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.
 *
 * <p>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 intrinsicHeight = 0;
  private int intrinsicWidth = 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);
    intrinsicHeight =
        a.getDimensionPixelSize(R.styleable.SuwIntrinsicSizeFrameLayout_android_height, 0);
    intrinsicWidth =
        a.getDimensionPixelSize(R.styleable.SuwIntrinsicSizeFrameLayout_android_width, 0);
    a.recycle();
  }

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

  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(intrinsicHeight, 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, intrinsicHeight), MeasureSpec.EXACTLY);
    }
    // Parent specified EXACTLY, or in all other cases, just return the original spec
    return measureSpec;
  }
}