LineOverlay.cpp

#include "MantidQtSliceViewer/LineOverlay.h"
#include <qwt_plot.h>
#include <qwt_plot_canvas.h>
#include <iostream>
#include <qpainter.h>
#include <QRect>
#include <QShowEvent>
#include "MantidKernel/Utils.h"

using namespace Mantid::Kernel;


namespace MantidQt
{
namespace SliceViewer
{


  //----------------------------------------------------------------------------------------------
  /** Constructor
   */
  LineOverlay::LineOverlay(QwtPlot * plot, QWidget * parent)
  : QWidget( parent ),
    m_plot(plot),
    m_snapEnabled(false),
    m_snapX(0.1), m_snapY(0.1), m_snapLength(0),
    m_shown(true), m_showHandles(true), m_showLine(true),
    m_angleSnapMode(false), m_angleSnap(45)
  {
    m_creation = true; // Will create with the mouse
    m_rightButton = false;
    m_dragHandle = HandleNone;

    m_pointA = QPointF(0.0, 0.0);
    m_pointB = QPointF(1.0, 1.0);
    m_width = 0.1;
    //setAttribute(Qt::WA_TransparentForMouseEvents);
    // We need mouse events all the time
    setMouseTracking(true);
    //setAttribute(Qt::WA_TransparentForMouseEvents);
    // Make sure mouse propagates
    setAttribute(Qt::WA_NoMousePropagation, false);
  }
    
  //----------------------------------------------------------------------------------------------
  /** Destructor
   */
  LineOverlay::~LineOverlay()
  {
  }
  
  //----------------------------------------------------------------------------------------------
  /** Reset the line. User will have to click to create it */
  void LineOverlay::reset()
  {
    m_creation = true; // Will create with the mouse
    m_rightButton = false;
    m_dragHandle = HandleNone;
    this->update();
  }


  //----------------------------------------------------------------------------------------------
  /** Set point A's position
   * @param pointA :: plot coordinates */
  void LineOverlay::setPointA(QPointF pointA)
  {
    m_pointA = pointA;
    this->update(); //repaint
    emit lineChanging(m_pointA, m_pointB, m_width);
  }

  /** Set point B's position
   * @param pointB :: plot coordinates */
  void LineOverlay::setPointB(QPointF pointB)
  {
    m_pointB = pointB;
    this->update(); //repaint
    emit lineChanging(m_pointA, m_pointB, m_width);
  }

  /** Set the width of integration
   * @param width :: in plot coordinates */
  void LineOverlay::setWidth(double width)
  {
    m_width = width;
    this->update(); //repaint
    emit lineChanging(m_pointA, m_pointB, m_width);
  }


  //----------------------------------------------------------------------------------------------
  /** Set the snap-to-grid spacing in the X direction.
   * @param spacing :: spacing */
  void LineOverlay::setSnapX(double spacing)
  {
    m_snapX = spacing;
  }

  /** Set the snap-to-grid spacing in the Y direction.
   * @param spacing :: spacing */
  void LineOverlay::setSnapY(double spacing)
  {
    m_snapY = spacing;
  }

  /** Set the snap-to-grid spacing in both directions.
   * @param spacing :: spacing */
  void LineOverlay::setSnap(double spacing)
  {
    m_snapX = spacing;
    m_snapY = spacing;
  }

  /** Set the snap-to-grid spacing in the Y direction.
   * @param enabled :: enable spacing */
  void LineOverlay::setSnapEnabled(bool enabled)
  {
    m_snapEnabled = enabled;
  }

  /** Set the snap-to-line-length spacing
   * @param spacing :: spacing */
  void LineOverlay::setSnapLength(double spacing)
  {
    m_snapLength = spacing;
  }


  /** Sets whether any of the control is visible
   * @param shown :: if false, the the control is not drawng */
  void LineOverlay::setShown(bool shown)
  {
    m_shown = shown;
  }

