Re: [Pysdl-devel] A little trivia

[David C. <D. C. <si...@te...>]

Mark Baker writes:

 >  
 > > Blitting a png takes about 50% longer than an identical bmp. (Of
 > > course, the png is compressed to 5% of the bmp's size :)
 > 
 > Are you including the loading time? PNGs are decompressed on load, like all
 > other image types, so after the load, it should blit at the same rate as a BMP.
 > 

The images were loaded to a non-visible surface before the timing
loop begins, so I believe there actually is a difference in blit rates
between PNGs and BMPs. Here's my (ugly) code:

<snip>

import sdl, random, sys, time

width = 640
height = 480
depth = 16

fb = sdl.video_set_mode(width, height, depth, sdl.SWSURFACE)

src = sdl.image_load("./happy.png")
#src = sdl.image_load("./happy.bmp")

start = time.time()

for i in range(500):
    x_pos = (random.random() * (width * 0.9))
    y_pos = (random.random() * (height * 0.9))
    fb.blit(src, (0, 0, 64, 48), (x_pos, y_pos, 64, 48))

    fb.update_rect((x_pos, y_pos, 64, 48))
#    fb.update_rect( (0,0,0,0) )

end = time.time()

print "500 repetions took", end-start, "seconds."
print "That's", (end-start) * 2, "milliseconds per blit."

sdl.quit()

sys.exit(0)

<snip>

As you can see, pretty unsophisticated - I switched between options
just by uncommenting and recommenting code :) Anyway, I realize that
the timed loop is pretty full, but I was looking for relative numbers
here, not absolute measurements.
  
Preliminary pySDL documentation:
http://www3.telus.net/futility/futility/docs/pysdl/index.html

-- 
-------------------------------------------------------------------------\
David "Futility [D!]" Clark  |  "Being healthy" is merely dying at the   |
si...@te...            |         slowest possible rate.            |