racket/collects/file/ico.rkt

807 lines
38 KiB
Racket

#lang racket/base
(require racket/contract)
(provide ico?
(contract-out
[ico-width (ico? . -> . (integer-in 1 256))]
[ico-height (ico? . -> . (integer-in 1 256))]
[ico-depth (ico? . -> . (one-of/c 1 2 4 8 16 24 32))]
[read-icos ((or/c path-string? input-port?) . -> . (listof ico?))]
[read-icos-from-exe ((or/c path-string? input-port?) . -> . (listof ico?))]
[write-icos ([(listof ico?) (or/c path-string? output-port?)]
[#:exists (or/c 'error 'append 'update 'can-update
'replace 'truncate
'must-truncate 'truncate/replace)]
. ->* .
void?)]
[replace-icos ((listof ico?) (or/c path-string? output-port?)
. -> . void?)]
[ico->argb (ico? . -> . bytes?)]
[argb->ico ([(integer-in 1 256) (integer-in 1 256) bytes? ]
[#:depth (one-of/c 1 2 4 8 24 32)]
. ->* .
ico?)]))
;; parse-ico build-ico
(define (byte->integer p)
(read-byte p))
(define (word->integer p)
(integer-bytes->integer (read-bytes 2 p) #f #f))
(define (dword->integer p)
(integer-bytes->integer (read-bytes 4 p) #f #f))
;; The 0 added in the alpha position apparently means "ignore the alpha
;; and use the mask, instead"
(define (3/2word->integer p)
(integer-bytes->integer (bytes-append (read-bytes 3 p) #"\0") #f #f))
(define (integer->word i p)
(display (integer->integer-bytes i 2 #f #f) p))
(define (integer->dword i p)
(display (integer->integer-bytes i 4 #f #f) p))
(define (integer->3/2word i p)
(display (subbytes (integer->integer-bytes i 4 #f #f) 0 3) p))
(define (flag v)
(positive? (bitwise-and #x80000000 v)))
(define (value v)
(bitwise-and #x7FFFFFFF v))
(define (skip-to-image-headers-after-signature p)
;; p is expected to be a file port
(file-position p 60)
(let ([pos (word->integer p)])
;; pos points to IMAGE_NT_HEADERS
(file-position p pos)
(unless (= #x4550 (dword->integer p))
(error "bad signature"))
pos))
(define (get-image-base p)
(let ([pos (skip-to-image-headers-after-signature p)])
(file-position p (+ 4
20
28))
(dword->integer p)))
(define (find-section p find-name)
(let ([pos (skip-to-image-headers-after-signature p)])
(word->integer p) ; skip machine
(let ([num-sections (word->integer p)]
[_ (begin (dword->integer p)
(dword->integer p)
(dword->integer p))]
[size (word->integer p)])
(let ([pos (+ pos
4 ; Signature : DWORD
20 ; FileHeader: IMAGE_FILE_HEADER
size)]) ; "optional" header
(let sloop ([section 0][section-pos pos])
(if (= section num-sections)
(error 'find-section "can't find section: ~e" find-name)
(begin
(file-position p section-pos)
;; p points to an IMAGE_SECTION_HEADER
(let ([name (read-bytes 8 p)])
(if (bytes=? find-name name)
(let ([_ (dword->integer p)]) ; skip
(values (dword->integer p) ; virtual address
(dword->integer p) ; length
(dword->integer p))); file pos
(sloop (add1 section) (+ section-pos 40)))))))))))
(define (find-rsrc-start p re:rsrc)
(let-values ([(rsrc-virtual-addr rsrc-len rsrc-pos)
(find-section p #".rsrc\0\0\0")])
(let loop ([dir-pos 0][path ""])
(file-position p (+ rsrc-pos dir-pos 12))
(let ([num-named (word->integer p)]
[num-ided (word->integer p)])
(let iloop ([i 0])
(if (= i (+ num-ided num-named))
#f
(let ([name-delta (dword->integer p)]
[data-delta (dword->integer p)]
[next (file-position p)])
(or (let ([name (if (flag name-delta)
(begin
(file-position p (+ rsrc-pos (value name-delta)))
(let* ([len (word->integer p)])
;; len is in unicode chars...
