simple-ontology/build/application.linux-arm64/source/ontology.java

import processing.core.*; 
import processing.data.*; 
import processing.event.*; 
import processing.opengl.*; 

import java.util.HashMap; 
import java.util.ArrayList; 
import java.io.File; 
import java.io.BufferedReader; 
import java.io.PrintWriter; 
import java.io.InputStream; 
import java.io.OutputStream; 
import java.io.IOException; 

public class ontology extends PApplet {

Node nodes[] = new Node[1000];
Link links[] = new Link[6000];

int textSize = 14;
boolean darkMode = true;

public void setup() {
  
  surface.setResizable(true);

  textSize(textSize);

  initButtons();
  
  /**
   * When saving, a copy of the save-file is stored locally which is opened when starting the program
   */
  try {
    loadCSV(dataPath("save.csv"));
  } 
  catch(Exception e) {
    println("No File found, starting blank");
  }
}

public void draw() {
  background(darkMode? 0 : 255);

  /**
   * Update and display links
   */
  for (int i = 0; i < linkCount; i++) {
    if (links[i].active) {
      links[i].update();
      links[i].display();
    }
  }

  /**
   * Update and display nodes
   */
  for (int i = 0; i < nodeCount; i++) {
    if (!nodes[i].deleted) {
      nodes[i].update();
      nodes[i].display();
    }
  }

  /**
   * Update and display ui, hide via exporting-flag for easy image-saving
   * Not all buttons always show, that's why this isn't in a loop
   */
  if (!exporting) {
    textSize(14);
    rectMode(CORNER);
    textAlign(CORNER);
    buttons[0].display();
    if (i_selectedNode != -1) buttons[1].display();
    buttons[2].display();
    buttons[3].display();
    buttons[4].display();
    buttons[5].display();
    rectMode(CENTER);
    textAlign(CENTER);
    textSize(textSize);
  } else {
    save(savePNGpath);
    exporting = false;
  }

  /**
   * Pull "wire" out of in/outlet before creating a link (see mouseReleased in ui)
   */
  if (dragLink) {
    stroke(darkMode? 255:0);
    strokeWeight(2);
    if (dragOriginLet == -1) {
      line(nodes[dragOriginId].inletCenter.x, nodes[dragOriginId].inletCenter.y, mouseX, mouseY);
    } else if (dragOriginLet == 1) {
      line(nodes[dragOriginId].outletCenter.x, nodes[dragOriginId].outletCenter.y, mouseX, mouseY);
    }
  }
}
int buttonCount = 6;
int i_buttonId;

public void initButtons() {
  buttons[0] = new Button(10, 10, "Add Node");
  buttons[1] = new Button(104, 10, "Delete Node");
  buttons[2] = new Button(10, 50, "Dark/Bright Mode");
  buttons[3] = new Button(10, 90, "Save");
  buttons[4] = new Button(10, 130, "Open");
  buttons[5] = new Button(10, 170, "Export Image");
/*  buttons[0] = new Button(10, 10, "Node Hinzufügen");
  buttons[1] = new Button(155, 10, "Löschen");
  buttons[2] = new Button(10, 50, "Farben umkehren");
  buttons[3] = new Button(10, 90, "Speichern");
  buttons[4] = new Button(10, 130, "Öffnen");
  buttons[5] = new Button(10, 170, "Bild Exportieren");*/
}

public void buttonFunctions(int functionID) {
  switch (functionID) {
    case(0):
    addNode(PApplet.parseInt(random(50, width-50)), PApplet.parseInt(random(30, height-150)), "");
    i_selectedNode = nodeCount-1;
    break;
    case(1):
    deleteSelectedNode();
    break;
    case(2):
    darkMode = !darkMode;
    break;
    case(3):
    saveCSV(dataPath("save.csv"));
    selectOutput("Where to save .csv file to?", "saveCSVFile");
    break;
    case(4):
    selectInput("Select csv File", "loadCSVFile");
    break;
    case(5):
    selectOutput("Where to export .png image file to?", "savePNGFile");
    break;
  default:
    break;
  }
}


