--- a/PNGReader.st	Fri Jul 31 19:56:56 2009 +0200
+++ b/PNGReader.st	Mon Aug 03 14:28:19 2009 +0200
@@ -63,19 +63,16 @@
     PNGReader fromFile:'C:\Users\cg\Desktop\croquet\cobalt-base-current-build-20090210\cobalt-base-current-build-20090210\content\models\textures\checkerboard.png'
     PNGReader fromFile:'C:\Dokumente und Einstellungen\cg\Desktop\misc\PNGs\Delete.png'
     PNGReader fromFile:'\\exeptn\unsaved\pd_stuff\PNGs\Delete.png'
+    PNGReader fromFile:'\\exeptn\unsaved\pd_stuff\PNGs\Down.png'
 "
 ! !
 
 !PNGReader class methodsFor:'initialization'!
 
 initialize
-    "install myself in the Image classes fileFormat table
-     for the `.png' extension."
+    "install myself in the Image classes fileFormat table for the `.png' extension."
 
-    "/ not yet finished - do not add
-    "/ MIMETypes defineImageType:'image/x-png'  suffix:'png' reader:self.
-
-    "Modified: 1.2.1997 / 15:02:47 / cg"
+    MIMETypes defineImageType:'image/x-png'  suffix:'png' reader:self.
 ! !
 
 !PNGReader class methodsFor:'testing'!
@@ -107,6 +104,22 @@
 
 !PNGReader methodsFor:'private-chunks'!
 
+doPass: pass
+    "Certain interlace passes are skipped with certain small image dimensions"
+
+    pass = 1 ifTrue: [ ^ true ].
+    ((width = 1) and: [height = 1]) ifTrue: [ ^ false ].
+    pass = 2 ifTrue: [ ^ width >= 5 ].
+    pass = 3 ifTrue: [ ^ height >= 5 ].
+    pass = 4 ifTrue: [ ^ (width >=3 ) or: [height >= 5] ].
+    pass = 5 ifTrue: [ ^ height >=3 ].
+    pass = 6 ifTrue: [ ^ width >=2 ].
+    pass = 7 ifTrue: [ ^ height >=2 ].
+
+    self error:'invalid argument'.
+    ^ true
+!
+
 processBKGDChunkLen:len
     inStream skip:len.
     ^ true
@@ -208,6 +221,51 @@
     ^ true
 !
 
+processInterlacedGlobalDATA
+    | zlibReader filter bytesPerPass startingCol colIncrement rowIncrement 
+      startingRow cx sc temp "filtersSeen" bitsPerPixel copyMethod|
+
+self error:'interlaced pictures not yet supported'.
+
+    "/ filtersSeen := Set new.
+
+    startingCol := #(0 4 0 2 0 1 0 ).
+    colIncrement := #(8 8 4 4 2 2 1 ).
+    rowIncrement := #(8 8 8 4 4 2 2 ).
+    startingRow := #(0 0 4 0 2 0 1 ).
+
+    zlibReader := ZipStream readOpenAsZipStreamOn:(globalDataChunk readStream).
+    zlibReader binary.
+    bytesPerScanline := self bytesPerRow.
+    bitsPerPixel := self bitsPerPixel.
+
+    copyMethod := #(copyPixelsGray: nil copyPixelsRGB: copyPixelsIndexed:
+                    copyPixelsGrayAlpha: nil copyPixelsRGBA:) at:colorType+1.     
+
+    1 to: 7 do: [:pass |
+        (self doPass: pass) ifTrue:[
+            cx := colIncrement at: pass.
+            sc := startingCol at: pass.
+            bytesPerPass := width - sc + cx - 1 // cx * bitsPerPixel + 7 // 8.
+            prevScanline := ByteArray new: bytesPerPass.
+            thisScanline := ByteArray new: bytesPerScanline.
+            (startingRow at: pass) to: height - 1 by: (rowIncrement at: pass) do: [:y |
+                filter := zlibReader next.
+                "/ filtersSeen add: filter.
+                (filter isNil or: [(filter between: 0 and: 4) not])
+                    ifTrue: [^ self].
+                zlibReader next: bytesPerPass into: thisScanline startingAt: 1.
+                filter ~~ 0 ifTrue:[ self filterScanline: filter count: bytesPerPass ].
+                self copyPixels:y at:sc by:cx.
+                temp := prevScanline.
+                prevScanline := thisScanline.
+                thisScanline := temp.
+            ]
+        ]
+    ].
+    zlibReader atEnd ifFalse:[self error:'Unexpected data'].
+!
+
 processNonInterlacedDATA:len
     | zlibReader filter temp prevScanline thisScanline bytesPerScanline filtersSeen|
 
