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Public method and XML attribute for setting minimum alpha #6

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Public method and XML attribute for setting minimum alpha #6

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2d8a9af
Added public method and XML attribute for setting minimum alpha for l…
Dec 24, 2018
2dbe52e
Added validations while applying XML attributes
Dec 24, 2018
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5 changes: 2 additions & 3 deletions lib/src/main/java/com/example/lib/CoverFlowTransformer.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -9,10 +9,9 @@ import android.view.View
*/
private const val SCALE_MIN = .3f
private const val SCALE_MAX = 1f
private const val MIN_ALPHA = .5f
private const val SCALE = .05f

class CoverFlowTransformer : ViewPager.PageTransformer {
class CoverFlowTransformer(var minAlpha: Float) : ViewPager.PageTransformer {

var paddingFactor: Float = 0.08f

Expand All @@ -23,7 +22,7 @@ class CoverFlowTransformer : ViewPager.PageTransformer {
page.scaleY = realScale
if (realPosition != 0f) {
val scaleFactor = Math.max(SCALE_MIN, 1 - Math.abs(realPosition))
page.alpha = MIN_ALPHA + (scaleFactor - SCALE_MIN) / (1 - SCALE_MIN) * (1 - MIN_ALPHA)
page.alpha = minAlpha + (scaleFactor - SCALE_MIN) / (1 - SCALE_MIN) * (1 - minAlpha)
}
}

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17 changes: 16 additions & 1 deletion lib/src/main/java/com/example/lib/Deck.kt
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Expand Up @@ -12,10 +12,11 @@ import android.util.TypedValue
* Created by bloder on 25/08/17.
*/
private const val DEFAULT_PERCENTAGE_PADDING = 8
private const val MIN_ALPHA = .5f

class Deck : ViewPager {

private val pageTransformer = CoverFlowTransformer()
private val pageTransformer = CoverFlowTransformer(MIN_ALPHA)

constructor(context: Context) : super(context) {
setPercentagePadding(context, DEFAULT_PERCENTAGE_PADDING)
Expand All @@ -31,6 +32,10 @@ class Deck : ViewPager {
if (dipPaddingXmlInPixel != Integer.MAX_VALUE) {
initProperties(context, dipPaddingXmlInPixel.toFloat())
}
val minAlphaXml = typedArray.getFloat(R.styleable.Deck_min_alpha, MIN_ALPHA)
if (minAlphaXml != MIN_ALPHA) {
setMinAlpha(minAlphaXml)
}
typedArray.recycle()

// set the default padding if no properties from XML
Expand Down Expand Up @@ -75,6 +80,16 @@ class Deck : ViewPager {
initProperties(context, padding)
}

/**
* Set minimum alpha for left and right views
*/
fun setMinAlpha(minAlpha: Float) {
when {
minAlpha < 0 || minAlpha > 1 -> throw IllegalArgumentException("Minimum alpha must be between 0 and 1")
else -> pageTransformer.minAlpha = minAlpha
}
}

private fun initProperties(context: Context, padding: Float) {
val intPadding = padding.toInt()
setPadding(intPadding, 0, intPadding, 0)
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1 change: 1 addition & 0 deletions lib/src/main/res/values/attrs.xml
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Expand Up @@ -3,5 +3,6 @@
<declare-styleable name="Deck">
<attr name="padding_percentage" format="integer"/>
<attr name="padding_dp" format="dimension"/>
<attr name="min_alpha" format="float"/>
</declare-styleable>
</resources>