Android 40 Devices and DisplaysWord格式文档下载.docx

Android 40 Devices and DisplaysWord格式文档下载.docx

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Beflexible

Stretchandcompressyourlayoutstoaccommodatevariousheightsandwidths.

Optimizelayouts

Onlargerdevices,takeadvantageofextrascreenrealestate.Createcompoundviewsthatcombinemultipleviewstorevealmorecontentandeasenavigation.

Assetsforall

Provideresourcesfordifferentscreendensities（DPI）toensurethatyourapplooksgreatonanydevice.

Strategies

Sowheredoyoubeginwhendesigningformultiplescreens?

Oneapproachistoworkinthebasestandard（mediumsize, 

MDPI）andscaleitupordownfortheotherbuckets.Anotherapproachistostartwiththedevicewiththelargestscreensize,andthenscaledownandfigureouttheUIcompromisesyou'

llneedtomakeonsmallerscreens.

Formoredetailedinformationonthistopic,pleasevisit 

SupportingMultipleScreens.

Themes

GmailinHoloLight.

SettingsinHoloDark.

TalkinHoloLightwithdarkactionbar.

ThemesareAndroid'

smechanismforapplyingaconsistentstyletoanapporactivity.Thestylespecifiesthevisualpropertiesoftheelementsthatmakeupyouruserinterface,suchascolor,height,paddingandfontsize.Topromotegreatercohesionbetweenallappsontheplatform,AndroidprovidesthreesystemthemesthatyoucanchoosefromwhenbuildingappsforIceCreamSandwich:

∙HoloLight

∙HoloDark

∙HoloLightwithdarkactionbars

ApplyingthesethemeswillgoalongwayinhelpingyoutobuildappsthatfitrightintothegeneralvisuallanguageofAndroid.

Pickthesystemthemethatbestmatchestheneedsanddesignaestheticsforyourapp.Ifyourdesireistohaveamoredistinctlookforyourapp,usingoneofthesystemthemesasastartingpointforyourcustomizationsisagoodidea.Thesystemthemesprovideasolidfoundationontopofwhichyoucanselectivelyimplementyourownvisualstylings.

TouchFeedback

Usecolorandilluminationtorespondtotouches,reinforcetheresultingbehaviorsofgestures,andindicatewhatactionsareenabledanddisabled.

Wheneverausertouchesanactionableareainyourapp,provideavisualresponse.Thisletstheuserknowwhichobjectwastouchedandthatyourappis"

listening"

.

States

MostofAndroid'

sUIelementshavetouch-feedbackbuiltin,includingstatesthatindicatewhethertouchingtheelementwillhaveanyeffect.

Communication

Whenyourobjectsreacttomorecomplexgestures,helpusersunderstandwhattheoutcomeoftheoperationwillbe.Forexample,inRecents,whenyoustartswipingathumbnailleftorright,itstartstodim.Thishelpstheuserunderstandthatswipingwillcausetheitemtoberemoved.

Boundaries

Whenuserstrytoscrollpasttheupperorlowerlimitofascrollablearea,communicatetheboundarywithavisualcue.Forexample,ifauserattemptstoscrollpastthefirsthomescreenpanel,thescreencontenttiltstotherighttoindicatethatfurthernavigationinthisdirectionisnotpossible.ManyofAndroid'

sscrollableUIwidgets（e.g.listsorgridlists）alreadyhavesupportforboundaryfeedbackbuiltin.Ifyouarebuildingcustom,keepboundaryfeedbackinmindandprovideitfromwithinyourapp.

MetricsandGrids

Devicesvarynotonlyinphysicalsize,butalsoinscreendensity（DPI）.Tosimplifythewayyoudesignformultiplescreens,thinkofeachdeviceasfallingintoaparticularsizebucketanddensitybucket.Thesizebucketsare 

handset（smallerthan600dp）and 

tablet 

（largerthanorequal600dp）.Thedensitybucketsare 

LDPI, 

MDPI, 

HDPI,and 

XHDPI.Optimizeyourapplication'

sUIbydesigningalternativelayoutsforsomeofthedifferentsizebuckets,andprovidealternativebitmapimagesfordifferentdensitybuckets.

Spaceconsiderations

Devicesvaryintheamountofdensity-independentpixels（dp）theycandisplay.

Toseemore,visitthe 

ScreenSizesandDensitiesDeviceDashboard.

48dpRhythm

TouchableUIcomponentsaregenerallylaidoutalong48dpunits.

Why48dp?

Onaverage,48dptranslatetoaphysicalsizeofabout9mm（withsomevariability）.Thisiscomfortablyintherangeofrecommendedtargetsizes（7-10mm）fortouchscreenobjectsanduserswillbeabletoreliablyandaccuratelytargetthemwiththeirfingers.

Ifyoudesignyourelementstobeatleast48dphighandwideyoucanguaranteethat:

∙yourtargetswillneverbesmallerthantheminimumrecommendedtargetsizeof7mmregardlessofwhatscreentheyaredisplayedon.

∙youstrikeagoodcompromisebetweenoverallinformationdensityontheonehand,andtargetabilityofUIelementso