(let ([unistr (read-bytes (* 2 len) p)])
;; Assume it fits into ASCII...
(regexp-replace* "\0"
(bytes->string/latin-1 unistr)
""))))
(value name-delta))])
;;(printf "Name: ~a~a = ~a\n" path name (+ rsrc-pos (value data-delta)))
(let ([full-name (format "~a~a" path name)])
(if (flag data-delta)
(loop (value data-delta) (string-append full-name "."))
;; Found the icon?
(and (regexp-match re:rsrc full-name)
;; Yes, so read IMAGE_RESOURCE_DATA_ENTRY
(begin
(file-position p (+ rsrc-pos (value data-delta)))
(cons
(+ (dword->integer p) ; offset (an RVA)
(- rsrc-pos
rsrc-virtual-addr))
(dword->integer p))))))) ; size
(begin
(file-position p next)
(iloop (add1 i)))))))))))
(define-struct ico (desc data) #:mutable)
;; desc is (list width height colors 0 planes bitcount)
;; data is (cons pos bytes)
(define (ico-width i) (let ([v (car (ico-desc i))])
(if (= v 0)
256
v)))
(define (ico-height i) (let ([v (cadr (ico-desc i))])
(if (= v 0)
256
v)))
(define (ico-depth i)
(let ([cols (caddr (ico-desc i))])
(if (zero? cols)
(list-ref (ico-desc i) 5)
(integer-length (sub1 cols)))))
(define (ico-colors i) (num-colors (ico-desc i)))
(define (num-colors l)
(let ([n (caddr l)])
(if (zero? n)
(arithmetic-shift 1 (list-ref l 5))
n)))
(define (replace-icos ico-icos exe-file)
(let ([exe-icos (read-icos-from-exe exe-file)])
(let ([p (open-output-file exe-file #:exists 'update)])
(dynamic-wind
void
(lambda ()
(for-each (lambda (exe-ico)
(let ([best-ico-ico
;; Find exact match?
(ormap (lambda (ico-ico)
(let ([le (ico-desc exe-ico)]
[li (ico-desc ico-ico)])
(and (= (car li) (car le))
(= (cadr li) (cadr le))
(= (num-colors li) (num-colors le))
(= (bytes-length (cdr (ico-data exe-ico)))
(bytes-length (cdr (ico-data ico-ico))))
ico-ico)))
ico-icos)])
(let ([ico-ico (or best-ico-ico
;; Look for a conversion, if we
;; need a 16x16, 32x32, or 48x48
;; ico
(and
(= (car (ico-desc exe-ico))
(cadr (ico-desc exe-ico)))
(memq (car (ico-desc exe-ico))
'(16 32 48))
(let ([biggest-colorest #f])
(for-each
(lambda (ico-ico)
(let ([w (ico-width ico-ico)]
[exew (ico-width exe-ico)])
(when (and
(= w (ico-width ico-ico))
(memq w '(16 32 48))
(or
(not biggest-colorest)
(and (= w exew)
(not (= exew (ico-width biggest-colorest))))
(and (= w exew)
(> (num-colors (ico-desc ico-ico))
(num-colors (ico-desc biggest-colorest))))
(and (not (= exew (ico-width biggest-colorest)))
(or (> w (ico-width biggest-colorest))
(> (num-colors (ico-desc ico-ico))
(num-colors (ico-desc biggest-colorest)))))))
(set! biggest-colorest ico-ico))))
ico-icos)
(and
biggest-colorest
;; Convert...
