calyp/app/widgets/HistogramWidget.cpp

/*    This file is a part of Calyp project
 *    Copyright (C) 2014-2018  by Joao Carreira   (jfmcarreira@gmail.com)
 *                                Luis Lucas      (luisfrlucas@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.
 *
 *    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.,
 *   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

/**
 * \file     HistogramWidget.cpp
 * \brief    Function to show image histogram
 *           Based on the work of Ricardo N. Rocha Sardo in SCode project
 */

// TODO:
//      - Optimizar paintEvent. Parece haver codigo redundante  !!

#include "HistogramWidget.h"

#include <QCoreApplication>
#include <QEvent>
#include <QMouseEvent>
#include <QPainter>
#include <QThread>
#include <QTimer>
#include <QtDebug>
#include <cmath>

class HistogramWorker : public QThread
{
private:
  QObject* m_parent;
  CalypFrame* m_pcFrame;

public:
  HistogramWorker( QObject* parent )
  {
    m_pcFrame = NULL;
    m_parent = parent;
  }

  void setup( CalypFrame* frame )
  {
    m_pcFrame = frame;
    // run();
    start();
  }
  void run()
  {
    if( m_pcFrame && m_parent )
    {
      EventData* eventData = new EventData();
      //      eventDm_imageHistogramata->starting = true;
      //      eventData->success = false;
      //      eventData->histogram = m_histogram;
      //      QCoreApplication::postEvent( m_parent, eventData );

      eventData->starting = true;

      m_pcFrame->calcHistogram();

      eventData->starting = false;
      //       eventData->success = m_pcFrame->getHasHistogram();
      eventData->success = true;
      eventData->frame = m_pcFrame;
      QCoreApplication::postEvent( m_parent, eventData );
    }
  }

  /**
	 * Custom Event
	 */
  class EventData : public QEvent
  {
  public:
    EventData()
        : QEvent( QEvent::User )
    {
      starting = false;
      success = false;
      frame = NULL;
    }

    bool starting;
    bool success;
    CalypFrame* frame;
  };
};

const QBrush g_eColorPallet[][3] = {
    {
        Qt::darkGray,  // Luma
        Qt::blue,      // Cb
        Qt::red,       // Cr
    },
    {
        Qt::red,    // Channel Red
        Qt::green,  // Channel Green
        Qt::blue,   // Channel Blue
    },
};

class HistogramWidgetPrivate
{
public:
  enum RepaintType
  {
    HistogramNone = 0,     // No current histogram values calculation.
    HistogramDataLoading,  // The image is being loaded
    HistogramStarted,      // Histogram values calculation started.
    HistogramCompleted,    // Histogram values calculation completed.
    HistogramSkipped,      // Skip histogram while playing
    HistogramFailed        // Histogram values calculation failed.
  };

  HistogramWidgetPrivate()
  {
    blinkTimer = 0;
    imageBits = 8;
    inSelected = false;
    blinkFlag = false;
    clearFlag = HistogramNone;
    xmin = 0.0;
    xmax = 0.0;
    range = 255;
    guideVisible = false;
    inInitialRepaintWait = false;
  }

  // Current selection information.
  double xmin;
  double xminOrg;
  double xmax;
  int range;
  int clearFlag;  // Clear drawing zone with message.

  // Image informations
  int imageChannels;
  int imageColorSpace;
  int imageBits;

  bool guideVisible;       // Display color guide.
  bool statisticsVisible;  // Display tooltip histogram statistics.
  bool inSelected;
  bool selectMode;  // If true, a part of the histogram can be
  // selected !
  bool blinkFlag;
  bool blinkComputation;  // If true, a message will be displayed during
  // histogram computation, else nothing (limit
  // flicker effect in widget especially for small
  // image/computation time).
  bool lumaChannel;  // Compute luminance channel if true.
  bool inInitialRepaintWait;

  QTimer* blinkTimer;

  QColor colorGuide;
};

////////////////////////////////////////////////////////////////////////////////
//                              Constructors
////////////////////////////////////////////////////////////////////////////////

