reegons


creeaating and paanting reegons

aa reegon is aa connbinaashon ou rectangls. reegons 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 reegon. lice pens and brushes, reegons ar separaat graphics obgects.

the pholouuing phuncshons nnaa bee ioosd too creeaat aa reegon.

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

reegons nnaa bee destroid ioosing the phuncshon deleet_obgect

the phuncshon connbiin_reegon is aa pouuerful phuncshon bii virtue ou its uaireeti. it giues riis too aa nunnber ou operaashons including union, intersecshon, sinnetric dipherence and subtracshon.

phuncshons that render reegons ar:

phil_reegon phills aa reegon.
phraann_reegon phraanns aa reegon.
inuert_reegon inuerts aa reegon.
paant_reegon paants aa reegon ioosing the curent brush.

clipping uuith rectangls and reegons

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

aa reegon nnaa bee ioosd too inualidaat aa portion ou aa uuindouu uiia the phuncshon inualidaat_reegon. inualidating aa reegon corses the generation ou aa paant nnesag. aa reegon ou aa uuindouu nnaa bee ualidated uiia phuncshon ualidaat_reegon.

the clouer progrann

the clouer progrann demonstraats the ioos ou reegons and its ouutpoot is shouun belouu.

the clouer progrann phornns aa reegon ioosing phour ellipses. aa series ou liins is then rendered, subgect too the giuen reegon beeing the clipping reegon. the clipping reegon 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);

uuuns the clipping reegon 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 reegon.