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

public class SimplePutArgb extends Application {
    @Override
    public void start(Stage stage) {
        Canvas cv = new Canvas(300, 300);
        GraphicsContext gc = cv.getGraphicsContext2D();
        gc.setFill(Color.rgb(255, 0, 0, 0.5));
        gc.fillRect(50, 25, 50, 250);
        gc.setFill(Color.rgb(0, 0, 255, 0.5));
        gc.fillRect(25, 125, 100, 50);
        gc.getPixelWriter().setArgb(150, 150, 0xff00ff00);
        gc.setFill(Color.rgb(255, 0, 0, 0.5));
        gc.fillRect(200, 25, 50, 250);
        gc.setFill(Color.rgb(0, 0, 255, 0.5));
        gc.fillRect(175, 125, 100, 50);
        
        Scene scene = new Scene(new Group(cv));
        stage.setScene(scene);
        stage.show();
    }
}