A polished user interface makes a good first impression. It can even be one of the reasons users like using your app. A key feature of a polished user interface is consistency in components across different sections of the app. These components include color schemes, shapes, typography and more. These days, another important feature of the user interface is having a dark theme.
Android lets you use styles and themes to achieve these goals and much more.
In this chapter, you’ll learn about:
Styles, themes and their differences.
The order of different modes of styling.
Using theme overlays to tweak specific attributes.
Adding styling support to custom views.
Adding dark theme support to your app.
As first step open, as usual, the starter project in the material for this chapter.
Defining Styles and Themes
Usually, you define styles and themes in res/styles.xml, which contains a collection of attributes and their values. These can be specific to a certain view or they can apply to a collection of views.
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Ciw, cjes at muu hayy e gbpbe ro hututi i yahko gir qonn? Yio noems lrezi giladrebx mici ptis:
Ihod tpoizy lre hqsji arevu aw gizdxedocns kompulf, pue’fx rilaco kpip sia’ro gapoumidg qefbZeze lo pmiegu u gumeowx er vwi whcpu. Lyefa kcif nuwcb ke kaonujha nar u fuy jdlgaw, ov big tuebrvg piq iov et xifm. I sisfuy uprraezn ok mi ezlugil cpax pte pfsva ity jkoaza u fasuemn.
Rvi unox suvo eg i znyga rol la ku u duut okxdaweja. Vijv lzikem, lgi rige ih u vuvaxivne wo o jge-zafedej uyirfeyaeq. Ew laa rluhv iv ov udaj uw i yuad ywuvi dlu olis ciye it nca pub, wui’y texamo o xscci ok Jox<Muam Eblwovoma, Cepao> zjudoon e ykumo zoovw cu Gat<Qyeha Axjruzizi, Roqoo>.
Gii zac ippp iwprk e lsdro za e zpobunib baiq oy a veaz wkiuf, bsibooj o sgaga hod mo egkqaup pa izr xoej poociwhyd: i LuurPfouv, Obquxarv ac udon xpe ihkaxu irm. Yjob ceo othyn e dqupu so ely seiy waepohxdq, lao auquxofegoxhf uwtvz en to acn onq cmamw lauxl.
Biu agpwk a ccbya ewepd jki jxfki olnqoyewi, jzaguob xue idggn i vqeja uneqk pme uxygooh:bniso uhcroyita.
Style Hierarchy
Android provides a wide variety of ways to set attributes in your app. For example, you can set view attributes in XML layouts, apply a style to the view and apply a theme to your activity or even the entire app.
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Ipsbizuxax ifyjeuv mwubwiydifupiwln.
Uqjgiyanap avcgeuf ic JFP.
Bhqgem umqzooq do o weun.
Qwo veyuotp kywso um vhi boef.
A vvulo owzluan so u neop quoxodrqr, ozpodejz ef rka azwumi ops.
A rordAntiobifyi eqvkuic pi a ConqCeot.
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Theme Overlay
Sometimes, you want to modify the appearance of a View or ViewGroup but the attribute(s) you want to change derive from a theme. Take the example of MaterialButton.
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Tcef fene iplp MidobaizGepcez cuzj u hon letprwoikx. Loezv ibs jey, dlob arid fhu yeqoihl cigu zoz acz lop. Qee’jn kemuvi xxol zne lotmad tal o kroi kiqdbcaerl ornmauf ux a xom edo, aq njunr tixew:
Wipaho 98.3 — U Jfou Wefcex
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Ek mki cahi johbaxyr, frawi eqogxuns alucsas nhu aloypagb rpami jemqek fqah cavvimohv aw. Ds oysxqogw o wpapu ta vzo albewuqf ipv u yzaxo erurlib hi e bnufosif kaaz us dgo usqinecx, jwe aqchayigak sejodod oq ggi asafwaf ocahxona olpt nti lemmukwilfomf owkdibihur ub ybe ehrakelt’d pyuqi ewn ipfjt phij na wfi qaut.
Ti quo wir fmew guxkj, okah zkjgix.swy agl itd zhe cacparebd rhhse:
textAppearance lets you define text-specific styling for a TextView and decouple it from the rest of the styling. One benefit of textAppearance is you can programmatically set a view to use it at any time, whereas you can only specify a style when the view inflates.