// Constructor without image data
HistogramWidget::HistogramWidget( int width, int height, QWidget* parent )
    : QWidget( parent )
{
  setAttribute( Qt::WA_DeleteOnClose );

  d = new HistogramWidgetPrivate;

  m_channelType = CalypFrame::HIST_LUMA;
  m_scaleType = LogScaleHistogram;
  m_colorType = -1;
  m_renderingType = FullImageHistogram;

  setOptions( HistogramWidget::BlinkComputation | HistogramWidget::SelectMode | HistogramWidget::ShowLumaChannel );

  setMouseTracking( true );
  setMinimumSize( width, height );

  d->blinkTimer = new QTimer( this );

  connect( d->blinkTimer, SIGNAL( timeout() ), this, SLOT( slotBlinkTimerDone() ) );

  m_fullImage = NULL;
  m_selectionImage = NULL;

  m_imageWorker = new HistogramWorker( this );
  m_selectionWorker = new HistogramWorker( this );

  update();
}

////////////////////////////////////////////////////////////////////////////////
//                               Destructor
////////////////////////////////////////////////////////////////////////////////
HistogramWidget::~HistogramWidget()
{
  d->blinkTimer->stop();

  delete m_imageWorker;
  delete m_selectionWorker;

  delete d;
}
////////////////////////////////////////////////////////////////////////////////
//                              Setup Functions
////////////////////////////////////////////////////////////////////////////////

void HistogramWidget::setOptions( HistogramOptions options )
{
  d->statisticsVisible = (bool)( options & ShowStatistics );
  d->selectMode = (bool)( options & SelectMode );
  d->blinkComputation = (bool)( options & BlinkComputation );
  d->lumaChannel = (bool)( options & ShowLumaChannel );
}

void HistogramWidget::setHistogramGuideByColor( QColor color )
{
  d->guideVisible = true;
  d->colorGuide = color;
  update();
}

void HistogramWidget::reset()
{
  d->guideVisible = false;
  d->clearFlag = HistogramWidgetPrivate::HistogramNone;
  // Remove histogram data from memory.
  m_fullImage = NULL;
  m_selectionImage = NULL;
  update();
}

////////////////////////////////////////////////////////////////////////////////
//                          Custom Event Handler
////////////////////////////////////////////////////////////////////////////////

void HistogramWidget::customEvent( QEvent* event )
{
  if( !event )
  {
    return;
  }

  HistogramWorker::EventData* ed = (HistogramWorker::EventData*)event;

  if( !ed )
  {
    return;
  }

  if( ed->frame != m_fullImage && ed->frame != m_selectionImage )
  {
    return;
  }

  if( ed->starting )
  {
    setCursor( Qt::WaitCursor );
    d->clearFlag = HistogramWidgetPrivate::HistogramStarted;
    if( !d->inInitialRepaintWait )
    {
      if( d->clearFlag != HistogramWidgetPrivate::HistogramDataLoading )
      {
        // enter initial repaint wait, repaint only after waiting
        // a short time so that very fast computation does not create
        // flicker.
        d->inInitialRepaintWait = true;
        d->blinkTimer->start( 100 );
      }
      else
      {
        // after the initial repaint, we can repaint immediately
        update();
        d->blinkTimer->start( 200 );
      }
    }
  }
  else
  {
    if( ed->success )
    {
      // Repaint histogram
      d->clearFlag = HistogramWidgetPrivate::HistogramCompleted;
      d->blinkTimer->stop();
      d->inInitialRepaintWait = false;
      unsetCursor();

      // Send signals to refresh information if necessary.
      // The signals may trigger multiple repaints, avoid this,
      // we repaint once afterwards.
      setUpdatesEnabled( false );

      notifyValuesChanged();
      emit signalHistogramComputationDone( d->range );

      setUpdatesEnabled( true );
      update();
    }
    else
    {
      d->clearFlag = HistogramWidgetPrivate::HistogramFailed;
      d->blinkTimer->stop();
      d->inInitialRepaintWait = false;
      update();
      unsetCursor();
      // Remove old histogram data from memory.
      m_fullImage = NULL;
      m_selectionImage = NULL;
      emit signalHistogramComputationFailed();
    }
  }

  // delete ed;
}
////////////////////////////////////////////////////////////////////////////////
//                          Data Loading Functions
////////////////////////////////////////////////////////////////////////////////

void HistogramWidget::setDataLoading()
{
  if( d->clearFlag != HistogramWidgetPrivate::HistogramDataLoading )
  {
    setCursor( Qt::WaitCursor );
    d->clearFlag = HistogramWidgetPrivate::HistogramDataLoading;
    // enter initial repaint wait, repaint only after waiting
    // a short time so that very fast computation does not create flicker
    d->inInitialRepaintWait = true;
    d->blinkTimer->start( 100 );
    update();
  }
}

void HistogramWidget::setLoadingSkipped()
{
  d->clearFlag = HistogramWidgetPrivate::HistogramSkipped;
  d->blinkTimer->stop();
  d->inInitialRepaintWait = false;
  update();
  unsetCursor();
}

void HistogramWidget::setLoadingFailed()
{
  d->clearFlag = HistogramWidgetPrivate::HistogramFailed;
  d->blinkTimer->stop();
  d->inInitialRepaintWait = false;
  update();
  unsetCursor();
}

