doc etc.

scsh/image-info/README

@@ -0,0 +1,97 @@
+sunterlib/scsh/image-info -- Extracting Vital Stats from Images
+
+Loose port of small parts from Marco Schmidt's public domain ImageInfo 1.3
+Java program.  The port supports gif, jpeg, png images and extracts 
+* the width and height in pixels, 
+* maybe the physical width and height in dpi,
+* the (unreliable) colour depth (#bits / pixel),
+* a symbolic format id: GIF87A, GIF89A, JPEG, PNG.
+All numbers are integers.  The colour depth may deviate from the actual
+value in multi-part gifs.  (It is taken from the global header, but
+local palettes may reset, typically increase, that value.)
+
+The original code, which does much more, is at
+http://www.geocities.com/marcoschmidt.geo/image-info.html
+
+Typical use:  in web-authoring, generate the width and height tags of 
+inline images programmatically, like so:
+
+;; ,open image-info
+(receive (w h) (with-input-from-file "pix/herb.jpg"
+                 (lambda () (image-dimension (current-input-port))))
+  `(img ((src "pix/herb.jpg")
+         (width ,w) (height ,h)
+         (alt "Enter!"))))
+
+--> (img ((src "pix/herb.jpg") (width 632) (height 474) (alt "Enter!")))
+
+                                  *
+
+Procedures
+
+exported by structure IMAGE-INFO.  IMAGE-DIMENSION is the convenient
+user interface for the most common usage:  getting pixel width and
+height.  Some procedures refer to ``b.s.''s.  These are described at
+bottom.
+
+
+(image-dimension img) --> [w h]
+
+Synopsis:  Extract the (numeric) width W and height H (in pixels) from
+the byte source (input port, file descriptor, byte-vector, b.s.(*))
+IMG -- or signal an error.
+
+                                  *
+                                
+(get-image-info bs) --> info | #f
+
+Synopsis:  Extract information on the image represented by b.s.(*) BS
+and return an image-info record or #f.  (Don't believe in the colour
+depth for gifs.)
+
+                                  *
+
+(image:info-format info) --> format | #f
+Get the symbolic format id from image-info record INFO.
+
+(image:info-depth info) --> depth | #f
+Get the colour DEPTH (#bits/pixel) from image-info record INFO.
+
+(image:info-width/pixel info) --> w | #f
+(image:info-height/pixel info) --> h | #f 
+Get the pixel width W resp. height H from image-info record INFO.
+
+(image:info-width/dpi info) --> width | #f
+(image:info-height/dpi info) --> height | #f 
+Get the physical width W resp. height H in dots per inch from INFO.
+
+                                 *
+
+(*) Creating and accessing ``byte streams''
+
+Byte-streams, or b.s.s for short, are random-access lazy byte sources.
+The image-info project doesn't commit to the current implementation,
+i.e. create and access b.s.s by the procedures below or blame yourself.
+
+(inport->byte-stream in) --> bs
+
+Synopsis:  Convert the input port (or file descriptor) IN to a
+b.s. BS.  (The BS will read from IN as needed.  It doesn't duplicate
+or close IN.) 
+
+                                 *
+
+(byte-vector->byte-stream bv) --> bs
+
+Synopsis: Convert the byte-vector bv to a b.s. BS.
+
+                                 *
+
+(segment-byte-stream bs start end) --> [bv bs']
+
+Synopsis:  Segment the b.s. BS into the first [start:end) bytes in the
+byte-vector BV and the following [end:*) bytes in the b.s. BS', or get
+the little that's there up to eof.  BV may be short, BV and BS' may be
+empty.
+
+                                oOo

scsh/image-info/imxize.scm

@@ -1,54 +1,6 @@
 ; Copyright (c) 2003 RT Happe <rthappe at web de>
 ; See the file COPYING distributed with the Scheme Untergrund Library
-
+; See the file README for documentation.
-#!
-Loose port of small parts from Marco Schmidt's public domain ImageInfo 1.3
-Java program.  The original code is at
-http://www.geocities.com/marcoschmidt.geo/image-info.html
-
-Synopses
-
-Extracting the image dimension etc.
-
-  (image-dimension img) ==> [w h]
-  extract the width W and height H (in pixels) from the byte source
-  (input port, byte-vector, b.s.(*)) repesenting an image -- or signal 
-  an error.  Supported formats: gif, jpeg, png.  
-
-  (get-image-info bs) ==> info | #f
-  extract information on the image represented by b.s.(*) BS and return
-  an image-info record or #f.  (Don't believe in the colour depth for 
-  gifs.)
-
-  (image:info-format info) ==> format | #f
-  get the symbolic format id from image-info record INFO 
-
-  (image:info-depth info) ==> depth | #f
-  get the colour DEPTH (#bits / pixel) from image-info record INFO 
-
-  (image:info-width/pixel info) ==> w | #f
-  (image:info-height/pixel info) ==> h | #f 
-  get the pixel width W resp. height H from image-info record INFO
-
-  (image:info-width/dpi info) ==> width | #f
-  (image:info-height/dpi info) ==> height | #f 
-  get the physical width W resp. height H in dots per inch from etc.
-
-
-(*) Creating and accessing ``byte streams''
-  byte-streams are random-access lazy byte sequences  
-
-  (inport->byte-stream in) ==> bs
-  convert the input port IN to a b.s. BS
-
-  (byte-vector->byte-stream bv) ==> bs
-  convert the byte-vector bv to a b.s. BS
-
-  (segment-byte-stream bs start end) ==> [bv bs']
-  segment the b.s. BS into the first [start:end) bytes (at most) in the 
-  byte-vector BV and the following [end:*) bytes in the b.s. BS'.  BV and
-  BS' may be empty.
-!#
 
 ;;; since there is no pre-fab lazy-list facility for s48/scsh but a 
 ;;; draft srfi, I don't use what's not there and don't set up a 
@@ -140,6 +92,8 @@ Extracting the image dimension etc.
 (define (image-dimension img)
   (let* ((bs (cond ((input-port? img)
                     (inport->byte-stream img))
+                   ((integer? img) ; fdes?
+                    (inport->byte-stream img))
                    ((byte-vector? img)
                     (byte-vector->byte-stream img))
                    ;; should be a promise