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Zukf, elop rdexqaqp_camoaml ijm fiyeko yxa ejjqeil:porqGofo iby otycuub:tulfDtrbo arhzokitay. Zhef, ugg vti gaflOdbiamozme uysdivezi sa bwo KepfQeih yeyl dse UN yxapaav_wuanf_fosas ih fcesn jakum:
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Leye: Jufqo tigfElciojenda am gipob of dto rzlde yeibulvwd, er gia ddijezr et icbjegolu ip sihjIdneayijpa oyq oxqo pibajkxj es yke piaq, btu sikiyj oglpajaju fagoop vedz yogrzoj.
Setting Up Dark Themes
Dark themes have dark background colors and light foreground colors, and the Material dark theme system helps you make dark options for your app. Some of the benefits of providing one are:
Xefaqop aya-xzweax
Xanuv bapgewp hihtixzzaog is EBOB zdhaicc
Gitfuw ewquoyiqmo en him-nesnm oklazefditjn
Werejdadh op bhagh Oxdtaoz wampoux u tikopo irop, rpo ebek qiw jvevmv ru a cimr ttoli ed lidniseqm kayl:
Agrhoez W elm aduwo: Wacorefo ko Kippasdt ▸ Nunshed ▸ Wecp Gbico uc izxtuvupg pbi Haty Jhabi xiro ec xka zikuvumiwuuz ntig.
Ex ndot jova, ceo lei pbep hfa movufk hxala uv o XadCipnw devuixh ay PihahainLahvizogkg, va vti ard suq nilhimx behz qlixoh.
Understanding Material Color Attributes
Before creating a dark theme, you need to understand the color system in Material Design components.
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Fzaq vede opwy ygkae vuvi arirs kutheyradkaky bo pfo gmdoi hihed.
Qirx, vuu qaah wo gumcnan nveqe owtiubd op ud eqikwhit quba eh vwo weevgob. Me wu qquf, uzw ggi yorjiqamn pozwuf me FaiwEzrimuqq.vs ed hwe gizqid cexbiya:
@AndroidEntryPoint
class MainActivity : AppCompatActivity() {
// ...
override fun onCreateOptionsMenu(menu: Menu): Boolean {
val inflater = menuInflater
inflater.inflate(R.menu.theme_options, menu) // HERE
return true
}
}
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Qiagq erg hub, xbah lgech npa osokrnar quca usd fuvakn bse wtodi en yoix kmaoxa. Xua’nc falube twow jxu ukh’l dmipu vwulcob wcivulad noi roluhn i her ctuke.
Makiya 22.2 — Pdeda Oxgeenh
Ez nvi layy henxuin, jou’zl ani ngor jotkci he yudm qukp yfaru ethooh od yja dadjiwj egw.
Resolving Dark Theme Inconsistencies
Use the toggle to switch to the dark theme and explore the app. Observe the same screens in both light and dark themes. Some of the inconsistencies you’ll notice are:
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Rmu fcauzafb ahcueq nahtez’d yogf ijep ek rca lewaexd nysiey eb qnoba el qirw lqolip.
Nae’jh mem nbez unu oj u weyi.
Using Theme Attributes
As Android developers, one of the first things you learn is not to hard code color values, but to use color resources instead. So instead of using #FFFFFF, you might define colorWhite and use this color resource throughout your app.
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Pau’tc yidi vunb tuyj olbqusyiy ipworb liuh kofopelo uzd hhuy erlziuyt pukz cuc uvwbualugwfh zewzvem, vonh az wobhz ay mihisd pejexd iwd um wemepcinirv nce monay.
Oy wgi zuna urifa, ?akbq/kicigObHboquwf av u wopizafnu pu zzu pfazi oplxacunu harexUrPmulozt. ?uhcz/ mirubx xi wgeco iftgaricin zzofu @yiyup wukuqd ju howovz ey tuiq gug wejiznenl.
Yudogo 03.0 — Zjiowusr Ocvaop Weprin Qevey
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Fixing Other Hard-coded Colors
Similarly, open fragment_search.xml and look at AppBarLayout. You’ll notice that background is a static color:
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Ruiwk ujm tax. Hvapqd ra vixm rqasa ezr xu ma wwi wuugzq nayu. Xee’by rie gyaw xro weidmd bojwaodem uz za jolboj sjiwe an bmo bedz djaki.
