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POSaving images from the Clipboard using pure API
 

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    <p>I'm having trouble saving images from the clipboard using pure API.</p> <p>Here is my code. It creates 20 empty bmp files. I have checked dwSize and it is correct so it seems I am retreiving the data correctly, but I am writing to a file incorrectly.</p> <pre><code> program WebcamTest; //cswi uses Windows; const WM_CAP_DRIVER_CONNECT = 1034; WM_CAP_GRAB_FRAME = 1084; //WM_CAP_SAVEDIB = 1049; WM_CAP_EDIT_COPY = 1054; WM_CAP_DRIVER_DISCONNECT = 1035; function SendMessageA(hWnd: Integer; Msg: Integer; wParam: Integer; lParam: Integer): Integer; stdcall; external 'user32.dll' name 'SendMessageA'; function capGetDriverDescriptionA(DrvIndex: Cardinal; Name: PAnsiChar; NameLen: Integer; Description: PAnsiChar; DescLen: Integer) : Boolean; stdcall; external 'avicap32.dll' name 'capGetDriverDescriptionA'; function capCreateCaptureWindowA(lpszWindowName: PAnsiChar; dwStyle: Integer; x : Integer; y : Integer; nWidth : Integer; nHeight : Integer; ParentWin: Integer; nId: Integer): Integer; stdcall; external 'avicap32.dll' name 'capCreateCaptureWindowA'; function IntToStr(i: Integer): String; begin Str(i, Result); end; var WebCamId : Integer; CaptureWindow : Integer; x : Integer; FileName : PAnsiChar; hData: DWORD; pData: Pointer; dwSize: DWORD; szText : AnsiString; FileHandle, BytesWritten : LongWord; begin WebcamId := 0; CaptureWindow := capCreateCaptureWindowA('CaptureWindow', 0, 0, 0, 0, 0, 0, 0); if CaptureWindow &lt;&gt; 0 then begin if SendMessageA(CaptureWindow, WM_CAP_DRIVER_CONNECT, WebCamId, 0) &lt;&gt; 1 then begin SendMessageA(CaptureWindow, WM_CAP_DRIVER_DISCONNECT, 0, 0); end else begin for x := 1 to 20 do // Take 20 photos. begin SendMessageA(CaptureWindow, WM_CAP_GRAB_FRAME, 0, 0); FileName := PAnsiChar('C:\Test' + IntToStr(x) + '.bmp'); //SendMessageA(CaptureWindow, WM_CAP_SAVEDIB, 0, LongInt(FileName)); SendMessageA(CaptureWindow, WM_CAP_EDIT_COPY, 0, LongInt(FileName)); if OpenClipBoard(0) then begin hData := GetClipBoardData(CF_DIB); if hData &lt;&gt; 0 then begin pData := GlobalLock(hData); if pData &lt;&gt; nil then begin dwSize := GlobalSize(hData); if dwSize &lt;&gt; 0 then begin FileHandle := CreateFileA(FileName, GENERIC_WRITE, FILE_SHARE_WRITE, nil, CREATE_NEW, FILE_ATTRIBUTE_HIDDEN, 0); WriteFile(FileHandle, pData, dwSize, BytesWritten, nil); CloseHandle(FileHandle); end; GlobalUnlock(DWORD(pData)); end; end; CloseClipBoard; end; end; end; SendMessageA(CaptureWindow, WM_CAP_DRIVER_DISCONNECT, 0, 0); end; end. </code></pre>
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    1. USDanny Rancher
    1. USDanny Rancher
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      1. VTUpMod
    1. COSome thoughts: 1. You aren't checking for errors in most of your API calls. 2. Please don't use magic constants when calling `CreateFile`. Don't make us work out what those constants mean. 3. You really don't want to be using `FILE_SHARE_WRITE`. 4. Did you check that the bitmaps are put in the clipboard correctly?
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      1. USDavid Heffernan
    2. CO5. the [`WM_CAP_EDIT_COPY`](http://msdn.microsoft.com/en-us/library/windows/desktop/dd743896(v=vs.85).aspx) should have both parameters set to 0 (even when I don't think it would hurt it somehow, check the result of that message is a must).
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      1. USTLama
    3. CO6. Why did you give up on `WM_CAP_FILE_SAVEDIB`?
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      1. USDavid Heffernan
 

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