Lectura y escritura de imágenes

# 演示大图片文件的读写操作

# 多线程
import threading

# 原图片路径
PIC_LOCATION = "E:/python重新学习/python核心编程/文件读写/picture.jpg"
# 待写入的图片路径
WRITE_LOCATION = "E:/python重新学习/python核心编程/文件读写/picture_6666.jpg"

# 读文件的次数
READ_PIC_COUNT = 0
# 写文件的次数
WRITE_PIC_COUNT = 0
# 图片数据
PIC_DATA = None


def read_pic():
    """读取指定图片"""
    global READ_PIC_COUNT
    global WRITE_PIC_COUNT
    global PIC_DATA
    with open(PIC_LOCATION, "rb") as pic_file:

        while True:
            # 当读的次数 等于 写的次数 时
            if (READ_PIC_COUNT == WRITE_PIC_COUNT) and (PIC_DATA is not None):
                # 每次读取10kb数据
                PIC_DATA = pic_file.read(10240)
                # 读操作+1
                READ_PIC_COUNT += 1
                print("当前读操作+1:[{}], 写操作:[{}]".format(READ_PIC_COUNT, WRITE_PIC_COUNT))

            # 初始化读取数据
            if PIC_DATA is None:
                # 每次读取10kb数据
                PIC_DATA = pic_file.read(10240)
                # 读操作+1
                READ_PIC_COUNT += 1
                print("当前读操作+1:[{}], 写操作:[{}]".format(READ_PIC_COUNT, WRITE_PIC_COUNT))

            # 当图片的数据为空字节时, 退出循环
            if PIC_DATA == b'':
                break


def write_pic():
    """将数据写到指定图片"""
    global WRITE_PIC_COUNT
    global READ_PIC_COUNT
    global PIC_DATA
    with open(WRITE_LOCATION, "wb") as pic_file:
        while True:
            # 当图片的数据为空字节时, 退出循环
            if PIC_DATA == b'':
                break
            # 当图片数据不为空 并且 读的次数大于1次 写次数 时
            if (PIC_DATA is not None) and ((READ_PIC_COUNT - WRITE_PIC_COUNT) == 1):
                # 将数据写入图片
                pic_file.write(PIC_DATA)
                # 写次数+1
                WRITE_PIC_COUNT += 1
                print("当前读操作:[{}], 写操作+1:[{}]".format(READ_PIC_COUNT, WRITE_PIC_COUNT))


def main():
    # 创建线程
    thread_read = threading.Thread(target=read_pic)
    thread_write = threading.Thread(target=write_pic)

    # 启动线程
    thread_read.start()
    thread_write.start()

    # 等待线程运行结束
    thread_read.join()
    thread_write.join()


if __name__ == '__main__':
    main()