bitmaps

[Dan Soper]

Ok, this is going to sound like a really, really stupid question...

But how do I display an image? I have the image info (height, width etc.) in a BITMAP structure, and the image itself is currently in one big (~2.5Mb) dynamic string.

The .bmBits member of the BITMAP structure is set as STRPTR(bits$), and then I use the CreateBitmapIndirect function, from the win32 API.

Not feeling brave enough to tackle device contexts and all that nonsense, I copied the code from Petzold to put a bitmap in the clipboard.
This gave me a nice black rectangle. Which is not what my original image looks like. I know that the image data is being generated correctly because I did manage to output if to a windows bitmap file, which is then correctly understood by graphics software, and can be set to the desktop wallpaper etc.

However, now I need to use (i.e. display) the image within my programme, which means persuading Windows that it is indeed an image, for which it can give me a handle. The API call I've been using should do the job, but all I get is a blank box, and having tried all the variations I can think of, and searched POFFS, I am now at a loss.
I wondered if its because I'm using a dynamic string, and tried to overlay an array using DIM... AT, but I have no idea if I was doing that properly, and it didn't work anyway.

Suggestions would be greatly appreciated.

------------------
--Dan

[Semen Matusovski]

Dan --
I have no idea, what are you doing.
That's why I suggest to look this training code.

   #Compile Exe
   #Register None
   #Dim All
   #Include "Win32Api.Inc"
  
   Sub CopyPicture(hWnd As Long)
      Static hBmpClip As Long
      Dim hDC As Long, hDC1 As Long, hBmp As Long, rc As Rect, hBmpOld As Long
      hDC = GetDC(hWnd)
      hDC1 = CreateCompatibleDC(hDC)
      GetClientRect hWnd, rc
      hBmp = CreateCompatibleBitMap (hDC, rc.nRight, rc.nBottom)
      hBmpOld = SelectObject (hDc1, hBmp)
      BitBlt hDC1, 0, 0, rc.nRight, rc.nBottom, hDC, 0, 0, %SRCCOPY
      SelectObject hDC1, hBmpOld
      OpenClipboard ByVal 0
      EmptyClipboard
      If hBmpClip > 0 Then DeleteObject hBmpClip
      SetClipboardData %CF_BITMAP, hBMP
      CloseClipboard
      DeleteObject hDC1
      hBmpClip = hBmp
      ReleaseDC hWnd, hDC
   End Sub
   
   Sub InsertPicture(hWnd As Long)
      Dim rc As Rect
      Dim hDC As Long, hBmp As Long, hDCMem As Long
   
      hDC = GetDC(hWnd)
      hdcMem = CreateCompatibleDC(hdc)
      If hdcMem Then
         If OpenClipboard(hWnd) Then
            hBmp = GetClipboardData(%CF_BITMAP)
            SelectObject hdcMem, hBmp
            GetClientRect hwnd, rc
            BitBlt hdc, 0, 0, rc.nRight, rc.nBottom, hdcMem, 0, 0, %SRCCOPY
            CloseClipboard
         End If
         DeleteDC hdcMem
      End If
      ReleaseDC hWnd, hDC
   End Sub

   Global hDlg As Long
   
   CallBack Function ButProc
      CopyPicture GetDesktopWindow
      InsertPicture GetDlgItem(hDlg, 102)
   End Function
   
   Function PbMain () As Long
      Dialog New 0, "Polus", ,, 200, 240, %WS_CAPTION Or %WS_SYSMENU  To hDlg
      Control Add Button, hDlg, 101, "Paste Desktop window", 10, 10, 180, 15  Call ButProc
      Control Add Label, hDlg, 102, "", 10, 30, 180, 200, , %WS_EX_CLIENTEDGE
      Dialog Show Modal hDlg
   End Function

------------------
E-MAIL: [email protected]

[Dan Soper]

Semen, thanks for your code.

