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/*
* Copyright (C) 2018 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 android.support.constraint.solver.widgets;
import android.support.constraint.solver.widgets.ConstraintWidget.DimensionBehaviour;
/**
* Class to represent a chain by its main elements.
*/
public class ChainHead {
protected ConstraintWidget mFirst;
protected ConstraintWidget mFirstVisibleWidget;
protected ConstraintWidget mLast;
protected ConstraintWidget mLastVisibleWidget;
protected ConstraintWidget mHead;
protected ConstraintWidget mFirstMatchConstraintWidget;
protected ConstraintWidget mLastMatchConstraintWidget;
protected float mTotalWeight = 0f;
private int mOrientation;
private boolean mIsRtl = false;
/**
* Initialize variables, then determine visible widgets, the head of chain and
* matched constraint widgets.
*
* @param first first widget in a chain
* @param orientation orientation of the chain (either Horizontal or Vertical)
* @param isRtl Right-to-left layout flag to determine the actual head of the chain
*/
public ChainHead(ConstraintWidget first, int orientation, boolean isRtl){
mFirst = first;
mOrientation = orientation;
mIsRtl = isRtl;
defineChainProperties();
}
private void defineChainProperties(){
int offset = mOrientation * 2;
// TraverseChain
ConstraintWidget widget = mFirst;
ConstraintWidget next = mFirst;
boolean done = false;
while (!done) {
widget.mListNextVisibleWidget[mOrientation] = null;
widget.mListNextMatchConstraintsWidget[mOrientation] = null;
if(widget.getVisibility() != ConstraintWidget.GONE) {
// Visible widgets linked list.
if (mFirstVisibleWidget == null) {
mFirstVisibleWidget = widget;
}
if(mLastVisibleWidget != null){
mLastVisibleWidget.mListNextVisibleWidget[mOrientation] = widget;
}
mLastVisibleWidget = widget;
// Match constraint linked list.
if(widget.mListDimensionBehaviors[mOrientation] == DimensionBehaviour.MATCH_CONSTRAINT){
mTotalWeight += widget.mWeight[mOrientation];
if(mFirstMatchConstraintWidget == null){
mFirstMatchConstraintWidget = widget;
}
if(mLastMatchConstraintWidget != null){
mLastMatchConstraintWidget.mListNextMatchConstraintsWidget[mOrientation] = widget;
}
mLastMatchConstraintWidget = widget;
}
}
// go to the next widget
ConstraintAnchor nextAnchor = widget.mListAnchors[offset + 1].mTarget;
if (nextAnchor != null) {
next = nextAnchor.mOwner;
if (next.mListAnchors[offset].mTarget == null
|| next.mListAnchors[offset].mTarget.mOwner != widget) {
next = null;
}
} else {
next = null;
}
if (next != null) {
widget = next;
} else {
done = true;
}
}
mLast = widget;
if(mOrientation == ConstraintWidget.HORIZONTAL && mIsRtl) {
mHead = mLast;
}else{
mHead = mFirst;
}
}
public ConstraintWidget getFirst() {
return mFirst;
}
public ConstraintWidget getFirstVisibleWidget() {
return mFirstVisibleWidget;
}
public ConstraintWidget getLast() {
return mLast;
}
public ConstraintWidget getLastVisibleWidget() {
return mLastVisibleWidget;
}
public ConstraintWidget getHead() {
return mHead;
}
public ConstraintWidget getFirstMatchConstraintWidget() {
return mFirstMatchConstraintWidget;
}
public ConstraintWidget getLastMatchConstraintWidget() {
return mLastMatchConstraintWidget;
}
public float getTotalWeight() {
return mTotalWeight;
}
}
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