(let* ([src-size (ico-width biggest-colorest)]
[dest-size (ico-width exe-ico)]
[src (parse-ico biggest-colorest)]
[image (list-ref src 3)]
[mask (list-ref src 4)]
[has-alpha? (<= 256 (num-colors (ico-desc biggest-colorest)))])
(if (= src-size dest-size)
(build-ico exe-ico
(if has-alpha?
image
(mask->alpha image mask))
mask
#t)
(let ([cvt
(cond
[(and (= src-size 32) (= dest-size 16))
(lambda (i) (48->16 (32->48 i)))]
[(and (= src-size 32) (= dest-size 48))
32->48]
[(and (= src-size 48) (= dest-size 16))
48->16]
[(and (= src-size 48) (= dest-size 32))
48->32]
[(and (= src-size 16) (= dest-size 32))
16->32]
[(and (= src-size 16) (= dest-size 48))
(lambda (i) (32->48 (16->32 i)))])])
(let ([mask (cvt mask)])
(build-ico exe-ico
(if has-alpha?
image
(mask->alpha (cvt image) mask))
mask
#t)))))))))])
(unless ico-ico (printf "no! ~a\n" (ico-desc exe-ico)))
(when ico-ico
(file-position p (car (ico-data exe-ico)))
(display (cdr (ico-data ico-ico)) p)))))
exe-icos))
(lambda () (close-output-port p))))))
;; ------------------------------
;; Image parsing
;; ------------------------------
(define (get-icos file res?)
(let ([p (if (input-port? file)
file
(open-input-file file))])
(dynamic-wind
void
(lambda ()
(unless (= 0 (word->integer p))
(error 'get-icos "~a doesn't start with 0" file))
(unless (= 1 (word->integer p))
(error "type isn't 1"))
(let ([cnt (word->integer p)])
(let ([icos (let loop ([i 0])
(if (= i cnt)
null
(cons
(make-ico
(list (byte->integer p) ; w
(byte->integer p) ; h
(byte->integer p) ; colors
(byte->integer p) ; 0
(word->integer p) ; planes
(word->integer p)) ; bitcount
(list (dword->integer p) ; bytes
((if res? ; where or icon id
word->integer
dword->integer)
p)))
(loop (add1 i)))))])
;; (printf "~a\n" icos)
(for-each (lambda (ico)
(set-ico-data!
ico
(let ([size (car (ico-data ico))]
[where (cadr (ico-data ico))])
(let ([ico-pos (if res?
;; last number is icon id:
(car (find-rsrc-start p (regexp (format "^3[.]~a[.]" where))))
;; last number is file position:
where)])
(file-position p ico-pos)
(cons ico-pos
(read-bytes size p)))))
;; If colors, planes, and bitcount are all 0,
;; get the info from the DIB data
(let ([desc (ico-desc ico)])
(when (and (zero? (list-ref desc 2))
(zero? (list-ref desc 4))
(zero? (list-ref desc 5)))
(let ([bi (bitmapinfo ico)])
(set-ico-desc! ico
(list*
(list-ref desc 0)
(list-ref desc 1)
(list-ref desc 2)
(list-ref desc 3)
(list-ref bi 3)
(list-ref bi 4)
(list-tail desc 6)))))))
icos)
icos)))
(lambda ()
(when (path-string? file)
(close-input-port p))))))
(define (bitmapinfo ico)
(let ([p (open-input-bytes (cdr (ico-data ico)))])
(list (dword->integer p) ; size == 40 in practice
(dword->integer p) ; width
(dword->integer p) ; height
(word->integer p) ; planes
(word->integer p) ; bitcount
(dword->integer p) ; compression == 0
(dword->integer p) ; size image
(dword->integer p) ; x pixels per meter == 0
(dword->integer p) ; y pixels per meter == 0
(dword->integer p) ; used == 0
(dword->integer p)))) ; important == 0
;; Assumes that bits-per-pixel is 1, 2, 4, 8, 16, 24, or 32.
;; Also assumes that (bits-per-pixel * width) is a multiple of 8.
