Python 与 Qt c++ 程序共享内存,传递图片

python 代码

这里Python 使用 shared_memory
QT 使用 QSharedMemory

简单协议：
前面4个字节是 图片with,height,0,0
后面是图片数据

import sys
import struct
def is_little_endian():
    x=0x12345678
    y = struct.pack('I',x)
    return y[0]==0x78

print(f"is_little_endian:{is_little_endian()}")



from multiprocessing import  shared_memory
import numpy as np
from PIL import Image
import matplotlib.pyplot as plt

# 随机颜色 RGBA
def random_color()->tuple:
    rgba = np.random.randint(0,255,size=4)
    return tuple(rgba)

# 用随机数填充像素
def fill_random_pixels(img):
    width, height = img.size
    for x in range(width):
        for y in range(height):
            img.putpixel((x, y), random_color())


if __name__ == "__main__":

    # 选择随机图片或者加载本地图片 
    random_image=False

    img_width = 100
    img_height = 100
    img = Image.new('RGBA', (img_width, img_height))

    if random_image:
        fill_random_pixels(img)
        origin_data = np.array(img)
    else:
        img_path = "C:\\Users\\mingxingwang\\Pictures\\qt-logo.png"
        # 打开图片并转换为numpy数组
        img = Image.open(fp=img_path)
        img = img.convert("RGBA")
        print(f"------------img.size------------:\n{img.size}\n")
        img_width,img_height = img.size
        origin_data = np.array(img)
        
        origin_data = np.insert(origin_data,0,[img_width,img_height,0,0])
        print(f"------------img------------:\n{img}\n")
        print(f"------------origin_data------------:\n{origin_data}\n")
        print(f"------------origin_data.dtype------------:\n{origin_data.dtype}\n")



    #------------- 数据写入共享内存

    # 创建共享内存对象
    shm_a = shared_memory.SharedMemory(create=True, name="my_share_mem",size=origin_data.nbytes)

    #构造关联共享内存的数组
    mem_array = np.ndarray(origin_data.shape, dtype=origin_data.dtype, buffer=shm_a.buf)

    #copy 数据到共享内存
    mem_array[:]=origin_data[:]

    print(f"------------mem_array------------:\n{mem_array}\n")

    #显示原始图片
    origin_image = Image.frombytes(mode='RGBA',size=img.size,data=origin_data)
    plt.imshow(origin_image)
    plt.show()

    #------------- 共享内存获取数据

    existing_shm = shared_memory.SharedMemory(name='my_share_mem')
    array_from_mem = np.ndarray(origin_data.shape, dtype=origin_data.dtype, buffer=existing_shm.buf)
    print(f"------------array_from_mem------------:\n{array_from_mem}\n")

    ##从共享内存构造图片
    img_from_mem = Image.frombytes(mode='RGBA',size=img.size,data=array_from_mem)
    
    ##显示从共享内存获取的图片
    plt.imshow(img_from_mem)
    plt.show()



    shm_a.close()
    shm_a.unlink()

QT 程序

#include 

#include 
#include 
QSharedMemory *sm;
    sm = new QSharedMemory();

	// sm->setKey("my_share_mem");
    /// 与非Qt 程序通信 setNativeKey
    sm->setNativeKey("my_share_mem");
    
    if(!sm->attach())
    {
        qDebug()<<"attach error";
        return;
    }
    qDebug() << "attach success";

    QBuffer buffer;
    QImage image;

    sm->lock();
    buffer.setData((char*)sm->data(),sm->size());
    sm->unlock();
    sm->detach();

    if(!buffer.open(QBuffer::ReadOnly))
    {
        qDebug()<<"open buffer error";
        return;
    }

    // 按照传输协议,获取图片信息
    quint8 img_width , img_height ,other = 0;
    buffer.read((char*)&img_width,1);
    buffer.read((char*)&img_height,1);
    buffer.read((char*)&other,1);
    buffer.read((char*)&other,1);

    qDebug()<<"img_width:"<<img_width<<"img_height:"<<img_height<<"other:"<<other;

    // image bytes = width*height*4 (RGBA8888)
    uint len = img_width*img_height*4;

    uchar *p=(uchar*)buffer.data().data();
    printf("buffer[0]=%d,buffer[1]=%d,buffer[2]=%d,buffer[3]=%d \n",p[0],p[1],p[2],p[3]);
    fflush(stdout);

    //按照协议,从缓冲区构造图片
    image = QImage((uchar*)(p+4),img_width,img_height,QImage::Format_RGBA8888);
    qDebug()<<image;