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/*
* Copyright (C) 2019 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.wallpaper.livepicker.widget;
import android.content.Context;
import android.util.AttributeSet;
import android.view.View;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.viewpager.widget.ViewPager;
import com.android.wallpaper.livepicker.R;
/**
* When ConstraintViewPager is being measured, it will get all height of pages and makes itself
* height as the same as the maximum height.
*/
public class ConstraintViewPager extends ViewPager {
private final int mExtraSpacerHeight;
public ConstraintViewPager(@NonNull Context context) {
this(context, null /* attrs */);
}
public ConstraintViewPager(@NonNull Context context, @Nullable AttributeSet attrs) {
super(context, attrs);
mExtraSpacerHeight = context.getResources().getDimensionPixelSize(
R.dimen.preview_attribution_pane_extra_spacer_height);
}
/**
* Visit all child views first and then determine the maximum height for ViewPager.
* Info page will add extra height in top area determined by empty space.
*/
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
int maxChildHeight = 0;
int infoChildHeight = 0;
int infoTopPadding = 0;
View infoPage = null;
for (int i = 0; i < getChildCount(); i++) {
View view = getChildAt(i);
view.measure(widthMeasureSpec,
MeasureSpec.makeMeasureSpec(0 /* size */, MeasureSpec.UNSPECIFIED));
int childHeight = view.getMeasuredHeight();
// Get info page height and top padding.
if (view.getId() == R.id.page_info) {
infoPage = view;
infoChildHeight = childHeight;
infoTopPadding = view.getPaddingTop();
}
if (childHeight > maxChildHeight) {
maxChildHeight = childHeight;
}
}
// Add extra padding in info page top area if info page has enough empty space to
// accommodate above and below extra height.
// 1. "infoChildHeight - infoTopPadding" means info page height without extra padding.
// 2. "mExtraSpacerHeight * 2" means above and below extra height.
if (maxChildHeight > (infoChildHeight - infoTopPadding + mExtraSpacerHeight * 2)) {
if (infoPage != null && infoTopPadding != mExtraSpacerHeight) {
infoPage.setPadding(infoPage.getPaddingLeft(), mExtraSpacerHeight,
infoPage.getPaddingRight(), infoPage.getPaddingBottom());
}
}
if (maxChildHeight != 0) {
heightMeasureSpec = MeasureSpec.makeMeasureSpec(maxChildHeight, MeasureSpec.EXACTLY);
}
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
}
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