ) &&
           p.y() <= MIN( center.y() + MOVE_THRESHOLD, bottomRight.y() ) &&
           p.x() > topLeft.x() + DRAG_THRESHOLD &&
           p.x() < bottomRight.x() - DRAG_THRESHOLD &&
           p.y() > topLeft.y() + DRAG_THRESHOLD &&
           p.y() < bottomRight.y() - DRAG_THRESHOLD )
{ return MOVE_SELECTION; } 
  //drag top left
  else if( QABS(topLeft.x() - p.x()) <= DRAG_THRESHOLD &&
           QABS(topLeft.y() - p.y()) <= DRAG_THRESHOLD )  
  { return MOVE_TOP_LEFT_CORNER; }
  //drag top right    
  else if( QABS(bottomRight.x() - p.x()) <= DRAG_THRESHOLD &&
           QABS(topLeft.y()     - p.y()) <= DRAG_THRESHOLD )  
  { return MOVE_TOP_RIGHT_CORNER; }
  //drag bottom left    
  else if( QABS(topLeft.x() - p.x()) <= DRAG_THRESHOLD &&
           QABS(bottomRight.y() - p.y()) <= DRAG_THRESHOLD )  
  { return MOVE_BOTTOM_LEFT_CORNER; }
  //drag bottom right
  else if( QABS(bottomRight.x() - p.x()) <= DRAG_THRESHOLD &&
           QABS(bottomRight.y() - p.y()) <= DRAG_THRESHOLD )  
  { return MOVE_BOTTOM_RIGHT_CORNER; }
  //drag left
  else if( QABS(topLeft.x() - p.x()) <= DRAG_THRESHOLD &&
           p.y() >= topLeft.y() &&
           p.y() <= bottomRight.y() )
  { return MOVE_LEFT_SIDE; }
  //drag right
  else if( QABS(bottomRight.x() - p.x()) <= DRAG_THRESHOLD &&
           p.y() >= topLeft.y() &&
           p.y() <= bottomRight.y() )
  { return MOVE_RIGHT_SIDE; }
  //drag top
  else if( QABS(topLeft.y() - p.y()) <= DRAG_THRESHOLD &&
           p.x() >= topLeft.x() &&
           p.x() <= bottomRight.x() )
  { return MOVE_TOP_SIDE; }
  //drag bottom
  else if( QABS(bottomRight.y() - p.y()) <= DRAG_THRESHOLD &&
           p.x() >= topLeft.x() &&
           p.x() <= bottomRight.x() )
  { return MOVE_BOTTOM_SIDE; }
  //else new selection
  else { return DRAW_SELECTION; }
}
//==============================================
void SelectionInterface::mousePressEvent(QMouseEvent *e)
{        
  //If CTRL pressed then emit ctrlClick event
  if( CTRL_Pressed) 
  {    
    emit ctrlClick();
    return;
  }
  
  //get mouse position in original image coordinates
  QPoint p = ConvertDisplayToImageCoordinate( e->pos() );
 
  //in draw line mode a mouse press has not immediate effect, 
  //mouse release is how a point is finally selected
  if( currentDragMode == DRAW_LINE )
  { return; }
  
  //construct topLeft and bottomRight points to make logic easier
  QPoint topLeft( MIN(mousePressPoint.x(), mouseDragPoint.x()),
                  MIN(mousePressPoint.y(), mouseDragPoint.y()) );
  QPoint bottomRight( MAX(mousePressPoint.x(), mouseDragPoint.x()),
                      MAX(mousePressPoint.y(), mouseDragPoint.y()) );  
 
