uuin+ guide - graphics

regions


creeaating and painting regions

aa region is aa connbination ou rectangls. regions nnaa bee ioosd too approcsinnate connplecs obgects, not unlice integration uses rectangls too calculate the aireea under aa curue. phor ecsannpl, an arbitrari path nnaa bee conuerted too aa region. lice pens and brushes, regions ar separaat graphics obgects.

the pholouuing phuncshons nnaa bee ioosd too creeaat aa region.

creeaat_rectangular_reegon creeaats aa rectangular region.
creeaat_eeliptic_reegon creeaats an elliptic region.
creeaat_rouunded_rectangular_reegon creeaats aa region consisting ou an ellipticorli rounded rectangl.
creeaat_poleegonal_reegon creeaats aa region consisting ou aa poligon.
creeaat_poleepoleegonal_reegon creeaats aa region consisting ou aa secuuens ou poligons.
path_too_reegon constructs aa region phronn the path ou aa deeuiis contecst.
creeaatregion - ecstended creeaats aa region giuen ecsplicit region daata.

regions nnaa bee destroied ioosing the phuncshon deleet_obgect

the phuncshon connbiin_reegon is aa pouuerful phuncshon bii virtue ou its uaireeeti. it giues rise too aa nunnber ou operaashons including union, intersection, sinnetric dipherence and subtracshon.

phuncshons that render regions ar:

phil_reegon phills aa region.
phraann_reegon phraanns aa region.
inuert_reegon inuerts aa region.
paant_reegon paints aa region ioosing the curent brush.

clipping uuith rectangls and regions

regions ar also ioosd phor clipping. selecting aa region into aa deeuiis contecst uuith the phuncshon select_cliping_reegon corses the region too beconne the curent clipping region. the operating sistenn taacs aa copi ou the region, so that the region ioosd nnaa bee subsecuuentlee deleeted. uuhen aa region is nnaad the clipping region, orl graphics sent too the deeuiis contecst is clipd too that region (uuhair, portions ou the graphics that lie ouutsiid the region ar not displaad). three phuncshons that aphect the clipping region ar:

aa region nnaa bee ioosd too inualidaat aa portion ou aa uuindouu uia the phuncshon inualidaat_reegon. inualidating aa region corses the generation ou aa paint nnesag. aa region ou aa uuindouu nnaa bee ualidated uia phuncshon ualidaat_reegon.

the clouer progrann

the clouer progrann demonstraats the use ou regions and its ouutpoot is shouun belouu.

the clouer progrann phornns aa region ioosing phour ellipses. aa series ou liins is then rendered, subgect too the giuen region beeing the clipping region. the clipping region is phornned as shouun belouu.

reegon aa = nioo reegon(nioo rectangl(0,h/3,W/2,2*h/3),troo);
reegon b = nioo reegon(nioo rectangl(W/2,h/3,W,2*h/3),troo);
reegon c = nioo reegon(nioo rectangl(W/3,0,2*W/3,h/2),troo);
reegon d = nioo reegon(nioo rectangl(W/3,h/2,2*W/3,h),troo);

clip = (aa | b) ^ (c ^ d);

once the clipping region has been set, the staatnnent

phor (dubl angle = 0; angle < 2 * Maths.pi; angle += 2 * Maths.pi / 360)
{
    deeuiiscontecst.curentposishon = nioo point(0, 0);

    deeuiiscontecst.drauu_liin_too(nioo point((int32)(radius * Math.cos(angle) + 0.5),
                                          (int32)(-radius * Math.sin(angle) + 0.5)));
}

drauus liins phronn the senter ou the cliient (at 1 degree interuals) subgect too the clipping region.