  /** Sets whether to show the mouse handles
   * @param shown :: if false, the mouse handles are invisible */
  void LineOverlay::setShowHandles(bool shown)
  {
    m_showHandles = shown;
  }

  /** Sets whether to show the central line
   * @param shown :: if false, the central line is invisible */
  void LineOverlay::setShowLine(bool shown)
  {
    m_showLine = shown;
  }

  /** Sets whether we are in "creation" mode
   * For use by python directly specifying the position
   *
   * @param creation :: True for creation mode.
   */
  void LineOverlay::setCreationMode(bool creation)
  {
    m_creation = creation;
    this->update();
  }

  //----------------------------------------------------------------------------------------------
  /** Turn angle snap on/off
   * @param angleSnap :: true for always angle snap. */
  void LineOverlay::setAngleSnapMode(bool angleSnap)
  {
    m_angleSnapMode = angleSnap;
  }

  /** Sets the angle increments to snap to.
   * @param snapDegrees :: snap amount, in degrees */
  void LineOverlay::setAngleSnap(double snapDegrees)
  {
    m_angleSnap = snapDegrees;
  }

  //----------------------------------------------------------------------------------------------
  /// @return point A's position in plot coordinates
  const QPointF & LineOverlay::getPointA() const
  { return m_pointA; }

  /// @return point B's position in plot coordinates
  const QPointF & LineOverlay::getPointB() const
  { return m_pointB; }

  /// @return width of the line in plot coordinates
  double LineOverlay::getWidth() const
  { return m_width; }


  //----------------------------------------------------------------------------------------------
  /// Return the recommended size of the widget
  QSize LineOverlay::sizeHint() const
  {
    //TODO: Is there a smarter way to find the right size?
    return QSize(20000, 20000);
    // Always as big as the canvas
    //return m_plot->canvas()->size();
  }

  QSize LineOverlay::size() const
  { return m_plot->canvas()->size(); }
  int LineOverlay::height() const
  { return m_plot->canvas()->height(); }
  int LineOverlay::width() const
  { return m_plot->canvas()->width(); }


  //----------------------------------------------------------------------------------------------
  /** Tranform from plot coordinates to pixel coordinates
   * @param coords :: coordinate point in plot coordinates
   * @return pixel coordinates */
  QPoint LineOverlay::transform(QPointF coords) const
  {
    int xA = m_plot->transform( QwtPlot::xBottom, coords.x() );
    int yA = m_plot->transform( QwtPlot::yLeft, coords.y() );
    return QPoint(xA, yA);
  }

  //----------------------------------------------------------------------------------------------
  /** Inverse transform: from pixels to plot coords
   * @param pixels :: location in pixels
   * @return plot coordinates (float)   */
  QPointF LineOverlay::invTransform(QPoint pixels) const
  {
    double xA = m_plot->invTransform( QwtPlot::xBottom, pixels.x() );
    double yA = m_plot->invTransform( QwtPlot::yLeft, pixels.y() );
    return QPointF(xA, yA);
  }

  //----------------------------------------------------------------------------------------------
  /** Snap a point to the grid (if enabled)
   * @param original :: original point
   * @return snapped to grid in either or both dimensions  */
  QPointF LineOverlay::snap(QPointF original) const
  {
    if (!m_snapEnabled)
      return original;
    else
    {
      QPointF out = original;
      // Snap to grid
      if (m_snapX > 0)
        out.setX( Utils::rounddbl(out.x()/m_snapX) * m_snapX);
      if (m_snapY > 0)
        out.setY( Utils::rounddbl(out.y()/m_snapY) * m_snapY);
      return out;
    }
  }

  //----------------------------------------------------------------------------------------------
  /** Draw a handle (for dragging) at the given plot coordinates */
  QRect LineOverlay::drawHandle(QPainter & painter, QPointF coords, QColor brush)
  {
    int size = 8;
    QPoint center = transform(coords);
    QRect marker(center.x()-size/2, center.y()-size/2, size, size);
    if (this->m_showHandles)
    {
      painter.setPen(QColor(255,0,0));
      painter.setBrush(brush);
      painter.drawRect(marker);
    }
    return marker;
  }

