ViewUtils.java

/*
 * Copyright 2012 Kevin Sawicki <kevinsawicki@gmail.com>
 *
 * 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.github.kevinsawicki.wishlist;

import static android.view.View.GONE;
import static android.view.View.INVISIBLE;
import static android.view.View.VISIBLE;

import android.graphics.Rect;
import android.util.DisplayMetrics;
import android.view.TouchDelegate;
import android.view.View;

/**
 * Utilities for working with the {@link View} class
 */
public class ViewUtils {

  /**
   * Set visibility of given view to be gone or visible
   * <p>
   * This method has no effect if the view visibility is currently invisible
   *
   * @param view
   * @param gone
   * @return view
   */
  public static <V extends View> V setGone(final V view, final boolean gone) {
    if (view != null)
      if (gone) {
        if (GONE != view.getVisibility())
          view.setVisibility(GONE);
      } else {
        if (VISIBLE != view.getVisibility())
          view.setVisibility(VISIBLE);
      }
    return view;
  }

  /**
   * Set visibility of given view to be invisible or visible
   * <p>
   * This method has no effect if the view visibility is currently gone
   *
   * @param view
   * @param invisible
   * @return view
   */
  public static <V extends View> V setInvisible(final V view,
      final boolean invisible) {
    if (view != null)
      if (invisible) {
        if (INVISIBLE != view.getVisibility())
          view.setVisibility(INVISIBLE);
      } else {
        if (VISIBLE != view.getVisibility())
          view.setVisibility(VISIBLE);
      }
    return view;
  }

  /**
   * Increases the hit rect of a view. This should be used when an icon is small and cannot be easily tapped on.
   * Source: http://stackoverflow.com/a/1343796/5210
   * @param amount The amount of dp's to be added to all four sides of the view hit purposes.
   * @param delegate The view that needs to have its hit rect increased.
   */
  public static void increaseHitRectBy(final int amount, final View delegate) {
    increaseHitRectBy(amount, amount, amount, amount, delegate);
  }

  /**
   * Increases the hit rect of a view. This should be used when an icon is small and cannot be easily tapped on.
   * Source: http://stackoverflow.com/a/1343796/5210
   * @param top The amount of dp's to be added to the top for hit purposes.
   * @param left The amount of dp's to be added to the left for hit purposes.
   * @param bottom The amount of dp's to be added to the bottom for hit purposes.
   * @param right The amount of dp's to be added to the right for hit purposes.
   * @param delegate The view that needs to have its hit rect increased.
   */
  public static void increaseHitRectBy(final int top, final int left, final int bottom, final int right, final View delegate) {
    final View parent = (View) delegate.getParent();
    if (parent != null && delegate.getContext() != null) {
      parent.post(new Runnable() {
        // Post in the parent's message queue to make sure the parent
        // lays out its children before we call getHitRect()
        public void run() {
          final float densityDpi = delegate.getContext().getResources().getDisplayMetrics().densityDpi;
          final Rect r = new Rect();
          delegate.getHitRect(r);
          r.top -= transformToDensityPixel(top, densityDpi);
          r.left -= transformToDensityPixel(left, densityDpi);
          r.bottom += transformToDensityPixel(bottom, densityDpi);
          r.right += transformToDensityPixel(right, densityDpi);
          parent.setTouchDelegate(new TouchDelegate(r, delegate));
        }
      });
    }
  }

  public static int transformToDensityPixel(int regularPixel, DisplayMetrics displayMetrics) {
      return transformToDensityPixel(regularPixel, displayMetrics.densityDpi);
  }

  public static int transformToDensityPixel(int regularPixel, float densityDpi) {
      return (int) (regularPixel * densityDpi);
  }

  private ViewUtils() {

  }
}