使用 c++ 调用 windows 打印 api 进行打印

时间 2020-07-06

标签使用 c++ 调用 windows 打印 api 进行栏目 C&C++ 繁體版

原文原文链接

前言

在近期开发的收银台项目中，须要使用打印机进行小票打印，打印流程的时序图以下所示：css

在客户的使用过程当中，遇到一个问题，若是机器安装了打印机驱动，那么调用厂商提供的 sdk 进行打印的话，会致使出现小票只打印一半的状况，对此，须要绕过厂商 sdk 使用系统的打印才可以解决这一问题。html

在 web 端打印中，须要调用浏览器打印 api 进行网页打印。这意味着，以前后端编写的esc/pos没法复用到，同时，前端还得花费精力来编写 html 以及css 来完成打印内容的排版，这无疑增长了复杂度以及工做量。正打算开始时，获得高人指点。前端

可使用 windows api 进行打印node

具体参见这篇文档ios

因而开始这方面的研究，功夫不负有心人，使用 windows api 完成了系统的打印，因而编写这篇文章记录踩过的坑。c++

首先看看如何进行打印：web

BOOL RawDataToPrinter(LPSTR szPrinterName, LPBYTE lpData, DWORD dwCount) {
    HANDLE     hPrinter;
    DOC_INFO_1 DocInfo;
    DWORD      dwJob;
    DWORD      dwBytesWritten;

    // Need a handle to the printer.
    if (!OpenPrinter(szPrinterName, &hPrinter, NULL)) {
        int y = GetLastError();
        cout << "openFail" << y << endl;
        return FALSE;
    }

    // Fill in the structure with info about this "document."

    DocInfo.pDocName = LPSTR("My Document\0");
    DocInfo.pOutputFile = NULL;
    DocInfo.pDatatype = NULL; // LPWSTR("RAW\0");
    // Inform the spooler the document is beginning.
    if ((dwJob = StartDocPrinter(hPrinter, 1, (LPBYTE)&DocInfo)) == 0)
    {
        int x = GetLastError();
        cout << "StartDocPrinter Fail" << x << endl;
        ClosePrinter(hPrinter);
        return FALSE;
    }
    // Start a page.
    if (!StartPagePrinter(hPrinter))
    {
        EndDocPrinter(hPrinter);
        ClosePrinter(hPrinter);
        return FALSE;
    }
    // Send the data to the printer.
    if (!WritePrinter(hPrinter, lpData, dwCount, &dwBytesWritten))
    {
        EndPagePrinter(hPrinter);
        EndDocPrinter(hPrinter);
        ClosePrinter(hPrinter);
        return FALSE;
    }
    // End the page.
    if (!EndPagePrinter(hPrinter))
    {
        EndDocPrinter(hPrinter);
        ClosePrinter(hPrinter);
        return FALSE;
    }
    // Inform the spooler that the document is ending.
    if (!EndDocPrinter(hPrinter))
    {
        ClosePrinter(hPrinter);
        return FALSE;
    }
    // Tidy up the printer handle.
    ClosePrinter(hPrinter);
    // Check to see if correct number of bytes were written.
    if (dwBytesWritten != dwCount)
        return FALSE;
    return TRUE;
}
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在文档中提到，打开打印机时"OpenPrinter"能够传入 null 以使用本地打印服务，由于不知道打印机名称，因而就传入了 null，结果在 StartDocPrinter 时一直提示失败，后来了解到使用 GetLastError 能够查看 error code，获得错误码后一对照，发现是 handle 是无效的，也就意味这 OpenPrinter 这一步骤没有打开须要的打印机。因而尝试使用设备与打印机中的打印机名称，还真就连上了，成功调用打印服务。windows

但客户电脑上的打印机名称是不固定的，不能使用固定打印机名称，因此得拿到已经链接了的打印机列表，因而搜索到了 EnumPrinters 这一api，具体用法以下：后端

void getPrinterList() {
    PRINTER_INFO_2* printerList;
    unsigned char size;
    unsigned long pcbNeeded;
    unsigned long pcReturned;

    EnumPrinters(PRINTER_ENUM_LOCAL, NULL, 2, NULL, 0, &pcbNeeded, &pcReturned);

    if ((printerList = (PRINTER_INFO_2*)malloc(pcbNeeded)) == 0) {
        return;
    }

    if (!EnumPrinters(PRINTER_ENUM_LOCAL, NULL, 2, (LPBYTE)printerList, pcbNeeded, &pcbNeeded, &pcReturned)) {
        free(printerList);
        return;
    }

    for (int i = 0; i < (int)pcReturned; i++) {

        string printName(printerList[i].pPrinterName);
        if (printerList[i].Attributes & PRINTER_ATTRIBUTE_NETWORK) {
            cout << "网络打印机" << printName << endl;
        }
        else {
            cout << "本地打印机" << printName << endl;
        }
    }

    cout << "number " << pcReturned << endl;

}
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经过这一方式，的确获取到了系统中可用的打印机，但是拿到可用的打印机后仍是有一个问题：“如何知道哪个是小票打印机”?api

为此又进行了搜索，又找到了一个 api GetDefaultPrinter，用法以下：

string getDefaultPrinterName() {
    DWORD size = 0;
    GetDefaultPrinter(NULL, &size);

    if (size) {
        TCHAR* buffer = new TCHAR[size];
        GetDefaultPrinter(buffer, &size);
        string printerName(buffer);
        return printerName;
    }
    else {
        return "";
    }
}
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经过此方法获取到系统默认打印机，客户只须要设置默认的打印机为小票打印机就完美解决问题了。