  //----------------------------------------------------------------------------------------------
  /// Paint the overlay
  void LineOverlay::paintEvent(QPaintEvent * /*event*/)
  {
    // Don't paint until created
    // Also, don't paint while right-click dragging (panning) the underlying pic
    if (m_creation || m_rightButton || !m_shown)
      return;

    QPainter painter(this);
//    int r = rand() % 255;
//    int g = rand() % 255;
//    int b = rand() % 255;

//    painter.setBrush(QBrush(QColor(r,g,b)));

    QPointF diff = m_pointB - m_pointA;
    // Angle of the "width" perpendicular to the line
    double angle = atan2(diff.y(), diff.x()) + M_PI / 2.0;
    QPointF widthOffset( m_width * cos(angle), m_width * sin(angle) );

    // Rectangle with a rotation
    QPointF pA1 = m_pointA + widthOffset;
    QPointF pA2 = m_pointA - widthOffset;
    QPointF pB1 = m_pointB + widthOffset;
    QPointF pB2 = m_pointB - widthOffset;


    QPen boxPenLight(QColor(255,255,255, 200));
    QPen boxPenDark(QColor(0,0,0, 200));
    QPen centerPen(QColor(192,192,192, 128));

    // Special XOR pixel drawing
    //painter.setCompositionMode( QPainter::RasterOp_SourceXorDestination ); // RHEL5 has an old version of QT?

    boxPenLight.setDashPattern(  QVector<qreal>() << 5 << 5  );
    boxPenDark.setDashPattern(  QVector<qreal>() << 0 << 5 << 5 << 0 );

    // --- Draw the box ---
    boxPenLight.setWidthF(1.0);
    boxPenDark.setWidthF(1.0);

//    QPoint points[4] = {transform(pA1), transform(pB1), transform(pB2), transform(pA2)};
//    painter.drawPolygon(points, 4);

    painter.setPen(boxPenLight);
    painter.drawLine(transform(pA1), transform(pB1));
    painter.drawLine(transform(pB1), transform(pB2));
    painter.drawLine(transform(pA2), transform(pB2));
    painter.drawLine(transform(pA2), transform(pA1));
    painter.setPen(boxPenDark);
    painter.drawLine(transform(pA1), transform(pB1));
    painter.drawLine(transform(pB1), transform(pB2));
    painter.drawLine(transform(pA2), transform(pB2));
    painter.drawLine(transform(pA2), transform(pA1));

    // Go back to normal drawing mode
    painter.setCompositionMode( QPainter::CompositionMode_SourceOver );

    // --- Draw the central line ---
    if (m_showLine)
    {
      centerPen.setWidth(2);
      centerPen.setCapStyle(Qt::FlatCap);
      painter.setPen(centerPen);
      painter.drawLine(transform(m_pointA), transform(m_pointB));
    }

    // --- Draw and store the rects of the 4 handles ---
    m_handles.clear();
    m_handles.push_back(drawHandle(painter, m_pointA, QColor(0,0,0) ));
    m_handles.push_back(drawHandle(painter, m_pointB, QColor(255,255,255) ));
    m_handles.push_back(drawHandle(painter, (m_pointA + m_pointB)/2 + widthOffset, QColor(0,255,255)) );
    m_handles.push_back(drawHandle(painter, (m_pointA + m_pointB)/2 - widthOffset, QColor(0,255,255)) );
  }


  //==============================================================================================
  //================================= MOUSE HANDLING =============================================
  //==============================================================================================

  //-----------------------------------------------------------------------------------------------
  /** Return the handle ID over which the mouse is
   * @param pos :: position in pixels of mouse */
  LineOverlay::eHandleID LineOverlay::mouseOverHandle(QPoint pos)
  {
    for (int i=0; i < m_handles.size(); i++)
    {
      if (m_handles[i].contains(pos))
      {
        return eHandleID(i);
      }
    }
    if (this->mouseOverCenter(pos))
      return HandleCenter;
    else
      return HandleNone;
  }

