Added bracket highlighter demo

richtextfx-demos/src/main/java/org/fxmisc/richtext/demo/brackethighlighter/BracketHighlighter.java

@@ -0,0 +1,183 @@
+package org.fxmisc.richtext.demo.brackethighlighter;
+
+import javafx.application.Platform;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Iterator;
+import java.util.List;
+
+public class BracketHighlighter {
+
+    // the code area
+    private final CustomCodeArea codeArea;
+
+    // the list of highlighted bracket pairs
+    private List<BracketPair> bracketPairs;
+
+    // constants
+    private static final List<String> CLEAR_STYLE = Collections.emptyList();
+    private static final List<String> MATCH_STYLE = Collections.singletonList("match");
+    private static final String BRACKET_PAIRS = "(){}[]<>";
+
+    /**
+     * Parameterized constructor
+     * @param codeArea the code area
+     */
+    public BracketHighlighter(CustomCodeArea codeArea) {
+        this.codeArea = codeArea;
+
+        this.bracketPairs = new ArrayList<>();
+
+        // listen for changes in text or caret position
+        this.codeArea.addTextInsertionListener((start, end, text) -> clearBracket());
+        this.codeArea.caretPositionProperty().addListener((obs, oldVal, newVal) -> Platform.runLater(() -> highlightBracket(newVal)));
+    }
+
+    /**
+     * Highlight the matching bracket at current caret position
+     */
+    public void highlightBracket() {
+        this.highlightBracket(codeArea.getCaretPosition());
+    }
+
+    /**
+     * Highlight the matching bracket at new caret position
+     *
+     * @param newVal the new caret position
+     */
+    private void highlightBracket(int newVal) {
+        // first clear existing bracket highlights
+        this.clearBracket();
+
+        // detect caret position both before and after bracket
+        String prevChar = (newVal > 0 && newVal <= codeArea.getLength()) ? codeArea.getText(newVal - 1, newVal) : "";
+        if (BRACKET_PAIRS.contains(prevChar)) newVal--;
+
+        // get other half of matching bracket
+        Integer other = getMatchingBracket(newVal);
+
+        if (other != null) {
+            // other half exists
+            BracketPair pair = new BracketPair(newVal, other);
+
+            // highlight pair
+            styleBrackets(pair, MATCH_STYLE);
+
+            // add bracket pair to list
+            this.bracketPairs.add(pair);
+        }
+    }
+
+    /**
+     * Find the matching bracket location
+     *
+     * @param index to start searching from
+     * @return null or position of matching bracket
+     */
+    private Integer getMatchingBracket(int index) {
+        if (index < 0 || index >= codeArea.getLength()) return null;
+
+        char initialBracket = codeArea.getText(index, index + 1).charAt(0);
+        int bracketTypePosition = BRACKET_PAIRS.indexOf(initialBracket); // "(){}[]<>"
+        if (bracketTypePosition < 0) return null;
+
+        // even numbered bracketTypePositions are opening brackets, and odd positions are closing
+        // if even (opening bracket) then step forwards, otherwise step backwards
+        int stepDirection = ( bracketTypePosition % 2 == 0 ) ? +1 : -1;
+
+        // the matching bracket to look for, the opposite of initialBracket
+        char match = BRACKET_PAIRS.charAt(bracketTypePosition + stepDirection);
+
+        index += stepDirection;
+        int bracketCount = 1;
+
+        while (index > -1 && index < codeArea.getLength()) {
+            char code = codeArea.getText(index, index + 1).charAt(0);
+            if (code == initialBracket) bracketCount++;
+            else if (code == match) bracketCount--;
+            if (bracketCount == 0) return index;
+            else index += stepDirection;
+        }
+
+        return null;
+    }
+
+    /**
+     * Clear the existing highlighted bracket styles
+     */
+    public void clearBracket() {
+        // get iterator of bracket pairs
+        Iterator<BracketPair> iterator = this.bracketPairs.iterator();
+
+        // loop through bracket pairs and clear all
+        while (iterator.hasNext()) {
+            // get next bracket pair
+            BracketPair pair = iterator.next();
+
+            // clear pair
+            styleBrackets(pair, CLEAR_STYLE);
+
+            // remove bracket pair from list
+            iterator.remove();
+        }
+    }
+
+    /**
+     * Set a list of styles to a pair of brackets
+     *
+     * @param pair pair of brackets
+     * @param styles the style list to set
+     */
+    private void styleBrackets(BracketPair pair, List<String> styles) {
+        styleBracket(pair.start, styles);
+        styleBracket(pair.end, styles);
+    }
+
+    /**
+     * Set a list of styles for a position
+     *
+     * @param pos the position
+     * @param styles the style list to set
+     */
+    private void styleBracket(int pos, List<String> styles) {
+        if (pos < codeArea.getLength()) {
+            String text = codeArea.getText(pos, pos + 1);
+            if (BRACKET_PAIRS.contains(text)) {
+                codeArea.setStyle(pos, pos + 1, styles);
+            }
+        }
+    }
+
+    /**
+     * Class representing a pair of matching bracket indices
+     */
+    static class BracketPair {
+
+        private int start;
+        private int end;
+
+        public BracketPair(int start, int end) {
+            this.start = start;
+            this.end = end;
+        }
+
+        public int getStart() {
+            return start;
+        }
+
+        public int getEnd() {
+            return end;
+        }
+
+        @Override
+        public String toString() {
+            return "BracketPair{" +
+                    "start=" + start +
+                    ", end=" + end +
+                    '}';
+        }
+
+    }
+
+}