(define (parse-dib ico)
(let* ([bi (bitmapinfo ico)]
[header-size (list-ref bi 0)]
[num-colors (caddr (ico-desc ico))]
[w (list-ref bi 1)]
[h (/ (list-ref bi 2) 2)]
[bits-per-pixel (list-ref bi 4)])
(let ([p (open-input-bytes (cdr (ico-data ico)))])
;; Skip header
(read-bytes header-size p)
(let* ([read-n
(lambda (n read-one combine)
(let loop ([i n][r null])
(if (= i 0)
(reverse r)
(loop (sub1 i)
(combine (read-one p) r)))))]
[read-lines
(lambda (w h read-one combine)
(if (zero? (modulo w 4))
(read-n (* w h) read-one combine)
(let loop ([h h])
(if (zero? h)
null
(append (read-n w read-one combine)
(begin
;; pad line to dword:
(read-n (- 4 (modulo w 4)) byte->integer cons)
;; read next line:
(loop (sub1 h))))))))]
[split-bits (lambda (b)
(list
(bitwise-and b 1)
(arithmetic-shift (bitwise-and b 2) -1)
(arithmetic-shift (bitwise-and b 4) -2)
(arithmetic-shift (bitwise-and b 8) -3)
(arithmetic-shift (bitwise-and b 16) -4)
(arithmetic-shift (bitwise-and b 32) -5)
(arithmetic-shift (bitwise-and b 64) -6)
(arithmetic-shift (bitwise-and b 128) -7)))])
(let ([main-image
(cond
[(= bits-per-pixel 32)
;; RGB mode:
(read-n (* w h) dword->integer cons)]
[(= bits-per-pixel 24)
;; RGB mode:
(read-n (* w h) 3/2word->integer cons)]
[else
;; Index mode:
(let ([color-table (list->vector
(read-n (if (zero? num-colors)
(arithmetic-shift 1 bits-per-pixel)
num-colors)
dword->integer cons))]
[image (read-lines (/ w (/ 8 bits-per-pixel))
h
(lambda (p)
(let ([b (byte->integer p)])
(case bits-per-pixel
[(1) (split-bits b)]
[(2)
(list
(bitwise-and b 3)
(arithmetic-shift (bitwise-and b 12) -2)
(arithmetic-shift (bitwise-and b 48) -4)
(arithmetic-shift (bitwise-and b 192) -6))]
[(4)
(list
(bitwise-and b 15)
(arithmetic-shift (bitwise-and b 240) -4))]
[(8) (list b)])))
append)])
(map (lambda (i) (vector-ref color-table i)) image))])])
(let ([mask (read-lines (/ w 8)
h
(lambda (p) (split-bits (byte->integer p)))
append)])
(unless (eof-object? (read-byte p))
(error 'parse-dib "not extactly at end"))
(list main-image mask)))))))
;; rgb->indexed
;; The color-reduction strategy isn't great, and because it
;; depends on hash-table order, it's non-deterministic in
;; principle. But the actual hash-table implementation is
;; deterministic, of course. Also, the re-ordering of the
;; image via the hash tables tends to produce better
;; (pseudo-random) representatives of the image for colors.
(define (rgb->indexed image num-colors)
(let ([image (map (lambda (i) (bitwise-and #xFFFFFF i)) image)] ; drop alphas, if any
[table (make-vector num-colors 0)]
[ht (make-hash)]
[map-ht (make-hash)]
[color-dist (lambda (a b)
(sqrt (+ (expt (- (bitwise-and #xFF a)
(bitwise-and #xFF b))
2)
(expt (- (arithmetic-shift (bitwise-and #xFF00 a) -8)
(arithmetic-shift (bitwise-and #xFF00 b) -8))
2)
(expt (- (arithmetic-shift (bitwise-and #xFF0000 a) -16)
(arithmetic-shift (bitwise-and #xFF0000 b) -16))
2))))])
(for-each (lambda (c)
(hash-set!
ht
c
(add1
(hash-ref ht c 0))))
image)
(let ([kv-sorted (sort (hash-map ht cons)
(lambda (a b) (< (cdr a) (cdr b))))])
(let ([n 0])
(for-each (lambda (kv)
(let ([key (car kv)])
(let ([n (if (< n (sub1 num-colors))
n
;; Find closest match:
(let ([n 0])
(let loop ([i 1])
(unless (= i num-colors)
(when (< (color-dist key (vector-ref table i))
(color-dist key (vector-ref table n)))
(set! n i))
(loop (add1 i))))
n))])
(vector-set! table n key)
(hash-set! map-ht key n))
(when (< n (sub1 num-colors))
(set! n (add1 n)))))
kv-sorted)))
(values (vector->list table)
(map (lambda (c) (hash-ref map-ht c)) image))))
;; Assumes that bits-per-pixel is 1, 2, 4, 8, or 32.
