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**William Burns** · 17 Nov 2008, 07:10 PM

Not sure if this is what you mean, but I have a application that sends/receives a bitmap string and loads the bitmap without having to save it to a temp file first. The function listed below will load the bitmap and return a bitmap handle you can use to display it. (I have never used the built in GRAPHICS commands so I can't say for sure that they will work with it, but I had no problems using the returned bitmap handle with SelectObject() in to a DC.) You should be able to modify it to suit your needs.

Code:

%LR_LOADFROMSTRING = -1
Function MemCopyD(ByVal src AS Long, ByVal dst AS Long, ByVal ln AS Long) AS Long
#Register None
   ! cld
   ! mov esi, src
   ! mov edi, dst
   ! mov ecx, ln
   ! shr ecx, 2
   ! rep movsd
   ! mov ecx, ln
   ! And ecx, 3
   ! rep movsb
   Function = 0

End Function
'==~==~==~==~==~==~==~==~==~==~==~==~==~==~==~==~==~==~==~==~==~==~==~==~==~==~==~==~==~==~==~==~==
Function BMPload(sBmp As String, ByVal flag As Long, hPalette As Long ) As Dword
   Local iRet     As Long
   Local dRet     As Dword
   Local hFile    As Long
   Local dcWindow AS Long
   Local dcBitmap As Long
   Local bmf      AS BITMAPFILEHEADER Ptr
   Local bmi      AS BITMAPINFO Ptr
   Local bm       As Bitmap
   Local hBmp     As Long

   bm.bmBits = 0  'make sure the pointer is init 0

   Try

      Select Case flag
         Case %LR_LOADFROMFILE
            hFile = FreeFile
            Open sBmp For Binary AS hFile
            If Err = 0 Then Get$ hFile, Lof(hFile), sBmp
            Close #hFile
         Case %LR_LOADFROMSTRING
         Case Else
            'MSGBOX "Invalid flag. Pls use %LR_LOADFROMFILE or %LR_LOADFROMSTRING", %MB_ICONSTOP, "loadBmp"
            Exit Function
      End Select
      If sBmp = "" Then Exit Function
      If Len( sBmp ) < ( Len(BITMAPFILEHEADER) + Len( BITMAPINFO ) ) Then Exit Function
      bmf = StrPtr(sBmp)
      bmi = bmf + Len(BITMAPFILEHEADER)
      If @bmi.bmiHeader.biBitCount = 8  Then
         hPalette = @bmi.bmiHeader.biClrUsed
         If hPalette = 0 Then hPalette = 256
         @bmi.bmiHeader.biClrImportant = MakLng(&H300, hPalette)
         hPalette = CreatePalette (ByVal VarPtr(@bmi.bmiHeader.biClrImportant))
      End If
      dcWindow = GetDC(%HWND_DESKTOP)
      If dcWindow Then
         dcBitmap = CreateCompatibleDC(dcWindow)
         If dcBitmap Then
            hBmp = CreateDIBSection(dcBitmap, @bmi, %DIB_RGB_COLORS, 0, 0, 0)
            If hBmp Then
               'Call GlobalLock(hBmp) 'says invalid handle so I dont think we need this for a bitmap object handle
               dRet = SelectObject(dcBitmap, hBmp)
               If dRet = %GDI_ERROR Or dRet = 0 Then
                  MyMsg "SelectObject Error in BMPLoad function."
               Else
                  If GetObject(hBmp, SizeOf(bm), bm) Then
                     If bm.bmBits <> 0 Then
                        Call MemCopyD(StrPtr(sBmp) + @bmf.bfOffBits, bm.bmBits, (bm.bmWidthBytes * bm.bmHeight))
                     Else
                        MyMsg "Pointer Error in BMPLoad function.   bm.bmBits=0"
                     End If
                  Else
                     MyMsg "GetObject Error in BMPLoad function."
                  End If
               End If
            Else
               iRet = GetLastError()
               MyMsg "CreateDIBSection Error in BMPLoad function.  Err=" + WinErrMsg(iRet)
            End If
         Else
            MyMsg "CreateCompatibleDC Error in BMPLoad function."
         End If
      Else
         MyMsg "GetDC Error in BMPLoad function."
      End If
      If dcBitmap Then Call DeleteDC(dcBitmap)
      If dcWindow Then Call ReleaseDC(%HWND_DESKTOP, dcWindow)
      Function = hBmp
   Catch
      MsgBox Error$(Err),,"BMPLoad trapped Error"
   End Try

End Function
'==~==~==~==~==~==~==~==~==~==~==~==~==~==~==~==~==~==~==~==~==~==~==~==~==~==~==~==~==~==~==~==~==

FYI, the MyMsg function just displays a message in the log, change them to msgbox statements if you want.

