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      1 /*
      2  * Copyright (C) 2011 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.hcgallery;
     18 
     19 import android.content.Context;
     20 import android.util.AttributeSet;
     21 import android.view.View;
     22 import android.view.ViewGroup;
     23 
     24 /**
     25  * A simple layout that fits and centers each child view, maintaining aspect ratio.
     26  */
     27 public class FitCenterFrameLayout extends ViewGroup {
     28     public FitCenterFrameLayout(Context context) {
     29         super(context);
     30     }
     31 
     32     public FitCenterFrameLayout(Context context, AttributeSet attrs) {
     33         super(context, attrs);
     34     }
     35 
     36     @Override
     37     protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
     38         // We purposely disregard child measurements.
     39         final int width = resolveSize(getSuggestedMinimumWidth(), widthMeasureSpec);
     40         final int height = resolveSize(getSuggestedMinimumHeight(), heightMeasureSpec);
     41         setMeasuredDimension(width, height);
     42 
     43         int childWidthSpec = MeasureSpec.makeMeasureSpec(width, MeasureSpec.UNSPECIFIED);
     44         int childHeightSpec = MeasureSpec.makeMeasureSpec(height, MeasureSpec.UNSPECIFIED);
     45 
     46         int childCount = getChildCount();
     47         for (int i = 0; i < childCount; i++) {
     48             getChildAt(i).measure(childWidthSpec, childHeightSpec);
     49         }
     50     }
     51 
     52     @Override
     53     protected void onLayout(boolean changed, int l, int t, int r, int b) {
     54         final int childCount = getChildCount();
     55 
     56         final int parentLeft = getPaddingLeft();
     57         final int parentTop = getPaddingTop();
     58         final int parentRight = r - l - getPaddingRight();
     59         final int parentBottom = b - t - getPaddingBottom();
     60 
     61         final int parentWidth = parentRight - parentLeft;
     62         final int parentHeight = parentBottom - parentTop;
     63 
     64         int unpaddedWidth, unpaddedHeight, parentUnpaddedWidth, parentUnpaddedHeight;
     65         int childPaddingLeft, childPaddingTop, childPaddingRight, childPaddingBottom;
     66 
     67         for (int i = 0; i < childCount; i++) {
     68             final View child = getChildAt(i);
     69             if (child.getVisibility() == GONE) {
     70                 continue;
     71             }
     72 
     73             // Fit and center the child within the parent. Make sure not to consider padding
     74             // as part of the child's aspect ratio.
     75 
     76             childPaddingLeft = child.getPaddingLeft();
     77             childPaddingTop = child.getPaddingTop();
     78             childPaddingRight = child.getPaddingRight();
     79             childPaddingBottom = child.getPaddingBottom();
     80 
     81             unpaddedWidth = child.getMeasuredWidth() - childPaddingLeft - childPaddingRight;
     82             unpaddedHeight = child.getMeasuredHeight() - childPaddingTop - childPaddingBottom;
     83 
     84             parentUnpaddedWidth = parentWidth - childPaddingLeft - childPaddingRight;
     85             parentUnpaddedHeight = parentHeight - childPaddingTop - childPaddingBottom;
     86 
     87             if (parentUnpaddedWidth * unpaddedHeight > parentUnpaddedHeight * unpaddedWidth) {
     88                 // The child view should be left/right letterboxed.
     89                 final int scaledChildWidth = unpaddedWidth * parentUnpaddedHeight
     90                         / unpaddedHeight + childPaddingLeft + childPaddingRight;
     91                 child.layout(
     92                         parentLeft + (parentWidth - scaledChildWidth) / 2,
     93                         parentTop,
     94                         parentRight - (parentWidth - scaledChildWidth) / 2,
     95                         parentBottom);
     96             } else {
     97                 // The child view should be top/bottom letterboxed.
     98                 final int scaledChildHeight = unpaddedHeight * parentUnpaddedWidth
     99                         / unpaddedWidth + childPaddingTop + childPaddingBottom;
    100                 child.layout(
    101                         parentLeft,
    102                         parentTop + (parentHeight - scaledChildHeight) / 2,
    103                         parentRight,
    104                         parentTop + (parentHeight + scaledChildHeight) / 2);
    105             }
    106         }
    107     }
    108 }
    109