Support @Preview params "widthDp" and "heightDp"

[sergio-sastre]

I'd like to add support for "widthDp" and "heightDp" params

For that, I've tried the solution described in this page

if (preview.previewInfo.widthDp != -1 && preview.previewInfo.heightDp != -1) {
        setDisplaySize(preview.previewInfo.widthDp, preview.previewInfo.heightDp)
}

private fun setDisplaySize(widthDp: Int, heightDp: Int) {
    val context = ApplicationProvider.getApplicationContext<Context>()
    val display = ShadowDisplay.getDefaultDisplay()
    val density = context.resources.displayMetrics.density
    widthDp.let {
        val widthPx = (widthDp * density).roundToInt()
        Shadows.shadowOf(display).setWidth(widthPx)
    }
    heightDp.let {
        val heightPx = (heightDp * density).roundToInt()
        Shadows.shadowOf(display).setHeight(heightPx)
    }
}

but it does not seem to work. Could be that I am missing something?

[sergio-sastre]

So I got it working in a private project, it seems to work but one has to call composeTestRule.activityRule.scenario.recreate() afterwards.

I'll try to create a PR to add this functionality to Roborazzi this week

[sergio-sastre]

Seems 2 or 3 more adjustments were necessary to make the Views look exactly as in the Previews and avoid using a ComposeTestRule, which was making the test execution considerably slower.

One point to discuss will be the RoborazziTransparentTheme, which does
android:windowActionBar = false and that influences the size set via Robolectric qualifiers or the ShadowDisplay. It should be wither set to true or use another Activity.

I’ll create a PR today or tomorrow when I find time, which will also include support for “showBackground” and “backgroundColor”.

[sergio-sastre]

@takahirom

Draft PR #576