Merge pull request #4 from hendrawd/Feat-AddPaddingMethods

Add padding methods by percentage of the screen width and dp

Author: bloderxd

README.md

@@ -18,31 +18,50 @@ First of all you need to declare it in your layout xml file
         android:layout_width="match_parent"
         android:layout_height="match_parent"/>
 ```
-
-then you just need to set deck default padding
+Then you can set the padding(Optional)
 
 ```kotlin
 private val deckPager by lazy { activity.findViewById<Deck>(R.id.deck_pager) }
+```
 
-private fun initDeck() {
-    deckPager.useDefaultPadding(activity)
-}
+Set padding based on percentage of the screen width
+
+```kotlin
+deckPager.setPercentagePadding(activity, 8)
+```
 
+or set padding based on dp value
+
+```kotlin
+deckPager.setDpPadding(activity, 16)
 ```
 
 ##### Remember you can set all other view pager properties with deck
 
+# Deck properties
+
+These are all properties supported in deck's xml
+
+```xml
+<com.example.lib.Deck
+        android:id="@+id/deck_pager"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        app:padding_percentage="8"
+        app:padding_dp="16dp"/>
+```
+
 # Import
 
-It's easy import deck in your project, first you need add jit pack maven reference in your project
+Add JitPack maven repository reference in your project
 
