An example looks like this:
using Cairo
# prepapration, an image of 2x2 pixels, an target of 8x8 pixels
d = [8 4; 2 1];
d0 = reinterpret(Uint32,d);
cs0 = Cairo.CairoImageSurface(d0,0); # 0 as FORMAT_ARGB32
show(cs0.data)
print('\n')
d2 = zeros(Uint32,8,8);
cs2 = Cairo.CairoImageSurface(d2,0);
p = Cairo.CairoPattern(cs0);
# just scale by using FILTER_NEAREST
pattern_set_filter(p,Cairo.FILTER_NEAREST);
c = Cairo.CairoContext(cs2);
scale(c,4,4);
set_source(c,p);
paint(c);
show(cs2.data)
print('\n')
# now interpolate
d3 = zeros(Uint32,8,8);
cs3 = Cairo.CairoImageSurface(d3,0);
pattern_set_filter(p,Cairo.FILTER_GOOD);
c = Cairo.CairoContext(cs3);
scale(c,4,4);
set_source(c,p);
paint(c);
show(cs3.data)
print('\n')
and gives on my command line:
julia> include("ca.jl")
Uint32[8 2
4 1]
Uint32[8 8 8 8 2 2 2 2
8 8 8 8 2 2 2 2
8 8 8 8 2 2 2 2
8 8 8 8 2 2 2 2
4 4 4 4 1 1 1 1
4 4 4 4 1 1 1 1
4 4 4 4 1 1 1 1
4 4 4 4 1 1 1 1]
Uint32[3 4 4 3 2 1 1 0
4 6 6 5 3 2 1 1
4 6 6 5 3 2 1 1
4 5 5 4 3 2 1 1
3 4 4 3 2 1 1 0
2 3 4 3 2 1 0 0
2 3 3 2 1 1 0 0
1 2 2 1 1 0 0 0]
But this is just how to handle the data. For interpreting the pixels
correctly you need to read little bit about the colormodel and pixel
formats.
Wishing a happy day,
Andreas