  //determine action mouse click will cause
  currentDragMode = mouseActionByPosition(e->pos());
 
  switch(currentDragMode)
  {
    case DRAW_SELECTION:
      mousePressPoint = p;
      mouseDragPoint = p;
      cropMaxDimen = -1.0;
      emit aspectRatioChanged();
      break;
    case MOVE_SELECTION:
      //nothing done until mouse moves
      break;
    case MOVE_TOP_LEFT_CORNER:
      mousePressPoint = bottomRight;
      mouseDragPoint = topLeft;
      break;
    case MOVE_BOTTOM_RIGHT_CORNER:
      mousePressPoint = topLeft;
      mouseDragPoint = bottomRight;
      break;
    case MOVE_TOP_RIGHT_CORNER:
      mousePressPoint = QPoint( topLeft.x(), bottomRight.y() );
      mouseDragPoint = QPoint( bottomRight.x(), topLeft.y() );
      break;
    case MOVE_BOTTOM_LEFT_CORNER:
      mousePressPoint = QPoint( bottomRight.x(), topLeft.y() );
      mouseDragPoint = QPoint( topLeft.x(), bottomRight.y() );
      break;
    case MOVE_LEFT_SIDE:
      mousePressPoint = bottomRight;
      mouseDragPoint  = topLeft;
      break;
    case MOVE_RIGHT_SIDE:
      mousePressPoint = topLeft;
      mouseDragPoint  = bottomRight;
      break;
    case MOVE_TOP_SIDE:
      mousePressPoint = bottomRight;
      mouseDragPoint  = topLeft;
      break;
    case MOVE_BOTTOM_SIDE:
      mousePressPoint = topLeft;
      mouseDragPoint  = bottomRight;
      break;
    //no effect
    default:
      return;
  }
  
  //repaint the selection  
  repaint(false);
  emit selectionChanged();
}
//==============================================
void SelectionInterface::updateCursorShape( QPoint rawP )
{  
  //if resizing a selection always use size all cursor
  if(SHIFT_Pressed) 
  { 
    setCursor( getCursor(SCALE_SELECTION_CURSOR) );
    return;
  }
  
  //if ctrl pressed show rotate selection cursor  
  if(CTRL_Pressed) 
  { 
    setCursor( getCursor(ROTATE_CURSOR) );
    return;
  }
   
  //if selecting a line the cursor is always the same
  if( currentDragMode == DRAW_LINE )
  {
    setCursor( getCursor(TARGET_CURSOR) );
    return;
  }
  
  //update mouse cursor based on coordinates
  currentMouseShape = mouseActionByPosition( rawP ); 
  switch(currentMouseShape)
  {
    case DRAW_SELECTION:
      setCursor( getCursor(CROSS_CURSOR) ); break;
    case MOVE_SELECTION:
      setCursor( getCursor(MOVE_SELECTION_CURSOR) ); break;
    case MOVE_TOP_LEFT_CORNER:
    case MOVE_BOTTOM_RIGHT_CORNER:
      setCursor( getCursor(MOVE_TL_CURSOR) ); break;
    case MOVE_TOP_RIGHT_CORNER:
    case MOVE_BOTTOM_LEFT_CORNER:
      setCursor( getCursor(MOVE_TR_CURSOR) ); break;
    case MOVE_LEFT_SIDE:
    case MOVE_RIGHT_SIDE:
      setCursor( getCursor(MOVE_HOR_CURSOR) ); break;
    case MOVE_TOP_SIDE:
    case MOVE_BOTTOM_SIDE:
      setCursor( getCursor(MOVE_VERT_CURSOR) ); break;
      break;
    default:
      setCursor( Qt::ArrowCursor );
      break;
  }  
}
//==============================================
bool SelectionInterface::scaleSelection( int delta )
{
  //construct topLeft and bottomRight points to make logic easier
  QPoint topLeft( MIN(mousePressPoint.x(), mouseDragPoint.x()),
                  MIN(mousePressPoint.y(), mouseDragPoint.y()) );
  QPoint bottomRight( MAX(mousePressPoint.x(), mouseDragPoint.x()),
                      MAX(mousePressPoint.y(), mouseDragPoint.y()) );     
 
  //compute new selection dimension
  int curSelectionWidth = bottomRight.x() - topLeft.x() + 1;
  int curSelectionHeight = bottomRight.y()- topLeft.y() + 1;      
  int newSelectionWidth = -1; 
  int newSelectionHeight = -1;      
 
