一个HTML5_Canvas练手程序，用Canvas标签绘制简单的动画效果：模拟十字路口绿灯亮，车走；红灯亮，车停效果，动画效果比较粗糙，供入门者参考。HTML5程序，目前暂不支持IE。-A practiced hand HTML5_Canvas program, Canvas tag draw simple animation effects: Analog crossroads green light, the car go red light, the car stopped effec