使用c++呼叫windows列印api進行列印的示例程式碼
前言
在近期開發的收銀臺專案中，需要使用印表機進行小票列印，列印流程的時序圖如下所示：
在客戶的使用過程中，遇到一個問題，如果機器安裝了印表機驅動，那麼呼叫廠商提供的 sdk 進行列印的話，會導致出現小票只打印一半的情況，對此，需要繞過廠商 sdk 使用系統的列印才能夠解決這一問題。
在 web 端列印中，需要呼叫瀏覽器列印 api 進行網頁列印。這意味著，之前後端編寫的esc/pos無法複用到，同時，前端還得花費精力來編寫 html 以及css 來完成列印內容的排版，這無疑增加了複雜度以及工作量。正打算開始時，得到高人指點。
可以使用 windows api 進行列印
具體參見這篇文件
於是開始這方面的研究，功夫不負有心人，使用 windows api 完成了系統的列印，於是編寫這篇文章記錄踩過的坑。
首先看看如何進行列印：
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;
}在文件中提到，開啟印表機時"OpenPrinter"可以傳入 null 以使用本地列印服務，因為不知道印表機名稱，於是就傳入了 null，結果在 StartDocPrinter 時一直提示失敗，後來瞭解到使用 GetLastError 可以檢視 error code，得到錯誤碼後一對照，發現是 handle 是無效的，也就意味這 OpenPrinter 這一步驟沒有開啟需要的印表機。於是嘗試使用 裝置與印表機中的印表機名稱，還真就連上了，成功呼叫列印服務。
但客戶電腦上的印表機名稱是不固定的，不能使用固定印表機名稱，所以得拿到已經連線了的印表機列表，於是搜尋到了 EnumPrinters 這一api，具體用法如下：
void getPrinterList() {
PRINTER_INFO_2* printerList;
unsigned char size;
unsigned long pcbNeeded;
unsigned long pcReturned;
EnumPrinters(PRINTER_ENUM_LOCAL,NULL,2,&pcbNeeded,&pcReturned);
if ((printerList = (PRINTER_INFO_2*)malloc(pcbNeeded)) == 0) {
return;
}
if (!EnumPrinters(PRINTER_ENUM_LOCAL,(LPBYTE)printerList,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 << "網路印表機" << printName << endl;
}
else {
cout << "本地印表機" << printName << endl;
}
}
cout << "number " << pcReturned << endl;
}
通過這一方式，的確獲取到了系統中可用的印表機，可是拿到可用的印表機後還是有一個問題：“如何知道哪一個是小票印表機”?
為此又進行了搜尋，又找到了一個 api GetDefaultPrinter，用法如下：
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 "";
}
}
通過此方法獲取到系統預設印表機，客戶只需要設定預設的印表機為小票印表機就完美解決問題了。
以下是完整程式碼：
#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,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,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,(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,&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,&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 << "網路印表機" << printName << endl;
}
else {
cout << "本地印表機" << printName << endl;
}
}
cout << "number " << pcReturned << endl;
}
string getDefaultPrinterName() {
DWORD size = 0;
GetDefaultPrinter(NULL,&size);
string printerName(buffer);
return printerName;
}
else {
return "";
}
}
void Initialize(Local<Object> exports) {
NODE_SET_METHOD(exports,"localPrintRawData",localPrintRawData);
}
NODE_MODULE(zq_device,Initialize)
參考：
https://support.microsoft.com/zh-cn/help/138594/howto-send-raw-data-to-a-printer-by-using-the-win32-api
https://docs.microsoft.com/en-us/windows/win32/printdocs/openprinter
https://stackoverflow.com/questions/6682286/understanding-a-c-sample-printers-handles-strings
https://social.msdn.microsoft.com/Forums/windowsdesktop/en-US/a27c6615-9452-44b1-90fc-9b91b15f0e50/openprinter-returing-errorinvalidprintername1801-when-called-with?forum=windowsgeneraldevelopmentissues
https://social.msdn.microsoft.com/Forums/vstudio/en-US/de7c55a1-ae63-49c9-a87a-fe3bf32822e4/how-to-use-the-enumprinters-function-to-be-able-to-classify-installed-printers-into-quot-network?forum=vclanguage
https://docs.microsoft.com/en-us/windows/win32/debug/system-error-codes--0-499-
https://docs.microsoft.com/zh-cn/windows/win32/debug/system-error-codes--1700-3999-?redirectedfrom=MSDN
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