  //adjust in dimension of greater resolution
  if( curSelectionWidth > curSelectionHeight )
  {
    newSelectionWidth = MIN( curSelectionWidth + delta, origImageSize.width() );
    newSelectionHeight = (newSelectionWidth * cachedSelectionSize.height()) / cachedSelectionSize.width();
  }
  else
  {
    newSelectionHeight = MIN( curSelectionHeight + delta, origImageSize.height() );
    newSelectionWidth = (newSelectionHeight * cachedSelectionSize.width()) / cachedSelectionSize.height();    
  }
  
  //if selection width or height already maxed out then ignore attempt to make selection bigger
  if(delta > 0 &&
     ( curSelectionWidth == origImageSize.width() ||
       curSelectionHeight == origImageSize.height() ) ) 
  { 
    return false;
  }  
  
  //again prevent from growing too big, now along y-axis
  if(newSelectionHeight > origImageSize.height())
  {
    newSelectionHeight = origImageSize.height();
    newSelectionWidth = (newSelectionHeight * cachedSelectionSize.width()) / cachedSelectionSize.height();
  }        
  
  //prevent selection becoming empty
  if(newSelectionWidth <= 0 || newSelectionHeight <= 0)
  {
    newSelectionWidth = curSelectionWidth;
    newSelectionHeight = curSelectionHeight;
  }
  
  //center new selection over current selection , move if necessary
  topLeft = QPoint(QMAX( cachedSelctionCenter.x() - newSelectionWidth/2, 0 ),
                   QMAX( cachedSelctionCenter.y() - newSelectionHeight/2, 0 ));
  bottomRight = QPoint( topLeft.x() + newSelectionWidth - 1,
                        topLeft.y() + newSelectionHeight - 1 );   
  
  //too far right
  if(bottomRight.x() > origImageSize.width() - 1 )
  {
    int diff = bottomRight.x() - (origImageSize.width() - 1);        
    topLeft.setX( topLeft.x() - diff );
    bottomRight.setX( bottomRight.x() - diff );
 
    //recompute center
    cachedSelctionCenter = QPoint( ( mouseDragPoint.x() + mousePressPoint.x() )/2,
                                   ( mouseDragPoint.y() + mousePressPoint.y() )/2 );          
  }                     
  
  //too far down
  if(bottomRight.y() > origImageSize.height() - 1 )
  {
    int diff = bottomRight.y() - (origImageSize.height() - 1);        
    topLeft.setY( topLeft.y() - diff );
    bottomRight.setY( bottomRight.y() - diff );
    
    //recompute center
    cachedSelctionCenter = QPoint( ( mouseDragPoint.x() + mousePressPoint.x() )/2,
                                   ( mouseDragPoint.y() + mousePressPoint.y() )/2 );      
  }                     
  
  //set new selection
  mousePressPoint = topLeft;
  mouseDragPoint = bottomRight;  
  
  //success
  return true;  
}
//==============================================
void SelectionInterface::mouseMoveEvent(QMouseEvent *e)
{
  //if the SHIFT_Pressed state variable is true but SHIFT is now not pressed
  //reset bool and mouse cursor!
  if( SHIFT_Pressed && !(e->state() & Qt::ShiftModifier) )
  {
    SHIFT_Pressed = false;
    updateCursorShape( ConvertImageToDisplayCoordinate( e->pos() ) );   
  }
      
  //if the CTRL_Pressed state variable is true but CTRL is now not pressed
  //reset bool and mouse cursor!
  if( CTRL_Pressed && !(e->state() & Qt::ControlModifier) )
  {
    CTRL_Pressed = false;
    updateCursorShape( ConvertImageToDisplayCoordinate( e->pos() ) );   
  }  
  
  //if mouse not pressed update mouse cursor if 
  //mode will change if user presses mouse button
  if(currentDragMode == NO_EFFECT)
  {  
    //only update the mouse cursor shape if it will change
    if( mouseActionByPosition( e->pos() ) != currentMouseShape )
      updateCursorShape( e->pos() );
    
    cachedMousePosition = ConvertDisplayToImageCoordinate( cropSelectedPoint(e->pos()) );
  }
  //if currently in draw line mode update the selected line
  else if(currentDragMode == DRAW_LINE)
  {
    //if the 1st point hasn't been set yet do nothing
    if( mousePressPoint.x() == -1 )
      return;
    