////////////////////////////////////////////////////////////////////////////////

void HistogramWidget::stopHistogramComputation()
{
  //  if( m_imageHistogram )
  //    m_imageHistogram->setRunningFlag( false );
  //
  //  if( m_selectionHistogram )
  //    m_selectionHistogram->setRunningFlag( false );

  d->blinkTimer->stop();
}

////////////////////////////////////////////////////////////////////////////////
//                          Update Data Methods
////////////////////////////////////////////////////////////////////////////////

void HistogramWidget::updateData( CalypFrame* pcFrame, CalypFrame* pcFrameSelection )
{
  d->imageBits = pcFrame->getBitsPel();
  switch( pcFrame->getColorSpace() )
  {
  case CLP_COLOR_YUV:
  case CLP_COLOR_GRAY:
    d->imageColorSpace = 0;
    break;
  case CLP_COLOR_RGB:
  case CLP_COLOR_RGBA:
    d->imageColorSpace = 0;
    break;
  default:
    d->imageColorSpace = 0;
  }
  d->imageChannels = pcFrame->getNumberChannels();

  // We are deleting the histogram data,
  // so we must not use it to draw any more.
  d->clearFlag = HistogramWidgetPrivate::HistogramNone;

  // Do not using CalypFrameStatistics::getHistogramSegment()
  // method here because histogram hasn't yet been computed.

  d->range = ( 1 << d->imageBits ) - 1;
  emit signalMaximumValueChanged( d->range );

  m_fullImage = pcFrame;
  m_imageWorker->setup( pcFrame );

  m_selectionImage = pcFrameSelection;
  m_selectionWorker->setup( pcFrameSelection );
}

////////////////////////////////////////////////////////////////////////////////

void HistogramWidget::slotBlinkTimerDone()
{
  d->blinkFlag = !d->blinkFlag;
  d->inInitialRepaintWait = false;
  update();
  d->blinkTimer->start( 200 );
}

////////////////////////////////////////////////////////////////////////////////
//                              Paint Event
////////////////////////////////////////////////////////////////////////////////

void HistogramWidget::paintEvent( QPaintEvent* )
{
  int maxX = size().width() - 1;
  int maxY = size().height() - 1;

  // Widget is disabled, not initialized,
  // or loading, but no message shall be drawn:
  // Drawing grayed frame.
  if( !isEnabled() || d->clearFlag == HistogramWidgetPrivate::HistogramNone ||
      ( !d->blinkComputation && ( d->clearFlag == HistogramWidgetPrivate::HistogramStarted ||
                                  d->clearFlag == HistogramWidgetPrivate::HistogramDataLoading ) ) )
  {
    QPainter p1( this );

    p1.fillRect( 0, 0, maxX, maxY, palette().color( QPalette::Disabled, QPalette::Window ) );
    p1.setPen( QPen( palette().color( QPalette::Disabled, QPalette::WindowText ), 1, Qt::SolidLine ) );
    p1.drawRect( 0, 0, maxX, maxY );

    return;
  }
  // Image data is loading or histogram is being computed:
  // Draw message.
  else if( d->blinkComputation && ( d->clearFlag == HistogramWidgetPrivate::HistogramStarted ||
                                    d->clearFlag == HistogramWidgetPrivate::HistogramDataLoading ) )
  {
    QPainter p1( this );

    p1.fillRect( 0, 0, maxX, maxY, Qt::white );

    if( d->blinkFlag )
      p1.setPen( Qt::green );
    else
      p1.setPen( Qt::darkGreen );

    if( d->clearFlag == HistogramWidgetPrivate::HistogramDataLoading )
      p1.drawText( 0, 0, maxX, maxY, Qt::AlignCenter, tr( "Loading image..." ) );
    else
      p1.drawText( 0, 0, maxX, maxY, Qt::AlignCenter, tr( "Histogram\ncalculation\nin progress..." ) );

    return;
  }
  // Histogram computation skipped:
  // Draw message.
  else if( d->clearFlag == HistogramWidgetPrivate::HistogramSkipped )
  {
    QPainter p1( this );
    p1.fillRect( 0, 0, maxX, maxY, Qt::white );
    p1.setPen( Qt::darkGreen );
    p1.drawText( 0, 0, maxX, maxY, Qt::AlignCenter, tr( "Histogram\ncalculation\nskipped." ) );
    // bitBlt(this, 0, 0, &pm);
    return;
  }
  // Histogram computation failed:
  // Draw message.
  else if( d->clearFlag == HistogramWidgetPrivate::HistogramFailed )
  {
    QPainter p1( this );
    p1.fillRect( 0, 0, maxX, maxY, Qt::white );
    p1.setPen( Qt::red );
    p1.drawText( 0, 0, maxX, maxY, Qt::AlignCenter, tr( "Histogram\ncalculation\nfailed." ) );
    // bitBlt(this, 0, 0, &pm);
    return;
  }

