import javafx.application.Application;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.canvas.Canvas;
import javafx.scene.canvas.GraphicsContext;
import javafx.stage.Stage;
import javafx.scene.paint.Color;

public class Gradation1 extends Application {
    public void start(Stage stage) {
        stage.setTitle("グラデーション");

        final Canvas canvas = new Canvas(256, 40);
        GraphicsContext gc = canvas.getGraphicsContext2D();

        int scale = 4;
        int i;

        for (i = 0; i < 64; i++) {
            gc.setFill(new Color((i * 4) / 255.0, 0, (255 - i * 4) / 255.0, 1));
            gc.fillRect(i * scale, 0, scale, scale * 10);
        }

        Group root = new Group();
        root.getChildren().addAll(canvas);
        Scene scene = new Scene(root);
        stage.setScene(scene);
        stage.show();
    }

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