create-file-provider.md

Create file provider authority

Warning!

If cloning from a repo, requires project to be rebuilt for first time use.
In Android Studio, go to Build -> Rebuild project

This will demonstrate defining file provider authority without a hard coded string.
This utilises the package name to create the authority, using some build.gradle magic!

Defining in build.gradle in app level.

android {
    // ...

    defaultConfig {
        // ...

        // generate provider authority string
        def contentProviderAuthority = applicationId + ".provider"
        
        // Creates a placeholder property to use in the manifest.
        // This will replace "${cpAuthority}" string in AndroidManifest.xml
        manifestPlaceholders = [cpAuthority: contentProviderAuthority]
        
        // Adds a new field for the authority to the BuildConfig class.
        buildConfigField("String", "CONTENT_PROVIDER_AUTHORITY", "\"${contentProviderAuthority}\"")

    }
}

Defining in AndroidManifest.xml

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    ...>

    <application
        ...
        >
        
        <!--       Define the android.authorities as a variable, to be replaced by build.gradle        -->

        <provider
            android:authorities="${cpAuthority}"
            android:name="androidx.core.content.FileProvider"
            android:exported="false"
            android:grantUriPermissions="true"
            >
            <meta-data android:name="android.support.FILE_PROVIDER_PATHS"
                android:resource="@xml/file_paths"/>
        </provider>

    </application>

</manifest>

Define file_paths.xml in under xml directory.

Check https://developer.android.com/reference/androidx/core/content/FileProvider
Example:

<?xml version="1.0" encoding="utf-8"?>
<paths xmlns:android="http://schemas.android.com/apk/res/android">
    <files-path name="image" path="app_images/"/>
</paths>

Using the content provider authority in the app

Use from BuildConfig file. (Requires a project rebuild if cloning for first time.)
Snippet:

private val imageFile by lazy {
    File(filesDir.canonicalPath + "/app_images/", "test.img").apply {
        parentFile.mkdirs()
    }
}
val imageFileUri = FileProvider.getUriForFile(this, BuildConfig.CONTENT_PROVIDER_AUTHORITY, imageFile)