Last updated at 11:44 am UTC on 22 October 2019
"Read a Form or ColorForm from given file, using the first byte of the file to guess its format.
Currently handles: GIF, uncompressed BMP, and both old = and new DisplayObject writeOn: formats, JPEG, and PCX.
Return nil if the file could not be read or was of an unrecognized format."
| firstByte |
firstByte := aBinaryStream next.
firstByte = 1 ifTrue: [
"old Squeakform format"
^ self new readFromOldFormat: aBinaryStream].
firstByte = 2 ifTrue: [
"new Squeak form format"
^ self new readFrom: aBinaryStream].
"Try for JPG, GIF, or PCX..."
"Note: The following call closes the stream."
^ ImageReadWriter formFromStream: aBinaryStream
theUrl := 'https://upload.wikimedia.org/wikipedia/commons/thumb/1/11/Squeak-x11.png/617px-Squeak-x11.png'.
Form fromBinaryStream: (WebClient httpGet: theUrl) content asByteArray readStream.
If it is known that the stream is over a jpg file you may directly call
JPEGReadWriter2 formFromStream: aStream
It is not necessary to look for a particular reader.