Make A11y Dump more generic via SnapshotTransformer

[yschimke]

The A11y dump #55 doesn't suit my purpose. There isn't an easy way to supply an alternate strategy.

Ideally the existing A11y dump feature and other features could be implemented using a clean API.

Examples

• Current Roborazzy a11y dump
• My A11y screenshots
• Highlighting / masking sections in a screenshot

I ended up using the RoboComponent.Screen class to grab a bitmap, then transforming it to show A11y info in a resized bitmap.

See here https://github.com/google/horologist/pull/2182/files#diff-7d20314095381dcb544af22f8ddd40d6dd3121bd95864b77eaa155d724afa678R124

    public fun captureScreenA11yRoboImage(
        filePath: String,
        roborazziOptions: RoborazziOptions,
    ) {
        Espresso.onIdle()

        val screenImage: Bitmap = captureScreenImageToBitmap(roborazziOptions) // uses RoboComponent.Screen

        val annotatedImage: Bitmap = A11ySnapshotTransformer().transform(composeRule.onRoot(), screenImage)

        annotatedImage.captureRoboImage(filePath, roborazziOptions)
    }

[yschimke]

Example

[takahirom]

Thank you, as always. It seems that you would like to access the screen bitmap, is that correct? Or is there something else you want to do?

[yschimke]

At minimum I guess a clean API to capture the bitmap.

But I'm hoping there is some interceptor style API to postprocess the bitmap with contextual info before comparison.

[takahirom]

I have a different use case for this. I want to focus on crucial screen elements, such as the visibility of a button. Therefore, I'd like to highlight that area with a square. We might need to develop more basic APIs rather than practical ones for this purpose.

captureRoboImage() { roboCanvas ->
  roboCanvas.drawRectWithText(onNodeWithTag('subscribe_button').toRoboComponent(), "Subscribe Button")
}

[yschimke]

@takahirom That sounds great. I think I could rework the current A11y transformer I have to do those draw operations.

Although I hope it's possible to expand or reduce the result bitmap size.