File indexing completed on 2025-07-06 03:31:53

 /*
     File                 : Segments.cpp
     Project              : LabPlot
     Description          : Contains methods to trace curve of image/plot
     --------------------------------------------------------------------
     SPDX-FileCopyrightText: 2015 Ankit Wagadre <wagadre.ankit@gmail.com>
     SPDX-License-Identifier: GPL-2.0-or-later
 */
 
 #include "Segments.h"
 #include "backend/datapicker/ImageEditor.h"
 #include "backend/datapicker/Segment.h"
 
 #include <QGraphicsItem>
 #include <QGraphicsScene>
 #include <QImage>
 
 /**
  * \class Segments
  * \brief container to open image/plot.
  *
  * this class is a container for all of the segment. a segment is a set
  * of linked lines that run along a curve in the original image. the
  * main complication is that curves in the original image cross each other
  * and other things like grid lines. we rely on the user to link
  * multiple segments together to get points along the entire curve length
  * * \ingroup datapicker
  */
 
 Segments::Segments(DatapickerImage* image)
     : m_image(image) {
 }
 
 /*!
     segments are built when the original image is loaded. they start out hidden
      and remain so until showSegments is called
 */
 void Segments::makeSegments(QImage& imageProcessed) {
     //  QElapsedTimer timer;
     //  timer.start();
     clearSegments();
 
     const int width = imageProcessed.width();
     const int height = imageProcessed.height();
 
     // for each new column of pixels, loop through the runs. a run is defined as
     // one or more colored pixels that are all touching, with one uncolored pixel or the
     // image boundary at each end of the set. for each set in the current column, count
     // the number of runs it touches in the adjacent (left and right) columns. here is
     // the pseudocode:
     //   if ((L > 1) || (R > 1))
     //     "this run is at a branch point so ignore the set"
     //   else
     //     if (L == 0)
     //       "this run is the start of a new segment"
     //     else
     //       "this run is appended to the segment on the left
 
     bool* lastBool = new bool[height];
     bool* currBool = new bool[height];
     bool* nextBool = new bool[height];
     auto** lastSegment = new Segment*[(size_t)height];
     auto** currSegment = new Segment*[(size_t)height];
     loadSegment(lastSegment, height);
 
     // initialize one column of boolean flags using the pixels of the specified column
     for (int y = 0; y < height; ++y) {
         lastBool[y] = false;
         currBool[y] = ImageEditor::processedPixelIsOn(imageProcessed, 0, y);
         nextBool[y] = ImageEditor::processedPixelIsOn(imageProcessed, 1, y);
     }
 
     for (int x = 0; x < width; ++x) {
         matchRunsToSegments(x, height, lastBool, lastSegment, currBool, currSegment, nextBool);
 
         // get ready for next column
         for (int y = 0; y < height; ++y) {
             lastBool[y] = currBool[y];
             currBool[y] = nextBool[y];
         }
 
         if (x + 1 < width) {
             for (int y = 0; y < height; ++y)
                 nextBool[y] = ImageEditor::processedPixelIsOn(imageProcessed, x + 1, y);
         }
         scrollSegment(lastSegment, currSegment, height);
     }
 
     delete[] lastBool;
     delete[] currBool;
     delete[] nextBool;
     delete[] lastSegment;
     delete[] currSegment;
     //  qDebug() << "Made segments in " << timer.elapsed() << "ms";
 }
 
 /*!
     scroll the segment pointers of the right column into the left column
 */
 void Segments::scrollSegment(Segment** left, Segment** right, int height) {
     for (int y = 0; y < height; ++y)
         left[y] = right[y];
 }
 
 /*!
     identify the runs in a column, and connect them to segments
 */
 void Segments::matchRunsToSegments(int x, int height, bool* lastBool, Segment** lastSegment, const bool* currBool, Segment** currSegment, bool* nextBool) {
     loadSegment(currSegment, height);
 
     int yStart = 0;
     bool inRun = false;
     for (int y = 0; y < height; ++y) {
         if (!inRun && currBool[y]) {
             inRun = true;
             yStart = y;
         }
 
         if ((y + 1 >= height) || !currBool[y + 1]) {
             if (inRun)
                 finishRun(lastBool, nextBool, lastSegment, currSegment, x, yStart, y, height);
 
             inRun = false;
         }
     }
 
     removeUnneededLines(lastSegment, currSegment, height);
 }
 
 /*!
     remove unneeded lines belonging to segments that just finished in the previous column.
 */
 void Segments::removeUnneededLines(Segment** lastSegment, Segment** currSegment, int height) {
     Segment* segLast = nullptr;
     for (int yLast = 0; yLast < height; ++yLast) {
         if (lastSegment[yLast] && (lastSegment[yLast] != segLast)) {
             segLast = lastSegment[yLast];
 
