# FullScreenCarouselStrategy

[View Source](https://github.com/material-components/material-components-android/blob/1.14.0/lib/java/com/google/android/material/carousel/FullScreenCarouselStrategy.java)

*** ** * ** ***


```
public class FullScreenCarouselStrategy extends CarouselStrategy
```

<br />

|---|---|---|
| [java.lang.Object](https://developer.android.com/reference/java/lang/Object) |||
| ↳ | [com.google.android.material.carousel.CarouselStrategy](https://developer.android.com/reference/com/google/android/material/carousel/CarouselStrategy) ||
|   | ↳ | [com.google.android.material.carousel.FullScreenCarouselStrategy](https://developer.android.com/reference/com/google/android/material/carousel/FullScreenCarouselStrategy) |

*** ** * ** ***

A `https://developer.android.com/reference/com/google/android/material/carousel/CarouselStrategy` that fits one full-width or full-height item into a container to create a layout to browse one item at a time.

Note that the item masks will be based on the items encompassing the full width or full height of the carousel. The carousel item dimensions should reflect this with `match_parent` dimensions.

This class will automatically be reversed by `https://developer.android.com/reference/com/google/android/material/carousel/CarouselLayoutManager` if being laid out right-to-left and does not need to make any account for layout direction itself.

For more information, see the [component developer guidance](https://github.com/material-components/material-components-android/blob/master/docs/components/Carousel.md) and [design guidelines](https://material.io/components/carousel/overview).

## Summary

| ### Public constructors |
|---|
| `https://developer.android.com/reference/com/google/android/material/carousel/FullScreenCarouselStrategy#FullScreenCarouselStrategy()()` |

| ### Public methods |
|---|---|
| `https://developer.android.com/reference/com/google/android/material/carousel/KeylineState` | `https://developer.android.com/reference/com/google/android/material/carousel/FullScreenCarouselStrategy#onFirstChildMeasuredWithMargins(com.google.android.material.carousel.Carousel,View)(https://developer.android.com/reference/com/google/android/material/carousel/Carousel carousel, View child)` Calculates a keyline arrangement and returns a constructed `https://developer.android.com/reference/com/google/android/material/carousel/KeylineState`. |

### Inherited methods

From [com.google.android.material.carousel.CarouselStrategy](https://developer.android.com/reference/com/google/android/material/carousel/CarouselStrategy) `static float` `https://developer.android.com/reference/com/google/android/material/carousel/CarouselStrategy#getChildMaskPercentage(float,float,float)(
float maskedSize,
float unmaskedSize,
float childMargins
)`

Helper method to calculate a child's mask percentage given its masked size, unmasked size, and margins.
`float` `https://developer.android.com/reference/com/google/android/material/carousel/CarouselStrategy#getSmallItemSizeMax()()`

Returns the maximum small item size value.
`float` `https://developer.android.com/reference/com/google/android/material/carousel/CarouselStrategy#getSmallItemSizeMin()()`

Returns the minimum small item size value.
`void` `https://developer.android.com/reference/com/google/android/material/carousel/CarouselStrategy#setSmallItemSizeMax(float)(float maxSmallItemSize)`

Sets the maximum size for the small items.
`void` `https://developer.android.com/reference/com/google/android/material/carousel/CarouselStrategy#setSmallItemSizeMin(float)(float minSmallItemSize)`

Sets the minimum size for the small items.
`boolean` `https://developer.android.com/reference/com/google/android/material/carousel/CarouselStrategy#shouldRefreshKeylineState(com.google.android.material.carousel.Carousel,int)(https://developer.android.com/reference/com/google/android/material/carousel/Carousel carousel, int oldItemCount)`

Whether or not the strategy keylines should be refreshed based on the old item count and the carousel's current parameters.

## Public constructors

### FullScreenCarouselStrategy

```
public FullScreenCarouselStrategy()
```

## Public methods

### onFirstChildMeasuredWithMargins

```
public KeylineState onFirstChildMeasuredWithMargins(Carousel carousel, View child)
```

Calculates a keyline arrangement and returns a constructed `https://developer.android.com/reference/com/google/android/material/carousel/KeylineState`.

This method is called when `https://developer.android.com/reference/com/google/android/material/carousel/Carousel` measures the first item to be added to its scroll container. This method then must create a `https://developer.android.com/reference/com/google/android/material/carousel/KeylineState` which tells `https://developer.android.com/reference/com/google/android/material/carousel/Carousel` how to fill the scroll container with items - how many are visible at once, what their sizes are, and where they're placed.

For example, take a simple arrangement that fills the scroll container with two large items and one small item. As the user scrolls the first large item moves off-screen to the left, the second large item moves to position 1, the small item unmasks into a large item at position 2, and a new small item scrolls into view from the right. To create this arrangement, pick any size for the small item that will be smaller than the large item. Next, take the carousel's total space, subtract the small item size and divide the remainder by two - this is your large item size. After determining the size of our large and small items, we can now construct a `https://developer.android.com/reference/com/google/android/material/carousel/KeylineState` and add keylines representing each item:

```
// Find the centers of the items in our arrangement, aligning the first item's left with the
// left of the scroll container (0).
float firstLargeItemCenter = largeChildSize / 2F;
float smallItemCenter = (largeChildSize * 2F) + (smallChildSize / 2F);

// Get our child margins to use when calculating mask percentage
LayoutParams childLayoutParams = (LayoutParams) child.getLayoutParams();
float childMargins = childLayoutParams.leftMargin + childLayoutParams.rightMargin;

return new KeylineState.Builder(largeChildWidth)
    .addKeylineRange(
        firstLargeItemCenter, // offsetLoc
        getChildMaskPercentage(largeChildSize, largeChildSize, childMargins), // mask
        largeChildSize, // maskedItemSize
        2, // count
        true) // isFocal
    .addKeyline(
        smallItemCenter, // offsetLoc
        getChildMaskPercentage(smallChildSize, largeChildSize, childMargins), // mask
        smallChildSize); // maskedItemSize
```

A strategy does not need to take layout direction into account. `https://developer.android.com/reference/com/google/android/material/carousel/CarouselLayoutManager` automatically reverses the strategy's `https://developer.android.com/reference/com/google/android/material/carousel/KeylineState` when laid out in right-to-left. Additionally, `https://developer.android.com/reference/com/google/android/material/carousel/CarouselLayoutManager` shifts the focal keylines to the start or end of the container when at the start or end of a list in order to allow every item in the list to pass through the focal state.

For additional guidelines on constructing valid KeylineStates, see `https://developer.android.com/reference/com/google/android/material/carousel/KeylineState.Builder`.

| Parameters |
|---|---|
| `https://developer.android.com/reference/com/google/android/material/carousel/Carousel carousel` | The carousel to create a `https://developer.android.com/reference/com/google/android/material/carousel/KeylineState` for |
| `View child` | The first measured view from the carousel. |

| Returns |
|---|---|
| `https://developer.android.com/reference/com/google/android/material/carousel/KeylineState` | A `https://developer.android.com/reference/com/google/android/material/carousel/KeylineState` to be used by the layout manager to offset and mask children along the scrolling axis. |