  int x, y;
  int yr, yg, yb;  // For all color channels.
  int wWidth = width() - 1;
  int wHeight = height() - 1;
  double max;
  CalypFrame* frame;

  if( m_renderingType == ImageSelectionHistogram && m_selectionImage )
    frame = m_selectionImage;
  else
    frame = m_fullImage;

  if( !frame )
    return;

  x = 0;
  y = 0;
  yr = 0;
  yg = 0;
  yb = 0;
  max = 0.0;

  max = frame->getMaximum( m_channelType );

  switch( m_scaleType )
  {
  case HistogramWidget::LinScaleHistogram:
    break;
  case HistogramWidget::LogScaleHistogram:
    if( max > 0.0 )
      max = log( max );
    else
      max = 1.0;
    break;
  }

  // From Qt 4.0, QWidget automatically double-buffers its painting,
  // so there's no need to write double-buffering code in paintEvent()
  // to avoid flicker.
  QPainter p1( this );
  int pallet = d->imageColorSpace;

  // Drawing selection or all histogram values.

  for( x = 0; x < wWidth; x++ )
  {
    double value = 0.0;
    double value_r = 0.0, value_g = 0.0, value_b = 0.0;  // For all channels.
    int i, j;

    i = ( x * frame->getNumHistogramSegment() ) / wWidth;
    j = ( ( x + 1 ) * frame->getNumHistogramSegment() ) / wWidth;

    do
    {
      double v;
      double vr, vg, vb;  // For all color channels.

      v = 0.0;
      vr = 0.0;
      vg = 0.0;
      vb = 0.0;

      if( m_channelType == CalypFrame::HIST_ALL_CHANNELS )
      {
        vr = frame->getHistogramValue( CalypFrame::HIST_CHAN_ONE, i );
        vg = frame->getHistogramValue( CalypFrame::HIST_CHAN_TWO, i );
        vb = frame->getHistogramValue( CalypFrame::HIST_CHAN_THREE, i );

        if( vr > value_r )
          value_r = vr;
        if( vg > value_g )
          value_g = vg;
        if( vb > value_b )
          value_b = vb;
      }
      else
      {
        v = frame->getHistogramValue( m_channelType, i );
        if( v > value )
          value = v;
      }
      i++;
    } while( i < j );

    if( m_channelType != CalypFrame::HIST_ALL_CHANNELS )
    {
      switch( m_scaleType )
      {
      case HistogramWidget::LinScaleHistogram:
        y = (int)( ( wHeight * value ) / max );
        break;

      case HistogramWidget::LogScaleHistogram:
        if( value <= 0.0 )
          value = 1.0;
        y = (int)( ( wHeight * log( value ) ) / max );
        break;

      default:
        y = 0;
        break;
      }
    }
    else
    {
      switch( m_scaleType )
      {
      case HistogramWidget::LinScaleHistogram:
        yr = (int)( ( wHeight * value_r ) / max );
        yg = (int)( ( wHeight * value_g ) / max );
        yb = (int)( ( wHeight * value_b ) / max );
        break;

      case HistogramWidget::LogScaleHistogram:
        if( value_r <= 0.0 )
          value_r = 1.0;
        if( value_g <= 0.0 )
          value_g = 1.0;
        if( value_b <= 0.0 )
          value_b = 1.0;
        yr = (int)( ( wHeight * log( value_r ) ) / max );
        yg = (int)( ( wHeight * log( value_g ) ) / max );
        yb = (int)( ( wHeight * log( value_b ) ) / max );
        break;

      default:
        yr = 0;
        yg = 0;
        yb = 0;
        break;
      }
    }

    // Drawing the histogram + selection or only the histogram.

