1 /* 2 * Copyright (C) 2019 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.android.wallpaper.widget; 18 19 import android.content.Context; 20 import android.util.AttributeSet; 21 import android.view.View; 22 23 import androidx.annotation.NonNull; 24 import androidx.annotation.Nullable; 25 import androidx.viewpager.widget.ViewPager; 26 27 /** 28 * When ConstraintViewPager is being measured, it will get all height of pages and makes itself 29 * height as the same as the maximum height. 30 */ 31 public class ConstraintViewPager extends ViewPager { 32 ConstraintViewPager(@onNull Context context)33 public ConstraintViewPager(@NonNull Context context) { 34 this(context, null /* attrs */); 35 } 36 ConstraintViewPager(@onNull Context context, @Nullable AttributeSet attrs)37 public ConstraintViewPager(@NonNull Context context, @Nullable AttributeSet attrs) { 38 super(context, attrs); 39 } 40 41 /** 42 * Visit all child views first and then determine the maximum height for ViewPager. 43 */ 44 @Override onMeasure(int widthMeasureSpec, int heightMeasureSpec)45 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { 46 int maxChildHeight = 0; 47 for (int i = 0; i < getChildCount(); i++) { 48 View view = getChildAt(i); 49 view.measure(widthMeasureSpec, 50 MeasureSpec.makeMeasureSpec(0 /* size */, MeasureSpec.UNSPECIFIED)); 51 int childHeight = view.getMeasuredHeight(); 52 if (childHeight > maxChildHeight) { 53 maxChildHeight = childHeight; 54 } 55 } 56 57 if (maxChildHeight != 0) { 58 heightMeasureSpec = MeasureSpec.makeMeasureSpec(maxChildHeight, MeasureSpec.EXACTLY); 59 } 60 super.onMeasure(widthMeasureSpec, heightMeasureSpec); 61 } 62 } 63