Powerbuilder WebCam

Question

I am using EZTWAIN from a powerbuilder application to acquire images from an HP scanner. Recently I tried a Kodak model (i1120) and it seems that it is not supported. Specifically the application freezes during the scanning process (perhaps the problem has to do with duplex scanning).

Can you recommend another library that you have used and works ok for you, and provides an easy-to-use wrapper for the TWAIN API that can be used from Powerbuilder?

Azedarach

After investigation the problem had to do with the way that I used to skip blank pages. (see on page 21 here dosadi.com/pub/eztp/EZTwain_User_Guide.pdf) I was using TWAIN_BeginMultipageFile and the Do loop. When I changed it to TWAIN_AcquireMultipageFile and TWAIN_SetBlankPageMode(1), the problem solved. You can also use TWAIN_SetBlankPageThreshold to adjust the dark pixel ratio for a page to be considered as ‘blank’. Eventually I decided to totally skip the blank page omission. Though I don't have that Kodak model available anymore, I believe that it would have no problem. – Azedarach

EZTwain was purchased by Atalasoft (now part of Kofax) in January 2011, but Atalasoft continues to offer e-mail & forum support for licensed EZTwain developers. They have a great support team. (Yes, I work for them ;-) – Silvery

Answer 1

Check out this company: http://www.data-tech.com/ we use their ImageMan ActiveX suite with PB 10.5 and it works without a problem.

Fibrilla

Thank you very much. Have you tried it with scanners which scan both sides of a page simultaneously? – Azedarach

Yes we have, actually implemented that last year, and it works like a charm. – Fibrilla

I have noticed that no code samples for powerbuilder are provided. Have you found any? – Azedarach

Sorry took me this long to respond, been under the weather: I don't know about code examples, but as far as ActiveX controls go in PB, it's just a matter of dropping the control on a form, naming it (e.g., ole_ImageMan) and then using the Methods/Properties exposed on that control (e.g. ole_ImageMan.Picture) Now, PB won't display the property/method names via Intellisense, like VS, so you'll have to make use of their Help files, to get that information. – Fibrilla

Answer 2

I had a similar problem with duplex scanning with several libraries. The solution is to use the scanner's interface directly when using duplex scanning instead of the ActiveX component. Most of the libraries have an option that can be enabled on the fly to use the scanner interface.

I currently use the Viscomsoft Scanner Pro ActiveX library.

Datary

I beg to disagree, having written a commercial TWAIN library - if you can scan one-sided but not duplex, with or without showing the scanner's UI, then there's a code problem either in the application or in the library, and it's probably in the library. Duplex scanning (through TWAIN) is only trivially different from simplex scanning. – Silvery

Answer 3

**object : n_webcam**
================================================================================

forward 
global  type nvo_webcam from nonvisualobject
 end  type 
end  forward

global  type nvo_webcam from nonvisualobject autoinstantiate 
end  type

 prototype type

function  ulong capCreateCaptureWindowA ( string lpszWindowName, ulong dwStyle, long li_x, long li_y, long nWidth, long nHeight, ulong ParentWin, long nId) LIBRARY  'AVICAP32.DLL'  alias  for  "capCreateCaptureWindowA; ansi"



Function  ulong GetDC ( ulong hWnd) Library  "user32.dll" 
Function  long ReleaseDC ( ulong hWnd, ulong hdcr) Library  "USER32.DLL" 
Function  ulong CreateCompatibleDC ( ulong hdc) Library  "gdi32.dll" 
Function  ulong CreateCompatibleBitmap ( ulong hdc, ulong nWidth, ulong nHeight) Library  "gdi32.dll" 
Function  boolean DeleteDC ( ulong hDC) Library "Gdi32.dll"

Function  boolean BitBlt ( ulong hdcDest, long nXDest, long nYDest, long nWidth, long nHeight, ulong hdcSrc, long nXSrc, long nYSrc, long dwRop) Library  "gdi32.dll" 
Function  boolean StretchBlt ( ulong hdcDest, long nXOriginDest, long nYOriginDest, long nWidthDest, long nHeightDest, ulong hdcSrc, long nXOriginSrc, longnYOriginSrc, long nWidthSrc, long nHeightSrc, long dwRop) Library  "gdi32.dll"