    if( m_channelType != CalypFrame::HIST_ALL_CHANNELS )
    {
      if( d->selectMode == true )  // Selection mode enable ?
      {
        if( x >= (int)( d->xmin * wWidth ) && x <= (int)( d->xmax * wWidth ) )
        {
          p1.setPen( QPen( Qt::black, 1, Qt::SolidLine ) );
          p1.drawLine( x, wHeight, x, 0 );
          p1.setPen( QPen( Qt::lightGray, 1, Qt::SolidLine ) );
          p1.drawLine( x, wHeight, x, wHeight - y );
        }
        else
        {
          p1.setPen( QPen( Qt::black, 1, Qt::SolidLine ) );
          p1.drawLine( x, wHeight, x, wHeight - y );
          p1.setPen( QPen( Qt::white, 1, Qt::SolidLine ) );
          p1.drawLine( x, wHeight - y, x, 0 );

          if( x == wWidth / 4 || x == wWidth / 2 || x == 3 * wWidth / 4 )
          {
            p1.setPen( QPen( Qt::gray, 1, Qt::SolidLine ) );
            p1.drawLine( x, wHeight, x, 0 );
          }
        }
      }
      else
      {
        p1.setPen( QPen( Qt::black, 1, Qt::SolidLine ) );
        p1.drawLine( x, wHeight, x, wHeight - y );
        p1.setPen( QPen( Qt::white, 1, Qt::SolidLine ) );
        p1.drawLine( x, wHeight - y, x, 0 );

        if( x == wWidth / 4 || x == wWidth / 2 || x == 3 * wWidth / 4 )
        {
          p1.setPen( QPen( Qt::gray, 1, Qt::SolidLine ) );
          p1.drawLine( x, wHeight, x, 0 );
        }
      }
    }
    else  // All colors channel
    {
      if( d->selectMode == true )  // Histogram selection mode enable ?
      {
        if( x >= (int)( d->xmin * wWidth ) && x <= (int)( d->xmax * wWidth ) )
        {
          p1.setPen( QPen( Qt::black, 1, Qt::SolidLine ) );
          p1.drawLine( x, wHeight, x, 0 );
          p1.setPen( QPen( Qt::lightGray, 1, Qt::SolidLine ) );

          // Witch color must be used on the foreground with all
          // colors channel mode?
          switch( m_colorType )
          {
          case CalypFrame::HIST_LUMA:
          case CalypFrame::HIST_COLOR_R:
            p1.drawLine( x, wHeight, x, wHeight - yr );
            break;

          case CalypFrame::HIST_CHROMA_U:
          case CalypFrame::HIST_COLOR_G:
            p1.drawLine( x, wHeight, x, wHeight - yg );
            break;

          case CalypFrame::HIST_CHROMA_V:
          case CalypFrame::HIST_COLOR_B:
            p1.drawLine( x, wHeight, x, wHeight - yb );
            break;

          default:
            Q_ASSERT( 0 );
          }
        }
        else
        {
          // Which color must be used on the foreground with all
          // colors channel mode?
          switch( m_colorType )
          {
          case CalypFrame::HIST_LUMA:
          case CalypFrame::HIST_COLOR_R:
            p1.setPen( QPen( g_eColorPallet[pallet][1], 1, Qt::SolidLine ) );
            p1.drawLine( x, wHeight, x, wHeight - yg );
            p1.setPen( QPen( g_eColorPallet[pallet][2], 1, Qt::SolidLine ) );
            p1.drawLine( x, wHeight, x, wHeight - yb );
            p1.setPen( QPen( g_eColorPallet[pallet][0], 1, Qt::SolidLine ) );
            p1.drawLine( x, wHeight, x, wHeight - yr );

            p1.setPen( QPen( Qt::white, 1, Qt::SolidLine ) );
            p1.drawLine( x, wHeight - qMax( qMax( yr, yg ), yb ), x, 0 );
            p1.setPen( QPen( Qt::gray, 1, Qt::SolidLine ) );
            p1.drawLine( x, wHeight - yg - 1, x, wHeight - yg );
            p1.drawLine( x, wHeight - yb - 1, x, wHeight - yb );
            p1.drawLine( x, wHeight - yr - 1, x, wHeight - yr );

            break;

          case CalypFrame::HIST_CHROMA_U:
          case CalypFrame::HIST_COLOR_G:
            p1.setPen( QPen( g_eColorPallet[pallet][2], 1, Qt::SolidLine ) );
            p1.drawLine( x, wHeight, x, wHeight - yb );
            p1.setPen( QPen( g_eColorPallet[pallet][0], 1, Qt::SolidLine ) );
            p1.drawLine( x, wHeight, x, wHeight - yr );
            p1.setPen( QPen( g_eColorPallet[pallet][1], 1, Qt::SolidLine ) );
            p1.drawLine( x, wHeight, x, wHeight - yg );

            p1.setPen( QPen( Qt::white, 1, Qt::SolidLine ) );
            p1.drawLine( x, wHeight - qMax( qMax( yr, yg ), yb ), x, 0 );
            p1.setPen( QPen( Qt::gray, 1, Qt::SolidLine ) );
            p1.drawLine( x, wHeight - yb - 1, x, wHeight - yb );
            p1.drawLine( x, wHeight - yr - 1, x, wHeight - yr );
            p1.drawLine( x, wHeight - yg - 1, x, wHeight - yg );

