Read the width of a image??

I need to read the with of a gif or a jpg, before the page has finished loaded. This is because I have to set the width of a floating div to get the layout right.

/Smirre

I'm not sure if this will work but its worth a try...

<script language="javascript" type="text/javascript">
document.write '<img src="image.jpg">';
// code to get width
</script>

...and put it in the head of the document as this is loaded before the rest of the page

Can I read the image as an object and then read the width of the object???


/Smirre

This doesn't work?

http://www.vbforums.com/showthread.php?threadid=153714

Yes, I got it to work, but I have a image and a image text. The Image is inside a div, the text is in another div, and the two divs is inside the div that floats.

But witout setting the size, the div took up all the width of the page. And setting the width with % and pixels to 1 made the div with the text act funny in netscape.

Have found a solution, reading the image file byte wise with asp and setting the width with the style tag.


The image width cant be read with javascript on a page load. Images are not loaded until the code on the page has loaded, this is in netscape only...

/Smirre

Wow... this is entirely too complicated.

Remember that CSS width is only the width of the content, and excludes border, padding, and margin. Also, I believe images fall under the replaced content rules.

Quote:

---

Originally posted by Smirre
Yes, I got it to work, but I have a image and a image text. The Image is inside a div, the text is in another div, and the two divs is inside the div that floats.

But witout setting the size, the div took up all the width of the page. And setting the width with % and pixels to 1 made the div with the text act funny in netscape.

Have found a solution, reading the image file byte wise with asp and setting the width with the style tag.


The image width cant be read with javascript on a page load. Images are not loaded until the code on the page has loaded, this is in netscape only...

/Smirre

---

Please, can you post the code to do this?

Maybe this link can be of help. Is this what you used?

http://www.4guysfromrolla.com/webtec...imgsz.asp.html

From the link above, the code that could be used:

VB Code:

':::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
  ':::                                                             :::
  ':::  This function does most of the real work. It will attempt  :::
  ':::  to read any file, regardless of the extension, and will    :::
  ':::  identify if it is a graphical image.                       :::
  ':::                                                             :::
  ':::  Passed:                                                    :::
  ':::       flnm        => Filespec of file to read               :::
  ':::       width       => width of image                         :::
  ':::       height      => height of image                        :::
  ':::       depth       => color depth (in number of colors)      :::
  ':::       strImageType=> type of image (e.g. GIF, BMP, etc.)    :::
  ':::                                                             :::
  ':::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
  function gfxSpex(flnm, width, height, depth, strImageType)
 
     dim strPNG 
     dim strGIF
     dim strBMP
     dim strType
     strType = ""
     strImageType = "(unknown)"
 
     gfxSpex = False
 
     strPNG = chr(137) & chr(80) & chr(78)
     strGIF = "GIF"
     strBMP = chr(66) & chr(77)
 
     strType = GetBytes(flnm, 0, 3)
 
     if strType = strGIF then               ' is GIF
 
        strImageType = "GIF"
        Width = lngConvert(GetBytes(flnm, 7, 2))
        Height = lngConvert(GetBytes(flnm, 9, 2))
        Depth = 2 ^ ((asc(GetBytes(flnm, 11, 1)) and 7) + 1)
        gfxSpex = True
 
     elseif left(strType, 2) = strBMP then      ' is BMP
 
        strImageType = "BMP"
        Width = lngConvert(GetBytes(flnm, 19, 2))
        Height = lngConvert(GetBytes(flnm, 23, 2))
        Depth = 2 ^ (asc(GetBytes(flnm, 29, 1)))
        gfxSpex = True
 
     elseif strType = strPNG then           ' Is PNG
 
        strImageType = "PNG"
        Width = lngConvert2(GetBytes(flnm, 19, 2))
        Height = lngConvert2(GetBytes(flnm, 23, 2))
        Depth = getBytes(flnm, 25, 2)
 
        select case asc(right(Depth,1))
           case 0
              Depth = 2 ^ (asc(left(Depth, 1)))
              gfxSpex = True
           case 2
              Depth = 2 ^ (asc(left(Depth, 1)) * 3)
              gfxSpex = True
           case 3
              Depth = 2 ^ (asc(left(Depth, 1)))  '8
              gfxSpex = True
           case 4
              Depth = 2 ^ (asc(left(Depth, 1)) * 2)
              gfxSpex = True
           case 6
              Depth = 2 ^ (asc(left(Depth, 1)) * 4)
              gfxSpex = True
           case else
              Depth = -1
        end select
 
 
     else
 
        strBuff = GetBytes(flnm, 0, -1)     ' Get all bytes from file
        lngSize = len(strBuff)
        flgFound = 0
 
        strTarget = chr(255) & chr(216) & chr(255)
        flgFound = instr(strBuff, strTarget)
 
        if flgFound = 0 then
           exit function
        end if
 
        strImageType = "JPG"
        lngPos = flgFound + 2
        ExitLoop = false
 
        do while ExitLoop = False and lngPos < lngSize
 
           do while asc(mid(strBuff, lngPos, 1)) = 255 and lngPos < lngSize
              lngPos = lngPos + 1
           loop
 
           if asc(mid(strBuff, lngPos, 1)) < 192 or asc(mid(strBuff, lngPos, 1)) > 195 then
              lngMarkerSize = lngConvert2(mid(strBuff, lngPos + 1, 2))
              lngPos = lngPos + lngMarkerSize  + 1
           else
              ExitLoop = True
           end if
 
       loop
       '
       if ExitLoop = False then
 
          Width = -1
          Height = -1
          Depth = -1
 
       else
 
          Height = lngConvert2(mid(strBuff, lngPos + 4, 2))
          Width = lngConvert2(mid(strBuff, lngPos + 6, 2))
          Depth = 2 ^ (asc(mid(strBuff, lngPos + 8, 1)) * 8)
          gfxSpex = True
 
       end if
                   
     end if
 
  end function

why dont u put the image in a layer with no width specifacation. then the layer will be exactly same width. Make this layer invisible and then just use the layer width as the image width

Because when you change the width of the layer you must also change the height of the image... In order to calculate the resizing factor, you need those properties.

In my case, I do not want an image to be uploaded to my site with dimensions larger than a variable integer. Also, when I resize, I want either the width or the height to me less or equal to a variable size. Therefore I need to know the properties and calculate the resizing factor...