Button buttons[] = new Button[buttonCount];

class Button {
  int id, x, y, w, h;
  String label;

  public boolean hover() {
    return (mouseX > x && mouseX <  x+w && mouseY > y && mouseY < y+h) ? true : false;
  }

  public void click() {
    buttonFunctions(id);
  }
  Button(int x_, int y_, String label_) {
    id = i_buttonId;
    i_buttonId++;
    x = x_;
    y = y_ ;
    label = label_;
    w = PApplet.parseInt(textWidth(label))+18;
    h = 32;
  }

  public void display() {
    stroke(0);
    strokeWeight(1);
    fill(255, 127);
    rect(x, y, w, h, 4);
    fill(0);
    text(label, x+9, y+h/2+5);
  }
}
int linkCount;

boolean dragLink; //state of dragging a link
int dragOriginLet = 0; //dragging from inlet: -1. dragging from outlet: 1.
int dragOriginId = -1; //which nodes out- / inlet did user click on?

public void Link(int parentNode, int targetNode) {
  /**
   * Check if user is adding or removing a link
   */
  int exists = -1;
  for (int i = 0; i < linkCount; i++) {
    if (links[i].parentNode == parentNode && links[i].targetNode == targetNode) {
      exists = i;
      break;
    }
  }
  if (exists != -1) {
    /**
     * !active state is pretty much the same as deleted state that the node-class comes with
     */
    links[exists].active = !links[exists].active;
  } else {
    links[linkCount] = new Link(parentNode, targetNode);
    linkCount++;
  }
}

class Link {
  int parentNode, targetNode;
  boolean active;
  PVector link = new PVector(0, 0);

  Link(int parentNode_, int targetNode_) {
    parentNode = parentNode_;
    targetNode = targetNode_;
    active = true;
  }

  /**
   * This could be an event that only gets called when nodes are moved or resized.
   */
  public void update() {
    link.x = nodes[targetNode].inletCenter.x - nodes[parentNode].outletCenter.x;
    link.y = nodes[targetNode].inletCenter.y - nodes[parentNode].outletCenter.y;
  }

  public void display() {
    stroke(darkMode? 255 : 0);
    strokeWeight(2);
    pushMatrix();
    translate(nodes[parentNode].outletCenter.x, nodes[parentNode].outletCenter.y);
    line(0, 0, link.x, link.y);
    translate(-nodes[parentNode].outletCenter.x+(nodes[parentNode].outletCenter.x+nodes[targetNode].inletCenter.x)/2, -nodes[parentNode].outletCenter.y+(nodes[parentNode].outletCenter.y+nodes[targetNode].inletCenter.y)/2);
    rotate(link.heading());
    fill(darkMode? 0 : 255);
    triangle(0, textSize/2, textSize, 0, 0, -textSize/2);
    popMatrix();
  }
}
int nodeCount;
int i_selectedNode = -1;
int padding = textSize/3*2; //Padding between text and surrounding box
int letTolerance = 10; //Widens the clickable areas of in/outlets a bit 

public void addNode(int x, int y, String title) {
  nodes[nodeCount] = new Node(x, y, title);
  nodeCount++;
}

public void deselect() {
  i_selectedNode = -1;
}

public void deleteSelectedNode() { //Seperate from class for garbage collector reasons
  if (i_selectedNode != -1) {
    for (int i = 0; i < linkCount; i++) {
      if (links[i].targetNode == i_selectedNode || links[i].parentNode == i_selectedNode) {
        links[i].active = false;
      }
    }
    nodes[i_selectedNode].deleted = true;
    i_selectedNode = -1;
  }
}

class Node {
  String title;
  int id;
  int inlets = 2;
  int outlets = 2;
  int x, y;
  int h = textSize+2*padding;
  int w = textSize+2*padding;
  PVector dragMouseStartPoint = new PVector(0, 0);
  PVector outletCenter = new PVector(0, 0);
  PVector inletCenter = new PVector(0, 0);
  boolean deleted;
  boolean drag;
  public boolean hover() {
    if (mouseX > x-w/2 && mouseX < x+w/2 && mouseY > y-h/2 && mouseY < y+h/2) {
      return true;
    } else {
      return false;
    }
  }
  public boolean hoverOutlet() {
    if (mouseX > x-(textSize+padding)/2-letTolerance && mouseX < x+(textSize+padding)/2+letTolerance && mouseY > y-padding-textSize/2-(textSize+padding)/2-letTolerance && mouseY < y-padding-textSize/2) {
      return true;
    } else {
      return false;
    }
  }
  public boolean hoverInlet() {
    if (mouseX > x-(textSize+padding)/2-letTolerance && mouseX < x+(textSize+padding)/2+letTolerance && mouseY > y+padding+textSize/2 && mouseY < y+padding+textSize/2+(textSize+padding)/2+letTolerance) {
      return true;
    } else {
      return false;
    }
  }

