| /* |
| * 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); |
| } |
| } |