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      1 /*
      2  * Copyright (C) 2015 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.internal.widget;
     18 
     19 import android.content.Context;
     20 import android.content.res.TypedArray;
     21 import android.util.AttributeSet;
     22 import android.view.Gravity;
     23 import android.view.View;
     24 import android.widget.LinearLayout;
     25 
     26 import com.android.internal.R;
     27 
     28 /**
     29  * An extension of LinearLayout that automatically switches to vertical
     30  * orientation when it can't fit its child views horizontally.
     31  */
     32 public class ButtonBarLayout extends LinearLayout {
     33     /** Minimum screen height required for button stacking. */
     34     private static final int ALLOW_STACKING_MIN_HEIGHT_DP = 320;
     35 
     36     /** Amount of the second button to "peek" above the fold when stacked. */
     37     private static final int PEEK_BUTTON_DP = 16;
     38 
     39     /** Whether the current configuration allows stacking. */
     40     private boolean mAllowStacking;
     41 
     42     private int mLastWidthSize = -1;
     43 
     44     private int mMinimumHeight = 0;
     45 
     46     public ButtonBarLayout(Context context, AttributeSet attrs) {
     47         super(context, attrs);
     48 
     49         final boolean allowStackingDefault =
     50                 context.getResources().getConfiguration().screenHeightDp
     51                         >= ALLOW_STACKING_MIN_HEIGHT_DP;
     52         final TypedArray ta = context.obtainStyledAttributes(attrs, R.styleable.ButtonBarLayout);
     53         mAllowStacking = ta.getBoolean(R.styleable.ButtonBarLayout_allowStacking,
     54                 allowStackingDefault);
     55         ta.recycle();
     56     }
     57 
     58     public void setAllowStacking(boolean allowStacking) {
     59         if (mAllowStacking != allowStacking) {
     60             mAllowStacking = allowStacking;
     61             if (!mAllowStacking && getOrientation() == LinearLayout.VERTICAL) {
     62                 setStacked(false);
     63             }
     64             requestLayout();
     65         }
     66     }
     67 
     68     @Override
     69     protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
     70         final int widthSize = MeasureSpec.getSize(widthMeasureSpec);
     71 
     72         if (mAllowStacking) {
     73             if (widthSize > mLastWidthSize && isStacked()) {
     74                 // We're being measured wider this time, try un-stacking.
     75                 setStacked(false);
     76             }
     77 
     78             mLastWidthSize = widthSize;
     79         }
     80 
     81         boolean needsRemeasure = false;
     82 
     83         // If we're not stacked, make sure the measure spec is AT_MOST rather
     84         // than EXACTLY. This ensures that we'll still get TOO_SMALL so that we
     85         // know to stack the buttons.
     86         final int initialWidthMeasureSpec;
     87         if (!isStacked() && MeasureSpec.getMode(widthMeasureSpec) == MeasureSpec.EXACTLY) {
     88             initialWidthMeasureSpec = MeasureSpec.makeMeasureSpec(widthSize, MeasureSpec.AT_MOST);
     89 
     90             // We'll need to remeasure again to fill excess space.
     91             needsRemeasure = true;
     92         } else {
     93             initialWidthMeasureSpec = widthMeasureSpec;
     94         }
     95 
     96         super.onMeasure(initialWidthMeasureSpec, heightMeasureSpec);
     97 
     98         if (mAllowStacking && !isStacked()) {
     99             final int measuredWidth = getMeasuredWidthAndState();
    100             final int measuredWidthState = measuredWidth & MEASURED_STATE_MASK;
    101             if (measuredWidthState == MEASURED_STATE_TOO_SMALL) {
    102                 setStacked(true);
    103 
    104                 // Measure again in the new orientation.
    105                 needsRemeasure = true;
    106             }
    107         }
    108 
    109         if (needsRemeasure) {
    110             super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    111         }
    112 
    113         // Compute minimum height such that, when stacked, some portion of the
    114         // second button is visible.
    115         int minHeight = 0;
    116         final int firstVisible = getNextVisibleChildIndex(0);
    117         if (firstVisible >= 0) {
    118             final View firstButton = getChildAt(firstVisible);
    119             final LayoutParams firstParams = (LayoutParams) firstButton.getLayoutParams();
    120             minHeight += getPaddingTop() + firstButton.getMeasuredHeight()
    121                     + firstParams.topMargin + firstParams.bottomMargin;
    122             if (isStacked()) {
    123                 final int secondVisible = getNextVisibleChildIndex(firstVisible + 1);
    124                 if (secondVisible >= 0) {
    125                     minHeight += getChildAt(secondVisible).getPaddingTop()
    126                             + PEEK_BUTTON_DP * getResources().getDisplayMetrics().density;
    127                 }
    128             } else {
    129                 minHeight += getPaddingBottom();
    130             }
    131         }
    132 
    133         if (getMinimumHeight() != minHeight) {
    134             setMinimumHeight(minHeight);
    135         }
    136     }
    137 
    138     private int getNextVisibleChildIndex(int index) {
    139         for (int i = index, count = getChildCount(); i < count; i++) {
    140             if (getChildAt(i).getVisibility() == View.VISIBLE) {
    141                 return i;
    142             }
    143         }
    144         return -1;
    145     }
    146 
    147     @Override
    148     public int getMinimumHeight() {
    149         return Math.max(mMinimumHeight, super.getMinimumHeight());
    150     }
    151 
    152     private void setStacked(boolean stacked) {
    153         setOrientation(stacked ? LinearLayout.VERTICAL : LinearLayout.HORIZONTAL);
    154         setGravity(stacked ? Gravity.RIGHT : Gravity.BOTTOM);
    155 
    156         final View spacer = findViewById(R.id.spacer);
    157         if (spacer != null) {
    158             spacer.setVisibility(stacked ? View.GONE : View.INVISIBLE);
    159         }
    160 
    161         // Reverse the child order. This is specific to the Material button
    162         // bar's layout XML and will probably not generalize.
    163         final int childCount = getChildCount();
    164         for (int i = childCount - 2; i >= 0; i--) {
    165             bringChildToFront(getChildAt(i));
    166         }
    167     }
    168 
    169     private boolean isStacked() {
    170         return getOrientation() == LinearLayout.VERTICAL;
    171     }
    172 }
    173