    //1st point set, set 2nd point to current mouse position and redraw
    mouseDragPoint = ConvertDisplayToImageCoordinate( cropSelectedPoint(e->pos()) );
 
    //repaint the line
    repaint(false);
  }  
  //update selection rectangle or selected line
  else
  {     
    //get mouse position in original image coordinates
    QPoint p = ConvertDisplayToImageCoordinate( cropSelectedPoint(e->pos()) );
 
    //construct topLeft and bottomRight points to make logic easier
    QPoint topLeft( MIN(mousePressPoint.x(), mouseDragPoint.x()),
                    MIN(mousePressPoint.y(), mouseDragPoint.y()) );
    QPoint bottomRight( MAX(mousePressPoint.x(), mouseDragPoint.x()),
                        MAX(mousePressPoint.y(), mouseDragPoint.y()) );     
    
    //if SHIFT pressed and both selction dimensions non-empty then scale selection
    if(SHIFT_Pressed && 
       bottomRight.x() > topLeft.x() && 
       bottomRight.y() > topLeft.y() )
    {
      //update width, prevent from growing beyond image boundaries
      int delta = p.x() - cachedMousePosition.x(); 
      if( !scaleSelection( delta ) )
      {
        //cache the current mouse position before returning without change
        cachedMousePosition = p;
        return;
      }
    }    
    //if draging the entire selection, update x and y coordinates for
    //both mousePress and mouseDrag points and update the dragSelectionPoint
    else if( currentDragMode == MOVE_SELECTION )
    {
      //compute offset
      QPoint offset( p.x() - cachedMousePosition.x(),
                     p.y() - cachedMousePosition.y() );
      
      //construct topLeft and bottomRight points to make logic easier
      QPoint topLeft( MIN(mousePressPoint.x(), mouseDragPoint.x()),
                      MIN(mousePressPoint.y(), mouseDragPoint.y()) );
      QPoint bottomRight( MAX(mousePressPoint.x(), mouseDragPoint.x()),
                          MAX(mousePressPoint.y(), mouseDragPoint.y()) );  
      
      //clip offset so selected area is always within image boundaries
      
      //left
      if(offset.x() < 0 && topLeft.x() + offset.x() < 0 )
        offset.setX( -topLeft.x() );
      
      //right
      if(offset.x() > 0 && bottomRight.x() + offset.x() >= origImageSize.width() )
        offset.setX( origImageSize.width() - 1 - bottomRight.x() );          
      
      //top
      if(offset.y() < 0 && topLeft.y() + offset.y() < 0 )
        offset.setY( -topLeft.y() );
      
      //bottom
      if(offset.y() > 0 && bottomRight.y() + offset.y() >= origImageSize.height() )
        offset.setY( origImageSize.height() - 1 - bottomRight.y() );            
      
      //update press and drag points
      mousePressPoint+= offset;
      mouseDragPoint+= offset;      
      
      //recompute selection center
      cachedSelctionCenter = QPoint( ( mouseDragPoint.x() + mousePressPoint.x() )/2,
                                     ( mouseDragPoint.y() + mousePressPoint.y() )/2 );          
    }        
    //if moving any corner or drawing the original selection, 
    //update x and y coords of drag point
    else if( currentDragMode == DRAW_SELECTION ||
             currentDragMode == MOVE_TOP_LEFT_CORNER ||
             currentDragMode == MOVE_TOP_RIGHT_CORNER ||
             currentDragMode == MOVE_BOTTOM_LEFT_CORNER ||
             currentDragMode == MOVE_BOTTOM_RIGHT_CORNER )
    {
      mouseDragPoint.setX( p.x() );
      mouseDragPoint.setY( p.y() );
      cropMaxDimen = -1.0;
      
