xref: /frameworks/opt/setupwizard/library/main/src/com/android/setupwizardlib/view/IntrinsicSizeFrameLayout.java

/*
 * Copyright (C) 2016 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.android.setupwizardlib.view;

import android.annotation.TargetApi;
import android.content.Context;
import android.content.res.TypedArray;
import android.os.Build.VERSION_CODES;
import android.util.AttributeSet;
import android.widget.FrameLayout;

import com.android.setupwizardlib.R;

/**
 * A FrameLayout subclass that has an "intrinsic size", which is the size it wants to be if that is
 * within the constraints given by the parent. The intrinsic size can be set with the
 * {@code android:width} and {@code android:height} attributes in XML.
 *
 * Note that for the intrinsic size to be meaningful, {@code android:layout_width} and/or
 * {@code android:layout_height} will need to be {@code wrap_content}.
 */
public class IntrinsicSizeFrameLayout extends FrameLayout {

    private int mIntrinsicHeight = 0;
    private int mIntrinsicWidth = 0;

    public IntrinsicSizeFrameLayout(Context context) {
        super(context);
        init(context, null, 0);
    }

    public IntrinsicSizeFrameLayout(Context context, AttributeSet attrs) {
        super(context, attrs);
        init(context, attrs, 0);
    }

    @TargetApi(VERSION_CODES.HONEYCOMB)
    public IntrinsicSizeFrameLayout(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init(context, attrs, defStyleAttr);
    }

    private void init(Context context, AttributeSet attrs, int defStyleAttr) {
        final TypedArray a = context.obtainStyledAttributes(attrs,
                R.styleable.SuwIntrinsicSizeFrameLayout, defStyleAttr, 0);
        mIntrinsicHeight =
                a.getDimensionPixelSize(R.styleable.SuwIntrinsicSizeFrameLayout_android_height, 0);
        mIntrinsicWidth =
                a.getDimensionPixelSize(R.styleable.SuwIntrinsicSizeFrameLayout_android_width, 0);
        a.recycle();
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(getIntrinsicMeasureSpec(widthMeasureSpec, mIntrinsicWidth),
                getIntrinsicMeasureSpec(heightMeasureSpec, mIntrinsicHeight));
    }

    private int getIntrinsicMeasureSpec(int measureSpec, int intrinsicSize) {
        if (intrinsicSize <= 0) {
            // Intrinsic size is not set, just return the original spec
            return measureSpec;
        }
        final int mode = MeasureSpec.getMode(measureSpec);
        final int size = MeasureSpec.getSize(measureSpec);
        if (mode == MeasureSpec.UNSPECIFIED) {
            // Parent did not give any constraint, so we'll be the intrinsic size
            return MeasureSpec.makeMeasureSpec(mIntrinsicHeight, MeasureSpec.EXACTLY);
        } else if (mode == MeasureSpec.AT_MOST) {
            // If intrinsic size is within parents constraint, take the intrinsic size.
            // Otherwise take the parents size because that's closest to the intrinsic size.
            return MeasureSpec.makeMeasureSpec(Math.min(size, mIntrinsicHeight),
                    MeasureSpec.EXACTLY);
        }
        // Parent specified EXACTLY, or in all other cases, just return the original spec
        return measureSpec;
    }
}