  ///@return true if value is between A and B. A can be < or > then B.
  bool isBetween(double value, double A, double B)
  {
    if (B > A)
      return (value >= A && value <= B);
    else if (B < A)
      return (value >= B && value <= A);
    else
      return (value == A);
  }

  /** Return true if the mouse is over the central line
   * @param pos :: position in pixels of mouse */
  bool LineOverlay::mouseOverCenter(QPoint pos)
  {
    // Mouse position in pixels
    QPointF current = pos;
    // Find the distance (in pixels) between the mouse and the center of the line
    QPointF pixA = transform(m_pointA);
    QPointF pixB = transform(m_pointB);
    QPointF diff = pixB - pixA;
    double distance = fabs( diff.x()*(current.y()-pixA.y()) - (current.x() - pixA.x())*diff.y() )
        / sqrt(diff.x()*diff.x() + diff.y()*diff.y());

    // Margin of 6 pixels, and must be between the 2 limits (if the limits are not the same)
    bool retval = false;
    if (distance < 7)
    {
      retval = true;
      if ((pixA.x() != pixB.x()) && (!isBetween( current.x(), pixA.x(), pixB.x())))
      {
        retval = false;
      }
      if ((pixA.y() != pixB.y()) && (!isBetween( current.y(), pixA.y(), pixB.y())))
      {
        retval = false;
      }
    }
    return retval;
  }

  //-----------------------------------------------------------------------------------------------
  /** Handle the mouse move event when the line is being dragged
   * @param event mouse event info */
  void LineOverlay::handleDrag(QMouseEvent * event)
  {
    // Is the shift key pressed?
    bool shiftPressed = (event->modifiers() & Qt::ShiftModifier);
    // Currently dragging!
    QPointF current = this->invTransform( event->pos() );
    QPointF currentSnap = this->snap(current);
    QPointF diff = m_pointB - m_pointA;
    QPointF dragAmount = current - this->m_dragStart;
    dragAmount = snap(dragAmount);
    double width = 0;

    // Adjust the current mouse position if needed.
    if ((m_snapLength > 0) || shiftPressed || m_angleSnapMode)
    {
      // This is the distance between the fixed and dragged point
      QPointF currentDiff;
      if (m_dragHandle == HandleA)
        currentDiff = current - m_pointB;
      else if (m_dragHandle == HandleB)
        currentDiff = current - m_pointA;

      // Limit angles to 45 degree increments with shift pressed
      double angle = atan2(currentDiff.y(), currentDiff.x());
      // Round angle to closest 45 degrees, if in angle snap mode
      if (shiftPressed || m_angleSnapMode)
      {
        // Convert the snap angle from degrees to radians
        double angleSnapRad = m_angleSnap / (180.0 / M_PI);
        angle = Utils::rounddbl(angle / angleSnapRad) * angleSnapRad;
      }

      // Round length to m_snapLength, if specified
      double length = sqrt(currentDiff.x()*currentDiff.x() + currentDiff.y()*currentDiff.y());
      if (m_snapLength > 0)
        length = Utils::rounddbl(length / m_snapLength) * m_snapLength;

      // Rebuild the mouse position
      currentDiff = QPointF( cos(angle) * length, sin(angle) * length);
      if (m_dragHandle == HandleA)
        currentSnap = snap(m_pointB + currentDiff);
      else if (m_dragHandle == HandleB)
        currentSnap = snap(m_pointA + currentDiff);
    }

    switch (m_dragHandle)
    {
    case HandleA:
      setPointA(currentSnap);
      break;

    case HandleB:
      setPointB(currentSnap);
      break;

    case HandleWidthBottom:
    case HandleWidthTop:
      // Find the distance between the mouse and the line (see http://mathworld.wolfram.com/Point-LineDistance2-Dimensional.html )
      width = fabs( diff.x()*(current.y()-m_pointA.y()) - (current.x() - m_pointA.x())*diff.y() )
          / sqrt(diff.x()*diff.x() + diff.y()*diff.y());
      setWidth(width);
      break;