  Node(int x_, int y_, String title_) {
    id = nodeCount;
    title = title_;
    x = x_;
    y = y_;
    setVectors();
    refreshSize();
  }

  public void setVectors() {
    outletCenter.x = x;
    outletCenter.y = y-(padding+textSize/2)*1.3f;
    inletCenter.x = x;
    inletCenter.y = y+(padding+textSize/2)*1.3f;
  }

  /**
   * Called when changing nodes title or when zooming via mouse-wheel
   */
  public void refreshSize() {
    w = PApplet.parseInt(textWidth(title))+2*padding;
    h = textSize+2*padding;
  }

  /**
   * Update-function is really only necessary when dragging the node
   */
  public void update() {
    if (drag) {
      x -= dragMouseStartPoint.x - mouseX;
      dragMouseStartPoint.x = mouseX;
      y -= dragMouseStartPoint.y - mouseY;
      dragMouseStartPoint.y = mouseY;
      setVectors();
    }
  }

  public void display() {
    /**
     * Selected nodes border
     */
    if (i_selectedNode == id) {
      noStroke();
      fill(150, 100);
      rect(x, y, w+20, h+20, 4);
    }

    /**
     * Inlet & Outlet
     */
    stroke(255, darkMode? 255 : 0);
    strokeWeight(1);
    fill(255, 0, 0);
    ellipse(x, y-padding-textSize/2, textSize+padding, textSize+padding);
    fill(0);
    ellipse(x, y+padding+textSize/2, textSize+padding, textSize+padding);

    /**
     * Box & Title
     */
    stroke(127);
    strokeWeight(2);
    fill(50);
    rect(x, y, w, h, 4);
    fill(255);
    text(title, x, y+textSize/3);
  }
}

/**
 * Saving and loading is a messy hack!
 * You'll get a blank line in your save file for each deleted object.
 * That's because of my lack of skills of dodging the garbage collector.
 * I didn't loose data to corruption yet.
 * Don't touch the save files if you don't want to mess them up!
 **/

boolean exporting; 
String savePNGpath = dataPath("save.png");

public void savePNGFile(File selection) {
  savePNGpath = selection.getPath();
  exporting = true;
}

public void saveCSVFile(File selection) {
  saveCSV(selection.getPath());
}

public void loadCSVFile(File selection) {
  loadCSV(selection.getPath());
}

public void loadCSV(String path) {
  for (int i = 0; i < nodeCount; i++) {
    //nodes[i].deleted = true;
    i_selectedNode = i;
    deleteSelectedNode();
  }
  nodeCount = 0;

  for (int i = 0; i < linkCount; i++) {
    links[i].active = false;
  }
  linkCount = 0;

  String[] loadString = loadStrings(path);
  for (int i = 0; i < loadString.length-1; i++) {
    //This is ultra shitty
    if (loadString[i].length() == 0) {
      addNode(-1000, -1000, " ");
      i_selectedNode = nodeCount - 1;
      deleteSelectedNode();
      //nodes[nodeCount-1].deleted = true;
    } else {
      String nodeData[] = split(loadString[i], ',');
      addNode(PApplet.parseInt(nodeData[1]), PApplet.parseInt(nodeData[2]), nodeData[0]);
    }
  }
  for (int i = 0; i < loadString.length-1; i++) {
    String nodeData[] = split(loadString[i], ',');
    for (int j = 3; j < nodeData.length; j++) {
      Link(i, PApplet.parseInt(nodeData[j]));
    }
  }
}

public void saveCSV(String path) {
  String saveString = "";
  for (int i = 0; i < nodeCount; i++) {
    if (!nodes[i].deleted) {
      saveString += nodes[i].title + "," + nodes[i].x + "," + nodes[i].y;
      for (int j = 0; j < linkCount; j++) {
        if (links[j].parentNode == i && links[j].active) {
          saveString += "," + str(links[j].targetNode);
        }
      }
    }
    saveString += "\n";
  }
  String[] saveArray = split(saveString, '\n');
  saveStrings(path, saveArray);
}

