working on png with alpha

pitfall/pdfkit/lib/document.coffee

@@ -145,11 +145,12 @@ class PDFDocument extends stream.Readable
     return this
 
   _refEnd: (ref) ->
-    console.log(ref.id)
-    console.log(@_offsets)
+    #console.log(ref.id)
+    #console.log(@_offsets)
     @_offsets[ref.id - 1] = ref.offset
     if --@_waiting is 0 and @_ended
-      console.log("finalize") ; @_finalize()
+      #console.log("finalize") ; 
+      @_finalize()
       @_ended = false
 
   write: (filename, fn) ->
@@ -173,8 +174,8 @@ class PDFDocument extends stream.Readable
     '
 
   end: ->
-    console.log("start document end")
-    console.log(@_offsets)
+    #console.log("start document end")
+    #console.log(@_offsets)
     @flushPages()
     @_info = @ref()
     for key, val of @info
@@ -182,25 +183,26 @@ class PDFDocument extends stream.Readable
         val = new String val
       @_info.data[key] = val
 
-    console.log(@_offsets)
+    #console.log(@_offsets)
     @_info.end()
 
     for name, font of @_fontFamilies
       font.finalize()
 
-    console.log(@_offsets)
+    #console.log(@_offsets)
 
     @_root.end()
-    console.log(@_offsets)
+    #console.log(@_offsets)
 
     @_root.data.Pages.end()
 
-    console.log(@_offsets)
+    #console.log(@_offsets)
     if @_waiting is 0
-      console.log(@_offsets.length)
-      console.log("finalize2") ; @_finalize()
+      #console.log(@_offsets.length)
+      #console.log("finalize2") ; @_finalize()
     else
-      console.log("ended is true") ; @_ended = true
+      #console.log("ended is true") ; 
+      @_ended = true
 
   _finalize: (fn) ->
     # generate xref

pitfall/pdfkit/lib/image/png.coffee

@@ -3,15 +3,15 @@ PNG = require 'png-js'
 
 class PNGImage
   constructor: (data, @label) ->
-    console.log("raw data")
-    console.log(data.slice(0, 20))
+    #console.log("raw data")
+    #console.log(data.slice(0, 20))
     @image = new PNG(data)
     @width = @image.width
     @height = @image.height
     @imgData = @image.imgData
-    console.log("result from png-js")
-    console.log(@imgData.slice(0, 20))
-    console.log(@image)
+    #console.log("result from png-js")
+    #console.log(@imgData.slice(0, 20))
+    #console.log(@image)
     @obj = null
 
   embed: (@document) ->
@@ -47,7 +47,7 @@ class PNGImage
 
     # For PNG color types 0, 2 and 3, the transparency data is stored in
     # a dedicated PNG chunk.
-    if @image.transparency.grayscale
+    if @image.transparency.grayscale  
       console.log("transparency.grayscale")
       # Use Color Key Masking (spec section 4.8.5)
       # An array with N elements, where N is two times the number of color components.
@@ -72,7 +72,7 @@ class PNGImage
       @loadIndexedAlphaChannel()
 
     else if @image.hasAlphaChannel
-      console.log("alphachannel")
+      console.log("got alphachannel " + @image.colorType + " in png.coffee")
       # For PNG color types 4 and 6, the transparency data is stored as a alpha
       # channel mixed in with the main image data. Separate this data out into an
       # SMask object and store it separately in the PDF.
@@ -97,7 +97,7 @@ class PNGImage
       @obj.data['SMask'] = sMask
 
     # add the actual image data
-    console.log(@imgData)
+    #console.log(@imgData)
     @obj.end @imgData
 
     # free memory
@@ -105,6 +105,7 @@ class PNGImage
     @imgData = null
 
   splitAlphaChannel: ->
+    console.log("start splitAlphaChannel in png.coffee")
     @image.decodePixels (pixels) =>
       colorByteSize = @image.colors * @image.bits / 8
       pixelCount = @width * @height

pitfall/pdfkit/lib/reference.coffee

@@ -48,7 +48,7 @@ class PDFReference extends stream.Writable
   end: (chunk) ->
     super
     
-    console.log("end! " + @id)
+    #console.log("end! " + @id)
     # console.log(@chunks)
     if @deflate
       @deflate.end()
@@ -75,7 +75,7 @@ class PDFReference extends stream.Writable
       @document._write '\nendstream'
       
