Summary: Ctors | Methods | Inherited Methods

GridLayoutManager.SpanSizeLookup

Kotlin |Java

public static abstract class GridLayoutManager.SpanSizeLookup
extends Object

java.lang.Object
↳	androidx.recyclerview.widget.GridLayoutManager.SpanSizeLookup

Known direct subclasses

GridLayoutManager.DefaultSpanSizeLookup

GridLayoutManager.DefaultSpanSizeLookup Default implementation for GridLayoutManager.SpanSizeLookup.

A helper class to provide the number of spans each item occupies.

Default implementation sets each item to occupy exactly 1 span.

See also:

GridLayoutManager.setSpanSizeLookup(SpanSizeLookup)

Summary

Public constructors
`SpanSizeLookup()`

Public methods
`int`	`getSpanGroupIndex(int adapterPosition, int spanCount)` Returns the index of the group this position belongs.
`int`	`getSpanIndex(int position, int spanCount)` Returns the final span index of the provided position.
`abstract int`	`getSpanSize(int position)` Returns the number of span occupied by the item at `position`.
`void`	`invalidateSpanGroupIndexCache()` Clears the span group index cache.
`void`	`invalidateSpanIndexCache()` Clears the span index cache.
`boolean`	`isSpanGroupIndexCacheEnabled()` Returns whether results of `getSpanGroupIndex(int, int)` method are cached or not.
`boolean`	`isSpanIndexCacheEnabled()` Returns whether results of `getSpanIndex(int, int)` method are cached or not.
`void`	`setSpanGroupIndexCacheEnabled(boolean cacheSpanGroupIndices)` Sets whether the results of `getSpanGroupIndex(int, int)` method should be cached or not.
`void`	`setSpanIndexCacheEnabled(boolean cacheSpanIndices)` Sets whether the results of `getSpanIndex(int, int)` method should be cached or not.

Inherited methods

From class


        
          java.lang.Object

`Object`	`clone()`
`boolean`	`equals(Object arg0)`
`void`	`finalize()`
`final Class<?>`	`getClass()`
`int`	`hashCode()`
`final void`	`notify()`
`final void`	`notifyAll()`
`String`	`toString()`
`final void`	`wait(long arg0, int arg1)`
`final void`	`wait(long arg0)`
`final void`	`wait()`

Public constructors

SpanSizeLookup

public SpanSizeLookup ()

Public methods

getSpanGroupIndex

public int getSpanGroupIndex (int adapterPosition, 
                int spanCount)

Returns the index of the group this position belongs.

For example, if grid has 3 columns and each item occupies 1 span, span group index for item 1 will be 0, item 5 will be 1.

Parameters
`adapterPosition`	`int`: The position in adapter
`spanCount`	`int`: The total number of spans in the grid

Returns
`int`	The index of the span group including the item at the given adapter position

getSpanIndex

public int getSpanIndex (int position, 
                int spanCount)

Returns the final span index of the provided position.

If you have a faster way to calculate span index for your items, you should override this method. Otherwise, you should enable span index cache (setSpanIndexCacheEnabled(boolean)) for better performance. When caching is disabled, default implementation traverses all items from 0 to position. When caching is enabled, it calculates from the closest cached value before the position.

If you override this method, you need to make sure it is consistent with getSpanSize(int). GridLayoutManager does not call this method for each item. It is called only for the reference item and rest of the items are assigned to spans based on the reference item. For example, you cannot assign a position to span 2 while span 1 is empty.

Note that span offsets always start with 0 and are not affected by RTL.

Parameters
`position`	`int`: The position of the item
`spanCount`	`int`: The total number of spans in the grid

Returns
`int`	The final span position of the item. Should be between 0 (inclusive) and `spanCount`(exclusive)

getSpanSize

public abstract int getSpanSize (int position)

Returns the number of span occupied by the item at position.

Parameters
`position`	`int`: The adapter position of the item

Returns
`int`	The number of spans occupied by the item at the provided position

invalidateSpanGroupIndexCache

public void invalidateSpanGroupIndexCache ()

Clears the span group index cache. GridLayoutManager automatically calls this method when adapter changes occur.

invalidateSpanIndexCache

public void invalidateSpanIndexCache ()

Clears the span index cache. GridLayoutManager automatically calls this method when adapter changes occur.

isSpanGroupIndexCacheEnabled

public boolean isSpanGroupIndexCacheEnabled ()

Returns whether results of getSpanGroupIndex(int, int) method are cached or not.

Returns
`boolean`	True if results of `getSpanGroupIndex(int, int)` are cached.

isSpanIndexCacheEnabled

public boolean isSpanIndexCacheEnabled ()

Returns whether results of getSpanIndex(int, int) method are cached or not.

Returns
`boolean`	True if results of `getSpanIndex(int, int)` are cached.

setSpanGroupIndexCacheEnabled

public void setSpanGroupIndexCacheEnabled (boolean cacheSpanGroupIndices)

Sets whether the results of getSpanGroupIndex(int, int) method should be cached or not. By default these values are not cached. If you are not overriding getSpanGroupIndex(int, int) with something highly performant, and you are using spans to calculate scrollbar offset and range, you should set this to true for better performance.

Parameters
`cacheSpanGroupIndices`	`boolean`: Whether results of getGroupSpanIndex should be cached or not.

setSpanIndexCacheEnabled

public void setSpanIndexCacheEnabled (boolean cacheSpanIndices)

Sets whether the results of getSpanIndex(int, int) method should be cached or not. By default these values are not cached. If you are not overriding getSpanIndex(int, int) with something highly performant, you should set this to true for better performance.

Parameters
`cacheSpanIndices`	`boolean`: Whether results of getSpanIndex should be cached or not.