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A library for programatically capturing screenshots on Android
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README.md

Screenshotty

The library combines MediaProjection, PixelCopy and Canvas drawing and provides an easy-to-use API, abstracted from the Android framework and the complexities of the underlying mechanisms, to capture precisely what a user sees on their screen.

The sample app shows how to use the library.

Gradle

Add this to your dependencies block.

implementation 'eu.bolt:screenshotty:1.0.2'

To use a reactive wrapper also add:

implementation 'eu.bolt:screenshotty-rx:1.0.2'

Wiki

General

If we want to capture a screenshot inside the app, the simplest approach is to draw the root view on a Bitmap, but this approach won't work correctly if there are open dialogs, or view hierarchy contains maps or other SurfaceViews. Screenshotty uses PixelCopy and MediaProjection to provide the correct image in all these cases.

First the library tries to make a PixelCopy with dialogs, retrieved via reflection, rendered on top.

If this approach fails, user will see a record screen permission dialog. Screenshotty minimizes the number of times the dialog is shown: permission has to be granted only once per process lifetime. If "Don't show again" option (removed in Android 10) is checked, the system will remember user's choice for all the future invocations. If the permission is granted, a MediaProjection API is used to take a single frame and provide it to result listeners.

In case MediaProjection fails, fallback strategies are invoked one-by-one until the first one succeeds to provide a Bitmap.

Usage

  1. Create a ScreenshotManager:
screenshotManager = ScreenshotManagerBuilder(this)
   .withPermissionRequestCode(REQUEST_SCREENSHOT_PERMISSION) //optional, 888 is the default
   .build()
  1. Make sure the object receives activity results:
override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
   super.onActivityResult(requestCode, resultCode, data)
   screenshotManager.onActivityResult(requestCode, resultCode, data)
}
  1. Request a screenshot and observe the result:
val screenshotResult = screenshotManager.makeScreenshot()
val subscription = screenshotResult.observe(
   onSuccess = { processScreenshot(it) },
   onError = { onMakeScreenshotFailed(it) }
)
  1. If you're no longer interested in the result (as when your Activity is destroyed), you can unsubscribe your observers using the object you got from observe().
override fun onDestroy() {
   super.onDestroy()
   subscription.dispose()
}

Working with result

When you receive a Screenshot you can either get a Bitmap object from it:

fun show(screenshot: Screenshot) {
   val bitmap = when (screenshot) {
      is ScreenshotBitmap -> screenshot.bitmap
   }
   screenshotPreview.setImageBitmap(bitmap)
}

Or use ScreenshotFileSaver provided by the library to write the image to a file:

fun writeToFile(screenshot: Screenshot): File {
   val fileSaver = ScreenshotFileSaver.create(Bitmap.CompressFormat.PNG)
   val targetFile = File(context.filesDir, "screenshot")
   fileSaver.saveToFile(targetFile, screenshot)
   return targetFile
}

Reactive wrapper

If you're using screenshotty-rx, you can transform your ScreenshotManager object into RxScreenshotManager:

val rxScreenshotManager = screenshotManager.asRxScreenshotManager() //or RxScreenshotWrapper.wrap(screenshotManager)

Usage is exactly the same, but makeScreenshot() returns Single<Screenshot> instead of ScreenshotResult, so you can use all the expressive power of reactive composition to process the result:

subscription = rxScreenshotManager.makeScreenshot()
   .observeOn(Schedulers.io())
   .map(::writeToFile)
   .doOnSuccess(::sendScreenshotFile)
   .observeOn(AndroidSchedulers.mainThread())
   .subscribe(
      onSuccess = ::onScreenshotSent,
      onError = ::handleError
   )

Fallback strategies

When constructing a ScreenshotManager you can add any number of objects that implement FallbackStrategy interface. If PixelCopy or MediaProjection fails for some reason, fallback strategies will be invoked one by one in the order they were added, until the first one succeeds to provide a Bitmap.

If no strategies were added or all of them failed, the default one (that simply calls draw on the root view and tries to render dialogs retrieved via reflection on top) will be invoked.

License

MIT License

Copyright (c) 2019 Bolt Technologies OÜ

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
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