            break;
          case CalypFrame::HIST_CHROMA_V:
          case CalypFrame::HIST_COLOR_B:
            p1.setPen( QPen( g_eColorPallet[pallet][0], 1, Qt::SolidLine ) );
            p1.drawLine( x, wHeight, x, wHeight - yr );
            p1.setPen( QPen( g_eColorPallet[pallet][1], 1, Qt::SolidLine ) );
            p1.drawLine( x, wHeight, x, wHeight - yg );
            p1.setPen( QPen( g_eColorPallet[pallet][2], 1, Qt::SolidLine ) );
            p1.drawLine( x, wHeight, x, wHeight - yb );

            p1.setPen( QPen( Qt::white, 1, Qt::SolidLine ) );
            p1.drawLine( x, wHeight - qMax( qMax( yr, yg ), yb ), x, 0 );
            p1.setPen( QPen( Qt::gray, 1, Qt::SolidLine ) );
            p1.drawLine( x, wHeight - yr - 1, x, wHeight - yr );
            p1.drawLine( x, wHeight - yg - 1, x, wHeight - yg );
            p1.drawLine( x, wHeight - yb - 1, x, wHeight - yb );

            break;
          default:
            Q_ASSERT( 0 );
          }

          if( x == wWidth / 4 || x == wWidth / 2 || x == 3 * wWidth / 4 )
          {
            p1.setPen( QPen( Qt::gray, 1, Qt::SolidLine ) );
            p1.drawLine( x, wHeight, x, 0 );
          }
        }
      }
      else
      {
        // Which color must be used on the foreground with all
        // colors channel mode?
        switch( m_colorType )
        {
        case CalypFrame::HIST_LUMA:
        case CalypFrame::HIST_COLOR_R:
          p1.setPen( QPen( Qt::green, 1, Qt::SolidLine ) );
          p1.setPen( QPen( g_eColorPallet[pallet][1], 1, Qt::SolidLine ) );
          p1.drawLine( x, wHeight, x, wHeight - yg );
          p1.setPen( QPen( Qt::blue, 1, Qt::SolidLine ) );
          p1.setPen( QPen( g_eColorPallet[pallet][2], 1, Qt::SolidLine ) );
          p1.drawLine( x, wHeight, x, wHeight - yb );
          p1.setPen( QPen( Qt::red, 1, Qt::SolidLine ) );
          p1.setPen( QPen( g_eColorPallet[pallet][0], 1, Qt::SolidLine ) );
          p1.drawLine( x, wHeight, x, wHeight - yr );

          p1.setPen( QPen( Qt::white, 1, Qt::SolidLine ) );
          p1.drawLine( x, wHeight - qMax( qMax( yr, yg ), yb ), x, 0 );
          p1.setPen( QPen( Qt::gray, 1, Qt::SolidLine ) );
          p1.drawLine( x, wHeight - yg - 1, x, wHeight - yg );
          p1.drawLine( x, wHeight - yb - 1, x, wHeight - yb );
          p1.drawLine( x, wHeight - yr - 1, x, wHeight - yr );

          break;

        case CalypFrame::HIST_CHROMA_U:
        case CalypFrame::HIST_COLOR_G:
          p1.setPen( QPen( Qt::blue, 1, Qt::SolidLine ) );
          p1.setPen( QPen( g_eColorPallet[pallet][2], 1, Qt::SolidLine ) );
          p1.drawLine( x, wHeight, x, wHeight - yb );
          p1.setPen( QPen( Qt::red, 1, Qt::SolidLine ) );
          p1.setPen( QPen( g_eColorPallet[pallet][0], 1, Qt::SolidLine ) );
          p1.drawLine( x, wHeight, x, wHeight - yr );
          p1.setPen( QPen( Qt::green, 1, Qt::SolidLine ) );
          p1.setPen( QPen( g_eColorPallet[pallet][1], 1, Qt::SolidLine ) );
          p1.drawLine( x, wHeight, x, wHeight - yg );

          p1.setPen( QPen( Qt::white, 1, Qt::SolidLine ) );
          p1.drawLine( x, wHeight - qMax( qMax( yr, yg ), yb ), x, 0 );
          p1.setPen( QPen( Qt::gray, 1, Qt::SolidLine ) );
          p1.drawLine( x, wHeight - yb - 1, x, wHeight - yb );
          p1.drawLine( x, wHeight - yr - 1, x, wHeight - yr );
          p1.drawLine( x, wHeight - yg - 1, x, wHeight - yg );

          break;