;; Also assumes that (bits-per-pixel * width) is a multiple of 8.
(define (build-dib ico image mask check?)
(let* ([bi (bitmapinfo ico)]
[header-size (list-ref bi 0)]
[num-colors (caddr (ico-desc ico))]
[w (list-ref bi 1)]
[h (/ (list-ref bi 2) 2)]
[bits-per-pixel (list-ref bi 4)])
(let ([orig-p (open-input-bytes (cdr (ico-data ico)))]
[result-p (open-output-bytes)])
;; Copy header:
(display (read-bytes header-size orig-p) result-p)
(let ([get-lines (lambda (image bits-per-pixel)
(map (lambda (line)
;; pad line to dword boundary
(let ([line-bytes (/ (* w bits-per-pixel) 8)])
(if (zero? (modulo line-bytes 4))
line
(append line
(vector->list
(make-vector (* (- 4 (modulo line-bytes 4))
(/ 8 bits-per-pixel))
0))))))
;; break out lines
(let loop ([l image])
(if (null? l)
null
(cons (let loop ([l l][i 0])
(if (= i w)
null
(cons (car l) (loop (cdr l) (add1 i)))))
(loop (list-tail l w)))))))]
[bits->dwords (lambda (l bpp)
(let ([chunk-size (/ 32 bpp)]
[1byte (lambda (l)
(bitwise-ior
(arithmetic-shift (list-ref l 0) 7)
(arithmetic-shift (list-ref l 1) 6)
(arithmetic-shift (list-ref l 2) 5)
(arithmetic-shift (list-ref l 3) 4)
(arithmetic-shift (list-ref l 4) 3)
(arithmetic-shift (list-ref l 5) 2)
(arithmetic-shift (list-ref l 6) 1)
(arithmetic-shift (list-ref l 7) 0)))]
[2byte (lambda (l)
(bitwise-ior
(arithmetic-shift (list-ref l 0) 6)
(arithmetic-shift (list-ref l 1) 4)
(arithmetic-shift (list-ref l 2) 2)
(arithmetic-shift (list-ref l 3) 0)))]
[4byte (lambda (l)
(bitwise-ior
(arithmetic-shift (list-ref l 0) 4)
(arithmetic-shift (list-ref l 1) 0)))])
(let loop ([l l])
(if (null? l)
null
(cons (case bpp
[(1) (bitwise-ior
(arithmetic-shift (1byte (list-tail l 0)) 0)
(arithmetic-shift (1byte (list-tail l 8)) 8)
(arithmetic-shift (1byte (list-tail l 16)) 16)
(arithmetic-shift (1byte (list-tail l 24)) 24))]
[(2) (bitwise-ior
(2byte l)
(arithmetic-shift (2byte (list-tail l 4)) 8)
(arithmetic-shift (2byte (list-tail l 8)) 16)
(arithmetic-shift (2byte (list-tail l 12)) 24))]
[(4) (bitwise-ior
(4byte l)
(arithmetic-shift (4byte (list-tail l 2)) 8)
(arithmetic-shift (4byte (list-tail l 4)) 16)
(arithmetic-shift (4byte (list-tail l 6)) 24))]
[(8) (bitwise-ior
(car l)
(arithmetic-shift (list-ref l 1) 8)
(arithmetic-shift (list-ref l 2) 16)
(arithmetic-shift (list-ref l 3) 24))])
(loop (list-tail l chunk-size)))))))])
(cond
[(= bits-per-pixel 32)
(for-each (lambda (col) (integer->dword col result-p))
image)]
[(= bits-per-pixel 24)
(for-each (lambda (col) (integer->3/2word col result-p))
image)]
[else
(let-values ([(colors indexed-image) (rgb->indexed image (arithmetic-shift 1 bits-per-pixel))])
;; color table
(for-each (lambda (col) (integer->dword col result-p))
colors)
(let* ([lines (get-lines indexed-image bits-per-pixel)]
[dwords (apply append (map (lambda (l) (bits->dwords l bits-per-pixel))
lines))])
(for-each (lambda (col) (integer->dword col result-p))
dwords)))])
(let* ([lines (get-lines mask 1)]
[dwords (apply append (map (lambda (l) (bits->dwords l 1)) lines))])
(for-each (lambda (col) (integer->dword col result-p))
dwords))
(let ([s (get-output-bytes result-p)])
(when check?
