Warning, file /education/kstars/kstars/skycomponents/linelistlabel.cpp was not indexed or was modified since last indexation (in which case cross-reference links may be missing, inaccurate or erroneous).

 /*
     SPDX-FileCopyrightText: 2007 James B. Bowlin <bowlin@mindspring.com>
     SPDX-License-Identifier: GPL-2.0-or-later
 */
 
 #include "linelistlabel.h"
 
 #include "linelist.h"
 #include "Options.h"
 #ifndef KSTARS_LITE
 #include "skymap.h"
 #endif
 #include "skylabeler.h"
 #include "projections/projector.h"
 
 LineListLabel::LineListLabel(const QString &text) : m_text(text)
 {
     m_skyLabeler = SkyLabeler::Instance();
 
     // prevent a crash if drawGuideLabel() is called before reset()
     for (int i = 0; i < 4; i++)
     {
         m_labList[i]  = nullptr;
         m_labIndex[i] = 0;
     }
 }
 
 void LineListLabel::reset()
 {
     // These are the indices of the farthest left point, farthest right point,
     // etc.  The are data members so the drawLabels() routine can use them.
     // Zero indicates an index that was never set and is considered invalid
     // inside of drawLabels().
     for (int i = 0; i < 4; i++)
     {
         m_labList[i]  = nullptr;
         m_labIndex[i] = 0;
     }
 
     // These are used to keep track of the element that is farthest left,
     // farthest right, etc.
     m_farLeft  = 100000.0;
     m_farRight = 0.0;
     m_farTop   = 100000.0;
     m_farBot   = 0.0;
 
     m_skyLabeler->getMargins(m_text, &m_marginLeft, &m_marginRight, &m_marginTop, &m_marginBot);
 }
 
 void LineListLabel::updateLabelCandidates(qreal x, qreal y, LineList *lineList, int i)
 {
     if (i < 1)
         return;
 
     if (x < m_marginLeft || x > m_marginRight || y < m_marginTop || y > m_marginBot)
         return;
 
     if (x < m_farLeft)
     {
         m_labIndex[LeftCandidate] = i;
         m_labList[LeftCandidate]  = lineList;
         m_farLeft                 = x;
     }
     if (x > m_farRight)
     {
         m_labIndex[RightCandidate] = i;
         m_labList[RightCandidate]  = lineList;
         m_farRight                 = x;
     }
     if (y > m_farBot)
     {
         m_labIndex[BotCandidate] = i;
         m_labList[BotCandidate]  = lineList;
         m_farBot                 = x;
     }
     if (y < m_farTop)
     {
         m_labIndex[TopCandidate] = i;
         m_labList[TopCandidate]  = lineList;
         m_farTop                 = x;
     }
 }
 
 void LineListLabel::draw()
 {
 #ifndef KSTARS_LITE
     const Projector *proj = SkyMap::Instance()->projector();
 
     double comfyAngle = 40.0; // the first valid candidate with an angle
     // smaller than this gets displayed.  If you set
     // this to > 90. then the first valid candidate
     // will be displayed, regardless of angle.
 
     // We store info about the four candidate points in arrays to make several
     // of the steps easier, particularly choosing the valid candidate with the
     // smallest angle from the horizontal.
 
     int idx[4];                                   // index of candidate
     LineList *list[4];                            // LineList of candidate
     double a[4] = { 360.0, 360.0, 360.0, 360.0 }; // angle, default to large value
     QPointF o[4];                                 // candidate point
     bool okay[4] = { true, true, true, true };    // flag  candidate false if it
     // overlaps a previous label.
 
     // We no longer adjust the order but if we were to it would be here
     static int Order[4] = { LeftCandidate, BotCandidate, TopCandidate, LeftCandidate };
 
     for (int j = 0; j < 4; j++)
     {
         idx[j]  = m_labIndex[Order[j]];
         list[j] = m_labList[Order[j]];
     }
 
     // Make sure start with a valid candidate
     int first = 0;
     for (; first < 4; first++)
     {
         if (idx[first])
             break;
     }
 
     // return if there are no valid candidates
     if (first >= 4)
         return;
 
     // Try the points in order and print the label if we can draw it at
     // a comfortable angle for viewing;
     for (int j = first; j < 4; j++)
     {
         o[j] = angleAt(proj, list[j], idx[j], &a[j]);
 
         if (!idx[j] || !proj->checkVisibility(list[j]->at(idx[j]).get()))
         {
             okay[j] = false;
             continue;
         }
 
         if (fabs(a[j]) > comfyAngle)
             continue;
 
         if (m_skyLabeler->drawGuideLabel(o[j], m_text, a[j]))
             return;
 
         okay[j] = false;
     }
 
     //--- No angle was comfy so pick the one with the smallest angle ---
 
     // Index of the index/angle/point that gets displayed
     int best = first;
 
     // find first valid candidate that does not overlap existing labels
     for (; best < 4; best++)
     {
         if (idx[best] && okay[best])
             break;
     }
 
     // return if all candidates either overlap or are invalid
     if (best >= 4)
         return;
 
     // find the valid non-overlap candidate with the smallest angle
     for (int j = best + 1; j < 4; j++)
     {
         if (idx[j] && okay[j] && fabs(a[j]) < fabs(a[best]))
             best = j;
     }
 
     m_skyLabeler->drawGuideLabel(o[best], m_text, a[best]);
 #endif
 }
 
 QPointF LineListLabel::angleAt(const Projector *proj, LineList *list, int i, double *angle)
 {
     const SkyPoint *pThis = list->at(i).get();
     const SkyPoint *pLast = list->at(i-1).get();
 
     QPointF oThis = proj->toScreen(pThis);
     QPointF oLast = proj->toScreen(pLast);
 
     double sx = double(oThis.x() - oLast.x());
     double sy = double(oThis.y() - oLast.y());
 
     *angle = atan2(sy, sx) * 180.0 / dms::PI;
 
     // FIXME: use clamp in KSUtils
     // Never draw the label upside down
     if (*angle < -90.0)
         *angle += 180.0;
     if (*angle > 90.0)
         *angle -= 180.0;
 
     return oThis;
 }