如何在VB6中检测打印机是否支持ESC/P 2？

在VB6中检测打印机是否支持ESC/P 2，可通过以下几种实用方法实现：

1. 读取打印机设备标识信息 #

通过Windows API获取打印机的设备描述或型号字符串，检查其中是否包含"ESC/P2"、"ESCP2"这类关键词——大部分支持该协议的打印机会在设备信息中明确标注。

示例代码：

Private Declare Function GetPrinter Lib "winspool.drv" Alias "GetPrinterA" (ByVal hPrinter As Long, ByVal Level As Long, pPrinter As Byte, ByVal cbBuf As Long, pcbNeeded As Long) As Long
Private Declare Function OpenPrinter Lib "winspool.drv" Alias "OpenPrinterA" (ByVal pPrinterName As String, phPrinter As Long, pDefault As Any) As Long
Private Declare Function ClosePrinter Lib "winspool.drv" (ByVal hPrinter As Long) As Long

Public Function CheckESCP2ByDeviceInfo(printerName As String) As Boolean
    Dim hPrinter As Long
    Dim cbNeeded As Long
    Dim pPrinterInfo() As Byte
    Dim printerInfo As String
    
    If OpenPrinter(printerName, hPrinter, ByVal 0&) = 0 Then Exit Function
    
    ' 获取所需缓冲区大小
    GetPrinter hPrinter, 2, ByVal 0&, 0, cbNeeded
    ReDim pPrinterInfo(cbNeeded - 1)
    
    If GetPrinter(hPrinter, 2, pPrinterInfo(0), cbNeeded, cbNeeded) Then
        ' 提取设备描述信息
        printerInfo = StrConv(pPrinterInfo, vbUnicode)
        ' 检查是否包含ESC/P2相关关键词
        If InStr(1, printerInfo, "ESC/P2", vbTextCompare) > 0 Or InStr(1, printerInfo, "ESCP2", vbTextCompare) > 0 Then
            CheckESCP2ByDeviceInfo = True
        End If
    End If
    
    ClosePrinter hPrinter
End Function

2. 发送ESC/P2专属测试指令并验证响应 #

发送ESC/P2协议定义的查询指令，读取打印机返回的响应，判断是否符合该协议格式。常用测试指令为ESC ? 1（十六进制：1B 3F 31），支持ESC/P2的打印机会返回特定格式的响应数据。

示例代码（针对并口打印机）：

Public Function CheckESCP2ByTestCmd(printerPort As String) As Boolean
    Dim cmd As String
    Dim response As String
    Dim fileNum As Integer
    
    On Error GoTo ErrorHandler
    fileNum = FreeFile()
    ' 打开打印机端口
    Open printerPort For Binary Access Read Write As #fileNum
    
    ' 发送ESC/P2查询指令
    cmd = Chr(&H1B) & "?1"
    Put #fileNum, , cmd
    
    ' 读取响应（根据打印机差异调整读取长度）
    response = String(10, Chr(0))
    Get #fileNum, , response
    
    ' 检查响应是否符合ESC/P2格式特征
    If Left(response, 1) = Chr(&H1B) Then
        CheckESCP2ByTestCmd = True
    End If
    
ErrorHandler:
    Close #fileNum
End Function

如果是USB打印机，需使用CreateFile API打开打印机设备路径，原理与上述一致，仅端口打开方式不同。

3. 检查打印机驱动属性 #

部分打印机驱动会在属性中明确标注支持的打印语言，你可以通过VB6调用API读取驱动扩展属性，或引导用户在控制面板的打印机属性“高级”选项卡下，查看“打印处理器”或“打印语言”设置。

内容的提问来源于stack exchange，提问作者ruby.lee