     @document._write 'endobj'
-    console.log(@id)
+    #console.log(@id)
     @document._refEnd(this)
     
   toString: ->

pitfall/pdfkit/node_modules/pako/lib/inflate.js

@@ -376,6 +376,7 @@ Inflate.prototype.onEnd = function (status) {
  * ```
  **/
 function inflate(input, options) {
+  console.log("inflating");
   var inflator = new Inflate(options);
 
   inflator.push(input, true);

pitfall/pdfkit/node_modules/pako/lib/zlib/inflate.js

@@ -361,6 +361,8 @@ function updatewindow(strm, src, end, copy) {
 }
 
 function inflate(strm, flush) {
+
+  console.log("inflating big time");
   var state;
   var input, output;          // input/output buffers
   var next;                   /* next input INDEX */

pitfall/pdfkit/node_modules/png-js/png-node.coffee

@@ -140,6 +140,9 @@ module.exports = class PNG
             pixelBytes = @pixelBitlength / 8
             scanlineLength = pixelBytes * @width
 
+            console.log("pixelBytes="+ pixelBytes)
+            console.log("scanlineLength="+ scanlineLength)
+
             pixels = new Buffer(scanlineLength * @height)
             length = data.length
             row = 0

pitfall/pdfkit/node_modules/png-js/png-node.js

@@ -56,8 +56,8 @@
       this.text = {};
       while (true) {
         chunkSize = this.readUInt32();
-        console.log("chunkSize")
-        console.log(chunkSize)
+        //console.log("chunkSize")
+        //console.log(chunkSize)
         section = ((function() {
           var _i, _results;
           _results = [];
@@ -66,8 +66,8 @@
           }
           return _results;
         }).call(this)).join('');
-        console.log("section")
-        console.log(section)
+        //console.log("section")
+        //console.log(section)
         switch (section) {
           case 'IHDR':
             this.width = this.readUInt32();
@@ -173,6 +173,7 @@
     };
 
     PNG.prototype.decodePixels = function(fn) {
+      console.log("start decodePixels in png-node.js")
       var _this = this;
       return zlib.inflate(this.imgData, function(err, data) {
         var byte, c, col, i, left, length, p, pa, paeth, pb, pc, pixelBytes, pixels, pos, row, scanlineLength, upper, upperLeft, _i, _j, _k, _l, _m;
@@ -181,6 +182,9 @@
         }
         pixelBytes = _this.pixelBitlength / 8;
         scanlineLength = pixelBytes * _this.width;
+        console.log("pixelBytes="+ pixelBytes);
+        console.log("scanlineLength="+ scanlineLength);
+
         pixels = new Buffer(scanlineLength * _this.height);
         length = data.length;
         row = 0;

pitfall/pdfkit/node_modules/png-js/png.coffee

@@ -145,8 +145,8 @@ class PNG
                         when 1 then 'DeviceGray'
                         when 3 then 'DeviceRGB'
                     
-                    console.log("imgdata")
-                    console.log(@imgData)
+                    #console.log("imgdata")
+                    #console.log(@imgData)
                     @imgData = new Uint8Array @imgData                        
                     return
                     
@@ -159,7 +159,7 @@ class PNG
             if @pos > @data.length
                 throw new Error "Incomplete or corrupt PNG file"
 
-            console.log("done parsing PNG")
+            #console.log("done parsing PNG")
             
         return
         

pitfall/pitfall/helper.rkt

@@ -74,6 +74,11 @@
     [(_ field o expr)
      #'(begin (set-field! field o (+ (get-field field o) expr)) (get-field field o))]))
 
+(define-syntax (increment! stx)
+  (syntax-case stx ()
+    [(_ id)  #'(increment! id 1)]
+    [(_ id expr)
+     #'(begin (set! id (+ id expr)) id)]))
 
 
 (module+ test
@@ -172,7 +177,7 @@
 
 (define (bytes->hex bstr)
   (map (λ (b) (string->symbol (string-append (if (< b 16)
-                                                   "x0" "x") (~r b #:base 16)))) (bytes->list bstr)))
+                                                 "x0" "x") (~r b #:base 16)))) (bytes->list bstr)))
 
 (module+ test
   (check-equal? (bytes->hex #"PNG") '(x50 x4e x47)))

pitfall/pitfall/png-reader.rkt

@@ -1,5 +1,6 @@
 #lang pitfall/racket
-(provide read-png)
+(require "zlib.rkt")
+(provide read-png decodePixels)
 
 #|