Function  ulong SelectObject ( ulong hdc, ulong HGDIOBJ) Library  "gdi32.dll"

Function  along GetDIBits ( ulong hdc, ulong hbmp, uint uStartScan, uint cScanLines, Ref  blob lpvBits, Ref BITMAPINFO lpbi, uint uUsage) Library  "gdi32.dll"  alias  for  "GetDIBits" 
Function  long GetDIBits ( ulong hdc, ulong hbmp, uint uStartScan , uint cScanLines, ulong lpvBits, ref bitmapinfo lpbi, uint uUsage) Library "gdi32.dll"  alias  for  "GetDIBits"

Subroutine CopyBitmapFileHeader ( Blob Ref  Destination, bitmapfileheader Source, long Length) Library "kernel32.dll" Alias For "RtlMoveMemory" Subroutine CopyBitmapInfo ( Blob Ref Destination, Source bitmapinfo, long Length) Library "kernel32.dll" Alias For "RtlMoveMemory"    


Function  boolean OpenClipboard ( ulong hWndNewOwner) Library  "user32.dll" 
Function  boolean CloseClipboard () Library  "user32.dll" 
Function  boolean EmptyClipboard () Library  "user32.dll" 
Function  ulong GetClipboardData ( ulong uFormat) Library  "user32.dll"

end  prototypes

such  variables 
Uint LHand
Constant  long GET_FRAME = 1084
Constant  long COPY = 1054
Constant  long WM_USER = 1024
Constant  long WM_CAP_START = WM_USER
Constant  long WM_CAP_STOP = WM_CAP_START + 68
Constant  long WM_CAP_DRIVER_CONNECT = WM_CAP_START + 10
Constant  long WM_CAP_DRIVER_DISCONNECT = WM_CAP_START + 11
Constant  long WM_CAP_SAVEDIB = WM_CAP_START + 25
Constant  Long WM_CAP_GRAB_FRAME = WM_CAP_START + 60
Constant  LongWM_CAP_SEQUENCE = WM_CAP_START + 62
Constant  long WM_CAP_FILE_SET_CAPTURE_FILEA = WM_CAP_START + 20
Constant  long WM_CAP_FILE_SAVEAS = WM_CAP_START + 23
Constant  long WM_CAP_SEQUENCE_NOFILE = WM_CAP_START + 63
Constant  long WM_CAP_SET_OVERLAY = WM_CAP_START + 51
Constant  long WM_CAP_SET_PREVIEW = WM_CAP_START + 50
Constant  long WM_CAP_SET_CALLBACK_VIDEOSTREAM = WM_CAP_START +6
Constant  long WM_CAP_SET_CALLBACK_ERROR = WM_CAP_START + 2
Constant  Long WM_CAP_SET_CALLBACK_STATUSA = WM_CAP_START +3
Long Constant WM_CAP_SET_CALLBACK_FRAME = WM_CAP_START +5
Long Constant  WM_CAP_SET_SCALE = WM_CAP_START + 53
Long Constant WM_CAP_SET_PREVIEWRATE = WM_CAP_START + 52 
end  variables

forward  prototypes 
public  subroutine of_close ()
public  subroutine of_initialize_webcam ( unsignedlong a_handle, string a_title, integer a_width, integer a_height)
public  function  blob of_copy_clipboard_to_blob ()
public  subroutine of_capture_pic ()
end  prototypes

public  subroutine of_close (); send (lhand, WM_CAP_DRIVER_DISCONNECT, 0, 0)
end  subroutine

public  subroutine of_initialize_webcam ( unsigned long a_handle, string a_title, integer a_width, integer a_height); string lpszName

lpszName = a_title
if lhand = 0 then
lhand = capCreateCaptureWindowA (lpszName, 262144 + 12582912 + 1073741824 + 268435456, 1.40, a_width, a_height, a_handle, 0)
end  if 
if lhand <> 0 then
send (lhand, WM_CAP_SET_CALLBACK_VIDEOSTREAM, 0, 0)
send (lhand, WM_CAP_SET_CALLBACK_ERROR, 0, 0)
send (lhand, WM_CAP_SET_CALLBACK_STATUSA, 0, 0)

