Invalid Image File / Original Image Size

[Phil Davis]

Hi Ralph,

Certainly Klaus's approach will work. Here is another that works.

As you know, image files have "signatures" in their headers to identify 
what kind of files they are:

    https://en.wikipedia.org/wiki/List_of_file_signatures
    (the "ISO 8859-1" column)


Once you know the signatures of the image file types you want to allow, 
you could do something like this:

on mouseUp
     answer file "Pick an image file:"
     if it is empty then exit to top

     answer isSupportedImage(it)
end mouseUp


function isSupportedImage pPath
     # Allow JPG, PNG and GIF images.

     put byte 1 to 12 of url ("binfile:" & pPath) into tHeader
     switch
         case "JFIF" is in tHeader
         case "PNG" is in tHeader
         case "GIF" is in tHeader
             return true
             break
         default
             return false
             break
     end switch
end isSupportedImage


I have used this approach in projects before and it seems to work reliably.

Phil Davis



On 2/17/20 1:08 PM, Ralph DiMola via use-livecode wrote:
> What's the best way to know if I set the filename of an image control and
> the file is either not an image or in an unsupported format? I'm getting
> https links to unknown images so I check images before app deployment.
>
> After resizing an image is there a way to know the original dimensions? Just
> wondering? I now save the original x/y sizes in properties so I know them
> after a resize.
>
> Thanks
>
> Ralph DiMola
> IT Director
> Evergreen Information Services
> rdimola at evergreeninfo.net
>
>
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-- 
Phil Davis
503-307-4363