add the ability to save the data from the file that was loaded

into a bitmap% object

related to racket/htdp#105

draw-doc/scribblings/draw/bitmap-class.scrbl

@@ -39,7 +39,8 @@ A bitmap is convertible to @racket['png-bytes] through the
                               'unknown]
                         [bg-color (or/c (is-a?/c color%) #f) #f]
                         [complain-on-failure? any/c #f]
-                        [backing-scale (>/c 0.0) 1.0])
+                        [backing-scale (>/c 0.0) 1.0]
+                        [save-data-from-file? any/c #f])
                        ([bits bytes?]
                         [width exact-positive-integer?]
                         [height exact-positive-integer?]))]{
@@ -78,8 +79,11 @@ When a @racket[bits] byte string is provided: Creates a monochrome
  @racket[height] is larger than 8 times the length of @racket[bits],
  @|MismatchExn|.
 
+See @method[bitmap% get-data-from-file] for information on @racket[save-data-from-file?]
+
 @history[#:changed "1.1" @elem{Added the @racket[backing-scale]
-optional arguments.}]}
+optional arguments.}
+         #:changed "1.17" @elem{Added @racket[save-data-from-file?]}]}
 
 @defmethod[(get-argb-pixels [x exact-nonnegative-integer?]
                             [y exact-nonnegative-integer?]
@@ -113,6 +117,26 @@ Returns the bitmap's @tech{backing scale}.
 
 @history[#:added "1.1"]}
 
+@defmethod[(get-data-from-file)
+           (or/c (vector/c (or/c 'unknown 'unknown/mask 'unknown/alpha
+                                 'gif 'gif/mask 'gif/alpha
+                                 'jpeg 'jpeg/alpha
+                                 'png 'png/mask 'png/alpha
+                                 'xbm 'xbm/alpha 'xpm 'xpm/alpha
+                                 'bmp 'bmp/alpha)
+                           (or/c (is-a?/c color%) #f)
+                           (and/c bytes? immutable?)
+                           #:immutable? #t)
+                 #f)]{
+  If the bitmap data in this bitmap was read from a file
+  and the @racket[_save-data-from-file?] was passed with
+  a true value when it was read (either in the constructor
+  or in @method[bitmap% load-file]), then this method
+  returns the contents of the loaded file as bytes. Otherwise,
+  it returns @racket[#f].
+
+  @history[#:added "1.17"]
+}
 
 @defmethod[(get-depth)
            exact-nonnegative-integer?]{
@@ -206,7 +230,8 @@ Returns @racket[#f] if the bitmap is monochrome, @racket[#t] otherwise.
                                   'bmp 'bmp/alpha)
                             'unknown]
                       [bg-color (or/c (is-a?/c color%) #f) #f]
-                      [complain-on-failure? any/c #f])
+                      [complain-on-failure? any/c #f]
+                      [#:save-data-from-file? save-data-from-file? any/c #f])
            boolean?]{
 
 Loads a bitmap from a file format that read from @racket[in], unless
@@ -278,7 +303,11 @@ For PNG and BMP loading, if @racket[bg-color] is not @racket[#f], then it is
  are both undefined, a platform-specific default is used.
 
 After a bitmap is created, @method[bitmap% load-file] can be used
- only if the bitmap's @tech{backing scale} is @racket[1.0].}
+ only if the bitmap's @tech{backing scale} is @racket[1.0].
+
+  See @method[bitmap% get-data-from-file] for information on @racket[save-data-from-file?]
+
+  @history[#:changed "1.17" @elem{Added @racket[save-data-from-file?]}]}
 
 
 @defmethod[(make-dc)

draw-doc/scribblings/draw/draw-funcs.scrbl

@@ -191,6 +191,7 @@ optional argument.}]}
                             'unknown/alpha]
                       [bg-color (or/c (is-a?/c color%) #f) #f]
                       [complain-on-failure? any/c #t]
+                      [#:get-data-from-file? get-data-from-file? any/c #f]
                       [#:backing-scale backing-scale (>/c 0.0) 1.0]
                       [#:try-@2x? try-@2x? any/c #f])
          (is-a?/c bitmap%)]{
@@ -207,8 +208,14 @@ but with @filepath{@"@"2x} added to the name (before the file suffix,
 if any). If the @filepath{@"@"2x} path exists, it is used instead of
 @racket[in], and @racket[backing-scale] is multiplied by @racket[2].
 
+If @racket[get-data-from-file?] is not @racket[#f], then the resulting
+bitmap's @method[bitmap% get-data-from-file] method will return
+the bytes from the file.
+
 @history[#:changed "1.1" @elem{Added the @racket[#:backing-scale]
-and @racket[#:try-@2x?] optional arguments.}]}
+and @racket[#:try-@2x?] optional arguments.}
+         #:changed "1.17" @elem{Added the @racket[#:get-data-from-file?]
+                                     argument.}]}
 
 
 @defproc[(recorded-datum->procedure [datum any/c]) ((is-a?/c dc<%>) . -> . void?)]{

draw-lib/info.rkt

@@ -17,4 +17,4 @@
 
 (define pkg-authors '(mflatt))
 
-(define version "1.16")
+(define version "1.17")

draw-lib/racket/draw.rkt

@@ -59,6 +59,7 @@
                                'bmp 'bmp/alpha)
                          (or/c (is-a?/c color%) #f)
                          any/c
+                         #:save-data-from-file? any/c
                          #:backing-scale (>/c 0.0)
                          #:try-@2x? any/c)
                         . ->* . (instanceof/c bitmap%/c))])