      //cache selection size and center, necessary for computing next size
      cachedSelectionSize = QSize( QABS( mouseDragPoint.x() - mousePressPoint.x() )+1,
                                   QABS( mouseDragPoint.y() - mousePressPoint.y() )+1);
      cachedSelctionCenter = QPoint( ( mouseDragPoint.x() + mousePressPoint.x() )/2,
                                     ( mouseDragPoint.y() + mousePressPoint.y() )/2 );    
      
      
      emit aspectRatioChanged();
    }
    //else if moving the left or right sides just update the x coordinate of 
    //the drag point
    else if( currentDragMode == MOVE_LEFT_SIDE ||
             currentDragMode == MOVE_RIGHT_SIDE )
    {
      mouseDragPoint.setX( p.x() );
      cropMaxDimen = -1.0;
      emit aspectRatioChanged();
      
      //cache selection size and center, necessary for computing next size
      cachedSelectionSize = QSize( QABS( mouseDragPoint.x() - mousePressPoint.x() )+1,
                                   QABS( mouseDragPoint.y() - mousePressPoint.y() )+1);                                               
      cachedSelctionCenter = QPoint( ( mouseDragPoint.x() + mousePressPoint.x() )/2,
                                     ( mouseDragPoint.y() + mousePressPoint.y() )/2 );    
    }
    //else if moving the top or bottom sides just update the x coordinate of 
    //the drag point
    else if( currentDragMode == MOVE_TOP_SIDE ||
             currentDragMode == MOVE_BOTTOM_SIDE )
    {
      mouseDragPoint.setY( p.y() );
      cropMaxDimen = -1.0;
      emit aspectRatioChanged();
      
      //cache selection size and center, necessary for computing next size
      cachedSelectionSize = QSize( QABS( mouseDragPoint.x() - mousePressPoint.x() )+1,
                                   QABS( mouseDragPoint.y() - mousePressPoint.y() )+1);                                               
      cachedSelctionCenter = QPoint( ( mouseDragPoint.x() + mousePressPoint.x() )/2,
                                     ( mouseDragPoint.y() + mousePressPoint.y() )/2 );    
      
    }    
    
    //cache current mouse position
    cachedMousePosition = p;
 
    //repaint the selection
    repaint(false);
    emit selectionChanged();
 
    //only update the mouse cursor shape if it will change
    if( mouseActionByPosition( e->pos() ) != currentMouseShape )
      updateCursorShape( e->pos() );
  }
}
//==============================================
void SelectionInterface::mouseReleaseEvent(QMouseEvent *e)
{
  //if in draw line mode
  if( currentDragMode == DRAW_LINE )
  {
    //get mouse location in image space
    QPoint p = ConvertDisplayToImageCoordinate( e->pos() );
 
    //if first point has not been set set it now
    if( mousePressPoint.x() == -1 )
    {
      mousePressPoint = p;
      repaint(false);
    }
    //else first point has been set then we're setting the 2nd point, emit the selected line
    else
    {
      //get two points on line
      QPoint p1 = mousePressPoint;
      QPoint p2 = p;
      
      //reset mode, press and drag points so there is no selection
      currentDragMode = NO_EFFECT;
      selectNone();
      updateCursorShape( ConvertImageToDisplayCoordinate(cachedMousePosition) );   
      
      //emit the selected line
      emit lineSelected( p1, p2 );       
    }
    return; 
  }
  
  //disable move moving from having an effect on the selection
  currentDragMode = NO_EFFECT;
  
  //construct topLeft and bottomRight points to make logic easier
  QPoint topLeft( MIN(mousePressPoint.x(), mouseDragPoint.x()),
                  MIN(mousePressPoint.y(), mouseDragPoint.y()) );
  QPoint bottomRight( MAX(mousePressPoint.x(), mouseDragPoint.x()),
                      MAX(mousePressPoint.y(), mouseDragPoint.y()) );  
 
  //convert selection region to display space to check for tiny selections to ignore
  topLeft = ConvertImageToDisplayCoordinate( topLeft );
  bottomRight = ConvertImageToDisplayCoordinate( bottomRight );
  
  //if selection is very small reset to select nothing
  if( bottomRight.x() - topLeft.x() + 1 < MINIMUM_SELECTION_SIZE ||
      bottomRight.y() - topLeft.y() + 1 < MINIMUM_SELECTION_SIZE ) { selectNone(); }  
}
//==============================================
QPoint SelectionInterface::ConvertDisplayToImageCoordinate( QPoint p )
{  
  QPoint newPoint = p;
  
