[AGG] Re: Beginner - how to put an image at X,Y in a rendering buffer

[snailCoder <sac...@sa...>]

Ken Resander <resander <at> speed.info.com.ph> writes:

> 
> Maxim, many thanks,
> 
> I have replaced
> 
>    agg::path_storage path; // partner rectangle
>     path.move_to( x,y);
>     path.line_to( x+imgwd, y );
>     pathmline_to( x+imgwd, y+imght);
>     path.line_to( x, y+imght);
>     path.close_polygon();
>     agg::conv_transform<agg::path_storage> tr(path, src_mtx);
>     pf.add_path(tr);
>     agg::render_scanlines(pf, sl, ri);
> 
> at the and of my image proc (code of the whole proc is at
> the end of my original post (and at the end of this email))
> 
> by
> 
>    double para [ 6 ]
>     = { 0,100 ,  0,0 , 100.0 } ; // 3 points (0,100) (0,0) and (100,0)
>    agg::trans_affine tr(para, 0, 0, imgwd, imght);
>    pf.add_path(tr);
>    agg::render_scanlines(pf, sl, ri);
> 
> Q1.   is this the right way?
> 
> Q2.  what should the para points be expressed as functions of
>         image top-left hand corner, image width and image height, i.e.
>         x,y, imgwd, imght?
> 
> My test cases includes image (x,y)=(0,0), so I defined para points
> (0,100), (0,0) and (100,0) just to see what would happen.
> 
> but got compilation errors:
> 
> ..\agg23\include\agg_rasterizer_scanline_aa.h(465) : error C2039: 'rewind' :
> is not a member of 'trans_affine'
>   ..\agg23\include\agg_trans_affine.h(88) : see declaration of
> 'trans_affine'
> 
> and one more very similar:  'vertex' : is not a member of 'trans_affine'
> 
> What might be the problem?
> 
> Best regards
> Ken
> 


Hi Ken,

You are adding a agg::trans_affine to the rasteriser!!

Try:
 double para [ 6 ] = { 0, 100 ,0, 0, 100 ,0 } ; 
agg::trans_affine src_mtx(para, 0, 0, imgwd, imght);

agg::path_storage path; // partner rectangle
path.move_to( x,y);
path.line_to( x+imgwd, y );
pathmline_to( x+imgwd, y+imght);
path.line_to( x, y+imght);
path.close_polygon();
agg::conv_transform<agg::path_storage> tr(path, src_mtx);

pf.add_path(tr);
agg::render_scanlines(pf, sl, ri);


However , I am also trying to figure out how I could put the image at any (x,y),
angle and scaling. I am able to get only images at (0,100) to work :(

-snailCoder