Datalogic .NET SDK
PostRequestMsgEx (Method)
Syntax
public int PostRequestMsgEx(DecodeRequest reqType, MessageWindow wnd, uint uDataMsg, uint uTimeoutMsg);
Description
Posts a request for data from a decoding device. The method will return immediately, and post a message to the specified window when either the request is fulfilled or the scan times out.
Parameters Table
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|
Type |
Parameter |
Description |
|
[in] |
DecodeRequest |
reqType |
Type of request being posted. It is a logical OR'ing of any of the values. |
|
[in] |
MessageWindow |
wnd |
A reference to an instance of the Microsoft.WindowsCE.Forms.MessageWindow class whose window procedure is to receive a message when the request is fulfilled. |
|
[in] |
uint |
uDataMsg |
Specifies the message to be posted when the request is fulfilled. This should be a value of WM_USER (defined in winuser.h) or higher. |
|
[in] |
uint |
uTimeoutMsg |
Specifies the message to be posted if the scan times out before the request is fulfilled. This should be a value of WM_USER (defined in winuser.h) or higher. |
|
|
|
|
|
|
[return] |
int |
|
On success, a request ID is returned. This should be used in a subsequent call Datalogic.API.DecodeHandle.ReadString and/or Datalogic.API.DecodeHandle.CancelRequest. |
|
[on error] |
-1 |
- |
Example
This example shows the noteworthy code lines to rise and manage a Request message: the message is sent to a customized MessageWindows that is able to manage our custom message (see WM_SCANNED) adding functionalities to WinProc method of standard MessageWindow Class.
(See Example page for the complete and executable example)
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// Standard using ... using Microsoft.WindowsCE.Forms; using Datalogic.API;
namespace Example { public class MainDlg : System.Windows.Forms.Form { // Private variables used for our sample private WndMessageWindow wndMsg; private DecodeHandle hDcd; private int reqID; // Other...
public MainDlg() { /*...*/ }
private void MainDlg_Load(object sender, System.EventArgs e) { try { hDcd = new DecodeHandle(DecodeDeviceCap.Exists | DecodeDeviceCap.Barcode); }catch(DecodeException){ /*...*/ }
DecodeRequest reqType = (DecodeRequest)1 | DecodeRequest.PostRecurring;
reqID = hDcd.PostRequestMsgEx(reqType, wndMsg, Constants.WM_SCANNED, Constants.WM_TIMEOUT); }
/* Other methods and settings ...*/ // ... public class WndMessageWindow : MessageWindow { // Reference to the window we will subclass. private MainDlg dlgParent;
public WndMessageWindow(MainDlg frm) { this.dlgParent = frm; } protected override void WndProc(ref Message msg) { switch(msg.Msg) { case Constants.WM_SCANNED: // Action to be performed ... break; case Constants.WM_TIMEOUT: // Action to be performed ... break;
} base.WndProc(ref msg); } } internal sealed class Constants { public const int WM_APP = 0x8000; public const int WM_SCANNED = WM_APP + 1; public const int WM_TIMEOUT = WM_APP + 2; } } |
See Also
DecodeHandle.ReadString (Method), DecodeRequest (Enum), Microsoft.WindowsCE.Forms.MessageWindow, WM_USER, DecodeHandle.CancelRequest (Method), Example #016.
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