**Norm Shupe** · 17 Nov 2008, 09:08 PM

Thanks for the response, William. Unfortunately, I am currently not familar enough with the API to immediately adapt your function to my problem. The function certainly looks applicable as I already have the BMP loaded into the byte array ( MapArray ) and could create the BMP string to pass to your code. It is a shame that the PB statement :

Code:

GRAPHIC BITMAP LOAD CompositePath,1280,1280 TO BMPHandle

cannot accept the BMP in a string form and avoid the entire issue. I will continue to try and understand how I might use your function in my application.

**Michael Mattias** · 18 Nov 2008, 08:41 AM

Is there some alternate approach which would avoid the need to firstly, save the contents of MapArray to disc

CreateBitmapIndirect() ==> hBMP

Whether or not "any valid hBMP" is usable with the PB GRAPHICS commands unknown (to me, anyway).

But what's so wrong/bad about saving to disk first? Windows itself does this zillions of times each day. And YOU can go one better by actually DELETING the temp disk file, which Windows is not really good about doing, as demonstrated by a directory of my temp folder.

MCM

**Norm Shupe** · 18 Nov 2008, 09:57 AM

Thanks for the suggestion, Mike. The motivation for trying to bypass to store to disc --- reload from disc --- procedure is computational speed. This application is a real-time map display, driven by a GPS receiver, in which one must decompress the appropriate map image from a library, create a 1280 by 1280 pixel BMP, rotate the BMP to the direction of travel, and overlay some complex symbology, all in about 1/2 second. I am looking to eliminate any apparently wasteful operations, one of which seems to be the store/reload procedure.

**Paul Dixon** · 18 Nov 2008, 10:12 AM

Norm,
if you process your 256 colour bitmap and lookup table into a 32 bit array of pixel values then you can copy that 32bit array into a bitmap using GRAPHIC SET BITS. I'm not sure how much time you might save because when writing a file to disk, immediately reading it back then deleting it, the file is almost certainly never written to disk but is held in cache for the duration.

Paul.

**Norm Shupe** · 18 Nov 2008, 11:07 AM

I'm not sure how much time you might save because when writing a file to disk, immediately reading it back then deleting it, the file is almost certainly never written to disk but is held in cache for the duration

This is an interesting comment, Paul. Actually, I never delete the temp file. I just overwrite it during the next processing cycle. I just timed the write/readback statements and got about 50 milliseconds for the process which seems like a lot if cache is being used. I used the Timer function which I suppose is somewhat suspect. How would one be sure that your cache assumption is correct?
Norm

**Michael Mattias** · 18 Nov 2008, 01:01 PM

If all bitmaps are the same size, why not use Paul's idea re GRAPHIC SET BITS?

Code:

  GRAPHIC BITMAP LOAD  dummyfileofcorrectsize  to hBMP 
  DO 
    Wait for next command or whatever
    GetNewBmpArrayBits 
    GRAPHIC SET BITS of hBMP =  New data 
    RENDER
  LOOP

MCM

**Norm Shupe** · 18 Nov 2008, 01:44 PM

Yes Mike. I am trying to work Paul's idea into the problem but I am having some trouble with the LUT issue. The computed BMPs are 256 color images and the GRAPHIC BITMAP LOAD and GRAPHIC SET BITS convert them to full-color BMPs. My image rotation algorithm is designed for 256 color images and conversion to a rotation of full-color images will really slow that aspect of the process. I haven't given up, however.

Do you have any thoughts on Paul's cache assumption and my 50 millisecond timing result on a 3GHz machine?

Norm

**Michael Mattias** · 18 Nov 2008, 03:59 PM

Do you have any thoughts on Paul's cache assumption and my 50 millisecond timing result on a 3GHz machine?

I trust Paul, he's better at this kind of thing than am I.

Of course, you could always learn the four or five API calls you'd need to do this whole job without relying on any of the GRAPHICS statements.

Or, engage someone to develop exactly what you need (Positions Wanted/Offered Forum). Imagine the "one line function call" you'd like to make to refresh the screen, and see if someone can write it that way for you at a reasonable price.. e.g.....

I want to write:

Code:

 
  CALL UpdateMyScreen (mapDataArray(), hWnd)

Please provide price,delivery and warranty information."