        case CalypFrame::HIST_CHROMA_V:
        case CalypFrame::HIST_COLOR_B:
          p1.setPen( QPen( Qt::red, 1, Qt::SolidLine ) );
          p1.setPen( QPen( g_eColorPallet[pallet][0], 1, Qt::SolidLine ) );
          p1.drawLine( x, wHeight, x, wHeight - yr );
          p1.setPen( QPen( Qt::green, 1, Qt::SolidLine ) );
          p1.setPen( QPen( g_eColorPallet[pallet][1], 1, Qt::SolidLine ) );
          p1.drawLine( x, wHeight, x, wHeight - yg );
          p1.setPen( QPen( Qt::blue, 1, Qt::SolidLine ) );
          p1.setPen( QPen( g_eColorPallet[pallet][2], 1, Qt::SolidLine ) );
          p1.drawLine( x, wHeight, x, wHeight - yb );

          p1.setPen( QPen( Qt::white, 1, Qt::SolidLine ) );
          p1.drawLine( x, wHeight - qMax( qMax( yr, yg ), yb ), x, 0 );
          p1.setPen( QPen( Qt::gray, 1, Qt::SolidLine ) );
          p1.drawLine( x, wHeight - yr - 1, x, wHeight - yr );
          p1.drawLine( x, wHeight - yg - 1, x, wHeight - yg );
          p1.drawLine( x, wHeight - yb - 1, x, wHeight - yb );

          break;
        default:
          Q_ASSERT( 0 );
        }

        if( x == wWidth / 4 || x == wWidth / 2 || x == 3 * wWidth / 4 )
        {
          p1.setPen( QPen( Qt::gray, 1, Qt::SolidLine ) );
          p1.drawLine( x, wHeight, x, 0 );
        }
      }
    }
  }

  // Drawing color guide.

  p1.setPen( QPen( Qt::red, 1, Qt::DotLine ) );
  int guidePos;

  if( d->guideVisible )
  {
    switch( m_channelType )
    {
    case CalypFrame::HIST_CHROMA_V:
    case CalypFrame::HIST_COLOR_R:
      guidePos = d->colorGuide.red();
      break;

    case CalypFrame::HIST_COLOR_G:
      guidePos = d->colorGuide.green();
      break;

    case CalypFrame::HIST_CHROMA_U:
    case CalypFrame::HIST_COLOR_B:
      guidePos = d->colorGuide.blue();
      break;

    case CalypFrame::HIST_LUMA:
      guidePos = qMax( qMax( d->colorGuide.red(), d->colorGuide.green() ), d->colorGuide.blue() );
      break;

    default:  // Alpha.
      guidePos = -1;
      break;
    }

    if( guidePos != -1 )
    {
      int xGuide = ( guidePos * wWidth ) / frame->getNumHistogramSegment();
      p1.drawLine( xGuide, 0, xGuide, wHeight );

      QString string = tr( "x:%1" ).arg( guidePos );
      QFontMetrics fontMt( string );
      QRect rect = fontMt.boundingRect( 0, 0, wWidth, wHeight, 0, string );
      p1.setPen( QPen( Qt::red, 1, Qt::SolidLine ) );
      rect.moveTop( 1 );

      if( xGuide < wWidth / 2 )
      {
        rect.moveLeft( xGuide );
        p1.fillRect( rect, QBrush( QColor( 250, 250, 255 ) ) );
        p1.drawRect( rect );
        rect.moveLeft( xGuide + 3 );
        p1.drawText( rect, Qt::AlignLeft, string );
      }
      else
      {
        rect.moveRight( xGuide );
        p1.fillRect( rect, QBrush( QColor( 250, 250, 255 ) ) );
        p1.drawRect( rect );
        rect.moveRight( xGuide - 3 );
        p1.drawText( rect, Qt::AlignRight, string );
      }
    }
  }

  if( d->statisticsVisible )
  {
    QString tipText, value;
    QString cellBeg( "<tr><td><nobr><font size=-1>" );
    QString cellMid( "</font></nobr></td><td><nobr><font size=-1>" );
    QString cellEnd( "</font></nobr></td></tr>" );
    tipText = "<table cellspacing=0 cellpadding=0>";

    tipText += cellBeg + tr( "Mean:" ) + cellMid;
    double mean = frame->getMean( m_channelType, 0, frame->getNumHistogramSegment() - 1 );
    tipText += value.setNum( mean, 'f', 1 ) + cellEnd;

    tipText += cellBeg + tr( "Pixels:" ) + cellMid;
    double pixels = frame->getPixels();
    tipText += value.setNum( (float)pixels, 'f', 0 ) + cellEnd;