 Grab key chunks from PNG. Doesn't require heavy lifting from libpng.
@@ -29,12 +30,40 @@ Grab key chunks from PNG. Doesn't require heavy lifting from libpng.
                                   'interlaceMethod (read-byte))]
            [(#"PLTE") (hash-set*! png 'palette (read-bytes chunk-size))]
            [(#"IDAT") (hash-set*! png 'imgData (read-bytes chunk-size))]
-           [(#"tRNS") (read-bytes chunk-size)] ; todo implement this section
-           [(#"tEXt") (read-bytes chunk-size)] ; todo implement this section
+           [(#"tRNS")
+            ;; This chunk can only occur once and it must occur after the
+            ;; PLTE chunk and before the IDAT chunk.
+            (define transparency (mhash))
+            (case (hash-ref png 'colorType (λ () (error 'read-png "PNG file is loco")))
+              [(3)
+               ;; Indexed color, RGB. Each byte in this chunk is an alpha for
+               ;; the palette index in the PLTE ("palette") chunk up until the
+               ;; last non-opaque entry. Set up an array, stretching over all
+               ;; palette entries which will be 0 (opaque) or 1 (transparent).
+               (hash-set! transparency 'indexed
+                          (append (read-bytes chunk-size)
+                                  (make-list (min 0 (- 255 chunk-size)) 255)))]
+              [(0)
+               ;; Greyscale. Corresponding to entries in the PLTE chunk.
+               ;; Grey is two bytes, range 0 .. (2 ^ bit-depth) - 1]
+               (hash-set! transparency 'grayscale (bytes-ref (read-bytes chunk-size) 0))]
+              [(2)
+               ;; True color with proper alpha channel.
+               (hash-set! transparency 'rgb (read-bytes chunk-size))])
+            (report (hash-set! png 'transparency transparency))]
+           [(#"tEXt")
+            (define text (read-bytes chunk-size))
+            #|
+ text = @read(chunkSize)                    
+                    index = text.indexOf(0)
+                    key = String.fromCharCode text.slice(0, index)...
+                    @text[key] = String.fromCharCode text.slice(index + 1)...
+|#
+            42]
            [(#"IEND") (define color-value (case (hash-ref png 'colorType)
                                             [(0 3 4) 1]
                                             [(2 6) 3]))
-                      (define alpha-value (member (hash-ref png 'colorType) '(4 6)))
+                      (define alpha-value (and (member (hash-ref png 'colorType) '(4 6)) (hash-ref png 'colorType)))
                       (hash-set*! png
                                   'colors color-value
                                   'hasAlphaChannel alpha-value
@@ -46,6 +75,100 @@ Grab key chunks from PNG. Doesn't require heavy lifting from libpng.
          (read-bytes 4) ; skip crc
          (loop)]))))
 
+(define/contract (decodePixels imgData pixelBitLength width height fn)
+  (bytes? number? number? number? procedure? . -> . any/c)
+  (define data (inflate imgData))
+  (define pixelBytes (/ pixelBitLength 8))
+  (define scanlineLength (* pixelBytes width))
+
+  (define pixels (make-bytes (* scanlineLength height)))
+  (define length (bytes-length data))
+  (define row 0)
+  (define pos 0)
+  (define c 0)
+
+  (report* width height)
+  (parameterize ([current-input-port (open-input-bytes data)])
+    (for/fold ([_ #f]) ([row (in-naturals)]
+                        #:break (eof-object? (peek-byte)))
+      (report row)
+      (define b (read-byte))
+      (case b
+        [(0) ; none
+         (for ([i (in-range scanlineLength)])
+           (define b (read-byte))
+           (bytes-set! pixels c b)
+           (increment! c))]
+        [(1) ; sub
+         (for ([i (in-range scanlineLength)])
+           (define byte (read-byte))
+           (define left (if (< i pixelBytes)
+                            0
+                            (bytes-ref pixels (- c pixelBytes))))
+           (bytes-set! pixels c (modulo (+ byte left) 256))
+           (increment! c))]
+        [(2) ; up
+         (for ([i (in-range scanlineLength)])
+           (define byte (read-byte))
+           (define col ((i . - . (modulo i pixelBytes)) . / . pixelBytes))
+           (define upper (if (zero? row)
