/*
* Copyright (C) 2014 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.android.systemui.recents.views;
import android.content.Context;
import android.view.InputDevice;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewParent;
import com.android.systemui.recents.Constants;
import com.android.systemui.recents.RecentsConfiguration;
/* Handles touch events for a TaskStackView. */
class TaskStackViewTouchHandler implements SwipeHelper.Callback {
static int INACTIVE_POINTER_ID = -1;
RecentsConfiguration mConfig;
TaskStackView mSv;
TaskStackViewScroller mScroller;
VelocityTracker mVelocityTracker;
boolean mIsScrolling;
float mInitialP;
float mLastP;
float mTotalPMotion;
int mInitialMotionX, mInitialMotionY;
int mLastMotionX, mLastMotionY;
int mActivePointerId = INACTIVE_POINTER_ID;
TaskView mActiveTaskView = null;
int mMinimumVelocity;
int mMaximumVelocity;
// The scroll touch slop is used to calculate when we start scrolling
int mScrollTouchSlop;
// The page touch slop is used to calculate when we start swiping
float mPagingTouchSlop;
SwipeHelper mSwipeHelper;
boolean mInterceptedBySwipeHelper;
public TaskStackViewTouchHandler(Context context, TaskStackView sv,
RecentsConfiguration config, TaskStackViewScroller scroller) {
ViewConfiguration configuration = ViewConfiguration.get(context);
mMinimumVelocity = configuration.getScaledMinimumFlingVelocity();
mMaximumVelocity = configuration.getScaledMaximumFlingVelocity();
mScrollTouchSlop = configuration.getScaledTouchSlop();
mPagingTouchSlop = configuration.getScaledPagingTouchSlop();
mSv = sv;
mScroller = scroller;
mConfig = config;
float densityScale = context.getResources().getDisplayMetrics().density;
mSwipeHelper = new SwipeHelper(SwipeHelper.X, this, densityScale, mPagingTouchSlop);
mSwipeHelper.setMinAlpha(1f);
}
/** Velocity tracker helpers */
void initOrResetVelocityTracker() {
if (mVelocityTracker == null) {
mVelocityTracker = VelocityTracker.obtain();
} else {
mVelocityTracker.clear();
}
}
void initVelocityTrackerIfNotExists() {
if (mVelocityTracker == null) {
mVelocityTracker = VelocityTracker.obtain();
}
}
void recycleVelocityTracker() {
if (mVelocityTracker != null) {
mVelocityTracker.recycle();
mVelocityTracker = null;
}
}
/** Returns the view at the specified coordinates */
TaskView findViewAtPoint(int x, int y) {
int childCount = mSv.getChildCount();
for (int i = childCount - 1; i >= 0; i--) {
TaskView tv = (TaskView) mSv.getChildAt(i);
if (tv.getVisibility() == View.VISIBLE) {
if (mSv.isTransformedTouchPointInView(x, y, tv)) {
return tv;
}
}
}
return null;
}
/** Constructs a simulated motion event for the current stack scroll. */
MotionEvent createMotionEventForStackScroll(MotionEvent ev) {
MotionEvent pev = MotionEvent.obtainNoHistory(ev);
pev.setLocation(0, mScroller.progressToScrollRange(mScroller.getStackScroll()));
return pev;
}
/** Touch preprocessing for handling below */
public boolean onInterceptTouchEvent(MotionEvent ev) {
// Return early if we have no children
boolean hasChildren = (mSv.getChildCount() > 0);
if (!hasChildren) {
return false;
}
// Pass through to swipe helper if we are swiping
mInterceptedBySwipeHelper = mSwipeHelper.onInterceptTouchEvent(ev);
if (mInterceptedBySwipeHelper) {
return true;
}
boolean wasScrolling = mScroller.isScrolling() ||
(mScroller.mScrollAnimator != null && mScroller.mScrollAnimator.isRunning());
int action = ev.getAction();
switch (action & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN: {
// Save the touch down info
mInitialMotionX = mLastMotionX = (int) ev.getX();
mInitialMotionY = mLastMotionY = (int) ev.getY();
mInitialP = mLastP = mSv.mLayoutAlgorithm.screenYToCurveProgress(mLastMotionY);
mActivePointerId = ev.getPointerId(0);
mActiveTaskView = findViewAtPoint(mLastMotionX, mLastMotionY);
// Stop the current scroll if it is still flinging
mScroller.stopScroller();
mScroller.stopBoundScrollAnimation();
// Initialize the velocity tracker
initOrResetVelocityTracker();
