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SquareFrameLayout.java

/*
 * Copyright (C) 2014 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.example.android.activityscenetransitionbasic;

import android.content.Context;
import android.util.AttributeSet;
import android.widget.FrameLayout;

/**
 * {@link android.widget.FrameLayout} which forces itself to be laid out as square.
 */
public class SquareFrameLayout extends FrameLayout {

public SquareFrameLayout(Context context) {
        super(context);
    }

public SquareFrameLayout(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

public SquareFrameLayout(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

public SquareFrameLayout(Context context, AttributeSet attrs,
            int defStyleAttr, int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);
    }

@Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        final int widthSize = MeasureSpec.getSize(widthMeasureSpec);
        final int heightSize = MeasureSpec.getSize(heightMeasureSpec);

if (widthSize == 0 && heightSize == 0) {
            // If there are no constraints on size, let FrameLayout measure
            super.onMeasure(widthMeasureSpec, heightMeasureSpec);

// Now use the smallest of the measured dimensions for both dimensions
            final int minSize = Math.min(getMeasuredWidth(), getMeasuredHeight());
            setMeasuredDimension(minSize, minSize);
            return;
        }

final int size;
        if (widthSize == 0 || heightSize == 0) {
            // If one of the dimensions has no restriction on size, set both dimensions to be the
            // on that does
            size = Math.max(widthSize, heightSize);
        } else {
            // Both dimensions have restrictions on size, set both dimensions to be the
            // smallest of the two
            size = Math.min(widthSize, heightSize);
        }

final int newMeasureSpec = MeasureSpec.makeMeasureSpec(size, MeasureSpec.EXACTLY);
        super.onMeasure(newMeasureSpec, newMeasureSpec);
    }
}