Delphi - 利用DLL编程控制摄像头实现拍照、录制视频

Delphi利用avicap32.dll编程控制摄像头实现拍照、录制视频

项目需求：平板电脑（Windows系统）一维/二维码扫描功能；

需求分析：

需要扫描一维/二维码时，分两步实现。

第一步，avicap32.dll或者dspack技术实现静默打开摄像头拍照、保存BMP图片。

第二步，ZXing技术实现对一维/二维码的解析，最终获取到码值。

本篇是利用avicap32.dll技术实现拍照/录制视频的测试Demo。

请看代码：

 unit uMain;

 interface

 uses
   Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
   Dialogs, ExtCtrls, StdCtrls, RzPanel, RzButton;

 type
   TFrmMain = class(TForm)
     gbScreen: TRzGroupBox;
     gbOperation: TRzGroupBox;
     btnStart: TRzBitBtn;
     btnStop: TRzBitBtn;
     btnSaveBMP: TRzBitBtn;
     btnStartR: TRzBitBtn;
     btnSaveAVI: TRzBitBtn;
     pMain: TPanel;
     procedure btnStartClick(Sender: TObject);
     procedure FormClose(Sender: TObject; var Action: TCloseAction);
     procedure btnStopClick(Sender: TObject);
     procedure btnSaveBMPClick(Sender: TObject);
     procedure btnStartRClick(Sender: TObject);
     procedure btnSaveAVIClick(Sender: TObject);
   private
     { Private declarations }
     hWndC: THandle;
   public
     { Public declarations }
   end;

 var
   FrmMain: TFrmMain;
 const WM_CAP_START = WM_USER;
 const WM_CAP_STOP = WM_CAP_START + ;
 const WM_CAP_DRIVER_CONNECT = WM_CAP_START + ;
 const WM_CAP_DRIVER_DISCONNECT = WM_CAP_START + ;
 const WM_CAP_SAVEDIB = WM_CAP_START + ;
 const WM_CAP_GRAB_FRAME = WM_CAP_START + ;
 const WM_CAP_SEQUENCE = WM_CAP_START + ;
 const WM_CAP_FILE_SET_CAPTURE_FILEA = WM_CAP_START + ;
 const WM_CAP_SEQUENCE_NOFILE = WM_CAP_START + ;
 const WM_CAP_SET_OVERLAY = WM_CAP_START + ;
 const WM_CAP_SET_PREVIEW = WM_CAP_START + ;
 const WM_CAP_SET_CALLBACK_VIDEOSTREAM = WM_CAP_START + ;
 const WM_CAP_SET_CALLBACK_ERROR = WM_CAP_START + ;
 const WM_CAP_SET_CALLBACK_STATUSA = WM_CAP_START + ;
 const WM_CAP_SET_CALLBACK_FRAME = WM_CAP_START + ;
 const WM_CAP_SET_SCALE = WM_CAP_START + ;
 const WM_CAP_SET_PREVIEWRATE = WM_CAP_START + ;

 function capCreateCaptureWindowA(lpszWindowName: PCHAR;
   dwStyle: longint; x: integer; y: integer; nWidth: integer;
   nHeight: integer; ParentWin: HWND; nId: integer): HWND;
 STDCALL EXTERNAL 'AVICAP32.DLL';

 implementation

 {$R *.dfm}

 procedure TFrmMain.btnStartClick(Sender: TObject);
 begin
   //开始拍摄
   hWndC := capCreateCaptureWindowA('My Own Capture Window', WS_CHILD or WS_VISIBLE, pMain.Left, pMain.Top, pMain.Width, pMain.Height, FrmMain.Handle, );
   if hWndC <>  then
   begin
     SendMessage(hWndC, WM_CAP_SET_CALLBACK_VIDEOSTREAM, , );
     SendMessage(hWndC, WM_CAP_SET_CALLBACK_ERROR, , );
     SendMessage(hWndC, WM_CAP_SET_CALLBACK_STATUSA, , );
     SendMessage(hWndC, WM_CAP_DRIVER_CONNECT, , );
     SendMessage(hWndC, WM_CAP_SET_SCALE, , );
     SendMessage(hWndC, WM_CAP_SET_PREVIEWRATE, , );
     SendMessage(hWndC, WM_CAP_SET_OVERLAY, , );
     SendMessage(hWndC, WM_CAP_SET_PREVIEW, , );
   end;
 end;

 procedure TFrmMain.FormClose(Sender: TObject; var Action: TCloseAction);
 begin
   //程序退出时，自动关闭摄像头
   if hWndC <>  then
   begin
     SendMessage(hWndC, WM_CAP_DRIVER_DISCONNECT, , );
   end;
 end;

 procedure TFrmMain.btnStopClick(Sender: TObject);
 begin
   //关闭摄像头
   if hWndC <>  then
   begin
     SendMessage(hWndC, WM_CAP_DRIVER_DISCONNECT, , );
     hWndC := ;
   end;
 end;

 procedure TFrmMain.btnSaveBMPClick(Sender: TObject);
 begin
   //保存BMP
   if hWndC <>  then
   begin
     SendMessage(hWndC, WM_CAP_SAVEDIB, , longint(pchar('D:/1.bmp')));
   end;
 end;

 procedure TFrmMain.btnStartRClick(Sender: TObject);
 begin
   //开始录制AVI视频
   if hWndC <>  then
   begin
     SendMessage(hWndC, WM_CAP_FILE_SET_CAPTURE_FILEA, , Longint(pchar('c:/test.avi')));
     SendMessage(hWndC, WM_CAP_SEQUENCE, , );
   end;
 end;

 procedure TFrmMain.btnSaveAVIClick(Sender: TObject);
 begin
   //停止录制并保存AVI视频
   if hWndC <>  then
   begin
     SendMessage(hWndC, WM_CAP_STOP, , );
   end;
 end;

 end.

运行效果：

作者：Jeremy.Wu
  出处：https://www.cnblogs.com/jeremywucnblog/

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