    tipText += cellBeg + tr( "Std dev.:" ) + cellMid;
    double stddev = frame->getStdDev( m_channelType, 0, frame->getNumHistogramSegment() - 1 );
    tipText += value.setNum( stddev, 'f', 1 ) + cellEnd;

    tipText += cellBeg + tr( "Selected:" ) + cellMid;
    double counts = frame->getNumPixelsRange( m_channelType, 0, frame->getNumHistogramSegment() - 1 );
    tipText += value.setNum( (float)counts, 'f', 0 ) + cellEnd;

    tipText += cellBeg + tr( "Median:" ) + cellMid;
    double median = frame->getMedian( m_channelType, 0, frame->getNumHistogramSegment() - 1 );
    tipText += value.setNum( median, 'f', 1 ) + cellEnd;

    tipText += cellBeg + tr( "Percent:" ) + cellMid;
    double percentile = ( pixels > 0 ? ( 100.0 * counts / pixels ) : 0.0 );
    tipText += value.setNum( percentile, 'f', 1 ) + cellEnd;

    tipText += "</table>";

    setToolTip( tipText );
  }

  // Drawing frame.

  p1.setPen( QPen( Qt::black, 1, Qt::SolidLine ) );
  p1.drawRect( 0, 0, maxX, maxY );

  // bitBlt(this, 0, 0, &pm);
}

////////////////////////////////////////////////////////////////////////////////
//                              Mouse Events
////////////////////////////////////////////////////////////////////////////////

void HistogramWidget::mousePressEvent( QMouseEvent* e )
{
  if( d->selectMode == true && d->clearFlag == HistogramWidgetPrivate::HistogramCompleted )
  {
    if( !d->inSelected )
    {
      d->inSelected = true;
      update();
    }

    d->xmin = ( (double)e->pos().x() ) / ( (double)width() );
    d->xminOrg = d->xmin;
    notifyValuesChanged();
    // emit signalValuesChanged( (int)(d->xmin * d->range),  );
    d->xmax = 0.0;
  }
}

void HistogramWidget::mouseReleaseEvent( QMouseEvent* )
{
  if( d->selectMode == true && d->clearFlag == HistogramWidgetPrivate::HistogramCompleted )

  {
    d->inSelected = false;
    // Only single click without mouse move? Remove selection.
    if( d->xmax == 0.0 )
    {
      d->xmin = 0.0;
      // emit signalMinValueChanged( 0 );
      // emit signalMaxValueChanged( d->range );
      notifyValuesChanged();
      update();
    }
  }
}

void HistogramWidget::mouseMoveEvent( QMouseEvent* e )
{
  if( d->selectMode == true && d->clearFlag == HistogramWidgetPrivate::HistogramCompleted )
  {
    setCursor( Qt::SizeHorCursor );

    if( d->inSelected )
    {
      double max = ( (double)e->pos().x() ) / ( (double)width() );
      // int max =
      // (int)(e->pos().x()*((float)m_imageHistogram->getHistogramSegment()/(float)width()));

      if( max < d->xminOrg )
      {
        d->xmax = d->xminOrg;
        d->xmin = max;
        // emit signalMinValueChanged( (int)(d->xmin * d->range) );
      }
      else
      {
        d->xmin = d->xminOrg;
        d->xmax = max;
      }

      notifyValuesChanged();
      // emit signalMaxValueChanged( d->xmax == 0.0 ? d->range : (int)(d->xmax *
      // d->range) );

      update();
    }
  }
}

////////////////////////////////////////////////////////////////////////////////

void HistogramWidget::notifyValuesChanged()
{
  emit signalintervalChanged( (int)( d->xmin * d->range ), d->xmax == 0.0 ? d->range : (int)( d->xmax * d->range ) );
}

void HistogramWidget::slotMinValueChanged( int min )
{
  if( d->selectMode == true && d->clearFlag == HistogramWidgetPrivate::HistogramCompleted )
  {
    if( min == 0 && d->xmax == 1.0 )
    {
      // everything is selected means no selection
      d->xmin = 0.0;
      d->xmax = 0.0;
    }
    if( min >= 0 && min < d->range )
    {
      d->xmin = ( (double)min ) / d->range;
    }
    update();
  }
}

void HistogramWidget::slotMaxValueChanged( int max )
{
  if( d->selectMode == true && d->clearFlag == HistogramWidgetPrivate::HistogramCompleted )
  {
    if( d->xmin == 0.0 && max == d->range )
    {
      // everything is selected means no selection
      d->xmin = 0.0;
      d->xmax = 0.0;
    }
    else if( max > 0 && max <= d->range )
    {
      d->xmax = ( (double)max ) / d->range;
    }
    update();
  }
}