MCM

**Paul Dixon** · 19 Nov 2008, 07:09 AM

Norm,
looks like I was wrong (perhaps not, see later message). It's only while the file is open that it remains in the cache, as soon as it's closed the cache gets flushed to disk so it takes around 30ms on my computer, about consistent with the disk speed.

The 2 alternatives that come to mind are:
1) set up a RAM drive on your computer and use that. I've never tried it but details are available on the internet, e.g.here:

Page not found – PicoBay

http://www.picobay.com/projects/2006/06/how-to-make-windows-xp-ram-disk-drive.html

2) do the conversion yourself in memory without using files.
The format of the original BMP file is known. The format you need to convert it to is as described in the PB documentation under "GRAPHIC SET BITS"
You need to extract the pallette from the original BMP, create a new string of size width*height*4+8 bytes. Fill in the height and width as the first 8 bytes then for each pixel in the original, look up the pixel value, look up the correcponding 32 bit colour from the pallette, put that colour into the string.
Then, use GRAPHIC SET BITS to write that to the graphic window.

That should be a lot quicker than files.

Paul.

**Gösta H. Lovgren-2** · 19 Nov 2008, 09:06 AM

Another Ram Drive location to try is:http://www.epinions.com/content_2941624452

What Do I Need?
Before I start, I must make this clear, this is aimed at Windows 98 and higher users, and secondly, there are two software programs available, RAMDisk and RAMDiskNT. The first one only offers a maximum of 30Mb, the latter offers up to 4Gb. ...

I just set up the (free) 30 mb drive and it shows in Explorer as Z drive. Very good instructions on the page above. What I did was C&P the instructions to a text editor (saved them to the sane folder the driver is in) before starting and then when had to reboot to initiate the driver, it was easy to continue.

Dunno if 30mb will be enough for you, Norm. If not the page points to the 4gig driver but it costs 50 bucks (after 100 uses free trial).

Another thought. If a Ram Drive doesn't work out (not big enough or ...), then maybe a flash drive. They come in pretty big sizes today (multi gig I think) and prices are coming down pretty fast. I think they're a lot faster than disk drives as well.

**Norm Shupe** · 19 Nov 2008, 10:44 AM

Paul
Thanks for your suggestions. Last night I tried a test to get some idea how long it might take to assemble the BMP string for a 1280 by 1280 pixel image and a dummy pixel color "ABCD". The quickest method seem to be to use Peek and Poke and the result was about 350 milliseconds. The GRAPHIC GET BITS command to assemble such a string works a lot faster than that so I am somewhat dismayed by my inexperienced approach.

Code:

   Global BMPString as String*6553600
   Global PixelString as String*4
 
   PixelString = "ABCD"
   SourceAddress = VARPTR(PixelString)
   ArrayLength=4
 
   BMPStringAddress = VARPTR(BMPString)
   LastAddress=BMPStringAddress + 6553596
 
   FOR TargetAddress = BMPStringAddress TO LastAddress STEP 4
      POKE$ TargetAddress, PEEK$(SourceAddress, ArrayLength)
   NEXT TargetAddress

**Norm Shupe** · 19 Nov 2008, 03:52 PM

Hello again, Paul
The report on your RAM disc idea is a big plus. There were some concerns expressed on the site listed in your last message as well as on the RAM disc site provided by Gosta that made me a bit nervous. I found the site below which provided a Microsoft-certified installation for all version of Vista and XP. It's cost is a modest $35 and it installed without the slightest hitch. Double click on the installation EXE and everything is roses thereafter. It is lighting fast and will save the constant pounding of the hard disc by the cyclic storage of the 4MB image file (i.e., on the order of twice per second driven by the GPS update rate). It is a brute force but functionally beautiful solution. Thanks to all for the assistance. Norm

Code:

[URL]http://www.superspeed.com/download/trialversions.php[/URL]

**Paul Dixon** · 21 Nov 2008, 06:33 PM

Norm,
good you got it sorted.
I didn't have time to look into it last week but the cache thing has been on my mind.
I've now investigated and the data is cached as I first thought BUT it is still written to disk as well. The time to write to disk is therefore still significant but the time to read it back is much less. On my system the data can be written to disk at around 60MBytes/sec (the disk speed) but it's read back at over 500MB/sec (the cache speed). So the data is cached but the benefit is only seen on reading.

This is probably not of interest to you now snce a RAM disk will be fast in both reading and writing and so should be significantly faster overall.

Paul.

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