Strict
Rem
bbdoc: IFF ILBM loader
End Rem
Module HOT.IFFILBMLoader
ModuleInfo "Version: 1.00"
ModuleInfo "Author: Toby Zuijdveld"
ModuleInfo "License: Blitz Shared Source Code"
ModuleInfo "Copyright: Jerry Morrison, Electronic Arts (public domain)"
ModuleInfo "Modserver: n/a"
ModuleInfo "History: 1.00 Release"
Import BRL.Pixmap
Import BRL.EndianStream
Private
Function ReadTag$( stream:TStream )
Local tag:Byte[4]
If stream.ReadBytes( tag,4 )<>4 Return
Return Chr(tag[0])+Chr(tag[1])+Chr(tag[2])+Chr(tag[3])
End Function
Function UStoSI%(a:Short)
If a>$7FFF Then Return -($8000-(a-$8000)) Else Return a
End Function ' unsigned short to signed integer
Rem
"cmpByteRun1" is the byte run encoding
End Rem ' End Rem
Const cmpNone = 0
Const cmpByteRun1 = 1
Global ColourMapRed[] = Null
Global ColourMapGreen[]
Global ColourMapBlue[] ' dodginess!
Public
Rem
bbdoc: Preload a Colour Map for use when loading future ILBM images
about:
#IFFCMAP loads CMAP information from the given @url file.<br>
<br>
Every subsequent ILBM image will be loaded using this palette.<br>
<br>
By default, the CMAP information stored with an ILBM picture would be used. To restore that behaviour, use #IFFCMAP without a @url specified.<br>
If the Colour Map cannot be loaded, 0 is returned and this function's default behaviour will apply.<br>
End Rem
Function IFFCMAP( url:Object="" )
If url=""
ColourMapRed = Null
ColourMapGreen = Null
ColourMapBlue = Null
Return 1
EndIf
Local stream:TStream=ReadStream( url )
If Not stream
ColourMapRed = Null
ColourMapGreen = Null
ColourMapBlue = Null
Return 0
EndIf
stream = BigEndianStream(stream)
If ReadTag( stream )<>"FORM" Return
Local dud% = stream.Readint() ' length of file after ILBM header
If ReadTag( stream )<>"ILBM" Return
Local cmap% = 0
Local i% = 0
Local n% = 0
While Not stream.Eof()
Local blahblah$=ReadTag$(stream)
Select blahblah$'Readtag$(stream)
Case "CMAP" ' ColorMap
dud = stream.ReadInt() ' length of ColourMap chunk
cmap = dud/3
ColourMapRed = ColourMapRed[..cmap+1]
ColourMapGreen = ColourMapGreen[..cmap+1]
ColourMapBlue = ColourMapBlue[..cmap+1]
For i=1 To cmap
ColourMapRed[i] = stream.ReadByte()
ColourMapGreen[i] = stream.ReadByte()
ColourMapBlue[i] = stream.ReadByte()
Next ' i=1 To cmap
n=1
Exit
Default ' unsupported chunks
stream.SkipBytes(stream.ReadInt()) ' skip chunk
End Select ' ReadTag$(stream)
If n=0 Then Exit
Wend ' Not stream.EOF()
stream.Close
Return n
End Function
Private
Type TPixmapLoaderILBM Extends TPixmapLoader
Method LoadPixmap:TPixmap(stream:TStream)
stream=BigEndianStream( stream )
If ReadTag( stream )<>"FORM" Return
Local dud% = stream.Readint() ' length of file after ILBM header
If ReadTag( stream )<>"ILBM" Return
Local cmap% = 0
Local w:Short = 0
Local h:Short = 0
Local x% = 0
Local y% = 0
Local nPlanes:Byte = 0
Local masking:Byte = 0
Local compression:Byte = 0
Local transparentColour:Short = 0
Local xAspect:Byte = 0
Local yAspect:Byte = 0
Local pageWidth% = 0
Local pageHeight% = 0
Local plane% = 0
Local scanline% = 1
Local i% = 0
Local n% = 0
Local nn% = 0
Local pixmap:TPixmap = Null
Local buffer2:Byte[]
While Not stream.Eof()
Local blahblah$=ReadTag$(stream)
Select blahblah$'Readtag$(stream)
Case "BMHD" ' BitMapHeader
dud = stream.ReadInt() ' length of BitMapHeader chunk
w = stream.ReadShort()
h = stream.ReadShort() ' raster width & height in pixels
x = UStoSI(stream.ReadShort())
y = UStoSI(stream.ReadShort()) ' pixel position for this image
nPlanes = stream.ReadByte() ' # source bitplanes
masking = stream.ReadByte() ' Choice of masking technique.
compression = stream.ReadByte() ' Choice of compression algorithm applied to the rows of all source and mask planes.