             bool found = false;
             for (int yCur = 0; yCur < height; ++yCur)
                 if (segLast == currSegment[yCur]) {
                     found = true;
                     break;
                 }
 
             if (!found) {
                 if (segLast->length < m_image->minSegmentLength()) {
                     // remove whole segment since it is too short
                     m_image->scene()->removeItem(segLast->graphicsItem());
                     segments.removeOne(segLast);
                 }
             }
         }
     }
 }
 
 /*!
     initialize one column of segment pointers
 */
 void Segments::loadSegment(Segment** columnSegment, int height) {
     for (int y = 0; y < height; ++y)
         columnSegment[y] = nullptr;
 }
 
 void Segments::clearSegments() {
     for (auto* seg : segments)
         m_image->scene()->removeItem(seg->graphicsItem());
 
     segments.clear();
 }
 
 /*!
     set segments visible
 */
 void Segments::setSegmentsVisible(bool on) {
     for (auto* seg : segments)
         seg->setVisible(on);
 }
 
 void Segments::setAcceptHoverEvents(bool on) {
     for (auto* seg : segments) {
         QGraphicsItem* item = seg->graphicsItem();
         item->setAcceptHoverEvents(on);
         item->setFlag(QGraphicsItem::ItemIsSelectable, on);
     }
 }
 
 /*!
     process a run of pixels. if there are fewer than two adjacent pixel runs on
     either side, this run will be added to an existing segment, or the start of
     a new segment
 */
 void Segments::finishRun(bool* lastBool, bool* nextBool, Segment** lastSegment, Segment** currSegment, int x, int yStart, int yStop, int height) {
     // count runs that touch on the left
     if (adjacentRuns(lastBool, yStart, yStop, height) > 1)
         return;
 
     // count runs that touch on the right
     if (adjacentRuns(nextBool, yStart, yStop, height) > 1)
         return;
 
     Segment* seg;
     int y = (int)((yStart + yStop) / 2);
     if (adjacentSegments(lastSegment, yStart, yStop, height) == 0) {
         seg = new Segment(m_image);
         QLine* line = new QLine(QPoint(x, y), QPoint(x, y));
         seg->path.append(line);
         seg->yLast = y;
         segments.append(seg);
     } else {
         // this is the continuation of an existing segment
         seg = adjacentSegment(lastSegment, yStart, yStop, height);
         QLine* line = new QLine(QPoint(x - 1, seg->yLast), QPoint(x, y));
         seg->length += abs(1 + (seg->yLast - y) * (seg->yLast - y));
         seg->path.append(line);
         seg->yLast = y;
     }
 
     seg->retransform();
 
     for (int y = yStart; y <= yStop; ++y)
         currSegment[y] = seg;
 }
 
 /*!
     return the number of runs adjacent to the pixels from yStart to yStop (inclusive)
 */
 int Segments::adjacentRuns(const bool* columnBool, int yStart, int yStop, int height) {
     int runs = 0;
     bool inRun = false;
     for (int y = yStart - 1; y <= yStop + 1; ++y) {
         if ((0 <= y) && (y < height)) {
             if (!inRun && columnBool[y]) {
                 inRun = true;
                 ++runs;
             } else if (inRun && !columnBool[y])
                 inRun = false;
         }
     }
 
     return runs;
 }
 
 /*!
     find the single segment pointer among the adjacent pixels from yStart-1 to yStop+1
 */
 Segment* Segments::adjacentSegment(Segment** lastSegment, int yStart, int yStop, int height) {
     for (int y = yStart - 1; y <= yStop + 1; ++y) {
         if ((0 <= y) && (y < height))
             if (lastSegment[y])
                 return lastSegment[y];
     }
 
     return nullptr;
 }
 
 /*!
     return the number of segments adjacent to the pixels from yStart to yStop (inclusive)
 */
 int Segments::adjacentSegments(Segment** lastSegment, int yStart, int yStop, int height) {
     int count = 0;
     bool inSegment = false;
     for (int y = yStart - 1; y <= yStop + 1; ++y) {
         if ((0 <= y) && (y < height)) {
             if (!inSegment && lastSegment[y]) {
                 inSegment = true;
                 ++count;
             } else if (inSegment && !lastSegment[y])
                 inSegment = false;
         }
     }
 
     return count;
 }