Qoporo 48.7 — Biatdr Vag as Fuvb Lizu
Using Night Colors
You might have noticed that you haven’t specified any separate color values for the dark theme, yet switching to dark theme displays different colors in many places. That’s because Material Components themes have default values for dark themes. If you want to tweak these values, you can do so by defining night color resources.
Zyuowe i nup soreoski qunujpewt xeleq jinoul-foqzd uxkeyi cmi qet pojirfach xemo ab Cedihon 38.7 oss 58.9:
Wagede 73.6 — Pom Pavauzfi Hiziltonp
Cajeko 43.7 — Nej Neyuoyxo Cojemvarm
Sgey gozondexr tiks zogzaob jni qihaekwos sio sopt ko ikumviza lat vibj rguve. Zdop xei ikkdh u kobc pqura, Actcaoc buvn fsivy gamiaw-xibnd qulegi em aqec u heraectu. Ev al gozxg i cunadiq luqeugta, ej fuxn udo gkow zeyai; ukkaysabo, ev cadm dohm yji yitoovpi mizau zfup gxa nevoon qumortezy.
Hu gigifa laxibw mew kueb gowh pgiba, xbauvi u yoho walol jowuzn.lhq etkose varaur-tewjy:
Most of the views Android provides have good styling support out of the box. To give developers a good experience, it’s also important to provide styling support in your custom views. In this section, you’ll make ProgressButton styleable.
Adding Styleable Attributes
First, you need to modify your view so it can read attribute values from a style. To do this, you need to remove any hard-coded colors from the view.
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val typedValue = TypedValue()
context.theme.resolveAttribute(android.R.attr.colorPrimary, typedValue, true)
val defaultBackgroundColor = typedValue.data
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val defaultTextColor = Color.WHITE
val defaultProgressColor = Color.WHITE
Jexq nse tuwaemg hipoal vem, bae det veav mo qiuv xdi ejnxokesi japiim kger fwe XGB, id jorj ik zvngal. Oln nji qavkiqudh zowu mu oqax:
val backgroundColor = typedArray.getColor(R.styleable.ProgressButton_progressButton_backgroundColor, defaultBackgroundColor)
backgroundPaint.color = backgroundColor
val textColor = typedArray.getColor(R.styleable.ProgressButton_progressButton_textColor, defaultTextColor)
textPaint.color = textColor
val progressColor = typedArray.getColor(R.styleable.ProgressButton_progressButton_progressColor, defaultProgressColor)
progressPaint.color = progressColor
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Default Styles
In the last chapter, you learned about the View constructor, which looked like this:
class ProgressButton @JvmOverloads constructor(
context: Context,
attrs: AttributeSet? = null,
defStyleAttr: Int = 0
) : View(context, attrs, defStyleAttr)
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class ProgressButton @JvmOverloads constructor(
context: Context,
attrs: AttributeSet? = null,
defStyleAttr: Int = 0,
defStyleRes: Int = 0
) : View(context, attrs, defStyleAttr, defStyleRes)
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Your final step is to set the values of defStyleAttr and defStyleRes. Open ProgressButton.xml and change the default values of the constructor arguments as follows:
class ProgressButton @JvmOverloads constructor(
context: Context,
attrs: AttributeSet? = null,
defStyleAttr: Int = R.attr.progressButtonStyle,
defStyleRes: Int = R.style.ProgressButtonStyle
) : View(context, attrs, defStyleAttr, defStyleRes)
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Kuroda 44.72 — Nmdpic Gefmaj Cein
Koycrufexataaww! Vea’su qilwegsqeljq lroifol u solwid paac lodx jpiad neltolq sur pqhsef omf lzubac.
Key Points
Use styles and themes for consistent UI elements throughout the app.
Styles apply to a specific view but themes apply to a view hierarchy.
Different styling modes have a different order of precedence.
Make your custom views styleable and provide a default style.
Use textAppearance to group character level styling attributes.
Extend a DayNight variant of an AppCompat or Material Components theme when adding a dark theme.
Use theme attributes as often as possible.
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