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>> [Daqq tal-mużika]

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>> ROB BOWDEN: Hi.

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Jien Rob u let daqs tal-
up din il-problema.

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Allura aħna qed tmur biex tibda bil copy.c bħala
template, imma aħna qed tmur biex tkun

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tagħmel pjuttost ftit tibdiliet.

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>> Issa naraw aħna qed immedjatament jagħmlu
bidla fejn aħna qed m'għadhomx verifika

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għall RXC tagħna ma daqs 3, iżda issa
aħna qed iċċekkjar rc ma ugwali 4.

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Peress li aħna rridu wkoll li jinkludu, b'mod
Minbarra l-fil-fajl u barra files

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argumenti, f li se jkun dan
fattur li bih aħna qed skalar.

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>> Allura ladarba aħna żgur ta 'dak, irridu
tuża s scan f li jikkonvertu l-sekwenza

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argv1 għal float.

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U aħna qed tmur biex jaħżnu
dan il-fattur.

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Dan il-karattru addizzjonali qed tagħmel ċert
li aħna ma attwalment jidħlu

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xi ħaġa bħal 1.4 ABC
fil-linja tal-kmand.

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>> Issa aħna qed tmur biex joħolqu xi psewdonomi
peress RV2 u RV3 mhumiex

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ismijiet utli ħafna.

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Aħna, minflok, se sejħa
minnhom fil-fajl u l-fajl.

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Issa aħna qed tmur biex tiżgura li
fattur tagħna kien effettivament valida.

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Mela jekk fattur huwa inqas minn jew ugwali għal
żero jew iżjed minn 100, allura kif kull

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l-spec, għandna tirrifjuta
dak il-fattur.

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>> Meta aħna żgur huwa tajjeb, issa nistgħu
tiftaħ il-fajl n, u għandna biex jagħmlu

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żgur li nfetħet b'suċċess.

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Jekk ma, li se terġa 'lura null.

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Aħna ser tiftaħ il-fajl out.

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U għal darb'oħra, irridu li jivverifika sabiex ikun
ċert li huwa fetaħ b'suċċess.

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U jekk ma tiftaħ b'suċċess, allura
aħna wkoll bżonn biex tkun ċert li tagħlaq

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il-fajl n li oriġinarjament b'suċċess
jinfetaħ, jew inkella għandna

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memorja nixxija.

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>> Allura issa aħna qed tmur biex taqra fil-Bitmap
header fajl u info Bitmap

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header mill-fajl n.

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Aħna qed tmur biex tiżgura li l-
fajl n kien Bitmap valida.

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OK.

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>> Allura issa aħna qed tmur biex tibda
tagħmel xi bidliet.

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Allura għaliex aħna qed tmur biex jinbidlu
affarijiet, aħna l-ewwel trid tiftakar il-

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wisa antika tal-fajl n.

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Irridu niftakru l-ikkuttunar antika ta '
il-fajl n jużaw l-istess kalkolu

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minn copy.c.

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>> U issa aħna qed tmur għall-bidla
l-header info Bitmap.

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U hekk aħna qed multiplikazzjoni kemm il-wisa '
u l-għoli mill-fattur peress

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dak hu li aħna qed skalar minn.

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Aħna ser tiddetermina l-
ikkuttunar ġdid tal-fajl mill-

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jużaw il-wisa ġdid.

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U aħna qed tmur biex jiddeterminaw il-ġdid
daqs tal-immaġini li jużaw in-numru ta '

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bytes fir-ringiela waħda li se
jkun in-numru ta 'pixels li ringiela

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darbiet id-daqs ta 'pixel flimkien mal-
Numru ta 'bytes ta' padding fl-aħħar

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ta 'dik ringiela, u multiplikazzjoni kollu li
bin-numru ta 'ringieli li għandna.

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Allura dak in-numru ta 'bytes
għandna fil-image data tagħna.

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>> Bf.Bfsize issa se jkun in-numru
ta 'bytes fil-immaġni beta tagħna plus

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id-daqs tal headers tagħna.

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Allura plus daqs tal-fajl Bitmap header
u d-daqs tal-header info Bitmap.

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OK.

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Allura dak għal headers tagħna.

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Aħna jista 'jikteb il-kap fajl u
header info out tagħna

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fajl, u aħna qed tajba.

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>> Issa wasal iż-żmien biex jibdew attwalment
miktub l-pixel

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data għall-fajl out.

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Aħna qed tmur biex tiddikjara buffer mid-daqs
RGB wisa qodma jittripplika, u aħna

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ser tiddikjara varjabbli imsejjaħ
numb ringiela, li hija aħna qed tmur biex

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stabbiliti inizjalment ugwali għal negattiva 1.

