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vtol
Valued Contributor
Joined: 05 Feb 2004
Posts: 656
Location: Eastern Indiana
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 Posted: Thu Dec 28, 2006 1:19 am Post subject: GET pixel size without loading a pic? hmm |
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GET pixel size without loading a pic?
I would like to be able to get the pixel width and pixel height of an imagefile within my VDS5 program without having to get this information inside a paint program.
EXAMPLE:
That way I can adjust the picture to fit in a frame(vds shape) in my vds5 dialog by way of one of the vds DLLs.
Thanks for looking.. and appreciate any input at all  |
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vtol
Valued Contributor
Joined: 05 Feb 2004
Posts: 656
Location: Eastern Indiana
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| Posted: Thu Dec 28, 2006 1:53 am Post subject: |
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I havent messed with binary for years, but heres something I found, the 4th and 5th byte is where the imagefile tells its pixel size.
Below code:
This example shows how to get size information from a GIF or JPG file without loading the whole picture in Visual Basic 6.
Subroutine GetGIFInfo gets the GIF file's size and then reads its first five bytes. The first three bytes should be "GIF" if this is a GIF file.
The next two bytes gives the image's width and the two after that give its height.
| Code: | Private Function GetGIFInfo(ByVal FileName As String) As _
BITMAPINFO
Dim bChar As Byte
Dim i As Integer
Dim dotPos As Integer
Dim Header As String
Dim blExit As Boolean
Dim a As String, b As String
Dim ImgSize As String
Dim fnum As Integer
Dim ImgWidth As Integer
Dim ImgHeight As Integer
On Error Resume Next
fnum = FreeFile
Open FileName For Binary As #fnum
ImgSize = LOF(fnum) / 1024
dotPos = InStr(ImgSize, ",")
ImgSize = Left(ImgSize, dotPos - 1)
For i = 0 To 5
Get #fnum, , bChar
Header = Header + Chr(bChar)
Next i
If Left(Header, 3) <> "GIF" Then
MsgBox FileName & ": not a GIF file"
Close #fnum
Exit Function
End
End If
Get #fnum, , bChar
a = a + Chr(bChar)
Get #fnum, , bChar
a = a + Chr(bChar)
ImgWidth = CInt(Asc(Left(a, 1)) + 256 * Asc(Right(a, _
1)))
Get #fnum, , bChar
b = b + Chr(bChar)
Get #fnum, , bChar
b = b + Chr(bChar)
ImgHeight = CInt(Asc(Left(b, 1)) + 256 * Asc(Right(b, _
1)))
Close #fnum
With ImageInfo
.Width = ImgWidth
.Height = ImgHeight
End With
GetGIFInfo = ImageInfo
End Function |
Hope this helps  |
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vtol
Valued Contributor
Joined: 05 Feb 2004
Posts: 656
Location: Eastern Indiana
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| Posted: Thu Dec 28, 2006 2:59 am Post subject: |
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Heres what it looks like below in an example sunset.gif pic:
The pixel width and height should be in the highlighted box 4 and 5.
I can't remember how to read binary 
Last edited by vtol on Thu Dec 28, 2006 8:40 pm; edited 1 time in total |
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DaveR
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Joined: 03 Sep 2005
Posts: 413
Location: Australia
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| Posted: Thu Dec 28, 2006 3:39 am Post subject: |
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You can ease up on the extra info 
I've got some example code here that I'm just tidying up and will post shortly...
BTW the width is the 2003 on the first line, and the height is the 5802 also on the first line.
