Method HandleMouseButtonDown

src/EnvelopeEditor.cpp:158–272

HandleMouseButtonDown either finds an existing control point or adds a NEW one which is then recorded as the point to drag. This is slightly complicated by there possibly being four control points for a given time value: We have an upper and lower envelope line. Also we may be showing an inner envelope (at 0.5 the range).

/// We have an upper and lower envelope line.
/// Also we may be showing an inner envelope (at 0.5 the range).
bool EnvelopeEditor::HandleMouseButtonDown(const wxMouseEvent & event, wxRect & r,
                                     const ZoomInfo &zoomInfo,
                                     bool dB, double dBRange,
                                     float zoomMin, float zoomMax)
{
   int ctr = (int)(r.height * zoomMax / (zoomMax - zoomMin));
   bool upper = !mMirrored || (zoomMin >= 0.0) || (event.m_y - r.y < ctr);

   int clip_y = event.m_y - r.y;
   if(clip_y < 0) clip_y = 0; //keeps point in rect r, even if mouse isn't
   if(clip_y > r.GetBottom()) clip_y = r.GetBottom();

   int bestNum = -1;
   int bestDistSqr = 100; // Must be within 10 pixel radius.

   // Member variables hold state that will be needed in dragging.
   mButton        = event.GetButton();
   mContourOffset = false;

   //   wxLogDebug(wxT("Y:%i Height:%i Offset:%i"), y, height, mContourOffset );
   int len = mEnvelope.GetNumberOfPoints();

   // TODO: extract this into a function FindNearestControlPoint()
   // TODO: also fix it so that we can drag the last point on an envelope.
   for (int i = 0; i < len; i++) { //search for control point nearest click
      const double time = mEnvelope[i].GetT() + mEnvelope.GetOffset();
      const wxInt64 position = zoomInfo.TimeToPosition(time);
      if (position >= 0 && position < r.width) {

         int x = (int)(position);
         int y[4];
         int numControlPoints;

         // Outer control points
         double value = mEnvelope[i].GetVal();
         y[0] = GetWaveYPos(value, zoomMin, zoomMax, r.height,
                                dB, true, dBRange, false);
         y[1] = GetWaveYPos(-value, zoomMin, zoomMax, r.height,
                                dB, true, dBRange, false);

         // Inner control points(contour)
         y[2] = GetWaveYPos(value, zoomMin, zoomMax, r.height,
                                dB, false, dBRange, false);
         y[3] = GetWaveYPos(-value -.00000001, zoomMin, zoomMax,
                                r.height, dB, false, dBRange, false);

         numControlPoints = 4;

         if (y[2] > y[3])
            numControlPoints = 2;

         if (!mMirrored)
            numControlPoints = 1;

         const int deltaXSquared = SQR(x - (event.m_x - r.x));
         for(int j=0; j<numControlPoints; j++){

            const int dSqr = deltaXSquared + SQR(y[j] - (event.m_y - r.y));