1 /* 2 * Copyright (C) 2013 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.example.android.expandingcells; 18 19 import android.content.Context; 20 import android.util.AttributeSet; 21 import android.widget.RelativeLayout; 22 23 /** 24 * This layout is used to contain the extra information that will be displayed 25 * when a certain cell is expanded. The custom relative layout is created in 26 * order to achieve a fading affect of this layout's contents as it is being 27 * expanded or collapsed as opposed to just fading the content in(out) after(before) 28 * the cell expands(collapses). 29 * 30 * During expansion, layout takes place so the full contents of this layout can 31 * be displayed. When the size changes to display the full contents of the layout, 32 * its height is stored. When the view is collapsing, this layout's height becomes 0 33 * since it is no longer in the visible part of the cell.By overriding onMeasure, and 34 * setting the height back to its max height, it is still visible during the collapse 35 * animation, and so, a fade out effect can be achieved. 36 */ 37 public class ExpandingLayout extends RelativeLayout { 38 39 40 private OnSizeChangedListener mSizeChangedListener; 41 private int mExpandedHeight = -1; 42 43 public ExpandingLayout(Context context) { 44 super(context); 45 } 46 47 public ExpandingLayout(Context context, AttributeSet attrs) { 48 super(context, attrs); 49 } 50 51 public ExpandingLayout(Context context, AttributeSet attrs, int defStyle) { 52 super(context, attrs, defStyle); 53 } 54 55 protected void onMeasure (int widthMeasureSpec, int heightMeasureSpec) { 56 if (mExpandedHeight > 0) { 57 heightMeasureSpec = MeasureSpec.makeMeasureSpec(mExpandedHeight, MeasureSpec.AT_MOST); 58 } 59 super.onMeasure(widthMeasureSpec, heightMeasureSpec); 60 } 61 62 protected void onSizeChanged (int w, int h, int oldw, int oldh) { 63 mExpandedHeight = h; 64 //Notifies the list data object corresponding to this layout that its size has changed. 65 mSizeChangedListener.onSizeChanged(h); 66 } 67 68 public int getExpandedHeight() { 69 return mExpandedHeight; 70 } 71 72 public void setExpandedHeight(int expandedHeight) { 73 mExpandedHeight = expandedHeight; 74 } 75 76 public void setSizeChangedListener(OnSizeChangedListener listener) { 77 mSizeChangedListener = listener; 78 } 79 } 80