  //remove display offset
  int xOffset = (width() - scaledImage.width()   ) / 2;
  int yOffset = (height() - scaledImage.height() ) / 2;  
  newPoint.setX( newPoint.x() - xOffset );
  newPoint.setY( newPoint.y() - yOffset );
  
  //if coordinate is at max set new value explicitly to avoid roundoff error,
  //otherwise scale to full image dimensions
  if(newPoint.x() == scaledImage.width() - 1)
    newPoint.setX( origImageSize.width() - 1);
  else 
    newPoint.setX( (int) (0.5 + ((double)(newPoint.x() * (origImageSize.width()-1))) / (scaledImage.width()-1) ) );
  
  if(newPoint.y() == scaledImage.height() - 1)
    newPoint.setY( origImageSize.height() - 1);
  else 
    newPoint.setY( (int) (0.5 + ((double)(newPoint.y() * (origImageSize.height()-1))) / (scaledImage.height()-1) ) );
  
  //return point in image coordinates
  return newPoint;
}
//==============================================
QPoint SelectionInterface::ConvertImageToDisplayCoordinate( QPoint p )
{       
  QPoint newPoint = p;
  
  //if coordinate is at max set new value explicitly to avoid roundoff error,
  //otherwise scale to full image dimensions
  if(newPoint.x() == origImageSize.width() - 1)
    newPoint.setX( scaledImage.width() - 1);
  else 
    newPoint.setX( (newPoint.x() * (scaledImage.width()-1)) / (origImageSize.width()-1) );
  
  if(newPoint.y() == origImageSize.height() - 1)
    newPoint.setY( scaledImage.height() - 1);
  else 
    newPoint.setY( (newPoint.y() * (scaledImage.height()-1)) / (origImageSize.height()-1) );
  
  //add display offset
  int xOffset = (width() - scaledImage.width()   ) / 2;
  int yOffset = (height() - scaledImage.height() ) / 2;  
  newPoint.setX( newPoint.x() + xOffset );
  newPoint.setY( newPoint.y() + yOffset );
    
  //return point in image coordinates
  return newPoint;
}
//==============================================
QPoint SelectionInterface::cropSelectedPoint(QPoint p)
{    
  int xOffset = (width() - scaledImage.width()   ) / 2;
  int yOffset = (height() - scaledImage.height() ) / 2;
 
  QPoint croppedPoint;
  croppedPoint.setX( MIN( MAX(xOffset, p.x()), xOffset + scaledImage.width() - 1 ) );
  croppedPoint.setY( MIN( MAX(yOffset, p.y()), yOffset + scaledImage.height() - 1 ) );
  return croppedPoint;
}
//==============================================
bool SelectionInterface::selectionEmpty()
{
  return (
          mousePressPoint.x() == -1 ||
          mouseDragPoint.x() - mousePressPoint.x() == 0 ||
          mouseDragPoint.y() - mousePressPoint.y() == 0
         );  
}
//==============================================
void SelectionInterface::selectAll()
{
  mousePressPoint.setX( 0 );
  mousePressPoint.setY( 0 );
  mouseDragPoint.setX( origImageSize.width() - 1 );
  mouseDragPoint.setY( origImageSize.height() - 1);
 
  //cache selection size and center, necessary for computing next size
  cachedSelectionSize = QSize( QABS( mouseDragPoint.x() - mousePressPoint.x() )+1,
                               QABS( mouseDragPoint.y() - mousePressPoint.y() )+1);           
  cachedSelctionCenter = QPoint( ( mouseDragPoint.x() + mousePressPoint.x() )/2,
                                 ( mouseDragPoint.y() + mousePressPoint.y() )/2 );      
  
  cropMaxDimen = -1.0;
  repaint(false);
  emit selectionChanged();
  emit aspectRatioChanged();
}
//==============================================
void SelectionInterface::selectNone()
{
  mousePressPoint = QPoint(-1,-1);
  mouseDragPoint = QPoint(-1,-1);
  cropMaxDimen = -1.0;
  repaint(false);
  emit selectionChanged();
  emit aspectRatioChanged();
}
//==============================================
void SelectionInterface::setSelection(QPoint topLeft, QPoint bottomRight,
                                      double cropMaxDimen)
{
  mousePressPoint = topLeft;
  mouseDragPoint = bottomRight;
  
  this->cropMaxDimen = cropMaxDimen;
  