_________________
cheers
Dave |
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DaveR
Valued Contributor
Joined: 03 Sep 2005
Posts: 413
Location: Australia
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| Posted: Thu Dec 28, 2006 3:53 am Post subject: |
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Ok, here's what I've got. But it's only working on small gif sizes. I'm not 100% today so I'm trouble concentrating (you'll have to get someone else to fill in the blanks).
| Code: |
#DEFINE FUNCTION,Hex2Dec
%%File = C:\Temp\test.gif
if @file(%%File)
binfile open,1,%%File,READ
# 0x00 - ID
%x = @binfile(read,1,TEXT,3)
if @unequal(%x,GIF)
warn File is not a GIF image! ,
end
# 0x06 - Width
binfile seek,1,6
%x = @binfile(read,1,HEX,1)
rem %x = @prod(1,@trim(@substr(%x,1,2))@trim(@substr(%x,4,5)))
rem %x = @trim(@substr(%x,1,2))@trim(@substr(%x,4,5))
%x = @trim(@substr(%x,1,2))
%y = @hex2dec(%x)
%%Width = %y
# 0x06 - Height
binfile seek,1,8
%x = @binfile(read,1,HEX,1)
%x = @trim(@substr(%x,1,2))
%y = @hex2dec(%x)
%%Height = %y
binfile close,1
info GIF Width and Height is %%Width x %%Height
else
warn %%File not found! ,
end
stop
#-----------------------------------------------------------------------------
# USER DEFINED FUNCTIONS
:Hex2Dec
%%hex = %1
%%decimal = 0
%%decx = 1
repeat
%%decchar = @upper(@substr(%%hex,%%decx,%%decx))
%%decpos = @fsub(@pos(%%decchar,"0123456789ABCDEF"),1)
%%decimal = @fadd(@fmul(%%decimal,16),%%decpos)
%%decx = @succ(%%decx)
until @greater(%%decx,@len(%%hex))
exit %%decimal |
_________________
cheers
Dave |
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vtol
Valued Contributor
Joined: 05 Feb 2004
Posts: 656
Location: Eastern Indiana
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| Posted: Thu Dec 28, 2006 4:06 am Post subject: |
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allright Dave Bin awesome
I'll play with it on some .gif and .jpg files in a bit.
Nice job and thanks a godzillion for the great help, this will be nice when all done someday I'm sure.
A DLL would work too, but I couldnt find one that GETs pixel width and height.
Thanks again Dave |
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PGWARE
Web Host
Joined: 29 Dec 2001
Posts: 1565
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| Posted: Thu Dec 28, 2006 5:12 am Post subject: |
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| VDSCONV.dll will get the width/height for bitmap, gif, and jpeg. |
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vtol
Valued Contributor
Joined: 05 Feb 2004
Posts: 656
Location: Eastern Indiana
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| Posted: Thu Dec 28, 2006 8:46 pm Post subject: |
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I updated the pic.
Thanks PGWARE, never knew that one would convert and read pixel size.
Thats great, I'll try it today.
Dave, I tried your code and the height worked but the width did not(I know you said you were tired).
I'll tinker with your code and see if I can get the width working, cause it would be fun.
Thank you both very very much  |
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DaveR
Valued Contributor
Joined: 03 Sep 2005
Posts: 413
Location: Australia
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| Posted: Fri Dec 29, 2006 6:48 am Post subject: |
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| vtol wrote: | | Dave, I tried your code and the height worked but the width did not(I know you said you were tired). |
The example code I posted would only work with small widths and heights that only used the 1st byte. i.e. 20 instead of 2003. The problem is that, compared to all previous hex files I've coded for, GIFs seem to use big endien (or little endien? - never did really learn the difference) for the file width and height. i.e. Other files I've played with would use '00 A0' for a size of 160 but GIFs use 'A0 00'. If you convert 'A0 00' to decimal you end up with 40960. But if you convert just A0 you get 160. So if the width or height is greater than 249 you need to read the 2 bytes and convert to decimal. But this then gives the wrong answer if the width is less than 250.
| Code: | %x = @binfile(read,1,HEX,2)
%x = @trim(@substr(%x,1,2))@trim(@substr(%x,4,5))
%y = @hex2dec(%x) |
| vtol wrote: | | I'll tinker with your code and see if I can get the width working, cause it would be fun. |
Yeah, I prefer to do everything in VDS if I can, to avoid the need to included large library files. And at 238KB vdsconv.dll is large by my standards. But the source is included so you 'could' compile a smaller dll with just what you needed.
_________________
cheers
Dave |
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