/* Like im_similarity(), but return the transform we generated.
*/
static int
apply_similarity( VipsTransformation *trn, IMAGE *in, IMAGE *out,
double a, double b, double dx, double dy )
{
trn->iarea.left = 0;
trn->iarea.top = 0;
trn->iarea.width = in->Xsize;
trn->iarea.height = in->Ysize;
trn->a = a;
trn->b = -b;
trn->c = b;
trn->d = a;
trn->idx = 0;
trn->idy = 0;
trn->odx = dx;
trn->ody = dy;
vips__transform_set_area( trn );
if( vips__transform_calc_inverse( trn ) )
return( -1 );
if( vips__affine( in, out, trn ) )
return( -1 );
return( 0 );
}
/* Combine two transformations. out can be one of the ins.
*/
int
vips__transform_add( const VipsTransformation *in1,
const VipsTransformation *in2, VipsTransformation *out )
{
out->a = in1->a * in2->a + in1->c * in2->b;
out->b = in1->b * in2->a + in1->d * in2->b;
out->c = in1->a * in2->c + in1->c * in2->d;
out->d = in1->b * in2->c + in1->d * in2->d;
// fixme: do idx/idy as well
out->odx = in1->odx * in2->a + in1->ody * in2->b + in2->odx;
out->ody = in1->odx * in2->c + in1->ody * in2->d + in2->ody;
if( vips__transform_calc_inverse( out ) )
return( -1 );
return( 0 );
}
/* Init a VipsTransform.
*/
void
vips__transform_init( VipsTransformation *trn )
{
trn->oarea.left = 0;
trn->oarea.top = 0;
trn->oarea.width = -1;
trn->oarea.height = -1;
trn->iarea.left = 0;
trn->iarea.top = 0;
trn->iarea.width = -1;
trn->iarea.height = -1;
trn->a = 1.0; /* Identity transform */
trn->b = 0.0;
trn->c = 0.0;
trn->d = 1.0;
trn->idx = 0.0;
trn->idy = 0.0;
trn->odx = 0.0;
trn->ody = 0.0;
(void) vips__transform_calc_inverse( trn );
}
