package cn.sinata.xldutils.view.gesture
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import android.view.MotionEvent
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/**
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* Component that detects translation, scale and rotation based on touch events.
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*
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*
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* This class notifies its listeners whenever a gesture begins, updates or ends.
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* The instance of this detector is passed to the listeners, so it can be queried
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* for pivot, translation, scale or rotation.
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*/
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class TransformGestureDetector(private val mDetector: MultiPointerGestureDetector) : MultiPointerGestureDetector.Listener {
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/** The listener for receiving notifications when gestures occur. */
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interface Listener {
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/** Responds to the beginning of a gesture. */
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fun onGestureBegin(detector: TransformGestureDetector)
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/** Responds to the update of a gesture in progress. */
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fun onGestureUpdate(detector: TransformGestureDetector)
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/** Responds to the end of a gesture. */
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fun onGestureEnd(detector: TransformGestureDetector)
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}
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private var mListener: Listener? = null
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init {
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mDetector.setListener(this)
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}
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/**
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* Sets the listener.
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* @param listener listener to set
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*/
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fun setListener(listener: Listener) {
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mListener = listener
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}
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/**
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* Resets the component to the initial state.
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*/
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fun reset() {
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mDetector.reset()
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}
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/**
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* Handles the given motion event.
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* @param event event to handle
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* *
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* @return whether or not the event was handled
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*/
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fun onTouchEvent(event: MotionEvent): Boolean {
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return mDetector.onTouchEvent(event)
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}
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override fun onGestureBegin(detector: MultiPointerGestureDetector) {
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if (mListener != null) {
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mListener!!.onGestureBegin(this)
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}
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}
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override fun onGestureUpdate(detector: MultiPointerGestureDetector) {
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if (mListener != null) {
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mListener!!.onGestureUpdate(this)
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}
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}
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override fun onGestureEnd(detector: MultiPointerGestureDetector) {
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if (mListener != null) {
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mListener!!.onGestureEnd(this)
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}
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}
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private fun calcAverage(arr: FloatArray, len: Int): Float {
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val sum = (0..len - 1)
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.map { arr[it] }
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.sum()
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return if (len > 0) sum / len else 0f
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}
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/** Restarts the current gesture */
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fun restartGesture() {
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mDetector.restartGesture()
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}
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/** Gets whether gesture is in progress or not */
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val isGestureInProgress: Boolean
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get() = mDetector.isGestureInProgress
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/** Gets the X coordinate of the pivot point */
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val pivotX: Float
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get() = calcAverage(mDetector.startX, mDetector.count)
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/** Gets the Y coordinate of the pivot point */
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val pivotY: Float
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get() = calcAverage(mDetector.startY, mDetector.count)
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/** Gets the X component of the translation */
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val translationX: Float
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get() = calcAverage(mDetector.currentX, mDetector.count) - calcAverage(mDetector.startX, mDetector.count)
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/** Gets the Y component of the translation */
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val translationY: Float
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get() = calcAverage(mDetector.currentY, mDetector.count) - calcAverage(mDetector.startY, mDetector.count)
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/** Gets the scale */
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val scale: Float
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get() {
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if (mDetector.count < 2) {
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return 1f
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} else {
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val startDeltaX = mDetector.startX[1] - mDetector.startX[0]
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val startDeltaY = mDetector.startY[1] - mDetector.startY[0]
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val currentDeltaX = mDetector.currentX[1] - mDetector.currentX[0]
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val currentDeltaY = mDetector.currentY[1] - mDetector.currentY[0]
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val startDist = Math.hypot(startDeltaX.toDouble(), startDeltaY.toDouble()).toFloat()
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val currentDist = Math.hypot(currentDeltaX.toDouble(), currentDeltaY.toDouble()).toFloat()
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return currentDist / startDist
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}
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}
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/** Gets the rotation in radians */
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val rotation: Float
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get() {
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if (mDetector.count < 2) {
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return 0f
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} else {
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val startDeltaX = mDetector.startX[1] - mDetector.startX[0]
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val startDeltaY = mDetector.startY[1] - mDetector.startY[0]
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val currentDeltaX = mDetector.currentX[1] - mDetector.currentX[0]
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val currentDeltaY = mDetector.currentY[1] - mDetector.currentY[0]
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val startAngle = Math.atan2(startDeltaY.toDouble(), startDeltaX.toDouble()).toFloat()
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val currentAngle = Math.atan2(currentDeltaY.toDouble(), currentDeltaX.toDouble()).toFloat()
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return currentAngle - startAngle
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}
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}
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companion object {
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/** Factory method that creates a new instance of TransformGestureDetector */
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fun newInstance(): TransformGestureDetector {
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return TransformGestureDetector(MultiPointerGestureDetector.newInstance())
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}
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}
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}
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