Author: Mike Mulchek (god at seekrut.com)
Description: A function to identify individual glyphs in a rendered text string, and make the glyph's pixels available for addressing.
pygame version required: Any
Comments: The main GetGlyphs function is pretty hairy, and it's fairly slow, but it does a neat thing - it identifies individual glyphs in an arbitrary text surface, without reference to the original text string. The example script doesn't really do justice to the power of this function; it just cycles each glyph through random colors.
#!/usr/bin/env python """ GetGlyphs is a function that will run through a given surface and retrieve all shapes of a given color. It packs each shape into a list of coordinate pairs, and then packs them all up in a list. It does NOT recognize what shape it has found, but with some cleverness you could maybe make it into a cheap-OCR kind of thing. I wrote this so you can pick out the letters in a rendered surface and manipulate them independantly. For shits and giggles, I make it make all the colors rainbow. That could probably be made into a function, or GetGlyphs() could be extended to do a lot of things, or ideally take a string and do stuff automagically. Whatever. Note: This is HORRENDOUSLY UNBELIEVABLY PHENOMENALLY SLOW. I have no idea what I am doing and you are more than welcome to make it faster or rewrite it in one line or delete it on sight for being ugly or whatever. On the bright side, it does not crash anymore. Intention -- Mike Mulchek -- email@example.com -- 12/04/2001 """ import pygame, pygame.font, random from pygame.locals import * def GetGlyphs(surf, COLOR): """ Pull All Glyphs and Shapes of a certain color from a certain surface """ print "Looking for glyphs and shapes... This could take a few minutes..." TempGlyph =  # Temporary Letter GlyphList =  # Finished Glyph binder Active =  # Scratch space SurfCopy = pygame.Surface(surf.get_size()) # Make a copy so we do not destroy anything SurfCopy.blit(surf, (0,0)) DONECOLOR = (random.randrange(10,250),random.randrange(10,250),random.randrange(10,250)) if DONECOLOR == COLOR: DONECOLOR += 1 # Pick a scratch color that is guaranteed not to be the one we're looking for for x in range(SurfCopy.get_width()): # Run over the entire surface until we find a pixel to start with for y in range(SurfCopy.get_height()): if SurfCopy.get_at([x,y])[:3] == COLOR: # [:3] is to chop off the alpha info.. if true, start pulling the glyph! TempGlyph =  Active =  Active.append([x,y]) while len(Active): # Check adjacent to a good-pixel in the order [Right Left Down Up] CurrPoint = Active.pop(0) # Keep adding good-color pixels... Point = [CurrPoint,CurrPoint] # Throwing them into TempGlyph until there are no more to pull try: if SurfCopy.get_at( [Point+1, Point] )[:3] == COLOR: Active.append( [Point+1, Point] ) SurfCopy.set_at([Point+1, Point], DONECOLOR) except IndexError: pass # Sometimes you test a nonexistant surface index.. try: if SurfCopy.get_at( [Point-1, Point] )[:3] == COLOR: Active.append( [Point-1, Point] ) SurfCopy.set_at([Point-1, Point], DONECOLOR) except IndexError: pass # but we don't care, so just ignore it.... try: if SurfCopy.get_at( [Point, Point+1] )[:3] == COLOR: Active.append( [Point, Point+1] ) SurfCopy.set_at([Point, Point+1], DONECOLOR) except IndexError: pass try: if SurfCopy.get_at( [Point, Point-1] )[:3] == COLOR: Active.append( [Point, Point-1] ) SurfCopy.set_at([Point, Point-1], DONECOLOR) except IndexError: pass TempGlyph.append(Point) # When done searching the pixel, store it away GlyphList.append(TempGlyph) # When the letter is done, save it in a binder pygame.display.flip() print "There are", print len(GlyphList), print "glyphs found altogether..." return GlyphList # And when the entire surface is scrubbed, give the binder back if __name__ == '__main__': # Whatever this does... pygame.init() # Start the pygame FALSE = 0 TRUE = 1 ANTIALIAS = FALSE # Antialiasing sucks. WHITE = (255,255,255) # Lots of pretty colors BLACK = (0,0,0) RED = (255,0,0) GRAY = (128,128,128) OLDCOLOR = BLACK # OLDCOLOR is the color you want to search for NEWCOLOR = RED # NEWCOLOR is the color you would like to change the glyph to BACKGROUND = WHITE # BACKGROUND is the background color FONTSIZE = 50 # How big to make the font? Messages =  # A list to keep your messages in Surfaces =  # A list of surfaces the messages will render to Messages.append("Hello there.") # What do you want to say? Add as many as you like. Messages.append("How are you?") Messages.append("This program is dull...") Messages.append("But is pretty when you click?!") CurrentFont = pygame.font.Font(None, FONTSIZE) # Set up a default font for x in Messages: # Generate all of our messages Surfaces.append(CurrentFont.render(x, ANTIALIAS, OLDCOLOR, BACKGROUND)) # A bunch of ugly crap to paste all the surfaces to the screen all lined up pretty MaxWidth =  TotalHeight = 0 CurrentHeight = 0 for x in Surfaces: MaxWidth.append(x.get_width()) for x in Surfaces: TotalHeight += x.get_height() screen = pygame.display.set_mode([max(MaxWidth),TotalHeight] ) screen.fill(BACKGROUND) for x in Surfaces: screen.blit(x, (0,CurrentHeight)) CurrentHeight += x.get_height() pygame.display.flip() # Finally, we are done with the test surface. Now to pull out the letters. Glyphs = GetGlyphs(screen, OLDCOLOR) # Super seekrut magic colorize for G in Glyphs: RANDCOLOR = (random.randrange(0,256),random.randrange(0,256),random.randrange(0,256)) for Point in G: screen.set_at(Point, RANDCOLOR) while pygame.event.poll().type != QUIT: if pygame.mouse.get_pressed(): for G in Glyphs: RANDCOLOR = (random.randrange(0,256),random.randrange(0,256),random.randrange(0,256)) for Point in G: screen.set_at(Point, RANDCOLOR) pygame.display.flip()