前言
在近期开发的收银台项目中，需要使用打印机进行小票打印，打印流程的时序图如下所示：
在客户的使用过程中，遇到一个问题，如果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，会导致出现小票只打印一半的情况，对此，需要绕过厂商 sdk 使用系统的打印才能够解决这一问题。
在 web 端打印中，需要调用浏览器打印 api 进行网页打印。这意味着，之前后端编写的esc/pos无法复用到，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，这无疑增加了复杂度以及工作量。正打算开始时，得到高人指点。
可以使用 windows api 进行打印
具体参见这篇文档
于是开始这方面的研究，功夫不负有心人，使用 windows api 完成了系统的打印，于是编写这篇文章记录踩过的坑。
首先看看如何进行打印：
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
|
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;} |
在文档中提到，打开打印机时"OpenPrinter"可以传入 null 以使用本地打印服务，因为不知道打印机名称，于是就传入了 null，结果在 StartDocPrinter 时一直提示失败，后来了解到使用 GetLastError 可以查看 error code，得到错误码后一对照，发现是 handle 是无效的，也就意味这 OpenPrinter 这一步骤没有打开需要的打印机。于是尝试使用 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。
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，所以得拿到已经连接了的打印机列表，于是搜索到了 EnumPrinters 这一api，具体用法如下：
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
|
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;} |
通过这一方式，的确获取到了系统中可用的打印机，可是拿到可用的打印机后还是有一个问题：“如何知道哪一个是小票打印机”?
为此又进行了搜索，又找到了一个 api GetDefaultPrinter，用法如下：
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
|
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 ""; }} |
通过此方法获取到系统默认打印机，客户只需要设置默认的打印机为小票打印机就完美解决问题了。
以下是完整代码：
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
|
#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) |
参考：
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
到此这篇关于使用c++调用windows打印api进行打印的示例代码的文章就介绍到这了,更多相关c++ 调用windows打印内容请搜索服务器之家以前的文章或继续浏览下面的相关文章希望大家以后多多支持服务器之家！
原文链接：https://juejin.im/post/5ef729cef265da22f24e52a3
