Describe
A simple example of calling this exe in C++.
Effect
Tried to find the DPI of a JPG in Qt, but have trouble getting the right DPI value by using QImage. The same problem as mentioned in this link. So I am using Pillow library in python to get the correct dpi. Then turn python code into stand-alone executables by using Pyinstaller library in Python. Finally, call the .exe with C++ code.
Python Code
import sys
from PIL import Image
image_path = sys.argv[0]
with Image.open(image_path) as img:
dpi = img.info.get('dpi')
sys.stdout = open("output.txt", "w") #write the result to output.txt
print(dpi)
sys.exit(1)
C++ Code
#include <iostream>
#include <string>
#include <windows.h>
#include <tchar.h>
int main()
{
// modified it to your exe path
TCHAR exePath[] = _T("C:\\Users\\main.exe");
// modified it to your JPG path
TCHAR cmd[] = _T("C:\\Users\\1.JPG");
// Create a process and pass arguments
STARTUPINFO si;
PROCESS_INFORMATION pi;
ZeroMemory(&si, sizeof(si));
si.cb = sizeof(si);
ZeroMemory(&pi, sizeof(pi));
if (!CreateProcess(
exePath, //Path of the called-exe
cmd, //cmd arguments
NULL,
NULL,
FALSE,
0,
NULL,
NULL,
&si,
&pi))
{
std::cout << "Error: CreateProcess failed!" << std::endl;
return -1;
}
// Wait for process to end
WaitForSingleObject(pi.hProcess, INFINITE);
// the return code of exe
DWORD exitCode;
GetExitCodeProcess(pi.hProcess, &exitCode);
CloseHandle(pi.hThread);
CloseHandle(pi.hProcess);
std::cout << "Return value: " << exitCode << std::endl;
return 0;
}
Summarize
It is not cost-effective to creating a new process and the Python exe is almost 10M. I wouldn’t consider this is a practical solution.
