android.view.View#isImportantForAccessibility ( )源码实例Demo

public static boolean isImportantForAccessibility(View view) {
    return view.isImportantForAccessibility();
}
 

/** See {@link View#isImportantForAccessibility()}. */
public static boolean isImportantForAccessibility(View view) {
  if (view == null) {
    return false;
  }

  if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
    return view.isImportantForAccessibility();
  } else if (Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN) {
    // Prior to Jelly Bean, all Views were considered important for accessibility.
    return true;
  } else {
    // On APIs between 16 and 21, we must piece together accessibility importance from the
    // available properties. We return false incorrectly for some cases where unretrievable
    // listeners prevent us from determining importance.

    // If the developer marked the view as explicitly not important, it isn't.
    int mode = view.getImportantForAccessibility();
    if ((mode == View.IMPORTANT_FOR_ACCESSIBILITY_NO)
        || (mode == View.IMPORTANT_FOR_ACCESSIBILITY_NO_HIDE_DESCENDANTS)) {
      return false;
    }

    // No parent view can be hiding us. (APIs 19 to 21)
    ViewParent parent = view.getParent();
    while (parent instanceof View) {
      if (((View) parent).getImportantForAccessibility()
          == View.IMPORTANT_FOR_ACCESSIBILITY_NO_HIDE_DESCENDANTS) {
        return false;
      }
      parent = parent.getParent();
    }

    // Interrogate the view's other properties to determine importance.
    return (mode == View.IMPORTANT_FOR_ACCESSIBILITY_YES)
        || isActionableForAccessibility(view)
        || hasListenersForAccessibility(view)
        || (view.getAccessibilityNodeProvider() != null)
        || (ViewCompat.getAccessibilityLiveRegion(view)
            != ViewCompat.ACCESSIBILITY_LIVE_REGION_NONE);
  }
}
 

/**
 * Sets the source to be a virtual descendant of the given <code>root</code>.
 * If <code>virtualDescendantId</code> equals to {@link View#NO_ID} the root
 * is set as the source.
 * <p>
 * A virtual descendant is an imaginary View that is reported as a part of the view
 * hierarchy for accessibility purposes. This enables custom views that draw complex
 * content to report them selves as a tree of virtual views, thus conveying their
 * logical structure.
 * </p>
 *
 * @param root The root of the virtual subtree.
 * @param virtualDescendantId The id of the virtual descendant.
 */
public void setSource(@Nullable View root, int virtualDescendantId) {
    enforceNotSealed();
    boolean important = true;
    int rootViewId = AccessibilityNodeInfo.UNDEFINED_ITEM_ID;
    mSourceWindowId = AccessibilityWindowInfo.UNDEFINED_WINDOW_ID;
    if (root != null) {
        important = root.isImportantForAccessibility();
        rootViewId = root.getAccessibilityViewId();
        mSourceWindowId = root.getAccessibilityWindowId();
    }
    setBooleanProperty(PROPERTY_IMPORTANT_FOR_ACCESSIBILITY, important);
    mSourceNodeId = AccessibilityNodeInfo.makeNodeId(rootViewId, virtualDescendantId);
}