 ```groovy
 repositories {
     maven { url 'https://jitpack.io' }
 }
 ```
 
-then add deck referente in your gradle dependencies
+then add deck reference in your gradle dependencies
 
 ##### Gradle
 

app/src/main/java/com/example/bloder/deck/DeckAdapter.kt

@@ -1,6 +1,7 @@
 package com.example.bloder.deck
 
 import android.content.Context
+import android.support.v4.content.ContextCompat
 import android.support.v4.view.PagerAdapter
 import android.support.v7.widget.CardView
 import android.view.LayoutInflater
@@ -18,7 +19,8 @@ class DeckAdapter(private val context: Context) : PagerAdapter() {
     override fun instantiateItem(container: ViewGroup?, position: Int): Any {
         val view = LayoutInflater.from(context).inflate(R.layout.card, null)
         container?.addView(view, 0)
-        view.findViewById<CardView>(R.id.card).cardBackgroundColor = context.getColorStateList(cards[position].color)
+        view.findViewById<CardView>(R.id.card).cardBackgroundColor =
+                ContextCompat.getColorStateList(context, cards[position].color)
         view.findViewById<TextView>(R.id.title).text = cards[position].name
         return view
     }

app/src/main/java/com/example/bloder/deck/MainActivity.kt

@@ -16,6 +16,5 @@ class MainActivity : AppCompatActivity() {
         setContentView(R.layout.activity_main)
         deckPager.offscreenPageLimit = 5
         deckPager.adapter = DeckAdapter(this)
-        deckPager.useDefaultPadding(this)
     }
 }

app/src/main/res/layout/activity_main.xml

@@ -1,5 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
-<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
+<RelativeLayout
+    xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
@@ -9,6 +10,7 @@
         android:id="@+id/deck_pager"
         android:layout_width="match_parent"
         android:layout_height="400dp"
-        android:layout_centerInParent="true"/>
+        android:layout_centerInParent="true"
+        />
 
 </RelativeLayout>

lib/src/main/java/com/example/lib/CoverFlowTransformer.kt

@@ -7,17 +7,18 @@ import android.view.View
 /**
  * Created by bloder on 25/08/17.
  */
+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 {
 
-    private var SCALE_MIN = 0.3f
-    private var SCALE_MAX = 1f
-    private var MIN_ALPHA = 0.5f
-    private var scale = .05f
-    private var paddingFactor: Float = 0.08f
+    var paddingFactor: Float = 0.08f
 
     override fun transformPage(page: View, position: Float) {
         val realPosition = position - paddingFactor
-        val realScale = getFloat(1 - Math.abs(realPosition * scale), SCALE_MIN, SCALE_MAX)
+        val realScale = getFloat(1 - Math.abs(realPosition * SCALE), SCALE_MIN, SCALE_MAX)
         page.scaleX = realScale
         page.scaleY = realScale
         if (realPosition != 0f) {

lib/src/main/java/com/example/lib/Deck.kt

@@ -2,28 +2,91 @@ package com.example.lib
 
 import android.app.Activity
 import android.content.Context
+import android.content.res.TypedArray
 import android.support.v4.view.ViewPager
 import android.util.AttributeSet
 import android.util.DisplayMetrics
+import android.util.TypedValue
 
 /**
  * Created by bloder on 25/08/17.
  */
+private const val DEFAULT_PERCENTAGE_PADDING = 8
+
 class Deck : ViewPager {
 
-    constructor(context: Context) : super(context)
-    constructor(context: Context, attributeSet: AttributeSet) : super(context, attributeSet)
+    private val pageTransformer = CoverFlowTransformer()
 
-    init { initView() }
+    constructor(context: Context) : super(context) {
+        setPercentagePadding(context, DEFAULT_PERCENTAGE_PADDING)
+    }
 
-    private fun initView() = this.setPageTransformer(true, CoverFlowTransformer())
+    constructor(context: Context, attributeSet: AttributeSet) : super(context, attributeSet) {
+        val typedArray: TypedArray = context.obtainStyledAttributes(attributeSet, R.styleable.Deck)
+        val percentagePaddingXml = typedArray.getInt(R.styleable.Deck_padding_percentage, Integer.MAX_VALUE)
+        if (percentagePaddingXml != Integer.MAX_VALUE) {
+            setPercentagePadding(context, percentagePaddingXml)
+        }
+        val dipPaddingXmlInPixel = typedArray.getDimensionPixelSize(R.styleable.Deck_padding_dp, Integer.MAX_VALUE)
+        if (dipPaddingXmlInPixel != Integer.MAX_VALUE) {
+            initProperties(context, dipPaddingXmlInPixel.toFloat())
+        }
+        typedArray.recycle()
 
-    fun useDefaultPadding(context: Activity) {
-        val metrics = DisplayMetrics()
-        context.windowManager.defaultDisplay.getMetrics(metrics)
-        val padding = (metrics.widthPixels * 0.08).toInt()
-        setPadding(padding, 0, padding, 0)
+        // set the default padding if no properties from XML
+        if (percentagePaddingXml == Integer.MAX_VALUE && dipPaddingXmlInPixel == Integer.MAX_VALUE) {
+            setPercentagePadding(context, DEFAULT_PERCENTAGE_PADDING)
+        }
+    }
+
+    init {
+        initView()
+    }
+
+    private fun initView() {
+        setPageTransformer(true, pageTransformer)
+    }
+
+    /**
+     * Set left and right padding based on percentage of the screen width
+     * If the percentage is more than 18, the left and right items height might not be consistent
+     */
+    fun setPercentagePadding(context: Context, percentage: Int) {
+        when {
+            percentage == 0 -> initProperties(context, 0f)
+            percentage < 0 -> throw IllegalArgumentException("Percentage can't be lower than 0")
+            percentage >= 50 -> throw IllegalArgumentException("Your layout will not visible if the percentage equals or higher than 50")
+            else -> {
+                val padding = screenWidth(context) * percentage / 100f
+                initProperties(context, padding)
+            }
+        }
+    }
+
+    /**
+     * Set left and right padding based on dp value
+     */
+    fun setDpPadding(context: Context, dp: Float) {
+        val padding = TypedValue.applyDimension(
+                TypedValue.COMPLEX_UNIT_DIP,
+                dp,
+                context.resources.displayMetrics
+        )
+        initProperties(context, padding)
+    }
+
+    private fun initProperties(context: Context, padding: Float) {
+        val intPadding = padding.toInt()
+        setPadding(intPadding, 0, intPadding, 0)
         clipToPadding = false
         pageMargin = 0
+
+        pageTransformer.paddingFactor = padding / screenWidth(context)
+    }
+
+    private fun screenWidth(context: Context): Int {
+        val metrics = DisplayMetrics()
+        (context as Activity).windowManager.defaultDisplay.getMetrics(metrics)
+        return metrics.widthPixels
     }
 }

lib/src/main/res/values/attrs.xml

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <declare-styleable name="Deck">
+        <attr name="padding_percentage" format="integer"/>
+        <attr name="padding_dp" format="dimension"/>
+    </declare-styleable>
+</resources>