(#) Accessibility in Custom Views !!! WARNING: Accessibility in Custom Views This is a warning. Id : `ClickableViewAccessibility` Summary : Accessibility in Custom Views Severity : Warning Category : Accessibility Platform : Android Vendor : Android Open Source Project Feedback : https://issuetracker.google.com/issues/new?component=192708 Since : Initial Affects : Kotlin and Java files Editing : This check runs on the fly in the IDE editor Implementation : [Source Code](https://cs.android.com/android-studio/platform/tools/base/+/mirror-goog-studio-main:lint/libs/lint-checks/src/main/java/com/android/tools/lint/checks/ClickableViewAccessibilityDetector.java) Tests : [Source Code](https://cs.android.com/android-studio/platform/tools/base/+/mirror-goog-studio-main:lint/libs/lint-tests/src/test/java/com/android/tools/lint/checks/ClickableViewAccessibilityDetectorTest.java) Copyright Year : 2014 If a `View` that overrides `onTouchEvent` or uses an `OnTouchListener` does not also implement `performClick` and call it when clicks are detected, the `View` may not handle accessibility actions properly. Logic handling the click actions should ideally be placed in `View#performClick` as some accessibility services invoke `performClick` when a click action should occur. (##) Example Here is an example of lint warnings produced by this check: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~text src/test/pkg/ClickableViewAccessibilityTest.java:15:Warning: Custom view ViewOverridesOnTouchEventButNotPerformClick overrides onTouchEvent but not performClick [ClickableViewAccessibility] public boolean onTouchEvent(MotionEvent event) { ------------ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Here is the source file referenced above: `src/test/pkg/ClickableViewAccessibilityTest.java`: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~java linenumbers package test.pkg; import android.content.Context; import android.view.MotionEvent; import android.view.View; public class ClickableViewAccessibilityTest { // Fails because should also implement performClick. private static class ViewOverridesOnTouchEventButNotPerformClick extends View { public ViewOverridesOnTouchEventButNotPerformClick(Context context) { super(context); } public boolean onTouchEvent(MotionEvent event) { return false; } } } ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ You can also visit the [source code](https://cs.android.com/android-studio/platform/tools/base/+/mirror-goog-studio-main:lint/libs/lint-tests/src/test/java/com/android/tools/lint/checks/ClickableViewAccessibilityDetectorTest.java) for the unit tests for this check to see additional scenarios. The above example was automatically extracted from the first unit test found for this lint check, `ClickableViewAccessibilityDetector.testWarningWhenViewOverridesOnTouchEventButNotPerformClick`. To report a problem with this extracted sample, visit https://issuetracker.google.com/issues/new?component=192708. (##) Suppressing You can suppress false positives using one of the following mechanisms: * Using a suppression annotation like this on the enclosing element: ```kt // Kotlin @Suppress("ClickableViewAccessibility") fun method() { setOnTouchListener(...) } ``` or ```java // Java @SuppressWarnings("ClickableViewAccessibility") void method() { setOnTouchListener(...); } ``` * Using a suppression comment like this on the line above: ```kt //noinspection ClickableViewAccessibility problematicStatement() ``` * Using a special `lint.xml` file in the source tree which turns off the check in that folder and any sub folder. A simple file might look like this: ```xml <?xml version="1.0" encoding="UTF-8"?> <lint> <issue id="ClickableViewAccessibility" severity="ignore" /> </lint> ``` Instead of `ignore` you can also change the severity here, for example from `error` to `warning`. You can find additional documentation on how to filter issues by path, regular expression and so on [here](https://googlesamples.github.io/android-custom-lint-rules/usage/lintxml.md.html). * In Gradle projects, using the DSL syntax to configure lint. For example, you can use something like ```gradle lintOptions { disable 'ClickableViewAccessibility' } ``` In Android projects this should be nested inside an `android { }` block. * For manual invocations of `lint`, using the `--ignore` flag: ``` $ lint --ignore ClickableViewAccessibility ...` ``` * Last, but not least, using baselines, as discussed [here](https://googlesamples.github.io/android-custom-lint-rules/usage/baselines.md.html).