如下是完整代码：

#include <iostream>
#include <windows.h>
#include "node.h"
#include "base64.h"

using namespace std;
using v8::FunctionCallbackInfo;
using v8::Isolate;
using v8::Local;
using v8::NewStringType;
using v8::Object;
using v8::String;
using v8::Value;
using v8::Integer;
using v8::Int8Array;

BOOL RawDataToPrinter(LPSTR szPrinterName, LPBYTE lpData, DWORD dwCount);
string getDefaultPrinterName();

void localPrintRawData(const FunctionCallbackInfo<Value>& args) {
    Isolate* isolate = args.GetIsolate();
    Local<v8::Context> context = isolate->GetCurrentContext();
    v8::String::Utf8Value portString(isolate, args[0]);
    std::string base64Str(*portString);

    vector<BYTE> bytes = base64_decode(base64Str);
    char* buffer = new char[bytes.size()];
    copy(bytes.begin(), bytes.end(), buffer);
    string printerName = getDefaultPrinterName();
    if (printerName.size() > 0) {
        printerName += "\0";
        wstring ws(printerName.begin(), printerName.end());
        RawDataToPrinter(const_cast<char*>(printerName.c_str()), &bytes[0], bytes.size());
    }
    else {
        cout << "no printer" << endl;
    }
}

BOOL RawDataToPrinter(LPSTR szPrinterName, LPBYTE lpData, DWORD dwCount)
{
    HANDLE     hPrinter;
    DOC_INFO_1 DocInfo;
    DWORD      dwJob;
    DWORD      dwBytesWritten;

    // Need a handle to the printer.
    if (!OpenPrinter(szPrinterName, &hPrinter, NULL)) {
        int y = GetLastError();
        cout << "openFial" << y << endl;
        return FALSE;
    }

    // Fill in the structure with info about this "document."

    DocInfo.pDocName = LPSTR("My Document\0");
    DocInfo.pOutputFile = NULL;
    DocInfo.pDatatype = NULL; // LPWSTR("RAW\0");
    // Inform the spooler the document is beginning.
    if ((dwJob = StartDocPrinter(hPrinter, 1, (LPBYTE)&DocInfo)) == 0)
    {
        int x = GetLastError();
        cout << "StartDocPrinter Fial" << x << endl;
        ClosePrinter(hPrinter);
        return FALSE;
    }
    // Start a page.
    if (!StartPagePrinter(hPrinter))
    {
        EndDocPrinter(hPrinter);
        ClosePrinter(hPrinter);
        return FALSE;
    }
    // Send the data to the printer.
    if (!WritePrinter(hPrinter, lpData, dwCount, &dwBytesWritten))
    {
        EndPagePrinter(hPrinter);
        EndDocPrinter(hPrinter);
        ClosePrinter(hPrinter);
        return FALSE;
    }
    // End the page.
    if (!EndPagePrinter(hPrinter))
    {
        EndDocPrinter(hPrinter);
        ClosePrinter(hPrinter);
        return FALSE;
    }
    // Inform the spooler that the document is ending.
    if (!EndDocPrinter(hPrinter))
    {
        ClosePrinter(hPrinter);
        return FALSE;
    }
    // Tidy up the printer handle.
    ClosePrinter(hPrinter);
    // Check to see if correct number of bytes were written.
    if (dwBytesWritten != dwCount)
        return FALSE;
    return TRUE;
}

void getPrinterList() {
    PRINTER_INFO_2* printerList;
    unsigned char size;
    unsigned long pcbNeeded;
    unsigned long pcReturned;

    EnumPrinters(PRINTER_ENUM_LOCAL, NULL, 2, NULL, 0, &pcbNeeded, &pcReturned);

    if ((printerList = (PRINTER_INFO_2*)malloc(pcbNeeded)) == 0) {
        return;
    }

    if (!EnumPrinters(PRINTER_ENUM_LOCAL, NULL, 2, (LPBYTE)printerList, pcbNeeded, &pcbNeeded, &pcReturned)) {
        free(printerList);
        return;
    }

    for (int i = 0; i < (int)pcReturned; i++) {

        string printName(printerList[i].pPrinterName);
        if (printerList[i].Attributes & PRINTER_ATTRIBUTE_NETWORK) {
            cout << "网络打印机" << printName << endl;
        }
        else {
            cout << "本地打印机" << printName << endl;
        }
    }

    cout << "number " << pcReturned << endl;

}

string getDefaultPrinterName() {
    DWORD size = 0;
    GetDefaultPrinter(NULL, &size);

    if (size) {
        TCHAR* buffer = new TCHAR[size];
        GetDefaultPrinter(buffer, &size);
        string printerName(buffer);
        return printerName;
    }
    else {
        return "";
    }
}

void Initialize(Local<Object> exports) {
    NODE_SET_METHOD(exports, "localPrintRawData", localPrintRawData);
}

NODE_MODULE(zq_device, Initialize)
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参考：

support.microsoft.com/zh-cn/help/…

docs.microsoft.com/en-us/windo…

stackoverflow.com/questions/6…

social.msdn.microsoft.com/Forums/wind…

social.msdn.microsoft.com/Forums/vstu…

docs.microsoft.com/en-us/windo…

docs.microsoft.com/zh-cn/windo…