8ea6cea39a
Summary: It's very important in complex UIs to be able to apply alpha channel-based masks to arbitrary content. Common use cases include adding gradient masks at the top or bottom of scroll views, creating masked text effects, feathering images, and generally just masking views while still allowing transparency of those views. The original motivation for creating this component stemmed from work on `react-navigation`. As I tried to mimic behavior in the native iOS header, I needed to be able to achieve the effect pictured here (this is a screenshot from a native iOS application):  In this image, there are two masks: - A mask on the back button chevron - A gradient mask on the right button In addition, the underlying view in the navigation bar is intended to be a UIBlurView. Thus, alpha masking is the only way to achieve this effect. Behind the scenes, the `maskView` property on `UIView` is used. This is a shortcut to setting the mask on the CALayer directly. This gives us the ability to mask any view with any other view. While building this component (and testing in the context of an Expo app), I was able to use a `GLView` (a view that renders an OpenGL context) to mask a `Video` component! I chose to implement this only on iOS right now, as the Android implementation is a) significantly more complicated and b) will most likely not be as performant (especially when trying to mask more complex views). Review the `<MaskedViewIOS>` section in the RNTester app, observe that views are masked appropriately.  Closes https://github.com/facebook/react-native/pull/14898 Differential Revision: D5398721 Pulled By: javache fbshipit-source-id: 343af874e2d664541aca1fefe922cf7d82aea701 |
||
|---|---|---|
| .. | ||
| RNTester | ||
| RNTester-tvOS | ||
| RNTester.xcodeproj | ||
| RNTesterIntegrationTests | ||
| RNTesterLegacy.xcodeproj | ||
| RNTesterUnitTests | ||
| android/app | ||
| js | ||
| README.md | ||
README.md
RNTester
The RNTester showcases React Native views and modules.
Running this app
Before running the app, make sure you ran:
git clone https://github.com/facebook/react-native.git
cd react-native
npm install
Running on iOS
Mac OS and Xcode are required.
- Open
RNTester/RNTester.xcodeprojin Xcode - Hit the Run button
See Running on device if you want to use a physical device.
Running on Android
You'll need to have all the prerequisites (SDK, NDK) for Building React Native installed.
Start an Android emulator (Genymotion is recommended).
cd react-native
./gradlew :RNTester:android:app:installDebug
./scripts/packager.sh
Note: Building for the first time can take a while.
Open the RNTester app in your emulator.
See Running on Device in case you want to use a physical device.
Running with Buck
Follow the same setup as running with gradle.
Install Buck from here.
Run the following commands from the react-native folder:
./gradlew :ReactAndroid:packageReactNdkLibsForBuck
buck fetch rntester
buck install -r rntester
./scripts/packager.sh
Note: The native libs are still built using gradle. Full build with buck is coming soon(tm).
Built from source
Building the app on both iOS and Android means building the React Native framework from source. This way you're running the latest native and JS code the way you see it in your clone of the github repo.
This is different from apps created using react-native init which have a dependency on a specific version of React Native JS and native code, declared in a package.json file (and build.gradle for Android apps).