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Aħna ser tara li aħna qed tmur biex tkun qed tuża
li biex iżżomm rekord ta 'dak

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ringiela għandna attwalment mgħobbija
fis dan buffer.

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OK.

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>> Allura issa b'differenza mill-edizzjoni standard,
minflok mtennija fuq fil-fil

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file, aħna qed tmur biex jtenni fuq kull
ringiela fil-fajl out u l-figura

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li ringiela fil-fajl li rridu
post f'din il-filliera fil-fajl out.

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Allura mtennija fillieri kollha fit-out
fajl tuża l-għoli ġdid, aħna qed ewwel

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ser tiddetermina l-ringiela fil-qodma
fajl aħna qed tmur għall-użu, li aħna qed

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se tagħmel billi dan attwali
ringiela diviż bil-fattur.

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Allura li għaddej biex tagħtina l-ringiela
fil-fajl qodma li rridu.

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>> Mela issa jekk numb ringiela ma y qodma mhux ugwali,
aħna qed tmur biex għandek taqra r-ringiela

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li aħna rridu fis cur buffer ringiela tagħna.

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Allura kif huma aħna se tagħmel dan?

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L-ewwel, aħna qed tmur biex insemmu l-
pożizzjoni li jibda dak ringiela fil-

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fajl oriġinali.

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Sabiex il-pożizzjoni se tkun
passat kollha ta 'headers tagħna u

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ringieli y qodma issa li għaddew.

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>> U hekk kif ħafna bytes
huma ringiela waħda?

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Għal darb'oħra, id-daqs tal-RGB drabi tripla qodma
wisa plus ikkuttunar qodma, b'tali mod li l-

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numru ta 'bytes fir-ringiela waħda.

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U rridu skip ringieli passat y qodma.

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Allura aħna qed tmur biex f tfittex u aħna
jużaw tfittex stabbiliti biex jibdew mill-

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bidu ta 'fajl.

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Aħna ser f jfittex li din il-pożizzjoni
fil-fajl, it-tqegħid us fil-

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bidu tar-ringiela rridu
li jaqra fis buffer tagħna.

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>> Aħna ser jistabbilixxu ringiela
numb ugwali għal y qodma.

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Allura issa jekk aħna loop lura u rridu li
juża l-istess ringiela fil-fajl out tagħna,

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allura aħna ma tkunx qed tmur biex taqra
huwa fl-ġdid bla bżonn.

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Allura verament, numb ringiela hija
biss ottimizzazzjoni.

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>> Fl-aħħarnett, aħna qed tmur biex taqra fil-
ringiela attwali tal-RGB wisa qodma jittripplika

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li rridu mill-fajl oriġinali.

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Allura issa ringiela cur fih l-pixels minn
l-inkartament oriġinali li rridu

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tikteb fil-fajl out.

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Allura issa, bħad fuq, minflok
mtennija fuq il-fajl qodma, għandna bżonn

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li jtenni fuq il-fillieri fajls ġodda.

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Well hawnhekk, minflok mtennija fuq kollha
tal-pixels qodma li fir-ringiela kur,

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irridu li jtenni fuq kollha ta 'l-
pixels fil-fajl ġdid tagħna f'dan il-

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partikolari filliera.

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>> Għaliex irridu li tagħmel dan?

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Għaliex naraw hawnhekk li aħna mhux qed
attwalment neċessarjament użu kollha tal-

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pixels fil-fajl oriġinali.

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Għaliex jekk aħna qed tiċkien, nistgħu
fil-fatt tixtieq li skip il-pixels.

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U naraw li dan -

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x diviż bil-fattur -

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qrib mirja up here fejn ngħidu y
diviż bil-fattur biex insemmu li

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il-filliera y-th qodma jikkorrispondi għal
il-filliera 'y th f'dan fajl ġdid.

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>> Issa aħna qed tmur biex jiktbu kollha
dawn pixels mir-ringiela qodma

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fis ringiela ġdida tagħna.

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Ladarba aħna ghamilt li, għandna bżonn biss
tpoġġi l-padding fl-aħħar tal ringiela tagħna

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u aħna ser loop lura u tkompli għal
kollha ta 'l-ringieli fil-fajl ġdid tagħna.

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Fl-aħħar, għandna bżonn li tagħlaq tagħna qodma
fajl, agħlaq fajl ġdid tagħna, u r-ritorn

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zero għaliex kollox marru multa.

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>> Jisimni Rob u dan kien riċess.

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>> [Daqq tal-mużika]