However, I observed the same speed differences on a 64-bit ubuntu with ghc 6.12 - I profiled my application with cairo-trace, and cairo-perf-trace drew in a fraction of a second the picture that my Haskell program spend a dozen seconds drawing.

On Wed, Nov 2, 2011 at 1:17 PM, Eugene Kirpichov <ekirpichov@gmail.com> wrote:

Hello,

I've got two very simple programs that draw a very simple picture using cairo, doing a couple hundred thousand of cairo calls.
One program is in C++. The other is in Haskell and uses the cairo library bindings.

The C++ program completes in a fraction of a second, the Haskell program takes about 7-8 seconds to run. They produce exactly the same output.

What could be at fault here? Why are the cairo bindings working so slow? (I suppose there isn't too much cairo-specific stuff here, perhaps it's a general FFI question?)

#include "cairo.h"
int main() {
cairo_surface_t *surface = cairo_image_surface_create(CAIRO_FORMAT_ARGB32, 1024, 768);
cairo_t *cr = cairo_create(surface);
cairo_set_source_rgb(cr, 0, 255, 0);
for(int x = 0; x < 1024; x += 2) for(int y = 0; y < 768; y += 2) {
cairo_rectangle(cr, x, y, 1, 1);
cairo_fill(cr);
}
cairo_surface_write_to_png(surface, "picture.png");
return 0;
}

module Main where

import qualified Graphics.Rendering.Cairo as C
import Control.Monad

main = C.withImageSurface C.FormatARGB32 1024 768 $ \s -> do
C.renderWith s $ do
C.setSourceRGBA 0 255 0 255
forM_ [0,2..1024] $ \x -> do
forM_ [0,2..768] $ \y -> do
C.rectangle x y 1 1
C.fill
C.surfaceWriteToPNG s "picture.png"

--
Eugene Kirpichov
Principal Engineer, Mirantis Inc. http://www.mirantis.com/
Editor, http://fprog.ru/

--
Eugene Kirpichov
Principal Engineer, Mirantis Inc. http://www.mirantis.com/
Editor, http://fprog.ru/