How to add an ImagePattern to a Rectangle while still maintaining the Rectangles background color - css

Question

I have a chess board and I am trying to add pieces to the board. Every spot on the board is a Rectangle so I thought the best way to add pieces would be to add an ImagePattern to each Rectangle that gets a piece. The problem I encountered was when I added an ImagePattern to a Rectangle it would make the background of that Rectangle white despite what the color was before the ImagePattern was added. So my question is, is there a way for me to preserve the background color of a Rectangle after an ImagePattern is added?
For demo purposes my code only adds one piece to the board.
public class ChessBoard extends Application {
GridPane root = new GridPane();
final int size = 8;
public void start(Stage primaryStage) {
for (int row = 0; row < size; row++) {
for (int col = 0; col < size; col++) {
Rectangle square = new Rectangle();
Color color;
if ((row + col) % 2 == 0)
color = Color.WHITE;
else
color = Color.BLACK;
square.setFill(color);
root.add(square, col, row);
if(row == 4 && col == 3){
Image p = new Image("Peices/Black/0.png");
ImagePattern pat = new ImagePattern(p);
square.setFill(pat);
}
square.widthProperty().bind(root.widthProperty().divide(size));
square.heightProperty().bind(root.heightProperty().divide(size));
square.setOnMouseClicked(e->{
square.setFill(Color.BLUE);
});
}
}
primaryStage.setScene(new Scene(root, 400, 400));
primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
}

Answer 1

I think you are searching for blending which is done with the BlendMode. For example:
Image p = new Image("Peices/Black/0.png");
ImagePattern pat = new ImagePattern(p);
Rectangle r1 = new Rectangle();
r1.setX(50);
r1.setY(50);
r1.setWidth(50);
r1.setHeight(50);
r1.setFill(pat);
Rectangle r = new Rectangle();
r.setX(50);
r.setY(50);
r.setWidth(50);
r.setHeight(50);
r.setFill(Color.BLUE);
r.setBlendMode(BlendMode.ADD);
As far as I know there is no direct way to accomplish this.
Source: https://docs.oracle.com/javase/8/javafx/api/javafx/scene/effect/BlendMode.html

Answer 2

No, you cannot use more than a single fill with a Rectangle. Theoretically you could use a Region with multiple backgrounds, but this is probably a bad idea. Most likely you'll want at least some of the following functionality for the pieces, which will not work, if you do not make pieces their own nodes:
Dragging a piece from one field to another
animating moves
I recommend using a StackPane and put the Board in the background and put a Pane on top of it to place the pieces. Simply use ImageViews for the pieces.
Example:
#Override
public void start(Stage primaryStage) {
GridPane board = new GridPane();
Region[][] fields = new Region[8][8];
for (int i = 0; i < fields.length; i++) {
Region[] flds = fields[i];
for (int j = 0; j < flds.length; j++) {
Region field = new Region();
flds[j] = field;
field.setBackground(new Background(new BackgroundFill((i + j) % 2 == 0 ? Color.WHITE : Color.BLACK, CornerRadii.EMPTY, Insets.EMPTY)));
}
board.addRow(i, flds);
}
// use 1/8 of the size of the Grid for each field
RowConstraints rowConstraints = new RowConstraints();
rowConstraints.setPercentHeight(100d / 8);
ColumnConstraints columnConstraints = new ColumnConstraints();
columnConstraints.setPercentWidth(100d / 8);
for (int i = 0; i < 8; i++) {
board.getColumnConstraints().add(columnConstraints);
board.getRowConstraints().add(rowConstraints);
}
Pane piecePane = new Pane();
StackPane root = new StackPane(board, piecePane);
NumberBinding boardSize = Bindings.min(root.widthProperty(), root.heightProperty());
ImageView queen = new ImageView("https://upload.wikimedia.org/wikipedia/commons/thumb/4/47/Chess_qdt45.svg/480px-Chess_qdt45.svg.png");
DropShadow shadow = new DropShadow(BlurType.GAUSSIAN, Color.WHITE, 2, 1, 0, 0);
// drop shadow for black piece on black field
queen.setEffect(shadow);
// trigger move to topleft field on mouse click
queen.setOnMouseClicked(evt -> {
Node source = (Node) evt.getSource();
TranslateTransition animation = new TranslateTransition(Duration.seconds(0.5), source);
Region targetRegion = fields[0][0];
final PositionChangeListener listener = (PositionChangeListener) source.getUserData();
listener.setField(null);
animation.setByX(targetRegion.getLayoutX() - source.getLayoutX());
animation.setByY(targetRegion.getLayoutY() - source.getLayoutY());
animation.setOnFinished(e -> {
source.setTranslateX(0);
source.setTranslateY(0);
listener.setField(targetRegion);
});
animation.play();
});
PositionChangeListener changeListener = new PositionChangeListener(queen);
queen.setUserData(changeListener);
changeListener.setField(fields[4][3]);
// board size should be as large as possible but at most the min of the parent sizes
board.setPrefSize(Double.MAX_VALUE, Double.MAX_VALUE);
board.maxWidthProperty().bind(boardSize);
board.maxHeightProperty().bind(boardSize);
// same size for piecePane
piecePane.setPrefSize(Double.MAX_VALUE, Double.MAX_VALUE);
piecePane.maxWidthProperty().bind(boardSize);
piecePane.maxHeightProperty().bind(boardSize);
// add piece to piecePane
piecePane.getChildren().add(queen);
Scene scene = new Scene(root, 400, 400);
primaryStage.setScene(scene);
primaryStage.show();
}
private static class PositionChangeListener implements ChangeListener<Bounds> {
private final ImageView piece;
public PositionChangeListener(ImageView piece) {
this.piece = piece;
}
private Region currentField;
public void setField(Region newRegion) {
// register/unregister listeners to bounds changes of associated field
if (currentField != null) {
currentField.boundsInParentProperty().removeListener(this);
}
currentField = newRegion;
if (newRegion != null) {
newRegion.boundsInParentProperty().addListener(this);
changed(null, null, newRegion.getBoundsInParent());
}
}
#Override
public void changed(ObservableValue<? extends Bounds> observable, Bounds oldValue, Bounds newValue) {
// align piece with field
piece.setLayoutX(newValue.getMinX());
piece.setLayoutY(newValue.getMinY());
piece.setFitHeight(newValue.getHeight());
piece.setFitWidth(newValue.getWidth());
}
}