+                             row
+                             (+ (* (bytes-ref pixels (sub1 row)) scanlineLength)
+                                (* col pixelBytes)
+                                (modulo i pixelBytes))))
+           (bytes-set! pixels c (modulo (+ upper byte) 256))
+           (increment! c))]
+        [(3) ; average
+         (for ([i (in-range scanlineLength)])
+           (define byte (read-byte))
+           (define col ((i . - . (modulo i pixelBytes)) . / . pixelBytes))
+           (define left (if (< i pixelBytes)
+                            0
+                            (bytes-ref pixels (- c pixelBytes))))
+           (define upper (if (zero? row)
+                             row
+                             (+ (* (bytes-ref pixels (sub1 row)) scanlineLength)
+                                (* col pixelBytes)
+                                (modulo i pixelBytes))))
+           (bytes-set! pixels c (modulo (+ byte (floor (/ (+ left upper) 2))) 256))
+           (increment! c))]
+        [(4) ; paeth
+         (for ([i (in-range scanlineLength)])
+           (define byte (read-byte))
+           (define col ((i . - . (modulo i pixelBytes)) . / . pixelBytes))
+           (define left (if (< i pixelBytes)
+                            0
+                            (bytes-ref pixels (- c pixelBytes))))
+           (match-define (list upper upperLeft)
+             (cond
+               [(zero? row) (list 0 0)]
+               [else (define upper (+ (* (bytes-ref pixels (sub1 row)) scanlineLength)
+                                      (* col pixelBytes)
+                                      (modulo i pixelBytes)))
+                     (define upperLeft (+ (* (bytes-ref pixels (sub1 row)) scanlineLength)
+                                          (* (sub1 col) pixelBytes)
+                                          (modulo i pixelBytes)))
+                     (list upper upperLeft)]))
+
+           (define p (+ left upper (- upperLeft)))
+           (define pa (abs (- p left)))
+           (define pb (abs (- p upper)))
+           (define pc (abs (- p upperLeft)))
+
+           (define paeth (cond
+                           [((pa . <= . pb) . and . (pa . <= . pc)) left]
+                           [(pb . <= . pc) upper]
+                           [else upperLeft]))
+           
+           (bytes-set! pixels c (modulo (+ byte paeth) 256))
+           (increment! c)
+               
+           )]
+        [else (error 'invalid-filter-algorithm (format "~a" b))])))
+  (report (bytes-length pixels))
+  (fn pixels))
+
+
 (define (read-32bit-integer)
   (define signed #f) (define big-endian #t)
   (integer-bytes->integer (read-bytes 4) signed big-endian))

pitfall/pitfall/png.rkt

@@ -1,21 +1,27 @@
 #lang pitfall/racket
-(require "png-reader.rkt")
+(require "png-reader.rkt" "zlib.rkt")
 (provide PNG)
 
-(define-subclass object% (PNG data label)
+(define-subclass object% (PNG data [label #f])
   (super-new)
   
   (field [image (read-png data)]
+         [pixelBitlength (· image pixelBitlength)]
          [width (· image width)]
          [height (· image height)]
          [imgData (· image imgData)]
+         [document #f]
+         [alphaChannel #f]
          [obj #f])
 
   (as-methods
-   embed))
+   embed
+   finalize
+   splitAlphaChannel))
 
 (define/contract (embed this doc-in)
   (object? . ->m . void?)
+  (set-field! document this doc-in)
   
   (unless (· this obj)
     (set-field! obj this
@@ -29,9 +35,9 @@
 
     (unless (· this image hasAlphaChannel)
       (define params (send doc-in ref (mhash 'Predictor 15
-                                                        'Colors (· this image colors)
-                                                        'BitsPerComponent (· this image bits)
-                                                        'Columns (· this width))))
+                                             'Colors (· this image colors)
+                                             'BitsPerComponent (· this image bits)
+                                             'Columns (· this width))))
       (hash-set! (· this obj payload) 'DecodeParms params)
       (send params end))
 
@@ -46,10 +52,80 @@