/**
 * Keys only get caught for changing a nodes title.
 * Previous title is remembered in savedTitle and restored when hitting Escape
 */
String savedTitle;
public void keyPressed() {
  if (key == ESC) {
    key = 0;
  }
  if (i_selectedNode != -1) {
    if (keyCode == BACKSPACE) {
      if (nodes[i_selectedNode].title.length() > 0) {
        nodes[i_selectedNode].title = nodes[i_selectedNode].title.substring(0, nodes[i_selectedNode].title.length()-1);
        nodes[i_selectedNode].refreshSize();
      }
    } else if (keyCode == DELETE) {
      deleteSelectedNode();
    } else if (keyCode == ESC) {
      nodes[i_selectedNode].title = savedTitle;
      nodes[i_selectedNode].refreshSize();
      deselect();
    } else if (keyCode == RETURN || keyCode == ENTER) {
      deselect();
    } else if (keyCode != SHIFT && keyCode != RETURN && keyCode != ENTER && keyCode != CONTROL) {
      nodes[i_selectedNode].title = nodes[i_selectedNode].title + key;
      nodes[i_selectedNode].refreshSize();
    }
  }
}


public void mousePressed() {
  if (mouseButton == LEFT) {
    /**
     * Either press a button...
     */
    boolean buttonClicked = false;
    for (int i = 0; i < buttons.length; i++) {
      if (buttons[i].hover()) {
        buttons[i].click();
        //Not able to break out of here without using a flag
        buttonClicked = true;
      }
    }

    if (!buttonClicked) {
      for (int i = 0; i < nodeCount; i++) {
        /**
         * ...or select / drag a node...
         */
        if (nodes[i].hover()) {
          i_selectedNode = i;
          savedTitle = nodes[i].title;
          nodes[i].drag = true;
          nodes[i].dragMouseStartPoint.x = mouseX;
          nodes[i].dragMouseStartPoint.y = mouseY;
          break;
        } 
        /**
         * ...or pull a new link out of an inlet or outlet.
         */
        else if (nodes[i].hoverInlet()) {
          dragLink = true;
          dragOriginLet = -1;
          dragOriginId = i;
        } else if (nodes[i].hoverOutlet()) {
          dragLink = true;
          dragOriginLet = 1;
          dragOriginId = i;
        }

        //deselecting the shit out of this for reasons I don't remember, no care to improve right now
        deselect();
      }
    }
  }
}

/**
 * Create links
 */
public void mouseReleased() {
  for (int i = 0; i < nodeCount; i++) {
    nodes[i].drag = false;
    if (dragLink && dragOriginId != i) {
      if (nodes[i].hoverInlet() && dragOriginLet == 1) {

        Link(dragOriginId, i);
      }
      if (nodes[i].hoverOutlet() && dragOriginLet == -1) {

        Link(i, dragOriginId);
      }
    }
  }

  /**
   * Reset drag&drop states
   */
  dragLink = false;
  dragOriginLet = 0;
  dragOriginId = -1;
}


/**
 * Scaling is tied to textSize. Having the UI on a seperate PGraphics would be better, but it's good enough for now
 */
int zoomDelta = 3;
public void mouseWheel(MouseEvent event) {
  float zoom = event.getAmount();
  if (zoom < 0) {
    textSize += zoomDelta;
  } else if (zoom > 0) {
    if (textSize - zoomDelta > 0) {
      textSize -= zoomDelta;
    }
  }
  padding = textSize/3*2;
  for (int i = 0; i < nodeCount; i++) {
    nodes[i].refreshSize();
    nodes[i].setVectors();
  }
}

  public void settings() {  size(800, 600); }
  static public void main(String[] passedArgs) {
    String[] appletArgs = new String[] { "ontology" };
    if (passedArgs != null) {
      PApplet.main(concat(appletArgs, passedArgs));
    } else {
      PApplet.main(appletArgs);
    }
  }
}