Created
December 12, 2019 02:20
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DepthPageTransformer
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class DepthPageTransformer: ViewPager.PageTransformer { | |
companion object { | |
private const val MIN_SCALE = 0.75f | |
} | |
override fun transformPage(view: View, position: Float) { | |
when { | |
position < -1 -> // [-Infinity,-1) | |
// This page is way off-screen to the left. | |
view.alpha = 0f | |
position <= 0 -> // [-1,0] | |
// Use the default slide transition when moving to the left page | |
view.apply { | |
alpha = 1f | |
translationX = 0f | |
scaleX = 1f | |
scaleY = 1f | |
} | |
position <= 1 -> // (0,1] | |
view.apply { | |
// Fade the page out. | |
alpha = 1 - position | |
// Counteract the default slide transition | |
translationX = width * -position | |
// Scale the page down (between MIN_SCALE and 1) | |
val scaleFactor = MIN_SCALE + (1 - MIN_SCALE) * (1 - Math.abs(position)) | |
scaleX = scaleFactor | |
scaleY = scaleFactor | |
} | |
else -> // (1,+Infinity] | |
// This page is way off-screen to the right. | |
view.alpha = 0f | |
} | |
} | |
} |
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