Lineargradient for Line in javafx - javafx

Question

How can I use lineargradient for Line in Javafx?
I tried this:
LinearGradient lg = new LinearGradient(...);
line.setFill(lg);
....
It doesn't work.

Answer 1

Based on this answer, you need to specify the gradient on absolute coordinates.
Something like this will work for any given ones:
LinearGradient linearGradient = new LinearGradient(x1, y1, x2, y2, false, CycleMethod.REFLECT, new Stop(0,Color.RED),new Stop(1,Color.GREEN));
line.setStroke(linearGradient);
Based on this answer, you can create a simple app to test it how it works when you move the anchor nodes around the scene:
private final DoubleProperty x1 = new SimpleDoubleProperty();
public final double getX1() { return x1.get(); }
public final void setX1(double value) { x1.set(value); }
public final DoubleProperty x1Property() { return x1; }
private final DoubleProperty x2 = new SimpleDoubleProperty();
public final double getX2() { return x2.get(); }
public final void setX2(double value) { x2.set(value); }
public final DoubleProperty x2Property() { return x2; }
private final DoubleProperty y1 = new SimpleDoubleProperty();
public final double getY1() { return y1.get(); }
public final void setY1(double value) { y1.set(value); }
public final DoubleProperty y1Property() { return y1; }
private final DoubleProperty y2 = new SimpleDoubleProperty();
public final double getY2() { return y2.get(); }
public final void setY2(double value) { y2.set(value); }
public final DoubleProperty y2Property() { return y2; }
private Line line;
#Override
public void start(Stage primaryStage) {
Group group = new Group();
primaryStage.setScene(new Scene(group, 400, 400));
x1.set(100);
y1.set(50);
x2.set(200);
y2.set(300);
line = new Line(x1.get(), y1.get(), x2.get(), y2.get());
line.startXProperty().bind(x1);
line.startYProperty().bind(y1);
line.endXProperty().bind(x2);
line.endYProperty().bind(y2);
line.setStrokeWidth(12);
line.setMouseTransparent(true);
Anchor start = new Anchor(Color.BLUE, x1, y1);
Anchor end = new Anchor(Color.YELLOW, x2, y2);
group.getChildren().setAll(line, start, end);
x1Property().addListener(o -> updateLine());
x2Property().addListener(o -> updateLine());
y1Property().addListener(o -> updateLine());
y2Property().addListener(o -> updateLine());
updateLine();
primaryStage.show();
}
private void updateLine() {
LinearGradient linearGradient = new LinearGradient(x1.get(), y1.get(), x2.get(), y2.get(), false, CycleMethod.REFLECT, new Stop(0,Color.RED),new Stop(1,Color.GREEN));
line.setStroke(linearGradient);
}
private class Anchor extends Circle {
Anchor(Color color, DoubleProperty x, DoubleProperty y) {
super(x.get(), y.get(), 10);
setFill(color.deriveColor(1, 1, 1, 0.5));
setStroke(color);
setStrokeWidth(2);
setStrokeType(StrokeType.OUTSIDE);
x.bind(centerXProperty());
y.bind(centerYProperty());
enableDrag();
}
// make a node movable by dragging it around with the mouse.
private void enableDrag() {
final Delta dragDelta = new Delta();
setOnMousePressed(mouseEvent -> {
// record a delta distance for the drag and drop operation.
dragDelta.x = getCenterX() - mouseEvent.getX();
dragDelta.y = getCenterY() - mouseEvent.getY();
getScene().setCursor(Cursor.MOVE);
});
setOnMouseReleased(mouseEvent -> {
getScene().setCursor(Cursor.HAND);
});
setOnMouseDragged(mouseEvent -> {
double newX = mouseEvent.getX() + dragDelta.x;
if (newX > 0 && newX < getScene().getWidth()) {
setCenterX(newX);
}
double newY = mouseEvent.getY() + dragDelta.y;
if (newY > 0 && newY < getScene().getHeight()) {
setCenterY(newY);
}
});
setOnMouseEntered(mouseEvent -> {
if (!mouseEvent.isPrimaryButtonDown()) {
getScene().setCursor(Cursor.HAND);
}
});
setOnMouseExited(mouseEvent -> {
if (!mouseEvent.isPrimaryButtonDown()) {
getScene().setCursor(Cursor.DEFAULT);
}
});
}
// records relative x and y co-ordinates.
private class Delta { double x, y; }
}

Answer 2

Use this
line.setStyle("-fx-background-color: linear-gradient(to right, #color_1, #color_2);");