1 files changed, 102 insertions, 0 deletions
diff --git a/scripts/png.py b/scripts/png.py
new file mode 100644
index 00000000..739b1a7a
--- /dev/null
+++ b/scripts/png.py
@@ -0,0 +1,102 @@
+import struct, zlib, sys
+
+class image:
+	w = 0
+	h = 0
+	data = []
+
+def read_tga(f):
+	image = f.read()
+	img_type = struct.unpack("<B", image[2:3])[0]
+	img_bpp = struct.unpack("<B", image[16:17])[0]
+	img_width = struct.unpack("<H", image[12:14])[0]
+	img_height = struct.unpack("<H", image[14:16])[0]
+
+	if img_type != 2 or img_bpp != 32:
+		print "image must be a RGBA"
+
+	start = 18+struct.unpack("B", image[0])[0]
+	end = start + img_width*img_height*4
+	image_data = image[start:end] # fetch raw data
+	return image_data
+
+def write_tga(f, w, h, bpp, data):
+	f.write(struct.pack("<BBBHHBHHHHBB", 0, 0, 2, 0, 0, 0, 0, 0, w, h, bpp, 0) + data)
+
+
+
+
+
+def load_png(f):
+	def read(fmt): return struct.unpack("!"+fmt, f.read(struct.calcsize("!"+fmt)))
+	def skip(count): f.read(count)
+
+	# read signature
+	if read("cccccccc") != ('\x89', 'P', 'N', 'G', '\r', '\n', '\x1a', '\n'):
+		return 0
+
+	# read chunks
+	width = -1
+	height = -1
+	imagedata = ""
+	while 1:
+		size, id = read("I4s")
+		if id == "IHDR": # read header
+			width, height, bpp, colortype, compression, filter, interlace = read("IIBBBBB")
+			if bpp != 8 or compression != 0 or filter != 0 or interlace != 0 or (colortype != 2 and colortype != 6):
+				print "can't handle png of this type"
+				print width, height, bpp, colortype, compression, filter, interlace
+				return 0
+			skip(4)
+		elif id == "IDAT":
+			imagedata += f.read(size)
+			skip(4) # read data
+		elif id == "IEND":
+			break # we are done! \o/
+		else:
+			skip(size+4) # skip unknown chunks
+
+	# decompress image data
+	rawdata = map(ord, zlib.decompress(imagedata))
+	
+	# apply per scanline filters
+	pitch = width*4+1
+	bpp = 4
+	imgdata = []
+	prevline = [0 for x in xrange(0, (width+1)*bpp)]
+	for y in xrange(0,height):
+		filter = rawdata[pitch*y]
+		pixeldata = rawdata[pitch*y+1:pitch*y+pitch]
+		thisline = [0 for x in xrange(0,bpp)]
+		def paeth(a, b, c):
+			p = a + b - c
+			pa = abs(p - a)
+			pb = abs(p - b)
+			pc = abs(p - c)
+			if pa <= pb and pa <= pc:
+				return a
+			if pb <= pc:
+				return b
+			return c
+		
+		if filter == 0: f = lambda a,b,c: 0
+		elif filter == 1: f = lambda a,b,c: a
+		elif filter == 2: f = lambda a,b,c: b
+		elif filter == 3: f = lambda a,b,c: (a+b)/2
+		elif filter == 4: f = paeth
+			
+		for x in xrange(0, width*bpp):
+			thisline += [(pixeldata[x] + f(thisline[x], prevline[x+bpp], prevline[x])) % 256]			
+			
+		prevline = thisline
+		imgdata += thisline[4:]
+	
+	raw = ""
+	for x in imgdata:
+		raw += struct.pack("B", x)
+		
+	#print len(raw), width*height*4
+	write_tga(file("test2.tga", "w"), width, height, 32, raw)
+	return 0
+	
+load_png(file("butterfly2.png", "rb"))
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