Expose row and column position of caret (#376)

rta/src/main/java/com/gluonhq/richtextarea/RichTextArea.java

@@ -334,6 +334,21 @@ public final Point2D getCaretOrigin() {
        return caretOriginProperty.get();
     }
 
+    /**
+     * A Point2D, with x for column and y for row, with integer values, for a given position of the caret.
+     * Column is defined by the number of characters from the beginning of the paragraph to the current position
+     * of the caret, starting in 0 (or -1 if the control has no text).
+     * Row is defined by the number of paragraph the caret is placed in, starting in 0 (or -1 if the control
+     * has no text).
+     */
+    final ReadOnlyObjectWrapper<Point2D> caretRowColumnProperty = new ReadOnlyObjectWrapper<>(this, "caretRowColumn", Point2D.ZERO);
+    public final ReadOnlyObjectProperty<Point2D> caretRowColumnProperty() {
+        return caretRowColumnProperty.getReadOnlyProperty();
+    }
+    public final Point2D getCaretRowColumn() {
+        return caretRowColumnProperty.get();
+    }
+
     /**
      * The current decoration at the caret.
      */

rta/src/main/java/com/gluonhq/richtextarea/RichTextAreaSkin.java

@@ -392,6 +392,7 @@ protected void invalidated() {
                 getSkinnable().decorationAtParagraph.bind(viewModel.decorationAtParagraphProperty());
                 caretPositionProperty.bind(viewModel.caretPositionProperty());
                 getSkinnable().caretOriginProperty.bind(caretOriginProperty);
+                getSkinnable().caretRowColumnProperty.bind(caretRowColumnProperty);
                 promptNode.visibleProperty().bind(promptVisibleBinding);
                 promptNode.fontProperty().bind(promptFontBinding);
             } else {
@@ -404,6 +405,7 @@ protected void invalidated() {
                 getSkinnable().decorationAtParagraph.unbind();
                 caretPositionProperty.unbind();
                 getSkinnable().caretOriginProperty.unbind();
+                getSkinnable().caretRowColumnProperty.unbind();
                 promptNode.visibleProperty().unbind();
                 promptNode.fontProperty().unbind();
             }
@@ -425,7 +427,17 @@ protected void invalidated() {
         }
     };
 
-    final ObjectProperty<Point2D> caretOriginProperty = new SimpleObjectProperty<>(this, "caretOrigin", DEFAULT_POINT_2D);
+    final ObjectProperty<Point2D> caretOriginProperty = new SimpleObjectProperty<>(this, "caretOrigin", DEFAULT_POINT_2D) {
+        @Override
+        protected void invalidated() {
+            viewModel.getParagraphWithCaret().ifPresentOrElse(p -> {
+                int row = viewModel.getParagraphList().indexOf(p);
+                int col = caretPositionProperty.get() - p.getStart();
+                caretRowColumnProperty.set(new Point2D(col, row));
+            }, () -> caretRowColumnProperty.set(DEFAULT_POINT_2D));
+        }
+    };
+    private final ObjectProperty<Point2D> caretRowColumnProperty = new SimpleObjectProperty<>(this, "caretRowColumn", DEFAULT_POINT_2D);
 
     private final ObjectBinding<Font> promptFontBinding = Bindings.createObjectBinding(this::getPromptNodeFont,
             viewModel.decorationAtCaretProperty(), viewModel.decorationAtParagraphProperty());