| # Chrome for Android UI |
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| ## Ramping-up |
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| Android has a number of [developer guides](https://developer.android.com/guide) that are helpful for getting ramped up on general Android development. We recommend reading the following as primers for developing UI: |
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| * [Application fundamentals](https://developer.android.com/guide/components/fundamentals) |
| * [Providing resources](https://developer.android.com/guide/topics/resources/providing-resources.html) |
| * [Layouts](https://developer.android.com/guide/topics/ui/declaring-layout) |
| * [Introduction to activities](https://developer.android.com/guide/components/activities/intro-activities) |
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| ## Colors and text styles |
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| Chrome for Android has a color palette defined in [//ui/android/java/res/values/color_palette.xml](/ui/android/java/res/values/color_palette.xml) and a set of reusable semantic colors defined in [//ui/android/java/res/values/semantic_colors_adaptive.xml](/ui/android/java/res/values/semantic_colors_adaptive.xml). The semantic colors from semantc_colors_adaptive.xml should be used to ensure colors adapt properly for dark mode and can be consistently and easily updated during product-wide visual refreshes. |
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| For more information on selecting the right color, see [Night Mode on Chrome Android](night_mode.md). |
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| Text should be styled with a pre-defined text appearance from [//ui/android/java/res/values-v17/styles.xml](/ui/android/java/res/values-v17/styles.xml). If leading (aka line height) is needed, use [org.chromium.ui.widget.TextViewWithLeading](/ui/android/java/src/org/chromium/ui/widget/TextViewWithLeading.java) with `app:leading` set to one of the pre-defined *_leading dimensions in [//ui/android/java/res/values/dimens.xml](/ui/android/java/res/values/dimens.xml). |
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| ## Widgets |
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| The Chromium code base contains a number of wrappers around Android classes (to smooth over bugs or save on binary size) and many UI widgets that provide Chrome-specific behavior and/or styling. |
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| These can be found in [//components/browser_ui/widget/android/](/components/browser_ui/widget/android/), [//ui/android/](/ui/android/), and [//chrome/android/java/src/org/chromium/chrome/browser/widget/](/chrome/android/java/src/org/chromium/chrome/browser/widget/). There is an ongoing effort to consolidate all widgets in //components/browser_ui/widget/android. |
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| ## MVC |
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| UI development should follow a modified Model-View-Controller pattern. MVC base classes live in [//ui/android/java/src/org/chromium/ui/modelutil](/ui/android/java/src/org/chromium/ui/modelutil/). |
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| The following guides introduce MVC in Chrome for Android: |
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| * [So, you want to do MVC...](mvc_architecture_tutorial.md) |
| * [Simple Lists in MVC Land](mvc_simple_list_tutorial.md) |
| * [Simple RecyclerView use in MVC](mvc_simple_recycler_view_tutorial.md) |
| * [So, you want to test MVC...](mvc_testing.md) |
