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/*
* Copyright (C) 2010 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.launcher3;
import android.content.Context;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
/* Class that does most of the work of enabling dragging items out of a PagedView by performing a
* vertical drag. Used by both CustomizePagedView and AllAppsPagedView.
* Subclasses must do the following:
* * call setDragSlopeThreshold after making an instance of the PagedViewWithDraggableItems
* * call child.setOnLongClickListener(this) and child.setOnTouchListener(this) on all children
* (good place to do it is in syncPageItems)
* * override beginDragging(View) (but be careful to call super.beginDragging(View)
*
*/
public abstract class PagedViewWithDraggableItems extends PagedView
implements View.OnLongClickListener, View.OnTouchListener {
private View mLastTouchedItem;
private boolean mIsDragging;
private boolean mIsDragEnabled;
private float mDragSlopeThreshold;
private Launcher mLauncher;
public PagedViewWithDraggableItems(Context context) {
this(context, null);
}
public PagedViewWithDraggableItems(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public PagedViewWithDraggableItems(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
mLauncher = (Launcher) context;
}
protected boolean beginDragging(View v) {
boolean wasDragging = mIsDragging;
mIsDragging = true;
return !wasDragging;
}
protected void cancelDragging() {
mIsDragging = false;
mLastTouchedItem = null;
mIsDragEnabled = false;
}
private void handleTouchEvent(MotionEvent ev) {
final int action = ev.getAction();
switch (action & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN:
cancelDragging();
mIsDragEnabled = true;
break;
case MotionEvent.ACTION_MOVE:
if (mTouchState != TOUCH_STATE_SCROLLING && !mIsDragging && mIsDragEnabled) {
determineDraggingStart(ev);
}
break;
}
}
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
handleTouchEvent(ev);
return super.onInterceptTouchEvent(ev);
}
@Override
public boolean onTouchEvent(MotionEvent ev) {
handleTouchEvent(ev);
return super.onTouchEvent(ev);
}
public void trimMemory() {
mLastTouchedItem = null;
}
@Override
public boolean onTouch(View v, MotionEvent event) {
mLastTouchedItem = v;
mIsDragEnabled = true;
return false;
}
@Override
public boolean onLongClick(View v) {
// Return early if this is not initiated from a touch
if (!v.isInTouchMode()) return false;
// Return early if we are still animating the pages
if (mNextPage != INVALID_PAGE) return false;
// When we have exited all apps or are in transition, disregard long clicks
if (!mLauncher.isAllAppsVisible() ||
mLauncher.getWorkspace().isSwitchingState()) return false;
// Return if global dragging is not enabled
if (!mLauncher.isDraggingEnabled()) return false;
return beginDragging(v);
}
/*
* Determines if we should change the touch state to start scrolling after the
* user moves their touch point too far.
*/
protected void determineScrollingStart(MotionEvent ev) {
if (!mIsDragging) super.determineScrollingStart(ev);
}
/*
* Determines if we should change the touch state to start dragging after the
* user moves their touch point far enough.
*/
protected void determineDraggingStart(MotionEvent ev) {
/*
* Locally do absolute value. mLastMotionX is set to the y value
* of the down event.
*/
final int pointerIndex = ev.findPointerIndex(mActivePointerId);
final float x = ev.getX(pointerIndex);
final float y = ev.getY(pointerIndex);
final int xDiff = (int) Math.abs(x - mLastMotionX);
final int yDiff = (int) Math.abs(y - mLastMotionY);
final int touchSlop = mTouchSlop;
boolean yMoved = yDiff > touchSlop;
boolean isUpwardMotion = (yDiff / (float) xDiff) > mDragSlopeThreshold;
if (isUpwardMotion && yMoved && mLastTouchedItem != null) {
// Drag if the user moved far enough along the Y axis
beginDragging(mLastTouchedItem);
// Cancel any pending long press
if (mAllowLongPress) {
mAllowLongPress = false;
// Try canceling the long press. It could also have been scheduled
// by a distant descendant, so use the mAllowLongPress flag to block
// everything
final View currentPage = getPageAt(mCurrentPage);
if (currentPage != null) {
currentPage.cancelLongPress();
}
}
}
}
public void setDragSlopeThreshold(float dragSlopeThreshold) {
mDragSlopeThreshold = dragSlopeThreshold;
}
@Override
protected void onDetachedFromWindow() {
cancelDragging();
super.onDetachedFromWindow();
}
}