This is my programme:

#COMPILE EXE
OPTION EXPLICIT

#INCLUDE "win32api.inc"
#INCLUDE "loadjpeg.inc"

FUNCTION PBMAIN
   
   LOCAL dib AS bitmap     'image info
   LOCAL result AS LONG    'did LoadJPG succeed?
   LOCAL file AS STRING    'Jpeg filename
   LOCAL hBmp AS LONG      'handle to bmp
   LOCAL bits AS STRING    'decoded jpeg image
   LOCAL bmfh AS BITMAPFILEHEADER
   LOCAL bmih AS BITMAPINFOHEADER

   file = "D:\PBDLL60\Mine\CD project\testpic1.jpg"

   result = LoadJPG(file, dib, bits)
   IF result THEN
      hBmp = CreateBitmapIndirect(dib)
      IF hBmp = 0 THEN
         MSGBOX "Failure to create bitmap!" + $CRLF + _
                "Error code: " + STR$(GetLastError())
      ELSE
         bmfh.bfType= CVWRD("BM")
         bmfh.bfSize = SIZEOF(bmfh) + SIZEOF(bmih) + LEN(bits)
         bmfh.bfOffBits = SIZEOF(bmfh) + SIZEOF(bmih)
         bmih.biSize = SIZEOF(bmih)
         bmih.biWidth = dib.bmWidth
         bmih.biHeight = dib.bmHeight
         bmih.biPlanes = 1
         bmih.biBitCount = 24
         OPEN "C:\temp\image.bmp" FOR BINARY AS #1
         PUT #1,, bmfh
         PUT #1,, bmih
         PUT$ #1, bits
         CLOSE #1
         MSGBOX "Image in file: C:\temp\image.bmp" + $CRLF + _
                $CRLF + "Image data:" + $CRLF + _
                "X: " + STR$(dib.bmWidth) + $CRLF + _
                "Y: " + STR$(dib.bmHeight)
         OpenClipboard %NULL
         EmptyClipboard
         SetClipboardData %CF_BITMAP, hBmp
         CloseClipboard
         'DeleteObject hBmp
         MSGBOX "Success!" + $CRLF + _
                "Image should now be in clipboard." + $CRLF + _
                "But probably isn't."
      END IF

   ELSE
      MSGBOX "Failure to load jpeg!!"
   END IF

END FUNCTION

The Loadjpeg.inc file contains the LoadJPG function, which is essentially a wrapper for the Intel JPEG Library DLL.
That function is working perfectly well: it opens the jpg image in file, and returns true if it succeeded, false otherwise. If it's succeeded, the variables dib and bits contain the image, as I described in my previous post.

This code does correctly outputs the bitmap image file, but leaves only an empty image in the clipboard. And I have no idea why.


------------------
--Dan

[Semen Matusovski]

Dan --
I can't say nothing without DLL + INC.
But if you can select dib-section into any (memory) hDC, in further you can use
a code, which I posted above or a code, which I posted in "source code" (to work directly with pixels).

PS. If this DLL is freeware, put it on ftp.

------------------
E-MAIL: [email protected]

[Dan Soper]

Semen, the DLL is free from Intel: http://developer.intel.com/vtune/PER.../ijl/index.htm

I translated the inc.h file provided with the DLL from C to PB. I am perfectly happy that my LoadJPG wrapper function works as it should. Rather than posting that and the lengthy header file, it would probably be better to use a "dummy" function instead of LoadJPG.
I'll put one together tomorrow.

I looked at your code for using a DIB section... but couldn't compile it ("String Operand Expected" line 57, IF @pi2.pDevMode = 0 THEN). I did try using the CreateDIBsection function in my code though, but with the same result as before - a bitmap image of the right size is created, but it's an empty box, no image data.
I also tried the SetDIBits function. Strangely, this returned zero, but GetLastError also returned zero. Which makes no sense at all.

I have now tried:
CreateBimapIndirect
CreateBitmap
CreateDIBSection
CreateDIBitmap
and possibly one or two others. Always the function either fails (without any reason being made available through GetLastError), or I get the big black rectangle instead of the image. I'm sure I'm just missing the wood for the trees, but it's very frustrating, and after about two weeks of this I'm fast running out of ideas. The only thing I haven't tried is to output the image as a bitmap file, then read it back in again using LoadImage. But that's horribly clumsy, and more importantly it would be very slow with such big images.


------------------
--Dan

[Jules Marchildon]

Dan,

You may want to relook what you are passing to this function "result = LoadJPG(file, dib, bits)"...

Function LoadJPG(ByRef cDib As cDIBSection, ByVal sFile As String, ByVal jpg_scale As Long) As LONG

Regards,
Jules