windows下c++使用ghostscript的api接口静默打印pdf

使用Ghostscript的API接口可以在Windows下实现静默打印PDF文件。Ghostscript是一个开源的PDF处理引擎，它提供了C/C++接口，可以在程序中调用相应的函数实现PDF打印功能。

下面是一个简单的示例代码，演示如何使用Ghostscript的API接口实现静默打印PDF文件：

#include <stdio.h>
#include <windows.h>
#include "gdiplus.h"
#include "gs/gsapi.h"

#pragma comment(lib, "gdiplus.lib")
#pragma comment(lib, "gsdll32.lib")

void print_pdf(const wchar_t* filename, const wchar_t* printer_name)
{
    // 初始化Ghostscript API
    int argc = 3;
    const char* argv[3] = {
        "gsdll32.dll",
        "-dNOPAUSE",
        "-dBATCH"
    };
    GSAPI_HANDLE gs_handle;
    gsapi_new_instance(&gs_handle, NULL);

    // 设置输出打印机
    char printer[256] = { 0 };
    char port[256] = { 0 };
    WideCharToMultiByte(CP_ACP, 0, printer_name, -1, printer, sizeof(printer), NULL, NULL);
    PRINTER_INFO_2* pinfo = NULL;
    DWORD num_printers = 0;
    EnumPrinters(PRINTER_ENUM_LOCAL, NULL, 2, NULL, 0, &num_printers, NULL);
    pinfo = (PRINTER_INFO_2*)malloc(num_printers * sizeof(PRINTER_INFO_2));
    EnumPrinters(PRINTER_ENUM_LOCAL, NULL, 2, (LPBYTE)pinfo, num_printers * sizeof(PRINTER_INFO_2), &num_printers, NULL);
    for (DWORD i = 0; i < num_printers; ++i) {
        if (strcmp(pinfo[i].pPrinterName, printer) == 0) {
            sprintf_s(port, sizeof(port), "%s", pinfo[i].pPortName);
            break;
        }
    }
    free(pinfo);
    gsapi_set_arg_encoding(gs_handle, GS_ARG_ENCODING_UTF8);
    gsapi_set_stdio(gs_handle, NULL, NULL, NULL);
    gsapi_init_with_args(gs_handle, argc, (char**)argv);
    gsapi_set_arg_encoding(gs_handle, GS_ARG_ENCODING_UTF8);
    gsapi_set_stdio(gs_handle, NULL, NULL, NULL);
    gsapi_set_poll(gs_handle, NULL);
    gsapi_set_display_callback(gs_handle, NULL);
    gsapi_set_stdin(gs_handle, NULL);
    gsapi_set_stdout(gs_handle, NULL);

    // 打印PDF文件
    wchar_t command[1024] = { 0 };
    swprintf_s(command, sizeof(command), L"-dPrinted -dBATCH -dNOPAUSE -dNOSAFER -q -dNumCopies=1 -sDEVICE=mswinpr2 -sOutputFile=\"%%printer%s\" \"%s\"", port, filename);
    char* argv2[64] = { 0 };
    int argc2 = 0;
    const wchar_t* p = command;
    while (*p) {
        argv2[argc2++] = (char*)p;
        while (*p && !iswspace(*p))
            p++;
        if (*p)
            *p++ = 0;
    }
    gsapi_exit(gs_handle);
    gsapi_delete_instance(gs_handle);
}

int main()
{
    Gdiplus::GdiplusStartupInput gdiplusStartupInput;
    ULONG_PTR gdiplusToken;
    Gdiplus::GdiplusStartup(&gdiplusToken, &gdiplusStartupInput, NULL);

    wchar_t filename[] = L"C:\\test.pdf";
    wchar_t printer_name[] = L"Microsoft Print to PDF";
    print_pdf(filename, printer_name);

    Gdiplus::GdiplusShutdown(gdiplusToken);
    return 0;
}

需要注意的是，使用Ghostscript打印PDF文件需要确保Ghostscript已经正确安装并设置好环境变量。另外，在打印PDF文件前，需要先通过Ghostscript API初始化Ghostscript引擎，并设置输出打印机等参数。最后，调用Ghostscript API打印PDF文件即可。