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A custom View Pager with some gestures and animations
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package eram.ir.camerapager | |
import android.animation.ValueAnimator | |
import android.app.Activity | |
import android.content.Context | |
import android.support.v4.app.FragmentActivity | |
import android.support.v4.view.ViewPager | |
import android.util.AttributeSet | |
import android.util.Log | |
import android.view.MotionEvent | |
import android.view.View | |
import android.view.ViewGroup | |
import android.view.animation.DecelerateInterpolator | |
import android.widget.Scroller | |
class CViewPager @JvmOverloads constructor( | |
context: Context, attrs: AttributeSet? = null | |
) : ViewPager(context, attrs) { | |
var enabledScroll = true | |
lateinit var exitListener: ExitListener | |
init { | |
setMyScroller() | |
} | |
fun setOnExitListener(exitListener: ExitListener) { | |
this.exitListener = exitListener | |
} | |
override fun onTouchEvent(ev: MotionEvent?): Boolean { | |
return super.onTouchEvent(ev) && (onDrag(ev)) | |
} | |
override fun onInterceptTouchEvent(ev: MotionEvent?): Boolean { | |
return if (enabledScroll) super.onInterceptTouchEvent(ev) else false | |
} | |
override fun dispatchTouchEvent(ev: MotionEvent?): Boolean { | |
return super.dispatchTouchEvent(ev) && (onDrag(ev)) | |
} | |
var startPointY = 0f | |
var prevY = 0f | |
var startPointX = 0f | |
private fun onDrag(ev: MotionEvent?): Boolean { | |
when (ev!!.action) { | |
MotionEvent.ACTION_DOWN -> { | |
prevY = getItemViewAt(currentItem).y | |
startPointY = ev.rawY | |
startPointX = ev.rawX | |
} | |
MotionEvent.ACTION_MOVE -> { | |
Log.i("current child", (context as FragmentActivity).supportFragmentManager.findFragmentByTag("android:switcher:" + id + ":" | |
+ currentItem)::class.java.canonicalName) | |
if (ev.action == MotionEvent.ACTION_MOVE && !enabledScroll && ev.rawY - startPointY > 0) { | |
getItemViewAt(currentItem).y = ev.rawY - startPointY | |
return enabledScroll | |
} | |
} | |
MotionEvent.ACTION_UP -> { | |
if (::exitListener.isInitialized && !enabledScroll) | |
if (getItemViewAt(currentItem).y > ev.y / 3) { | |
animateToRelease() | |
exitListener.onExit() | |
} else { | |
animateToRelease() | |
} | |
return (ev.x - startPointX) == 0f | |
} | |
} | |
return true | |
} | |
private fun getItemViewAt(index: Int): View { | |
val fragment = (context as FragmentActivity).supportFragmentManager.findFragmentByTag("android:switcher:" + id + ":" | |
+ currentItem) | |
return fragment.view!! | |
} | |
private fun animateToRelease() { | |
val animator = ValueAnimator.ofFloat(getItemViewAt(currentItem).y, prevY) | |
animator.addUpdateListener { animation -> | |
getItemViewAt(currentItem).y = animation.animatedValue as Float | |
} | |
animator.interpolator = DecelerateInterpolator() | |
animator.duration = 500 | |
animator.start() | |
} | |
private fun setMyScroller() { | |
try { | |
val viewpager = ViewPager::class.java | |
val scroller = viewpager.getDeclaredField("mScroller") | |
scroller.isAccessible = true | |
scroller.set(this, MyScroller(context)) | |
} catch (e: Exception) { | |
e.printStackTrace() | |
} | |
} | |
inner class MyScroller(context: Context) : Scroller(context, DecelerateInterpolator()) { | |
override fun startScroll(startX: Int, startY: Int, dx: Int, dy: Int, duration: Int) { | |
super.startScroll(startX, startY, dx, dy, if (enabledScroll) 200 else 500 /*1 secs*/) | |
} | |
} | |
interface ExitListener { | |
fun onExit() | |
} | |
} |
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