main/src/com/google/android/setupdesign/view/ButtonBarLayout.java

/*
 * Copyright (C) 2017 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.google.android.setupdesign.view;

import android.content.Context;
import android.util.AttributeSet;
import android.view.View;
import android.widget.LinearLayout;
import com.google.android.setupdesign.R;

/**
 * An extension of LinearLayout that automatically switches to vertical orientation when it can't
 * fit its child views horizontally.
 *
 * <p>Modified from {@code com.android.internal.widget.ButtonBarLayout}
 */
public class ButtonBarLayout extends LinearLayout {

  private boolean stacked = false;
  private int originalPaddingLeft;
  private int originalPaddingRight;

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

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

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

    setStacked(false);

    boolean needsRemeasure = false;

    int initialWidthMeasureSpec = widthMeasureSpec;
    if (MeasureSpec.getMode(widthMeasureSpec) == MeasureSpec.EXACTLY) {
      // Measure with WRAP_CONTENT, so that we can compare the measured size with the
      // available size to see if we need to stack.
      initialWidthMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED);

      // We'll need to remeasure again to fill excess space.
      needsRemeasure = true;
    }

    super.onMeasure(initialWidthMeasureSpec, heightMeasureSpec);

    if (getMeasuredWidth() > widthSize) {
      setStacked(true);

      // Measure again in the new orientation.
      needsRemeasure = true;
    }

    if (needsRemeasure) {
      super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    }
  }

  private void setStacked(boolean stacked) {
    if (this.stacked == stacked) {
      return;
    }
    this.stacked = stacked;
    int childCount = getChildCount();
    for (int i = 0; i < childCount; i++) {
      View child = getChildAt(i);
      LayoutParams childParams = (LayoutParams) child.getLayoutParams();
      if (stacked) {
        child.setTag(R.id.sud_original_weight, childParams.weight);
        childParams.weight = 0;
      } else {
        Float weight = (Float) child.getTag(R.id.sud_original_weight);
        if (weight != null) {
          childParams.weight = weight;
        }
      }
      child.setLayoutParams(childParams);
    }

    setOrientation(stacked ? LinearLayout.VERTICAL : LinearLayout.HORIZONTAL);

    // Reverse the child order, so that the primary button is towards the top when vertical
    for (int i = childCount - 1; i >= 0; i--) {
      bringChildToFront(getChildAt(i));
    }

    if (stacked) {
      // HACK: In the default button bar style, the left and right paddings are not
      // balanced to compensate for different alignment for borderless (left) button and
      // the raised (right) button. When it's stacked, we want the buttons to be centered,
      // so we balance out the paddings here.
      originalPaddingLeft = getPaddingLeft();
      originalPaddingRight = getPaddingRight();
      int paddingHorizontal = Math.max(originalPaddingLeft, originalPaddingRight);
      setPadding(paddingHorizontal, getPaddingTop(), paddingHorizontal, getPaddingBottom());
    } else {
      setPadding(originalPaddingLeft, getPaddingTop(), originalPaddingRight, getPaddingBottom());
    }
  }
}