send (lhand, WM_CAP_DRIVER_CONNECT, 0, 0)
send (lhand, WM_CAP_SET_SCALE, 1, 0)
send (lhand, WM_CAP_SET_PREVIEWRATE, 66, 0)
send (lhand, WM_CAP_SET_OVERLAY, 1, 0)
send (lhand, WM_CAP_SET_PREVIEW, 1, 0)
end  if 
end  subroutine

public  function  blob of_copy_clipboard_to_blob (); BitmapInfo lstr_Info
BitmapFileHeader lstr_Header
Blob   lblb_header, lblb_info, lblb_bitmap, lbl_final
ULong lul_hdc, lul_hdcMem, lul_hBitmap, lul_hWnd, lul_blpos
UInt DIB_RGB_COLORS
Integer li_pixels
Boolean lb_result
long al_width, ll_height, ll_ret

constant  integer BITMAPTYPE = 19778 // 4D42 = BM
constant  integer CF_BITMAP = 2
constant  integer CF_DIB = 8

lul_hWnd = Handle ( this )
lb_result = OpenClipboard (lul_hWnd)

// Get the device context and allocate memory
lul_hdc = GetDC (lul_hWnd)
lul_hdcMem = CreateCompatibleDC (lul_hdc)
lul_hBitmap = getclipboarddata (CF_BITMAP)

// try to store the bitmap into a blob so we can save it
lstr_Info.bmiHeader.biSize = 40
ll_height = 480 // ... 480 should be enough for everyone? ;)
DIB_RGB_COLORS = 0
// Get the bitmapinfo
If GetDIBits (lul_hdcMem, lul_hBitmap, 0, ll_height, 0, lstr_Info, DIB_RGB_COLORS)> 0 Then
li_pixels = lstr_Info.bmiHeader.biBitCount
lstr_Info.bmiColors [li_pixels] = 0
lblb_bitmap = Blob (Space (lstr_Info.bmiHeader.biSizeImage), EncodingANSI!)
ll_height = lstr_Info.bmiHeader.biheight
// get the actual bits
ll_ret = GetDIBits (lul_hdcMem, lul_hBitmap, 0, ll_height, lblb_bitmap, lstr_Info, DIB_RGB_COLORS) 
// ls_msg = hexdump_blob (lblb_bitmap, false)
// create a bitmap header
lstr_Header.bfType = BITMAPTYPE
lstr_Header.bfSize = lstr_Info.bmiHeader.biSizeImage
lstr_Header.bfOffBits = 54 + (li_pixels * 4)
// copy the header structure to a blob
lblb_header = Blob (Space (7)) //
14/2 CopyBitmapFileHeader (lblb_header, lstr_Header, 14)
// copy the info structure to a blob
lblb_Info = Blob (Space (40 + li_pixels * 4) / 2))
CopyBitmapInfo (lblb_Info, lstr_Info, len (lblb_Info))
// add all together and we have a window bitmap in a blob
lbl_final = lblb_header + lblb_info + lblb_bitmap
End  If

CloseClipboard ()
ReleaseDC (lul_hwnd, lul_hdc)
DeleteDC (lul_hdcMem)

return lbl_final
end  function

public  subroutine of_capture_pic (); Send (lhand, GET_FRAME, 0, 0)
Send (lhand, COPY, 0, 0)


end  subroutine

we have nvo_webcam. create 
call  super :: create 
TriggerEvent ( this , "constructor" )
end  on

we have nvo_webcam. destroy 
TriggerEvent ( this , "destructor" )
call  super :: destroy 
end  on

**instantiate the object and initialize it:**
================================================================================

n_webcam.of_initialize_webcam (handle ( this ), "Webcam" , il_width, il_height)

**capture:**
================================================================================

n_webcam.of_capture_pic ()

**image processing:**
================================================================================

lb_blob = n_webcam..of_copy_clipboard_to_blob ()
 // reinitialize for the webcam to continue live
 i_nvo_webcam.of_initialize_webcam (handle ( this ), "Webcam" , il_width, il_height)

**Close:**
================================================================================

n_webcam.of_close ()

Watch Video https://youtu.be/ojcJs1ajWRc

Inpatient

Links in posts are welcomed; however, please avoid post relayed mainly on the link or links. Links can be changed in time or became unavailable, please describe your thoughts in your post for a case if info behind links will be changed or removed. Please describe more how your code can answer the question – Twotone