1/* 2 * Copyright (C) 2016 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 17package android.support.design.internal; 18 19import android.content.Context; 20import android.util.AttributeSet; 21import android.view.View; 22import android.view.ViewGroup; 23 24/** 25 * A simple ViewGroup that aligns all the views inside on a baseline. Note: bottom padding for this 26 * view will be measured starting from the baseline. 27 * 28 * @hide 29 */ 30public class BaselineLayout extends ViewGroup { 31 private int mBaseline = -1; 32 33 public BaselineLayout(Context context) { 34 super(context, null, 0); 35 } 36 37 public BaselineLayout(Context context, AttributeSet attrs) { 38 super(context, attrs, 0); 39 } 40 41 public BaselineLayout(Context context, AttributeSet attrs, int defStyleAttr) { 42 super(context, attrs, defStyleAttr); 43 } 44 45 @Override 46 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { 47 final int count = getChildCount(); 48 int maxWidth = 0; 49 int maxHeight = 0; 50 int maxChildBaseline = -1; 51 int maxChildDescent = -1; 52 int childState = 0; 53 54 for (int i = 0; i < count; i++) { 55 final View child = getChildAt(i); 56 if (child.getVisibility() == GONE) { 57 continue; 58 } 59 60 measureChild(child, widthMeasureSpec, heightMeasureSpec); 61 final int baseline = child.getBaseline(); 62 if (baseline != -1) { 63 maxChildBaseline = Math.max(maxChildBaseline, baseline); 64 maxChildDescent = Math.max(maxChildDescent, child.getMeasuredHeight() - baseline); 65 } 66 maxWidth = Math.max(maxWidth, child.getMeasuredWidth()); 67 maxHeight = Math.max(maxHeight, child.getMeasuredHeight()); 68 childState = View.combineMeasuredStates(childState, child.getMeasuredState()); 69 } 70 if (maxChildBaseline != -1) { 71 maxChildDescent = Math.max(maxChildDescent, getPaddingBottom()); 72 maxHeight = Math.max(maxHeight, maxChildBaseline + maxChildDescent); 73 mBaseline = maxChildBaseline; 74 } 75 maxHeight = Math.max(maxHeight, getSuggestedMinimumHeight()); 76 maxWidth = Math.max(maxWidth, getSuggestedMinimumWidth()); 77 setMeasuredDimension( 78 View.resolveSizeAndState(maxWidth, widthMeasureSpec, childState), 79 View.resolveSizeAndState(maxHeight, heightMeasureSpec, 80 childState << MEASURED_HEIGHT_STATE_SHIFT)); 81 } 82 83 @Override 84 protected void onLayout(boolean changed, int left, int top, int right, int bottom) { 85 final int count = getChildCount(); 86 final int parentLeft = getPaddingLeft(); 87 final int parentRight = right - left - getPaddingRight(); 88 final int parentContentWidth = parentRight - parentLeft; 89 final int parentTop = getPaddingTop(); 90 91 for (int i = 0; i < count; i++) { 92 final View child = getChildAt(i); 93 if (child.getVisibility() == GONE) { 94 continue; 95 } 96 97 final int width = child.getMeasuredWidth(); 98 final int height = child.getMeasuredHeight(); 99 100 final int childLeft = parentLeft + (parentContentWidth - width) / 2; 101 final int childTop; 102 if (mBaseline != -1 && child.getBaseline() != -1) { 103 childTop = parentTop + mBaseline - child.getBaseline(); 104 } else { 105 childTop = parentTop; 106 } 107 108 child.layout(childLeft, childTop, childLeft + width, childTop + height); 109 } 110 } 111 112 @Override 113 public int getBaseline() { 114 return mBaseline; 115 } 116} 117