  //cache selection size and center, necessary for computing next size
  cachedSelectionSize = QSize( QABS( mouseDragPoint.x() - mousePressPoint.x() )+1,
                               QABS( mouseDragPoint.y() - mousePressPoint.y() )+1);           
  cachedSelctionCenter = QPoint( ( mouseDragPoint.x() + mousePressPoint.x() )/2,
                                 ( mouseDragPoint.y() + mousePressPoint.y() )/2 );    
  
  repaint(false);
  emit selectionChanged();
}
//==============================================
void SelectionInterface::getSelection(QPoint &topLeft, QPoint &bottomRight)
{
  //if none selected just return immediately
  if(mousePressPoint.x() == -1)
  {
    topLeft.setX(-1); topLeft.setY(-1);
    bottomRight.setX(-1); bottomRight.setY(-1);
    return;
  }
 
  //set coordinates based on raw selection  
  topLeft.setX( MIN(mousePressPoint.x(), mouseDragPoint.x()) );
  topLeft.setY( MIN(mousePressPoint.y(), mouseDragPoint.y()) );
  bottomRight.setX( MAX( mousePressPoint.x(), mouseDragPoint.x()) );                
  bottomRight.setY( MAX( mousePressPoint.y(), mouseDragPoint.y()) );                  
}
//==============================================
void SelectionInterface::getDisplaySize(int &width, int &height)
{
  width = scaledImage.width();
  height = scaledImage.height();  
}
//==============================================
void SelectionInterface::keyPressEvent(QKeyEvent *e)
{
  //if currently drawing a line, allow the user
  //to escape the current acction by hiting escape, all other
  //key presses are ignored
  if( currentDragMode == DRAW_LINE )
  {
    if(e->key() == Qt::Key_Escape )
    {
      //reset mode, press and drag points so there is no selection, and mouse cursor
      currentDragMode = NO_EFFECT;
      selectNone();
      updateCursorShape( ConvertImageToDisplayCoordinate(cachedMousePosition) );   
    
      //emit an invalid line
      emit lineSelected( QPoint(-1,-1), QPoint(-1,-1) );       
    }
 
    return; 
  }
  
  //if user pressed SHIFT button and selection non-empty 
  //then note state change, 
  //this will effect resizing selections during drag events
  if(e->key() == Qt::Key_Shift && !selectionEmpty() )
  {    
    SHIFT_Pressed = true;
    updateCursorShape( ConvertImageToDisplayCoordinate(cachedMousePosition) );   
    return;
  }
 
  //if user pressed CTRL button and selection non-empty 
  //then note state change, 
  //this will effect mouse clicks by rotating the current selection
  if(e->key() == Qt::Key_Control && !selectionEmpty() && !SHIFT_Pressed )
  {    
    CTRL_Pressed = true;
    updateCursorShape( ConvertImageToDisplayCoordinate(cachedMousePosition) );   
    return;
  }
    
  //ignore keypress if selection is empty
  if(mousePressPoint.x() == -1 ||
     mousePressPoint.x() - mouseDragPoint.x() == 0 ||
     mousePressPoint.y()  - mouseDragPoint.y() == 0)
  {
    e->ignore();
    return;
  }
 
  //ignore keypresses while mouse button is down since
  //intended behavious is unclear
  if( currentDragMode != NO_EFFECT )
  {
    e->ignore();
    return;
  }
  
  //-------  
  //if += / -_ keys are pressed scale selection
  if( e->key() == Qt::Key_Plus ||
      e->key() == Qt::Key_Equal ||
      e->key() == Qt::Key_Minus ||
      e->key() == Qt::Key_Underscore )
  {
    int delta = 2*QMAX( origImageSize.width(), scaledImage.width() ) / scaledImage.width();
    
    delta = 1;
    
