Package io.flutter.util

# Class ViewUtils

java.lang.Object
io.flutter.util.ViewUtils

public final class ViewUtils extends Object

- ## Nested Class Summary

  Nested Classes
  Modifier and Type
  Class
  Description
  `static interface`
  `ViewUtils.DisplayUpdater`
  `static interface`
  `ViewUtils.ViewVisitor`
  Allows to visit a view.

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `ViewUtils()`

- ## Method Summary

  Modifier and Type
  Method
  Description
  `static void`
  `calculateMaximumDisplayMetrics(Context context, ViewUtils.DisplayUpdater updater)`
  Calculates the maximum display metrics for the given context, and pushes the metric data to the updater.
  `static boolean`
  `childHasFocus(View root)`
  Determines if the current view or any descendant view has focus.
  `static int`
  `generateViewId(int fallbackId)`
  Generates a view id.
  `static Activity`
  `getActivity(Context context)`
  Retrieves the `Activity` from a given `Context`.
  `static boolean`
  `hasChildViewOfType(View root, Class<? extends View>[] viewTypes)`
  Returns true if the root or any child view is an instance of the given types.
  `static boolean`
  `traverseHierarchy(View root, ViewUtils.ViewVisitor visitor)`
  Traverses the view hierarchy in pre-order and runs the visitor for each child view including the root view.

  ### Methods inherited from class java.lang.Object

  `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- ## Constructor Details

  - ### ViewUtils

    public ViewUtils()

- ## Method Details

  - ### calculateMaximumDisplayMetrics

    public static void calculateMaximumDisplayMetrics(@Nullable Context context, @NonNull ViewUtils.DisplayUpdater updater)
    Calculates the maximum display metrics for the given context, and pushes the metric data to the updater.

  - ### getActivity

    @Nullable public static Activity getActivity(@Nullable Context context)
    Retrieves the `Activity` from a given `Context`.

    This method will recursively traverse up the context chain if it is a `ContextWrapper` until it finds the first instance of the base context that is an `Activity`.

  - ### generateViewId

    public static int generateViewId(int fallbackId)
    Generates a view id.

    In API level 17 and above, this ID is unique. Below 17, the fallback id is used instead.

    Parameters:
      `fallbackId` - the fallback id.
    Returns:
      the view id.

  - ### childHasFocus

    public static boolean childHasFocus(@Nullable View root)
    Determines if the current view or any descendant view has focus.
    Parameters:
      `root` - The root view.
    Returns:
      True if the current view or any descendant view has focus.

  - ### hasChildViewOfType

    public static boolean hasChildViewOfType(@Nullable View root, Class<? extends View>[] viewTypes)
    Returns true if the root or any child view is an instance of the given types.
    Parameters:
      `root` - The root view.
      `viewTypes` - The types of views.
    Returns:
      true if any child view is an instance of any of the given types.

  - ### traverseHierarchy

    public static boolean traverseHierarchy(@Nullable View root, @NonNull ViewUtils.ViewVisitor visitor)
    Traverses the view hierarchy in pre-order and runs the visitor for each child view including the root view.

    If the visitor returns true, the traversal stops, and the method returns true.

    If the visitor returns false, the traversal continues until all views are visited.

    Parameters:
      `root` - The root view.
      `visitor` - The visitor.
    Returns:
      true if the visitor returned true for a given view.