richtextfx-demos/src/main/java/org/fxmisc/richtext/demo/brackethighlighter/BracketHighlighterDemo.java

@@ -0,0 +1,31 @@
+package org.fxmisc.richtext.demo.brackethighlighter;
+
+import javafx.application.Application;
+import javafx.scene.Scene;
+import javafx.scene.layout.StackPane;
+import javafx.stage.Stage;
+import org.fxmisc.flowless.VirtualizedScrollPane;
+
+public class BracketHighlighterDemo extends Application {
+
+    @Override
+    public void start(Stage primaryStage) {
+        // create a new code area
+        CustomCodeArea codeArea = new CustomCodeArea();
+
+        // highlight brackets
+        BracketHighlighter bracketHighlighter = new BracketHighlighter(codeArea);
+
+        // initialize and show scene
+        Scene scene = new Scene(new StackPane(new VirtualizedScrollPane<>(codeArea)), 600, 400);
+        scene.getStylesheets().add(BracketHighlighterDemo.class.getResource("bracket-highlighter.css").toExternalForm());
+        primaryStage.setScene(scene);
+        primaryStage.setTitle("Bracket Highlighter Demo");
+        primaryStage.show();
+    }
+
+    public static void main(String[] args) {
+        launch(args);
+    }
+
+}

richtextfx-demos/src/main/java/org/fxmisc/richtext/demo/brackethighlighter/CustomCodeArea.java

@@ -0,0 +1,46 @@
+package org.fxmisc.richtext.demo.brackethighlighter;
+
+import org.fxmisc.richtext.CodeArea;
+import org.fxmisc.richtext.model.EditableStyledDocument;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+
+public class CustomCodeArea extends CodeArea {
+
+    private List<TextInsertionListener> insertionListeners;
+
+    public CustomCodeArea() {
+        this.insertionListeners = new ArrayList<>();
+    }
+
+    public CustomCodeArea(String text) {
+        super(text);
+        this.insertionListeners = new ArrayList<>();
+    }
+
+    public CustomCodeArea(EditableStyledDocument<Collection<String>, String, Collection<String>> document) {
+        super(document);
+        this.insertionListeners = new ArrayList<>();
+    }
+
+    public void addTextInsertionListener(TextInsertionListener listener) {
+        insertionListeners.add(listener);
+    }
+
+    public void removeTextInsertionListener(TextInsertionListener listener) {
+        insertionListeners.remove(listener);
+    }
+
+    @Override
+    public void replaceText(int start, int end, String text) {
+        // notify all listeners
+        for (TextInsertionListener listener : insertionListeners) {
+            listener.codeInserted(start, end, text);
+        }
+
+        super.replaceText(start, end, text);
+    }
+
+}

richtextfx-demos/src/main/java/org/fxmisc/richtext/demo/brackethighlighter/TextInsertionListener.java

@@ -0,0 +1,7 @@
+package org.fxmisc.richtext.demo.brackethighlighter;
+
+public interface TextInsertionListener {
+
+    void codeInserted(int start, int end, String text);
+
+}

richtextfx-demos/src/main/resources/org/fxmisc/richtext/demo/brackethighlighter/bracket-highlighter.css

@@ -0,0 +1,6 @@
+.code-area .paragraph-box .text {
+    -fx-font-size: 18px;
+}
+.code-area .paragraph-box .text.match {
+    -rtfx-background-color: #00000033;
+}