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      1 /*
      2  * Copyright (C) 2017 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.google.android.setupdesign.view;
     18 
     19 import android.content.Context;
     20 import android.content.res.TypedArray;
     21 import android.util.AttributeSet;
     22 import android.view.View;
     23 import android.widget.FrameLayout;
     24 import com.google.android.setupdesign.R;
     25 
     26 /**
     27  * A layout that will measure its children size based on the space it is given, by using its {@code
     28  * android:minWidth}, {@code android:minHeight}, {@code android:maxWidth}, and {@code
     29  * android:maxHeight} values.
     30  *
     31  * <p>Typically this is used to show an illustration image or video on the screen. For optimal UX,
     32  * those assets typically want to occupy the remaining space available on screen within a certain
     33  * range, and then stop scaling beyond the min/max size attributes. Therefore this view is typically
     34  * used inside a ScrollView with {@code fillViewport} set to true, together with a linear layout
     35  * weight or relative layout to fill the remaining space visible on screen.
     36  *
     37  * <p>When measuring, this view ignores its children and simply layout according to the minWidth /
     38  * minHeight given. Therefore it is common for children of this layout to have width / height set to
     39  * {@code match_parent}. The maxWidth / maxHeight values will then be applied to the children to
     40  * make sure they are not too big.
     41  */
     42 public class FillContentLayout extends FrameLayout {
     43 
     44   private int maxWidth;
     45   private int maxHeight;
     46 
     47   public FillContentLayout(Context context) {
     48     this(context, null);
     49   }
     50 
     51   public FillContentLayout(Context context, AttributeSet attrs) {
     52     this(context, attrs, R.attr.sudFillContentLayoutStyle);
     53   }
     54 
     55   public FillContentLayout(Context context, AttributeSet attrs, int defStyleAttr) {
     56     super(context, attrs, defStyleAttr);
     57     init(context, attrs, defStyleAttr);
     58   }
     59 
     60   private void init(Context context, AttributeSet attrs, int defStyleAttr) {
     61     TypedArray a =
     62         context.obtainStyledAttributes(attrs, R.styleable.SudFillContentLayout, defStyleAttr, 0);
     63 
     64     maxHeight = a.getDimensionPixelSize(R.styleable.SudFillContentLayout_android_maxHeight, -1);
     65     maxWidth = a.getDimensionPixelSize(R.styleable.SudFillContentLayout_android_maxWidth, -1);
     66 
     67     a.recycle();
     68   }
     69 
     70   @Override
     71   protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
     72     // Measure this view with the minWidth and minHeight, without asking the children.
     73     // (Children size is the drawable's intrinsic size, and we don't want that to influence
     74     // the size of the illustration).
     75     setMeasuredDimension(
     76         getDefaultSize(getSuggestedMinimumWidth(), widthMeasureSpec),
     77         getDefaultSize(getSuggestedMinimumHeight(), heightMeasureSpec));
     78 
     79     int childCount = getChildCount();
     80     for (int i = 0; i < childCount; i++) {
     81       measureIllustrationChild(getChildAt(i), getMeasuredWidth(), getMeasuredHeight());
     82     }
     83   }
     84 
     85   private void measureIllustrationChild(View child, int parentWidth, int parentHeight) {
     86     // Modified from ViewGroup#measureChildWithMargins
     87     final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();
     88 
     89     // Create measure specs that are no bigger than min(parentSize, maxSize)
     90 
     91     int childWidthMeasureSpec =
     92         getMaxSizeMeasureSpec(
     93             Math.min(maxWidth, parentWidth),
     94             getPaddingLeft() + getPaddingRight() + lp.leftMargin + lp.rightMargin,
     95             lp.width);
     96     int childHeightMeasureSpec =
     97         getMaxSizeMeasureSpec(
     98             Math.min(maxHeight, parentHeight),
     99             getPaddingTop() + getPaddingBottom() + lp.topMargin + lp.bottomMargin,
    100             lp.height);
    101 
    102     child.measure(childWidthMeasureSpec, childHeightMeasureSpec);
    103   }
    104 
    105   private static int getMaxSizeMeasureSpec(int maxSize, int padding, int childDimension) {
    106     // Modified from ViewGroup#getChildMeasureSpec
    107     int size = Math.max(0, maxSize - padding);
    108 
    109     if (childDimension >= 0) {
    110       // Child wants a specific size... so be it
    111       return MeasureSpec.makeMeasureSpec(childDimension, MeasureSpec.EXACTLY);
    112     } else if (childDimension == LayoutParams.MATCH_PARENT) {
    113       // Child wants to be our size. So be it.
    114       return MeasureSpec.makeMeasureSpec(size, MeasureSpec.EXACTLY);
    115     } else if (childDimension == LayoutParams.WRAP_CONTENT) {
    116       // Child wants to determine its own size. It can't be
    117       // bigger than us.
    118       return MeasureSpec.makeMeasureSpec(size, MeasureSpec.AT_MOST);
    119     }
    120     return 0;
    121   }
    122 }
    123