    //negate delta if decreasing size
    if( e->key() == Qt::Key_Minus ||
        e->key() == Qt::Key_Underscore )
      delta = -delta;
    
    if( scaleSelection( delta ) )
    {    
      //repaint the selection
      repaint(false);
      emit selectionChanged();
    }
    return;
  }
  //-------  
  
  //find topleft and bottom right of current selection
  QPoint topLeft, bottomRight;
  topLeft.setX( MIN(mousePressPoint.x(), mouseDragPoint.x()) );
  topLeft.setY( MIN(mousePressPoint.y(), mouseDragPoint.y()) );
  bottomRight.setX( MAX( mousePressPoint.x(), mouseDragPoint.x()) );                
  bottomRight.setY( MAX( mousePressPoint.y(), mouseDragPoint.y()) );                  
  
  //compute the number of pixels in the image correspond to one display pixel
  //this is the unit by which the selection will be moved
  int moveBy = 0;
  if( e->key() == Qt::Key_Left ||
      e->key() == Qt::Key_Right )
  {
    moveBy = QMAX( origImageSize.width(), scaledImage.width() ) / scaledImage.width();
  }
  else
  {
    moveBy = QMAX( origImageSize.height(), scaledImage.height() ) / scaledImage.height();
  }
  
  //boundary checked moved by value. must be decalred outside switch statement below
  int dx = 0;
  int dy = 0;
  switch( e->key() )
  {
    case Qt::Key_Left:
      dx = QMAX( topLeft.x() - moveBy, 0) - topLeft.x();
      break;
    case Qt::Key_Right:
      dx = MIN( bottomRight.x() + moveBy, origImageSize.width() - 1) - bottomRight.x();
      break;
    case Qt::Key_Up:
      dy = MAX( topLeft.y() - moveBy, 0) - topLeft.y();
      break;
    case Qt::Key_Down:
      dy = MIN( bottomRight.y() + moveBy, origImageSize.height() - 1) - bottomRight.y();
      break;
    default:
      e->ignore();
      return;
  }
  
  //shift by dx
  mousePressPoint.setX( mousePressPoint.x() + dx );
  mouseDragPoint.setX( mouseDragPoint.x() + dx );      
 
  //shift by dy
  mousePressPoint.setY( mousePressPoint.y() + dy );
  mouseDragPoint.setY( mouseDragPoint.y() + dy );      
 
  //recompute center
  cachedSelctionCenter = QPoint( ( mouseDragPoint.x() + mousePressPoint.x() )/2,
                                 ( mouseDragPoint.y() + mousePressPoint.y() )/2 );    
  
  //only bother with repaint and updating cursor shape if shift actually occured
  if(dx != 0 || dy != 0) 
  { 
    repaint(false);
    updateCursorShape( ConvertImageToDisplayCoordinate(cachedMousePosition) );  
  }
}
//==============================================
void SelectionInterface::keyReleaseEvent(QKeyEvent *e)
{
  //if user released SHIFT button then note state change, 
  //this will effect resizing selections during drag events
  if(e->key() == Qt::Key_Shift)
  {
    SHIFT_Pressed = false;
    updateCursorShape( ConvertImageToDisplayCoordinate(cachedMousePosition) );   
  }
  //if user released CTRL button then note state change, 
  //this will effect mouse clicks
  else  if(e->key() == Qt::Key_Control)
  {
    CTRL_Pressed = false;
    updateCursorShape( ConvertImageToDisplayCoordinate(cachedMousePosition) );   
  }
  //unhandled key press: pass up the object tree
  else { e->ignore(); }
}
//==============================================
void SelectionInterface::enterDrawLineMode()
{
  //set the current mode
  currentDragMode = DRAW_LINE;
 
  //during draw line mode ignore control and shift keys, they are only useful for adjusting
  //selections, not lines
  SHIFT_Pressed = false;
  CTRL_Pressed = false;
  
  //reset 1st point
  mousePressPoint = QPoint( -1, -1 );
  mouseDragPoint = QPoint( -1, -1 );
  
  //repaint and reset the mouse cursor
  updateCursorShape( ConvertImageToDisplayCoordinate(cachedMousePosition) );   
  repaint(false);
}
//==============================================