@@ -324,6 +382,20 @@
 
 !PNGReader methodsFor:'private-filtering'!
 
+filterAverage: count
+    "Use the average of the pixel to the left and the pixel above as a predictor"
+
+    | delta |
+    delta := self bitsPerPixel // 8 max: 1.
+    1 to: delta do: [:i |
+        thisScanline at: i put: ((thisScanline at: i) + ((prevScanline at: i) // 2) bitAnd: 255)].
+    delta + 1 to: count do: [:i |
+        thisScanline at: i put:
+            ((thisScanline at: i)
+            + ((prevScanline at: i)
+            + (thisScanline at: i - delta) // 2) bitAnd: 255)]
+!
+
 filterHorizontal:count
     "use the pixel to the left as a predictor"
 
@@ -335,6 +407,9 @@
     ]
 !
 
+filterNone: count
+!
+
 filterPaeth: count
     "Select one of (the pixel to the left, the pixel above and the pixel to above left) to
     predict the value of this pixel"
@@ -387,7 +462,50 @@
     ^ c
 ! !
 
-!PNGReader methodsFor:'private-reading'!
+!PNGReader methodsFor:'private-pixel copy'!
+
+copyPixels: y at: startX by: incX
+    "Handle interlaced pixels of supported colorTypes"
+
+    | s |
+
+    s := #(copyPixelsGray:at:by: nil copyPixelsRGB:at:by: copyPixelsIndexed:at:by:
+          copyPixelsGrayAlpha:at:by: nil copyPixelsRGBA:at:by:) at: colorType+1.
+    self perform: s asSymbol with: y with: startX with: incX
+!
+
+copyPixelsGray: y
+    "Handle non-interlaced Gray color modes (colorType = 0)"
+
+    |bpr i|
+
+    bpr := self bytesPerRow.
+    i := y * bpr.
+
+    data replaceFrom:1+i to:(i+bpr-1) with:thisScanline startingAt:1.
+!
+
+copyPixelsIndexed:y
+    "Handle non-interlaced palette color modes (colorType = 3)"
+
+    |bpr i|
+
+    bpr := self bytesPerRow.
+    i := y * bpr.
+
+    data replaceFrom:1+i to:(i+bpr-1) with:thisScanline startingAt:1.
+!
+
+copyPixelsRGB: y
+    "Handle non-interlaced RGB color modes (colorType = 2)"
+
+    |bpr i|
+
+    bpr := self bytesPerRow.
+    i := y * bpr.
+
+    data replaceFrom:1+i to:(i+bpr-1) with:thisScanline startingAt:1.
+!
 
 copyPixelsRGBA: y
     "Handle non-interlaced RGBA color modes (colorType = 6)"
@@ -398,7 +516,9 @@
     i := y * bpr.
 
     data replaceFrom:1+i to:(i+bpr-1) with:thisScanline startingAt:1.
-!
+! !
+
+!PNGReader methodsFor:'private-reading'!
 
 getChunk
     |len type crc|
@@ -657,7 +777,7 @@
 !PNGReader class methodsFor:'documentation'!
 
 version
-    ^ '$Header: /cvs/stx/stx/libview2/PNGReader.st,v 1.16 2009-07-31 17:56:56 cg Exp $'
+    ^ '$Header: /cvs/stx/stx/libview2/PNGReader.st,v 1.17 2009-08-03 12:28:19 cg Exp $'
 ! !
 
 PNGReader initialize!