JavaFX9でTextAreaに行番号がついたTextAreaを作ってみた

MyTextArea.java

package nodamushi.jfx;


import javafx.scene.control.TextArea;
import javafx.scene.control.skin.TextInputControlSkin;
import static javafx.collections.FXCollections.observableArrayList;
import static javafx.collections.FXCollections.unmodifiableObservableList;

import java.util.ArrayList;
import java.util.List;

import javafx.collections.ObservableList;
import javafx.geometry.Rectangle2D;

/**
 *
 * @author nodamushi
 */
public class MyTextArea extends TextArea{
    
    public static class Line{
        int begin;
        int end;
        int line;
        
        public int getBegin(){return begin;}
        public int getEnd(){return end;}
        public int getLine(){return line;}
        public boolean contains(int index){return begin <= index && index < end;}
        private boolean update(int begin,int end,int line){
            if( begin == this.begin && end == this.end && line == this.line){
                return false;
            }
            this.begin = begin;
            this.end = end;
            this.line = line;
            return true;
        }
        
    }
    
    public static class YRange{
        public final double start;
        public final double end;
        public YRange(double s,double e){start = s;end = e;}
        public double getStart(){return start;}
        public double getEnd(){return end;}
    }

    @Override
    protected MyTextAreaSkin createDefaultSkin() {
        return new MyTextAreaSkin(this);
    }
    
    
    

    private ObservableList<Line> linesData ,unmodify;
    
    public ObservableList<Line> getLines(){
        if(unmodify == null){
            linesData = observableArrayList();
            unmodify = unmodifiableObservableList(linesData);
            textProperty().addListener(o->updateText());
            updateText();
        }
        return unmodify;
    }
    
    
    public YRange getLineYRange(Line line){
        TextInputControlSkin<?> skin =  (TextInputControlSkin<?>)getSkin();
        Rectangle2D r1 = skin.getCharacterBounds(line.begin);
        Rectangle2D r2 = skin.getCharacterBounds(line.end);
        double begin = Math.min(r1.getMinY(),r2.getMinY());
        double end = Math.max(r1.getMaxY(),r2.getMaxY());
        return new YRange(begin,end);
    }
    
    public YRange getLineYRange(int line){
        List<Line> lines = getLines();
        if(lines.size() < line){
            throw new IndexOutOfBoundsException(line);
        }
        Line l = lines.get(line);
        return getLineYRange(l);
    }
    
    
    
    private void updateText(){
        String text = getText();
        List<Line> cloneData = this.cloneData = new ArrayList<>(linesData);
        int line = 0;
        int begin = 0;
        boolean update=false;
        int len = text.length();
        int i=0;
        
        for(;i<len;i++){
            switch(text.charAt(i)){
                case '\r':
                    if(i+1 < len && text.charAt(i+1)=='\n'){
                        i++;
                    }
                case '\n':
                    update|=updateLine(begin, i, line);
                    line++;
                    begin = i+1;
                    break;
            }
        }
        if(i!=begin){
            update|=updateLine(begin, i, line);
        }
        this.cloneData = null;
        if(line+1 < cloneData.size()){
            update = true;
            cloneData.subList(line+1, cloneData.size()).clear();
        }
        if(linesData.isEmpty()){
            Line l =new Line();
            l.begin = 0;l.end = 0;l.line = 0;
            linesData.add(l);
        }
        if(update){
            linesData.setAll(cloneData);
        }
    }
    
    private List<Line> cloneData;
    private boolean updateLine(int begin,int end,int line){
        if(cloneData.size() < line+1){
            Line l =new Line();
            l.begin = begin;l.end = end;l.line = line;
            cloneData.add(l);
            return true;
        }else{
            return cloneData.get(line).update(begin, end, line);
        }
    }
}

MyTextAreaSkin.java

package nodamushi.jfx;

import java.util.List;
import javafx.collections.ObservableList;
import javafx.geometry.Bounds;
import javafx.scene.Group;
import javafx.scene.Node;
import javafx.scene.control.skin.TextAreaSkin;

import javafx.scene.text.Text;

/**
 *
 * @author nodamushi
 */
public class MyTextAreaSkin extends TextAreaSkin{
    
    private final MyTextArea textarea;

    private final Group lineNumbers;
    private final Text dummy;
    
    public MyTextAreaSkin(MyTextArea area){
        super(area);
        textarea = area;

        lineNumbers = new Group();
        lineNumbers.setManaged(false);
        dummy = new Text();
        getChildren().addAll(lineNumbers);
        textarea.setWrapText(true);
        textarea.scrollTopProperty().addListener(o->textarea.requestLayout());
    }
    
    private double prefLineNumbersWidth(double h){
        int n =textarea.getLines().size();
        StringBuilder sb = new StringBuilder();
        do{
            sb.append('9');
            n/=10;
        }while(n != 0);
        dummy.setText(sb.toString());
        ObservableList<Node> l =lineNumbers.getChildren();
        l.add(dummy);
        Bounds b = dummy.getBoundsInLocal();
        l.remove(l.size()-1);
        return b.getWidth();
    }
    
    
    
    
    @Override
    protected void layoutChildren(double x, double y, double w, double h) {

        double lnw = prefLineNumbersWidth(h);
        double taw = w - lnw - 6;
        
        super.layoutChildren(lnw+6+x, y, taw, h);
        double zeroY =    -getCharacterBounds(0).getMinY();
        int insertPoint = getInsertionPoint(0,zeroY);
        int lastInsertPoint = getInsertionPoint(0,zeroY + h);
        if(lastInsertPoint < 0){
            lastInsertPoint = textarea.getLength();
        }
        List<MyTextArea.Line> lines = textarea.getLines();
        ObservableList<Node> nums = lineNumbers.getChildren();
        
        
        int index =0,nlen = nums.size();
        double minY = -100000000;
        for(int l=0,end = lines.size();l<end;l++){
            MyTextArea.Line line = lines.get(l);
            if(line.end <insertPoint)continue;
            if(line.begin > lastInsertPoint)break;
            
            MyTextArea.YRange ly = textarea.getLineYRange(l);
            if(ly.end < 0)continue;
            if(ly.start > y + h || minY > y+h){
                break;
            }
            Text text;
            if(index < nlen){
                text = (Text)nums.get(index);
            }else{
                text = new Text();
                text.setManaged(false);
                nums.add(text);
            }
            index++;
            text.setFont(textarea.getFont());
            text.setText(Integer.toString(l+1));
            double nextY = ly.start+3;
            double yy = Math.max(nextY, minY);
            
            text.relocate(0, yy);
            minY = Math.max(text.getBoundsInParent().getMaxY() ,ly.end);
        }
        if(index < nlen){
            nums.remove(index, nlen);
        }
    }
}

TextAreaApplication.java

package nodamushi.jfx;

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.stage.Stage;

/**
 *
 * @author nodamushi
 */
public class TextAreaApplication extends  Application{

    public static void main(String[] args) {
        launch(args);
    }

    @Override
    public void start(Stage stage) throws Exception {
        MyTextArea area = new MyTextArea();
        area.setWrapText(true);
        area.setPrefSize(500, 500);
        Scene scene = new Scene(area);
        stage.setScene(scene);
        stage.show();
    }
}