JVCL Help:TJvHidDeviceController.CheckOutByCallback

 JVCL Help: TJvHidDeviceController.CheckOutByCallback Method

TJvHidDeviceController

► TJvHidDeviceController Events

[+] TJvHidDeviceController Events

► TJvHidDeviceController Methods

[+] TJvHidDeviceController Methods

► TJvHidDeviceController Properties

[+] TJvHidDeviceController Properties

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Summary

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Pascal

 functionCheckOutByCallback(varHidDev: TJvHidDevice; Check: TJvHidCheckCallback): Boolean;

Parameters

Parameters	Description
var HidDev: TJvHidDevice	JvHidDevice-Object which matches the search criteria of the callback function.
Check: TJvHidCheckCallback	Address of function which will be called by Windows to check the matching criteria.

Return Value

True: A HID device which matches the search criteria has been found and HidDev is valid.

False: No HID device found, HidDev is invalid.

Description

Checks out ("reserves") a hid-device which matches the given criteria. The criteria are defined by the programmer.

Example:

interface
  uses JvHidControllerClass;

TMyController = class(TObject)
  private
  HidController : TJvHidDeviceController; // HID-Controller-Object = interface to hardware
  HidDev        : TJvHidDevice;
  (...)

  public
  constructor Create(const IniFileName: string); // IOW-Controller-Objekt anlegen
  (...)
end;

var
  MyController: TMyController; // Controller-Object which does important tasks :-)

implementation

constructor TMyController.Create(const IniFileName: string);
  (...)
  HidController := TJvHidDeviceController.Create(nil);
  // define event function
  HidController.OnDeviceChange := HidControllerDeviceChange; // the event will automatically be activated
  (..)
end;

procedure TMyController.HidControllerDeviceChange(Sender: TObject);
  // Search for all HID-devices with 
end;

function FindMyDevice(AHidDev: TJvHidDevice): Boolean; stdcall;
begin
  Result := (AHidDev.Attributes.VendorID = MY_VENDOR_ID) and
   (AHidDev.Attributes.ProductID = MY_PRODUCT_ID) and
   (AHidDev.Caps.InputReportByteLength = 8);
end;

See Also

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