(unless (= (bytes-length s) (bytes-length (cdr (ico-data ico))))
(error 'build-dib "bad result size ~a != ~a"
(bytes-length s) (bytes-length (cdr (ico-data ico))))))
s)))))
(define (parse-ico ico)
(let ([image (parse-dib ico)])
(list (ico-width ico)
(ico-height ico)
(ico-colors ico)
(car image) ; list of image pixels
(cadr image)))) ; list of mask pixels
(define (ico->argb ico)
(let* ([image (parse-ico ico)]
[pixels (list-ref image 3)]
[len (length pixels)]
[bstr (make-bytes (* 4 len))]
[w (ico-width ico)]
[h (ico-height ico)]
[has-alpha? (= 32 (ico-depth ico))])
(for ([p (in-list pixels)]
[m (in-list (list-ref image 4))]
[i (in-naturals)])
(let* ([y (- h (quotient i w) 1)]
[x (modulo i w)]
[i (+ x (* w y))])
(bytes-set! bstr (+ 0 (* i 4)) (if has-alpha?
(bitwise-and #xff (arithmetic-shift p -24))
(if (zero? m) 255 0)))
(bytes-set! bstr (+ 1 (* i 4)) (bitwise-and #xff (arithmetic-shift p -16)))
(bytes-set! bstr (+ 2 (* i 4)) (bitwise-and #xff (arithmetic-shift p -8)))
(bytes-set! bstr (+ 3 (* i 4)) (bitwise-and #xff p))))
bstr))
(define (build-ico base-ico image mask check?)
(make-ico (ico-desc base-ico)
(cons (car (ico-data base-ico))
(build-dib base-ico image mask check?))))
(define (read-icos ico-file)
(get-icos ico-file #f))
(define (read-icos-from-exe exe-file)
(let ([p (open-input-file exe-file)])
(dynamic-wind
void
(lambda ()
(let ([pos+size (find-rsrc-start p #rx"^14[.]")])
(file-position p (car pos+size))
(get-icos p #t)))
(lambda () (close-input-port p)))))
(define (write-header w h depth o)
(integer->dword 40 o) ; size
(integer->dword w o) ; width
(integer->dword (* 2 h) o) ; height
(integer->word 1 o) ; planes
(integer->word depth o) ; bitcount
(integer->dword 0 o) ; compression
(integer->dword 0 o) ; size image
(integer->dword 0 o) ; x pixels per meter
(integer->dword 0 o) ; y pixels per meter
(integer->dword 0 o) ; used
(integer->dword 0 o)) ; important
(define (argb->ico w h argb #:depth [depth 32])
(let ([o (open-output-bytes)])
(write-header w h 32 o)
;; Got ARGB, need BGRA
(let* ([flip-pixels (lambda (s)
(let ([s (bytes-copy s)])
(let loop ([p 0])
(unless (= p (bytes-length s))
(let ([a (bytes-ref s p)]
[r (bytes-ref s (+ p 1))]
[g (bytes-ref s (+ p 2))]
[b (bytes-ref s (+ p 3))])
(bytes-set! s p b)
(bytes-set! s (+ p 1) g)
(bytes-set! s (+ p 2) r)
(bytes-set! s (+ p 3) a)
(loop (+ p 4)))))
s))]
[rgba (flip-pixels argb)]
[row-size (if (zero? (modulo w 32))
w
(+ w (- 32 (remainder w 32))))]
[mask (make-bytes (* h row-size 1/8) 0)])
(let loop ([i (* w h 4)])
(unless (zero? i)
(let ([alpha (bytes-ref rgba (- i 1))])
(when (< alpha 10)
;; white mask -> zero alpha; add white pixel to mask
(bytes-set! rgba (- i 1) 0)
(let ([pos (+ (* (quotient (sub1 (/ i 4)) w) row-size)
(remainder (sub1 (/ i 4)) w))])
(bytes-set! mask
(quotient pos 8)
(bitwise-ior
(arithmetic-shift 1 (- 7 (remainder pos 8)))