    case HandleCenter:
      // Move the whole line around
      m_pointA = m_dragStart_PointA + dragAmount;
      m_pointB = m_dragStart_PointB + dragAmount;
      this->update();
      emit lineChanging(m_pointA, m_pointB, m_width);
      break;

    default:
      break;
    }
  }

  //-----------------------------------------------------------------------------------------------
  /** Event when the mouse moves
   * @param event mouse event info */
  void LineOverlay::mouseMoveEvent(QMouseEvent * event)
  {
    if (event->buttons() & Qt::RightButton)
      m_rightButton = true;

    // Do not respond to mouse when hidden
    if (!m_showHandles || !m_shown)
    {
      event->ignore();
      return;
    }

    // --- Initial creation mode - wait for first click ----
    if (m_creation)
    {
      // TODO: Custom mouse cursor?
      this->setCursor(Qt::PointingHandCursor);
      // Pass-through event to underlying widget, so that it shows the mouse position
      event->ignore();
      return;
    }

    // --- Initial creation mode ----
    if (m_dragHandle != HandleNone)
    {
      this->handleDrag(event);
    }
    else
    {
      // ---- Just moving the mouse -------------
      if (event->buttons() == Qt::NoButton)
      {
        LineOverlay::eHandleID hdl = mouseOverHandle(event->pos());
        switch (hdl)
        {
        case HandleA:
        case HandleB:
          this->setCursor(Qt::SizeHorCursor);
          break;
        case HandleWidthBottom:
        case HandleWidthTop:
          this->setCursor(Qt::SizeVerCursor);
          break;
        case HandleCenter:
          this->setCursor(Qt::PointingHandCursor);
          break;

        default:
          this->setCursor(Qt::CrossCursor);
          break;
        }
      }
    }
    // In all cases, we pass-through the event to underlying widget,
    // so that it shows the mouse position.
    event->ignore();
  }

  //-----------------------------------------------------------------------------------------------
  /** Event when the mouse button is pressed down
   * @param event mouse event info */
  void LineOverlay::mousePressEvent(QMouseEvent * event)
  {
    // Do not respond to mouse when hidden
    if (!m_showHandles || !m_shown)
    {
      event->ignore();
      return;
    }

    // First left-click = create!
    if (m_creation && (event->buttons() & Qt::LeftButton))
    {
      QPointF pt = snap(this->invTransform( event->pos() ));
      m_pointB = pt;
      setPointA(pt);
      // And now we are in drag B mode
      m_creation = false;
      m_dragStart = pt;
      m_dragHandle = HandleB;
      return;
    }

    LineOverlay::eHandleID hdl = mouseOverHandle(event->pos());
    // Drag with the left mouse button
    if (hdl != HandleNone && (event->buttons() & Qt::LeftButton))
    {
      // Start dragging
      m_dragHandle = hdl;
      m_dragStart = this->invTransform( event->pos() );
      m_dragStart_PointA = m_pointA;
      m_dragStart_PointB = m_pointB;
    }
    else
      // Pass-through event to underlying widget if not over a marker
      event->ignore();

  }

  //-----------------------------------------------------------------------------------------------
  /** Event when the mouse moves
   * @param event mouse event info */
  void LineOverlay::mouseReleaseEvent(QMouseEvent * event)
  {
    if (!(event->buttons() & Qt::RightButton))
      m_rightButton = false;

    // Do not respond to mouse when hidden
    if (!m_showHandles || !m_shown)
    {
      event->ignore();
      return;
    }

    if (m_dragHandle != HandleNone)
    {
      // Stop draggin
      m_dragHandle = HandleNone;
      // Drag is over - signal that
      emit lineChanged(m_pointA, m_pointB, m_width);
    }
    else
      // Pass-through event to underlying widget if not dragging
      event->ignore();

  }


} // namespace Mantid
} // namespace SliceViewer