我正在使用biometrics SDK。我将标题转换为delphi以使用dll。
它看起来像这样：
const
{VrBio_EventType}
VRBIO_CAPTURE_EVENT_UNPLUG = $001; {Fingerprint scanner unplugged from the computer.}
VRBIO_CAPTURE_EVENT_PLUG = $002; {Fingerprint scanner plugged on the computer.}
VRBIO_CAPTURE_EVENT_REMOVED = $004; {Finger removed from the fingerprint scanner.}
VRBIO_CAPTURE_EVENT_PLACED = $008; {Finger placed on the fingerprint scanner.}
VRBIO_CAPTURE_EVENT_IMAGE_FRAME = $10; {A fingerprint frame was captured on the fingerprint scanner.}
VRBIO_CAPTURE_EVENT_IMAGE_CAPTURED = $020; {A fingerprint image was captured on the fingerprint scanner.}
VRBIO_CAPTURE_EVENT_FAKE_FINGER_DETECTED = $400; {A false finger has been detected on the sensor}
VRBIO_CAPTURE_EVENT_FAKE_FINGER_REMOVED = $800; {A false finger has been removed from the sensor}
type
(* Stores the parameters of the ISO 19794-4 image format. @see VGetReaderProperties @see VrBio_ReaderProperty
typedef struct
{
/** @see VrBio_ISO197944CompressionMode*/
int compressionMode;
/** @see VrBio_ISO197944ImpressionType*/
int impressionType;
/** @see VrBio_ISO197944FingerPosition*/
int fingerPosition;
}VrBio_ISO197944Parameters;
*)
PISO197944Parameters = ^TISO197944Parameters;
TISO197944Parameters = record
compressionMode: Integer; { @see VrBio_ISO197944CompressionMode}
impressionType: Integer; { @see VrBio_ISO197944ImpressionType}
fingerPosition: Integer; { @see VrBio_ISO197944FingerPosition}
end;
(* Represents a biometric image. @see VrBio_CaptureEventCallback \ref VSyncCapture
struct VrBio_BiometricImage
{
/** Image width.*/
int width;
/**Image height*/
int height;
/**Image resolution in dpi. For the obsolete functions, use pixels/cm.*/
int resolution;
/**Number of channels in the image. Fingerprint images should always be grayscale, so this value is always 1.*/
int channels;
/**Biometric modality.
* Always use VRBIO_BIOMETRIC_MODALITY_FINGERPRINT.
* \ref VrBio_BiometricModality.
*/
int biometricModality;
/**Scanner type.
* \ref VrBio_ScannerType.
*/
int scannerType;
/**Formato de imagem: Formato da imagem.
*\ ref VrBio_ImageFormat.*/
int imageFormat;
/**Size of the buffer*/
int bufferSize;
/**Compression rate. Valid for images that allow compression.
* \ref VrBio_CompressionRate
*/
int compressionRate;
/**Quality of the fingerprint image.
* \ref VrBio_FingerQuality
*/
int fingerQuality;
/** Only valid if the image if imageFormat is \ref VrBio_ImageFormat::VRBIO_IMAGEFORMAT_ISO19794_4
*\ref VrBio_ISO197944Parameters
*/
VrBio_ISO197944Parameters* ISO197944_parameters;
/** Buffer storing the pixels of the image.
The position(x,y,c) of a pixel is y*width*channels+x*channels+c.
*/
unsigned char* buffer;
/**Reserved for future use*/
void* reserved;
};
typedef struct VrBio_BiometricImage VrBio_BiometricImage;
*)
PBiometricImage = ^TBiometricImage;
TBiometricImage = record
width: Integer; { Image width. }
height: Integer; { Image height }
resolution: Integer; { Image resolution in dpi. For the obsolete functions, use pixels/cm.}
channels: Integer; { Number of channels in the image. Fingerprint images should always be grayscale, so this value is always 1. }
biometricModality: Integer; { Biometric modality. Always use VRBIO_BIOMETRIC_MODALITY_FINGERPRINT. \ref VrBio_BiometricModality. }
scannerType: Integer; { Scanner type. \ref VrBio_ScannerType. }
imageFormat: Integer; { Formato de imagem: Formato da imagem. \ ref VrBio_ImageFormat. }
bufferSize: Integer; { Size of the buffer }
compressionRate: Integer; { Compression rate. Valid for images that allow compression. \ref VrBio_CompressionRate }
fingerQuality: Integer; { Quality of the fingerprint image. \ref VrBio_FingerQuality }
ISO197944_parameters: PISO197944Parameters; { Only valid if the image if imageFormat is \ref VrBio_ImageFormat::VRBIO_IMAGEFORMAT_ISO19794_4 \ref VrBio_ISO197944Parameters }
buffer: PByte; { Buffer storing the pixels of the image. The position(x,y,c) of a pixel is y*width*channels+x*channels+c. }
reserved: Pointer; { Reserved for future use }
end;
(*
#include "VTypes.h"
#ifdef WIN32
#define DLLIMPORT extern "C" __declspec(dllimport) int __stdcall
#else
#define DLLIMPORT extern "C"
#endif
*)
{ Callback function that receives events..