                   (list "Indexed" "DeviceRGB" (sub1 (bytes-length (· this image palette))) palette-ref))]
       [else (hash-set! (· this obj payload) 'ColorSpace "DeviceRGB")])
 
-    
+   
+    (cond
+      [(hash-ref (· this image) 'transparency #f)
+       (cond
+         [(hash-ref (hash-ref (· this image) 'transparency) 'grayscale #f)
+          ]
+         [(hash-ref (hash-ref (· this image) 'transparency) 'rgb #f)
+          ]
+         [(hash-ref (hash-ref (· this image) 'transparency) 'indexed #f)
+          ])]
+      [(hash-ref (· this image) 'hasAlphaChannel #f)
+       ;; For PNG color types 4 and 6, the transparency data is stored as a alpha
+       ;; channel mixed in with the main image data. Separate this data out into an
+       ;; SMask object and store it separately in the PDF.]
+       (· this splitAlphaChannel)]
+      [else (· this finalize)])))
+
+(define/contract (finalize this)
+  (->m void?)
+  (when (· this alphaChannel)
+    (define sMask
+      (send (· this document) ref
+            (mhash 'Type "XObject"
+                   'Subtype "Image"
+                   'Height (· this height)
+                   'With (· this width)
+                   'BitsPerComponent 8
+                   'Filter "FlateDecode"
+                   'ColorSpace "DeviceGray"
+                   'Decode '(0 1))))
+    (send sMask end (· this alphaChannel))
+    (hash-set! (· this obj payload) 'SMask sMask))
+  
+  ;; embed the actual image data
+  (send (· this obj) end (· this imgData)))
+
+(define/contract (splitAlphaChannel this)
+  (->m void?)
+  (define (pixel-proc pixels)
+    (define colorByteSize (* (· this image colors) (/ (· this image bits) 8)))
+    (define pixelCount (* (· this width) (· this height)))
+    (define imgData (make-bytes (* pixelCount colorByteSize)))
+    (define alphaChannel (make-bytes pixelCount))
+
+    (define i 0)
+    (define p 0)
+    (define a 0)
+    (define len (bytes-length pixels))
+
+    (for ([idx (in-naturals)]
+          #:when (< i len))
+      (bytes-set! imgData p (bytes-ref pixels i))
+      (increment! p) (increment! i)
+      (bytes-set! imgData p (bytes-ref pixels i))
+      (increment! p) (increment! i)
+      (bytes-set! imgData p (bytes-ref pixels i))
+      (increment! p) (increment! i)
+      (bytes-set! alphaChannel a (bytes-ref pixels i))
+      (increment! a) (increment! i))
+
+    (define done 0)
+    (set-field! imgData this (deflate imgData))
+    (increment! done)
+    (when (= done 2) (· this finalize))
+
+    (set-field! alphaChannel this (deflate alphaChannel))
+    (increment! done)
+    (when (= done 2) (· this finalize))
+      
 
-    ;; todo: transparency & alpha channel shit
 
-    ;; embed the actual image data
-    (send (· this obj) end (· this imgData))))
+    )
+  (decodePixels (· this imgData) (· this pixelBitlength) (· this width) (· this height) pixel-proc))
 
+(module+ test
+  (define pic (make-object PNG (file->bytes "test/assets/test.png")))
+  (splitAlphaChannel pic))

pitfall/pitfall/test/test8.coffee

@@ -3,18 +3,18 @@ fs = require 'fs'
 
 make = (doc) -> 
     # Set the font, draw some text, and embed an image
-    doc.font('Times-Italic')
+    doc.font('Helvetica-Bold')
        .fontSize(25)
-       .text('Here comes a JPEG!', 100, 100, lineBreak: no)
-       .image('assets/test.jpeg', 100, 160, width: 412)
+       .text('Another fantastic pic', 100, 100, lineBreak: no)
+       .image('assets/test.png', 100, 160, width: 412)
 
     doc.end()
 
 doc = new PDFDocument({compress: no})
-doc.pipe(fs.createWriteStream('test5.pdf'))
+doc.pipe(fs.createWriteStream('test8.pdf'))
 make doc
 
 doc = new PDFDocument({compress: yes})
-doc.pipe(fs.createWriteStream('test5c.pdf'))
+doc.pipe(fs.createWriteStream('test8c.pdf'))
 make doc
 

pitfall/pitfall/test/test8.rkt

@@ -0,0 +1,16 @@
+#lang pitfall/pdftest
+
+(define-runtime-path pic "assets/test.png")
+
+(define (proc doc)
+  (send* doc
+  [font "Helvetica-Bold"]
+  [fontSize 25]
+  [text "Another fantastic pic" 100 100 (hash 'lineBreak #f)]
+  [image pic 100 160 (hash 'width 412)]))
+
+(define-runtime-path this "test8rkt.pdf")
+(make-doc this #f proc #:test #f)
+
+#;(define-runtime-path that "test8crkt.pdf")
+#;(make-doc that #t proc)