Android Background Processing
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Next episode: 06. Conclusion
Notes: 05. Challenge - Workers
The student materials have been reviewed and are updated as of SEPTEMBER 2022.
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To master using the WorkManager API, before implementing it in a more complex application, you first have to solve a fun challenge! :] In this challenge you have to build a worker to apply a sepia filter to your bitmap. Here’s a hint: the Sepia Filter code is prepared for you, in the ImageUtils class!
class SepiaFilterWorker(context: Context, workerParameters: WorkerParameters) :
Worker(context, workerParameters) {
override fun doWork(): Result {
}
}
class SepiaFilterWorker(context: Context, workerParameters: WorkerParameters) :
Worker(context, workerParameters) {
override fun doWork(): Result {
val imagePath = inputData.getString("image_path") ?: return Result.failure()
val bitmap = BitmapFactory.decodeFile(imagePath)
val newBitmap = ImageUtils.applySepiaFilter(bitmap)
val outputStream = FileOutputStream(imagePath)
outputStream.use { output ->
newBitmap.compress(Bitmap.CompressFormat.PNG, 100, output)
output.flush()
}
val output = workDataOf("image_path" to imagePath)
return Result.success(output)
}
}
val sepiaFilterWorker = OneTimeWorkRequestBuilder<SepiaFilterWorker>()
.setConstraints(constraints)
.build()
workManager.beginWith(clearFilesRequest)
.then(downloadRequest)
.then(sepiaFilterWorker)
.enqueue()
workManager.getWorkInfoByIdLiveData(sepiaFilterWorker.id)