如何在ggplot中高亮显示曲线上的点

library(ggplot2)

df <- data.frame(x = c(1, 2, 3, 4, 5),
                 y = c(2, 4, 6, 8, 10),
                 highlight_x = c(2, 4),
                 highlight_y = c(4, 8))

p <- ggplot(data = df, aes(x = x, y = y))

p <- p + geom_line()

p <- p + geom_point(data = df, aes(x = highlight_x, y = highlight_y), color = "red", size = 3)

p <- p + labs(title = "曲线图", x = "X轴", y = "Y轴")

print(p)