imagex

[Michael Mattias]

can't see the joint but if I ask bmp that the only thing show.
( I try gif or jpeg in the PB forum and FF forum with no real result )

 nFile& = FREEFILE
 OPEN "myimage.bmp" FOR BINARY AS nFile&
 GET #nFile&, 19, nWidth&
 GET #nFile&, 23, nHeight&
 CLOSE nFile&

The real question I can"t find no demo or source or documentation

The reason this code is not too easy to figure out is because it is written using "magic numbers". Had it been written without magic numbers, you could see what it is doing. Let's see if we can do that.

First, let's look at the way bitmap files are stored on disk:

Bitmaps should be saved in a file that uses the established bitmap file format and assigned a name with the three-character .bmp extension. The established bitmap file format consists of a BITMAPFILEHEADER structure followed by a BITMAPINFOHEADER, BITMAPV4HEADER, or BITMAPV5HEADER structure

If we translate that into user defined types representing the start of a file we get...

UNION BITMAPUNION
  BMIH  AS BITMAPINFOHEADER
  BMV4H AS BITMAPV4HEADER
  BMV5H As BITMAPV5HEADER
END UNION

TYPE BITMAPSTARTOFFILE
 BMFH  AS BITMAPFILEHEADER  ' size = 14 
 BMU   AS BITMAPUNION
END TYPE

The three members of BITMAPUNION as well as the BITMAPFILEHEADER are defined in your Win32API.INC file.

But that is a lot more complex than we need for these purposes.

When you inspect the three UNION members, you find in all cases the width and height of the bitmap are located at offsets 4 and 8 respectively of the BITMAPINFOHEADER, BITMAPv4HEADER or BITMAPV5HEADER; which, when you add the 14 bytes for the BITMAPFILEHEADER, puts the width and height at offsets 18 and 22.. which correspond to 'positions' 19 and 23 (the 'magic numbers!') when the file is opened for BINARY with the default BASE of 1.

Since we don't really need all the info from the UNION, we can simplify the type we use for the start of the file...

TYPE BITMAPSTARTOFFILE
  BMIH    AS BITMAPINFOHEADER
  Unused  AS LONG     '  actually structure size, but we don't need that. 
  nWidth  AS LONG
  nHeight AS LONG 
END TYPE

So a little better - that is, more understandable - code might read...

   LOCAL BMSOF AS BITMAPSTARTOFILE   ' the simple version above 


   nFile& = FREEFILE
   OPEN     "myimage.bmp" FOR BINARY AS nFile&
   GEt       #nFile, , BMSOF          '  read the data at start of file
   CLOSE     nFile&                    ' done with file, close it 
   ' get our values from the file data in BMSOF:
   nWidth&  =   BMSOF.nWidth
   nHeight& =   BMSOF.nHeight

Does that make it a bit more clear what that "magic number" code is doing?


FWIw, I think I'd create a "Write once, use many" FUNCTION or SUB for this

FUNCTION GetBitmapWidthandHeightFromFile (szBmpFile AS ASIICZ, nWidth  as Long, nHeight As LONG) AS LONG

   LOCAL BMSOF AS BITMAPSTARTOFILE   ' the simple version above 
   LOCAL nFile AS LONG, fv AS LONG

   ON ERROR RESUME NEXT 

   nFile   = FREEFILE
   OPEN     "myimage.bmp" FOR BINARY AS nFile&
   IF ISFALSE ERR THEN 
      GET      #nFile, , BMSOF          '  read the data at start of file
      CLOSE     nFile                    ' done with file, close it 
      nWidth =   BMSOF.nWidth
      nHeight =   BMSOF.nHeight
      fv =        0                 ' success!
   ELSE
      fv = ERRCLEAR                 ' assign and reset 
   END IF

   FUNCTION = fv 

END FUNCTION

  CALL GetBitmapWidthAndHeightFromFile ("myimage.bmp", nWidth, nHeight) to lresult

  IF ISFALSE lresult THEN 
     we got the width and height OK, do cool stuff
  ELSE
     MSGBOX USING$("Error getting Bitmap width and height # &", lResult, ERROR$(lresult)), %MB_ICONHAND, "Bitmap file access error" 
  .....

MCM

[Elias Montoya]

one more question.
many programmer use this variable ( lRslt ) What is the real definition.
Thanks

Long Result. The result of a function stored in a Long (32 BIT integer) variable.

[Chris Holbrook]

If you want to use image types other than BMP you will have to load them using a suitable library such as GDIPlus. There are plenty of examples here, this one might be useful to you, good luck!

[Robert Duham]

Hi, I try to find more information on imagex, according the online manual,
CONTROL SET IMAGEX hDlg, id&, newimage$
after you use
CONTROL ADD IMAGEX, hDlg, id&, image$, x, y, xx, yy [, [style&] [, [exstyle&]]] [[,] CALL callback]
I read about bitmap and icon select.
%SS_BITMAP
Display only bitmap images. Also see %SS_ICON. (persistent)
%SS_ICON
Display only icon images. Also see %SS_ICON. (persistent)
((or you may choose not to specify the image format at all.))
I got wrong that suggest it support other format.
-------------------------------------
Now I'm lost
The only explanation is load bitmap
I can't see the joint but if I ask bmp that the only thing show.
( I try gif or jpeg in the PB forum and FF forum with no real result )
nFile& = FREEFILE
OPEN "myimage.bmp" FOR BINARY AS nFile&
GET #nFile&, 19, nWidth&
GET #nFile&, 23, nHeight&
CLOSE nFile&
The real question I can"t find no demo or source or documentation.
IF PB support (gif,tiff,jpeg,png or gig animated) seem only bmp.
The EZGUI seem more advence in documentation said support gif
with no documentation.
In real basic the image is very close to html form like src img.
we load the file to define windows like control add imagex.
If you find some info how load and use imagex with format file support.

one more question.
many programmer use this variable ( lRslt ) What is the real definition.
Thanks