(bytes-ref mask (quotient pos 8)))))))
(loop (- i 4))))
;; Windows icos are upside-down:
(let ([flip (lambda (str row-width)
(apply
bytes-append
(reverse
(let loop ([pos 0])
(if (= pos (bytes-length str))
null
(cons (subbytes str pos (+ pos row-width))
(loop (+ pos row-width))))))))])
(display (flip rgba (* w 4)) o)
(display (flip mask (/ row-size 8)) o))
(define (256->0 v) (if (= v 256) 0 v))
(let ([ico (make-ico (list (256->0 w) (256->0 h) 0 0 1 32)
(cons 0 (get-output-bytes o)))])
(cond
[(= depth 32) ico]
[else (let ([o (open-output-bytes)])
(write-header w h depth o)
(define image (parse-dib ico))
(build-ico (make-ico (list (256->0 w) (256->0 h)
(if (depth . <= . 8)
(256->0 (expt 2 depth))
0)
0 1 depth)
(cons 0 (get-output-bytes o)))
(car image)
(cadr image)
#f))])))))
(define (write-icos icos file #:exists [exists 'error])
(let ([p #f])
(dynamic-wind
(lambda ()
(set! p (if (output-port? file)
file
(open-output-file file #:exists exists))))
(lambda ()
(integer->word 0 p)
(integer->word 1 p) ; 1 = icon
(define count (length icos))
(integer->word count p)
(for/fold ([offset (+ 6 (* 16 count))]) ([i (in-list icos)])
(define size (bytes-length (cdr (ico-data i))))
(write-byte (car (ico-desc i)) p)
(write-byte (cadr (ico-desc i)) p)
(write-byte (list-ref (ico-desc i) 2) p)
(write-byte 0 p)
(integer->word (list-ref (ico-desc i) 4) p)
(integer->word (list-ref (ico-desc i) 5) p)
(integer->dword size p)
(integer->dword offset p)
(+ offset size))
(for ([i (in-list icos)])
(write-bytes (cdr (ico-data i)) p)))
(lambda ()
(unless (output-port? file)
(close-output-port p))))))
;; ------------------------------
;; Image conversion
;; ------------------------------
(define (mask->alpha image mask)
(map (lambda (i m)
(if (zero? m)
(bitwise-ior #xFF000000 i)
m))
image mask))
(define (first-n n l)
(let loop ([l l][i n])
(if (zero? i)
null
(cons (car l) (loop (cdr l) (sub1 i))))))
(define (16->32 l)
(let loop ([l l])
(if (null? l)
null
(let ([l2 (let loop ([l (first-n 16 l)])
(if (null? l)
null
(list* (car l) (car l) (loop (cdr l)))))])
(append l2 l2
(loop (list-tail l 16)))))))
(define (32->48 l)
(let loop ([l l][dup? #t])
(if (null? l)
null
(let ([l2 (let loop ([l (first-n 32 l)])
(if (null? l)
null
(list* (car l) (car l) (cadr l)
(loop (cddr l)))))])
(append l2
(if dup? l2 null)
(loop (list-tail l 32) (not dup?)))))))
(define (48->16 l)
(let loop ([l l])
(if (null? l)
null
(let ([l2 (let loop ([l (first-n 48 l)])
(if (null? l)
null
(cons (car l) (loop (cdddr l)))))])
(append l2
(loop (list-tail l 144)))))))
(define (48->32 l)
(let loop ([l l][step 0])
(if (null? l)
null
(let ([l2 (let loop ([l (first-n 48 l)][step 0])
(if (null? l)
null
(if (= 1 (modulo step 3))
(loop (cdr l) 2)
(cons (car l) (loop (cdr l) (add1 step))))))])
(append (if (= 1 (modulo step 3)) null l2)
(loop (list-tail l 48) (add1 step)))))))