typedef void (*VrBio_CaptureEventCallback) (
int eventType,
const char* readerName,
VrBio_BiometricImage* image,
const void* userData)
}
TCaptureEventCallback = procedure(eventType: Integer; readerName: PAnsiChar; image: PBiometricImage; userData: Pointer); stdcall;
{ Function responsible for initializing the SDK. This function MUST be called before calling any other method, except \ref VInstallLicense
DLLIMPORT VStartSDK(VrBio_CaptureEventCallback eventCallback);
}
function VStartSDK(eventCallback: TCaptureEventCallback): Integer; stdcall;
{ Function responsible for finalizing the SDK. This function should be called when the SDK is not needed in the application anymore.
DLLIMPORT VStopSDK();
}
function VStopSDK(): Integer; stdcall;
{ Function responsible for starting the capture on a specific fingerprint reader.
After calling this function, the application is able to receive events.
DLLIMPORT VStartReader(const char* readerName);
}
function VStartReader(readerName: PAnsiChar): Integer; stdcall;
使用它看起来像这样：
implementation
{$R *.dfm}
procedure EventCallback(eventType: Integer; readerName: PAnsiChar; image: PBiometricImage; userData: Pointer); stdcall;
begin
case eventType of
VRBIO_CAPTURE_EVENT_UNPLUG: Form1.Memo1.Lines.Add('Leitor desconectado!');
VRBIO_CAPTURE_EVENT_REMOVED: Form1.Memo1.Lines.Add('Dedo removido!');
VRBIO_CAPTURE_EVENT_PLACED: Form1.Memo1.Lines.Add('Dedo detectado!');
VRBIO_CAPTURE_EVENT_IMAGE_FRAME: Form1.Memo1.Lines.Add('Frame capturado!');
VRBIO_CAPTURE_EVENT_IMAGE_CAPTURED: Form1.Memo1.Lines.Add('Imagem capturada!');
VRBIO_CAPTURE_EVENT_FAKE_FINGER_DETECTED: Form1.Memo1.Lines.Add('Dedo falso detectado!');
VRBIO_CAPTURE_EVENT_FAKE_FINGER_REMOVED: Form1.Memo1.Lines.Add('Dedo falso removido!');
VRBIO_CAPTURE_EVENT_PLUG:
begin
VStartReader(readerName);
Form1.Memo1.Lines.Add('Leitor conectado!');
end;
end;
end;
procedure TForm1.Button2Click(Sender: TObject);
begin
VStartSDK(EventCallback);
end;
我的问题：
我可以使用该应用程序并获取Plug，Unplug和Placed事件，但是当我收到Image Captured事件时，我有访问权限。
在有效的事件中，EventCallback参数图像为nil。 TBiometricImage记录转换是否正确？
如何将TBiometricImage缓冲区转换为TBitmap并在TImage中显示捕获的图像？
答案 0 :(得分：2)
当我收到Image Captured事件时，我有一个访问vilation。在正在运行的事件中，EventCallback参数图像为nil。 TBiometricImage记录转换是否正确？
单个字段被声明为正常，但请仔细检查Delphi记录的对齐和填充是否与C / C ++中结构使用的相同对齐和填充匹配。
另外，更重要的是，声明了C / C ++中的VrBio_CaptureEventCallback typedef而没有指定任何调用约定，因此它将使用编译器的默认约定，通常为__cdecl而不是__stdcall TCaptureEventCallback（可以在编译器设置中配置）。在Delphi中，您声明stdcall使用cdecl而不是stdcall。你必须确保正确匹配调用约定（导出的DLL函数确实使用buffer，所以你没关系。）
如何将TBiometricImage缓冲区转换为TBitmap并在TImage中显示捕获的图像？
SDK文档未说明如何处理各种图像格式。但是，只需查看结构声明，imageFormat字段指向实际图像数据，VrBio_ImageFormat字段指示该数据的格式（您有imageFormat枚举尚未翻译）。因此，您必须首先查看buffer以了解如何解释VConvertImage()。
我确实看到了buffer功能。所以你应该能够将图像转换为BMP格式，如果它们还没有。根据SDK中的示例，看起来buffer数据可能是标准的BMP文件格式，因此您可以尝试将TMemoryStream复制到{{1}然后使用TBitmap.LoadFromStream()方法。
还有GIF和JPG图片格式，如果您想要显示扫描的GIF / JPG图像，可以分别由TGIFImage和TJPEGImage处理，甚至可以TWICImage处理无需先将它们转换为BMP。还有一个RAW图像格式（显然你的图像正在使用），但没有标准的VCL TGraphic类来处理RAW图像，但我认为如果你环顾四周可能会有一些第三方类
否则，您可以尝试将图像数据转换为BMP（如果需要），然后将buffer传递给Win32 API CreateBitmap/Indirect()或CreateDibSection()函数，然后分配结果{如果成功，则{1}}到HBITMAP属性。