mVelocityTracker.addMovement(createMotionEventForStackScroll(ev));
break;
}
case MotionEvent.ACTION_MOVE: {
if (mActivePointerId == INACTIVE_POINTER_ID) break;
// Initialize the velocity tracker if necessary
initVelocityTrackerIfNotExists();
mVelocityTracker.addMovement(createMotionEventForStackScroll(ev));
int activePointerIndex = ev.findPointerIndex(mActivePointerId);
int y = (int) ev.getY(activePointerIndex);
int x = (int) ev.getX(activePointerIndex);
if (Math.abs(y - mInitialMotionY) > mScrollTouchSlop) {
// Save the touch move info
mIsScrolling = true;
// Disallow parents from intercepting touch events
final ViewParent parent = mSv.getParent();
if (parent != null) {
parent.requestDisallowInterceptTouchEvent(true);
}
}
mLastMotionX = x;
mLastMotionY = y;
mLastP = mSv.mLayoutAlgorithm.screenYToCurveProgress(mLastMotionY);
break;
}
case MotionEvent.ACTION_CANCEL:
case MotionEvent.ACTION_UP: {
// Animate the scroll back if we've cancelled
mScroller.animateBoundScroll();
// Reset the drag state and the velocity tracker
mIsScrolling = false;
mActivePointerId = INACTIVE_POINTER_ID;
mActiveTaskView = null;
mTotalPMotion = 0;
recycleVelocityTracker();
break;
}
}
return wasScrolling || mIsScrolling;
}
/** Handles touch events once we have intercepted them */
public boolean onTouchEvent(MotionEvent ev) {
// Short circuit if we have no children
boolean hasChildren = (mSv.getChildCount() > 0);
if (!hasChildren) {
return false;
}
// Pass through to swipe helper if we are swiping
if (mInterceptedBySwipeHelper && mSwipeHelper.onTouchEvent(ev)) {
return true;
}
// Update the velocity tracker
initVelocityTrackerIfNotExists();
int action = ev.getAction();
switch (action & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN: {
// Save the touch down info
mInitialMotionX = mLastMotionX = (int) ev.getX();
mInitialMotionY = mLastMotionY = (int) ev.getY();
mInitialP = mLastP = mSv.mLayoutAlgorithm.screenYToCurveProgress(mLastMotionY);
mActivePointerId = ev.getPointerId(0);
mActiveTaskView = findViewAtPoint(mLastMotionX, mLastMotionY);
// Stop the current scroll if it is still flinging
mScroller.stopScroller();
mScroller.stopBoundScrollAnimation();
// Initialize the velocity tracker
initOrResetVelocityTracker();
mVelocityTracker.addMovement(createMotionEventForStackScroll(ev));
// Disallow parents from intercepting touch events
final ViewParent parent = mSv.getParent();
if (parent != null) {
parent.requestDisallowInterceptTouchEvent(true);
}
break;
}
case MotionEvent.ACTION_POINTER_DOWN: {
final int index = ev.getActionIndex();
mActivePointerId = ev.getPointerId(index);
mLastMotionX = (int) ev.getX(index);
mLastMotionY = (int) ev.getY(index);
mLastP = mSv.mLayoutAlgorithm.screenYToCurveProgress(mLastMotionY);
break;
}
case MotionEvent.ACTION_MOVE: {
if (mActivePointerId == INACTIVE_POINTER_ID) break;
mVelocityTracker.addMovement(createMotionEventForStackScroll(ev));
int activePointerIndex = ev.findPointerIndex(mActivePointerId);
int x = (int) ev.getX(activePointerIndex);
int y = (int) ev.getY(activePointerIndex);
int yTotal = Math.abs(y - mInitialMotionY);
float curP = mSv.mLayoutAlgorithm.screenYToCurveProgress(y);
float deltaP = mLastP - curP;
if (!mIsScrolling) {
if (yTotal > mScrollTouchSlop) {
mIsScrolling = true;
// Disallow parents from intercepting touch events
final ViewParent parent = mSv.getParent();
if (parent != null) {
parent.requestDisallowInterceptTouchEvent(true);
}
}
}
if (mIsScrolling) {
float curStackScroll = mScroller.getStackScroll();
float overScrollAmount = mScroller.getScrollAmountOutOfBounds(curStackScroll + deltaP);
if (Float.compare(overScrollAmount, 0f) != 0) {
// Bound the overscroll to a fixed amount, and inversely scale the y-movement
// relative to how close we are to the max overscroll
float maxOverScroll = mConfig.taskStackOverscrollPct;
deltaP *= (1f - (Math.min(maxOverScroll, overScrollAmount)
/ maxOverScroll));
}
mScroller.setStackScroll(curStackScroll + deltaP);
}
mLastMotionX = x;
