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/*
* Copyright (C) 2016 Cyanogen, Inc.
* Copyright (C) 2016 The CyanogenMod 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 org.cyanogenmod.theme.widget;
import android.content.Context;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.widget.HorizontalScrollView;
import android.widget.LinearLayout;
public class AutoSnapHorizontalScrollView extends HorizontalScrollView {
private static final int SNAP_ON_UP_DELAY = 250;
private int mScrollPositionOnUp;
enum EventStates {
SCROLLING,
FLING
}
private EventStates mSystemState = EventStates.SCROLLING;
public AutoSnapHorizontalScrollView(Context context) {
super(context);
}
public AutoSnapHorizontalScrollView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public AutoSnapHorizontalScrollView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
Runnable mSnapRunnable = new Runnable(){
@Override
public void run() {
snapItems();
mSystemState = EventStates.SCROLLING;
}
};
/**
* Added runnable for snapping on an item when the user lifts up their finger and
* there is no scrolling taking place (i.e. no flinging)
*/
Runnable mSnapOnUpRunnable = new Runnable(){
@Override
public void run() {
int scrollX = getScrollX();
if (scrollX != mScrollPositionOnUp) {
mScrollPositionOnUp = scrollX;
postDelayed(mSnapOnUpRunnable, SNAP_ON_UP_DELAY);
} else {
snapItems();
mSystemState = EventStates.SCROLLING;
}
}
};
@Override
public boolean onTouchEvent(MotionEvent ev) {
int action = ev.getAction();
if (action == MotionEvent.ACTION_CANCEL || action == MotionEvent.ACTION_UP) {
mSystemState = EventStates.FLING;
removeCallbacks(mSnapRunnable);
mScrollPositionOnUp = getScrollX();
postDelayed(mSnapOnUpRunnable, SNAP_ON_UP_DELAY);
} else if (action == MotionEvent.ACTION_DOWN) {
mSystemState = EventStates.SCROLLING;
removeCallbacks(mSnapRunnable);
removeCallbacks(mSnapOnUpRunnable);
}
return super.onTouchEvent(ev);
}
private void snapItems() {
Rect parentBounds = new Rect();
getDrawingRect(parentBounds);
Rect childBounds = new Rect();
ViewGroup parent = (ViewGroup) getChildAt(0);
for (int i = 0; i < parent.getChildCount(); i++) {
View view = parent.getChildAt(i);
view.getHitRect(childBounds);
if (childBounds.right >= parentBounds.left && childBounds.left <= parentBounds.left) {
// First partially visible child
if ((childBounds.right - parentBounds.left) >=
(parentBounds.left - childBounds.left)) {
smoothScrollTo(Math.abs(childBounds.left), 0);
} else {
/**
* Added code to take into account dividers so that we do not see
* one on the edge of the screen when items snap in place.
*/
int dividerWidth = 0;
if (parent instanceof LinearLayout) {
dividerWidth = ((LinearLayout) parent).getDividerWidth();
}
smoothScrollTo(Math.abs(childBounds.right) + dividerWidth, 0);
}
break;
}
}
}
// Overwrite measureChildX as we want our child to be able to tell the
// parents width but do not impose any limits (AT_MOST; AT_MAX)
@Override
protected void measureChild(View child, int parentWidthMeasureSpec,
int parentHeightMeasureSpec) {
ViewGroup.LayoutParams lp = child.getLayoutParams();
int childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec, mPaddingTop
+ mPaddingBottom, lp.height);
int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(
MeasureSpec.getSize(parentWidthMeasureSpec) - (mPaddingLeft + mPaddingRight),
MeasureSpec.UNSPECIFIED);
child.measure(childWidthMeasureSpec, childHeightMeasureSpec);
}
@Override
protected void measureChildWithMargins(View child, int parentWidthMeasureSpec, int widthUsed,
int parentHeightMeasureSpec, int heightUsed) {
MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();
int childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec,
mPaddingTop + mPaddingBottom + lp.topMargin + lp.bottomMargin
+ heightUsed, lp.height);
int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(
MeasureSpec.getSize(parentWidthMeasureSpec) -
(mPaddingLeft + mPaddingRight + lp.leftMargin + lp.rightMargin
+ widthUsed), MeasureSpec.UNSPECIFIED);
child.measure(childWidthMeasureSpec, childHeightMeasureSpec);
}
@Override
protected void onScrollChanged(int l, int t, int oldl, int oldt) {
if (mSystemState == EventStates.SCROLLING) {
return;
}
if (Math.abs(l - oldl) <= 1 && mSystemState == EventStates.FLING) {
removeCallbacks(mSnapRunnable);
postDelayed(mSnapRunnable, 100);
}
}
}
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