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Diffstat (limited to 'pngcanvas.py')
| -rw-r--r-- | pngcanvas.py | 291 |
1 files changed, 0 insertions, 291 deletions
diff --git a/pngcanvas.py b/pngcanvas.py deleted file mode 100644 index 394ff4f..0000000 --- a/pngcanvas.py +++ /dev/null @@ -1,291 +0,0 @@ -#!/usr/bin/env python - -"""Simple PNG Canvas for Python""" -__version__ = "0.8" -__author__ = "Rui Carmo (http://the.taoofmac.com)" -__copyright__ = "CC Attribution-NonCommercial-NoDerivs 2.0 Rui Carmo" -__contributors__ = ["http://collaboa.weed.rbse.com/repository/file/branches/pgsql/lib/spark_pr.rb"], ["Eli Bendersky"] - -import zlib, struct - -signature = struct.pack("8B", 137, 80, 78, 71, 13, 10, 26, 10) - -# alpha blends two colors, using the alpha given by c2 -def blend(c1, c2): - return [c1[i]*(0xFF-c2[3]) + c2[i]*c2[3] >> 8 for i in range(3)] - -# calculate a new alpha given a 0-0xFF intensity -def intensity(c,i): - return [c[0],c[1],c[2],(c[3]*i) >> 8] - -# calculate perceptive grayscale value -def grayscale(c): - return int(c[0]*0.3 + c[1]*0.59 + c[2]*0.11) - -# calculate gradient colors -def gradientList(start,end,steps): - delta = [end[i] - start[i] for i in range(4)] - grad = [] - for i in range(steps+1): - grad.append([start[j] + (delta[j]*i)/steps for j in range(4)]) - return grad - -class PNGCanvas: - def __init__(self, width, height,bgcolor=[0xff,0xff,0xff,0xff],color=[0,0,0,0xff]): - self.canvas = [] - self.width = width - self.height = height - self.color = color #rgba - bgcolor = bgcolor[0:3] # we don't need alpha for background - for i in range(height): - self.canvas.append([bgcolor] * width) - - def point(self,x,y,color=None): - if x<0 or y<0 or x>self.width-1 or y>self.height-1: return - if color == None: color = self.color - self.canvas[y][x] = blend(self.canvas[y][x],color) - - def _rectHelper(self,x0,y0,x1,y1): - x0, y0, x1, y1 = int(x0), int(y0), int(x1), int(y1) - if x0 > x1: x0, x1 = x1, x0 - if y0 > y1: y0, y1 = y1, y0 - return [x0,y0,x1,y1] - - def verticalGradient(self,x0,y0,x1,y1,start,end): - x0, y0, x1, y1 = self._rectHelper(x0,y0,x1,y1) - grad = gradientList(start,end,y1-y0) - for x in range(x0, x1+1): - for y in range(y0, y1+1): - self.point(x,y,grad[y-y0]) - - def rectangle(self,x0,y0,x1,y1): - x0, y0, x1, y1 = self._rectHelper(x0,y0,x1,y1) - self.polyline([[x0,y0],[x1,y0],[x1,y1],[x0,y1],[x0,y0]]) - - def filledRectangle(self,x0,y0,x1,y1): - x0, y0, x1, y1 = self._rectHelper(x0,y0,x1,y1) - for x in range(x0, x1+1): - for y in range(y0, y1+1): - self.point(x,y,self.color) - - def copyRect(self,x0,y0,x1,y1,dx,dy,destination): - x0, y0, x1, y1 = self._rectHelper(x0,y0,x1,y1) - for x in range(x0, x1+1): - for y in range(y0, y1+1): - destination.canvas[dy+y-y0][dx+x-x0] = self.canvas[y][x] - - def blendRect(self,x0,y0,x1,y1,dx,dy,destination,alpha=0xff): - x0, y0, x1, y1 = self._rectHelper(x0,y0,x1,y1) - for x in range(x0, x1+1): - for y in range(y0, y1+1): - rgba = self.canvas[y][x] + [alpha] - destination.point(dx+x-x0,dy+y-y0,rgba) - - # draw a line using Xiaolin Wu's antialiasing technique - def line(self,x0, y0, x1, y1): - # clean params - x0, y0, x1, y1 = int(x0), int(y0), int(x1), int(y1) - if y0>y1: - y0, y1, x0, x1 = y1, y0, x1, x0 - dx = x1-x0 - if dx < 0: - sx = -1 - else: - sx = 1 - dx *= sx - dy = y1-y0 - - # 'easy' cases - if dy == 0: - for x in range(x0,x1,sx): - self.point(x, y0) - return - if dx == 0: - for y in range(y0,y1): - self.point(x0, y) - self.point(x1, y1) - return - if dx == dy: - for x in range(x0,x1,sx): - self.point(x, y0) - y0 = y0 + 1 - return - - # main loop - self.point(x0, y0) - e_acc = 0 - if dy > dx: # vertical displacement - e = (dx << 16) / dy - for i in range(y0,y1-1): - e_acc_temp, e_acc = e_acc, (e_acc + e) & 0xFFFF - if (e_acc <= e_acc_temp): - x0 = x0 + sx - w = 0xFF-(e_acc >> 8) - self.point(x0, y0, intensity(self.color,(w))) - y0 = y0 + 1 - self.point(x0 + sx, y0, intensity(self.color,(0xFF-w))) - self.point(x1, y1) - return - - # horizontal displacement - e = (dy << 16) / dx - for i in range(x0,x1-sx,sx): - e_acc_temp, e_acc = e_acc, (e_acc + e) & 0xFFFF - if (e_acc <= e_acc_temp): - y0 = y0 + 1 - w = 0xFF-(e_acc >> 8) - self.point(x0, y0, intensity(self.color,(w))) - x0 = x0 + sx - self.point(x0, y0 + 1, intensity(self.color,(0xFF-w))) - self.point(x1, y1) - - def polyline(self,arr): - for i in range(0,len(arr)-1): - self.line(arr[i][0],arr[i][1],arr[i+1][0], arr[i+1][1]) - - def dump(self): - raw_list = [] - for y in range(self.height): - raw_list.append(chr(0)) # filter type 0 (None) - for x in range(self.width): - raw_list.append(struct.pack("!3B",*self.canvas[y][x])) - raw_data = ''.join(raw_list) - - # 8-bit image represented as RGB tuples - # simple transparency, alpha is pure white - return signature + \ - self.pack_chunk('IHDR', struct.pack("!2I5B",self.width,self.height,8,2,0,0,0)) + \ - self.pack_chunk('tRNS', struct.pack("!6B",0xFF,0xFF,0xFF,0xFF,0xFF,0xFF)) + \ - self.pack_chunk('IDAT', zlib.compress(raw_data,9)) + \ - self.pack_chunk('IEND', '') - - def pack_chunk(self,tag,data): - to_check = tag + data - return struct.pack("!I",len(data)) + to_check + struct.pack("!I", zlib.crc32(to_check) & 0xFFFFFFFF) - - def load(self,f): - assert f.read(8) == signature - self.canvas=[] - for tag, data in self.chunks(f): - if tag == "IHDR": - ( width, - height, - bitdepth, - colortype, - compression, filter, interlace ) = struct.unpack("!2I5B",data) - self.width = width - self.height = height - if (bitdepth,colortype,compression, filter, interlace) != (8,2,0,0,0): - raise TypeError('Unsupported PNG format') - # we ignore tRNS because we use pure white as alpha anyway - elif tag == 'IDAT': - raw_data = zlib.decompress(data) - rows = [] - i = 0 - for y in range(height): - filtertype = ord(raw_data[i]) - i = i + 1 - cur = [ord(x) for x in raw_data[i:i+width*3]] - if y == 0: - rgb = self.defilter(cur,None,filtertype) - else: - rgb = self.defilter(cur,prev,filtertype) - prev = cur - i = i+width*3 - row = [] - j = 0 - for x in range(width): - pixel = rgb[j:j+3] - row.append(pixel) - j = j + 3 - self.canvas.append(row) - - def defilter(self,cur,prev,filtertype,bpp=3): - if filtertype == 0: # No filter - return cur - elif filtertype == 1: # Sub - xp = 0 - for xc in range(bpp,len(cur)): - cur[xc] = (cur[xc] + cur[xp]) % 256 - xp = xp + 1 - elif filtertype == 2: # Up - for xc in range(len(cur)): - cur[xc] = (cur[xc] + prev[xc]) % 256 - elif filtertype == 3: # Average - xp = 0 - for xc in range(len(cur)): - cur[xc] = (cur[xc] + (cur[xp] + prev[xc])/2) % 256 - xp = xp + 1 - elif filtertype == 4: # Paeth - xp = 0 - for i in range(bpp): - cur[i] = (cur[i] + prev[i]) % 256 - for xc in range(bpp,len(cur)): - a = cur[xp] - b = prev[xc] - c = prev[xp] - p = a + b - c - pa = abs(p - a) - pb = abs(p - b) - pc = abs(p - c) - if pa <= pb and pa <= pc: - value = a - elif pb <= pc: - value = b - else: - value = c - cur[xc] = (cur[xc] + value) % 256 - xp = xp + 1 - else: - raise TypeError('Unrecognized scanline filter type') - return cur - - def chunks(self,f): - while 1: - try: - length = struct.unpack("!I",f.read(4))[0] - tag = f.read(4) - data = f.read(length) - crc = struct.unpack("!i",f.read(4))[0] - except: - return - if zlib.crc32(tag + data) != crc: - raise IOError - yield [tag,data] - -if __name__ == '__main__': - width = 128 - height = 64 - print "Creating Canvas..." - c = PNGCanvas(width,height) - c.color = [0xff,0,0,0xff] - c.rectangle(0,0,width-1,height-1) - print "Generating Gradient..." - c.verticalGradient(1,1,width-2, height-2,[0xff,0,0,0xff],[0x20,0,0xff,0x80]) - print "Drawing Lines..." - c.color = [0,0,0,0xff] - c.line(0,0,width-1,height-1) - c.line(0,0,width/2,height-1) - c.line(0,0,width-1,height/2) - # Copy Rect to Self - print "Copy Rect" - c.copyRect(1,1,width/2-1,height/2-1,0,height/2,c) - # Blend Rect to Self - print "Blend Rect" - c.blendRect(1,1,width/2-1,height/2-1,width/2,0,c) - # Write test - print "Writing to file..." - f = open("test.png", "wb") - f.write(c.dump()) - f.close() - # Read test - print "Reading from file..." - f = open("test.png", "rb") - c.load(f) - f.close() - # Write back - print "Writing to new file..." - f = open("recycle.png","wb") - f.write(c.dump()) - f.close() - |