Local dud2% = stream.ReadByte() ' unused; for consistency, put 0 here
transparentColour = stream.ReadShort() ' transparent "colour number" (sort of)
xAspect = stream.ReadByte()
yAspect = stream.ReadByte() ' pixel aspect, a ratio width : height
pageWidth = UStoSI(stream.ReadShort())
pageHeight = UStoSI(stream.ReadShort()) ' source "page" size in pixels
stream.SkipBytes(dud-20) ' extended chunk compatibility
Case "CMAP" ' ColorMap
dud = stream.ReadInt() ' length of ColourMap chunk
If Not ColourMapRed
cmap = dud/3
ColourMapRed = ColourMapRed[..cmap+1]
ColourMapGreen = ColourMapGreen[..cmap+1]
ColourMapBlue = ColourMapBlue[..cmap+1]
For i=1 To cmap
ColourMapRed[i] = stream.ReadByte()
ColourMapGreen[i] = stream.ReadByte()
ColourMapBlue[i] = stream.ReadByte()
Next ' i=1 To cmap
If dud & 1 Then stream.SkipBytes(1) ' padded chunk compatibility
Else
stream.SkipBytes(dud) ' skip chunk
If dud & 1 Then stream.SkipBytes(1) ' padded chunk compatibility
EndIf ' ColourMap=Null
Case "BODY" '
dud = stream.ReadInt() ' length of BODY chunk
Local row[]
Local buffer%[17]
pixmap = TPixmap.Create(w,h,PF_RGB888)
If 2^nPlanes>cmap
ColourMapRed=ColourMapRed[..(2^nPlanes)+1]
ColourMapGreen=ColourMapGreen[..(2^nPlanes)+1]
ColourMapBlue=ColourMapBlue[..(2^nPlanes)+1]
EndIf ' 2^nPlanes>cmap
For Local column%=1 To h
row = New Int[w+17]
Select compression
Case cmpNone
For plane=1 To nPlanes
For scanline=1 To w Step 16
buffer[1] = stream.ReadShort()
For dud=2 To 16
buffer[dud] = (buffer[1] Shr (dud-1)) & 1
Next ' dud=2 To 16
buffer[1] = buffer[1] & 1
For dud=1 To 16
row[scanline+(16-dud)] = row[scanline+(16-dud)]+(buffer[dud] Shl (plane-1))
Next ' dud=1 To 16
Next ' scanline=1 To w Step 8
Next ' plane=1 To nPlanes
Case cmpByteRun1
Local dud2 = 1
nn = 1
Local ii
If Not buffer2
buffer2 = New Byte[w*h*(nPlanes+1)]
Repeat
n=stream.ReadByte();dud2:+1
If n>127 Then n:-256 ' unsigned to signed conversion
If n<>-128 ' noop
If n<0 ' replicate the next byte -n+1 times
n = Abs(n)+1
ii = stream.ReadByte();dud2:+1
For i=1 To n
buffer2[nn]=ii;nn:+1
Next ' i=1 To n
Else ' copy the next n+1 bytes literally
For i=0 To n
buffer2[nn]=stream.ReadByte();dud2:+1;nn:+1
Next ' i=0 To n
EndIf ' n<0
EndIf ' n<>-128
Until dud2>dud
EndIf ' Not buffer2
For plane=1 To nPlanes
For i=1 To w Step 16
buffer[1] = buffer2[scanline+1]+(buffer2[scanline] Shl 8);scanline:+2
For dud=2 To 16
buffer[dud] = (buffer[1] Shr (dud-1)) & 1
Next ' dud=2 To 16
buffer[1] = buffer[1] & 1
For dud=1 To 16
row[i+(16-dud)] = row[i+(16-dud)]+(buffer[dud] Shl (plane-1))
Next ' dud=1 To 16
Next ' i=1 To w Step 16
Next ' plane=1 To nPlanes
Default ' unsupported compression algorithm
dud = 0
Exit
End Select ' compression
If dud=0 Then pixmap = Null;Exit
For dud=1 To w
pixmap.WritePixel dud-1,column-1,(ColourMapRed[row[dud]+1] Shl 16)+(ColourMapGreen[row[dud]+1] Shl 8)+ColourMapBlue[row[dud]+1]
Next ' row=1 To w
Next ' column=1 To h
If cmap Then ColourMapRed = Null
Exit
Default ' unsupported chunks
stream.SkipBytes(stream.ReadInt()) ' skip chunk
End Select ' ReadTag$(stream)
If pixmap Then Exit
Wend ' Not stream.EOF()
Return pixmap
End Method
End Type
New TPixmapLoaderILBM