mLastMotionY = y;
mLastP = mSv.mLayoutAlgorithm.screenYToCurveProgress(mLastMotionY);
mTotalPMotion += Math.abs(deltaP);
break;
}
case MotionEvent.ACTION_UP: {
mVelocityTracker.computeCurrentVelocity(1000, mMaximumVelocity);
int velocity = (int) mVelocityTracker.getYVelocity(mActivePointerId);
if (mIsScrolling && (Math.abs(velocity) > mMinimumVelocity)) {
float overscrollRangePct = Math.abs((float) velocity / mMaximumVelocity);
int overscrollRange = (int) (Math.min(1f, overscrollRangePct) *
(Constants.Values.TaskStackView.TaskStackMaxOverscrollRange -
Constants.Values.TaskStackView.TaskStackMinOverscrollRange));
mScroller.mScroller.fling(0,
mScroller.progressToScrollRange(mScroller.getStackScroll()),
0, velocity,
0, 0,
mScroller.progressToScrollRange(mSv.mLayoutAlgorithm.mMinScrollP),
mScroller.progressToScrollRange(mSv.mLayoutAlgorithm.mMaxScrollP),
0, Constants.Values.TaskStackView.TaskStackMinOverscrollRange +
overscrollRange);
// Invalidate to kick off computeScroll
mSv.invalidate();
} else if (mScroller.isScrollOutOfBounds()) {
// Animate the scroll back into bounds
mScroller.animateBoundScroll();
}
mActivePointerId = INACTIVE_POINTER_ID;
mIsScrolling = false;
mTotalPMotion = 0;
recycleVelocityTracker();
break;
}
case MotionEvent.ACTION_POINTER_UP: {
int pointerIndex = ev.getActionIndex();
int pointerId = ev.getPointerId(pointerIndex);
if (pointerId == mActivePointerId) {
// Select a new active pointer id and reset the motion state
final int newPointerIndex = (pointerIndex == 0) ? 1 : 0;
mActivePointerId = ev.getPointerId(newPointerIndex);
mLastMotionX = (int) ev.getX(newPointerIndex);
mLastMotionY = (int) ev.getY(newPointerIndex);
mLastP = mSv.mLayoutAlgorithm.screenYToCurveProgress(mLastMotionY);
mVelocityTracker.clear();
}
break;
}
case MotionEvent.ACTION_CANCEL: {
if (mScroller.isScrollOutOfBounds()) {
// Animate the scroll back into bounds
mScroller.animateBoundScroll();
}
mActivePointerId = INACTIVE_POINTER_ID;
mIsScrolling = false;
mTotalPMotion = 0;
recycleVelocityTracker();
break;
}
}
return true;
}
/** Handles generic motion events */
public boolean onGenericMotionEvent(MotionEvent ev) {
if ((ev.getSource() & InputDevice.SOURCE_CLASS_POINTER) ==
InputDevice.SOURCE_CLASS_POINTER) {
int action = ev.getAction();
switch (action & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_SCROLL:
// Find the front most task and scroll the next task to the front
float vScroll = ev.getAxisValue(MotionEvent.AXIS_VSCROLL);
if (vScroll > 0) {
if (mSv.ensureFocusedTask()) {
mSv.focusNextTask(true, false);
}
} else {
if (mSv.ensureFocusedTask()) {
mSv.focusNextTask(false, false);
}
}
return true;
}
}
return false;
}
/**** SwipeHelper Implementation ****/
@Override
public View getChildAtPosition(MotionEvent ev) {
return findViewAtPoint((int) ev.getX(), (int) ev.getY());
}
@Override
public boolean canChildBeDismissed(View v) {
return true;
}
@Override
public void onBeginDrag(View v) {
TaskView tv = (TaskView) v;
// Disable clipping with the stack while we are swiping
tv.setClipViewInStack(false);
// Disallow touch events from this task view
tv.setTouchEnabled(false);
// Disallow parents from intercepting touch events
final ViewParent parent = mSv.getParent();
if (parent != null) {
parent.requestDisallowInterceptTouchEvent(true);
}
}
@Override
public void onSwipeChanged(View v, float delta) {
// Do nothing
}
@Override
public void onChildDismissed(View v) {
TaskView tv = (TaskView) v;
// Re-enable clipping with the stack (we will reuse this view)
tv.setClipViewInStack(true);
// Re-enable touch events from this task view
tv.setTouchEnabled(true);
// Remove the task view from the stack
mSv.onTaskViewDismissed(tv);
}
@Override
public void onSnapBackCompleted(View v) {
TaskView tv = (TaskView) v;
// Re-enable clipping with the stack
tv.setClipViewInStack(true);
// Re-enable touch events from this task view
tv.setTouchEnabled(true);
}
@Override
public void onDragCancelled(View v) {
// Do nothing
}
}