Android APIs
public static abstract class

GridLayoutManager.SpanSizeLookup

extends Object
java.lang.Object
   ↳ android.support.v7.widget.GridLayoutManager.SpanSizeLookup
Known Direct Subclasses

Class Overview

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

Default implementation sets each item to occupy exactly 1 span.

See Also

Summary

Public Constructors
GridLayoutManager.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 invalidateSpanIndexCache()
Clears the span index cache.
boolean isSpanIndexCacheEnabled()
Returns whether results of getSpanIndex(int, int) method are cached or not.
void setSpanIndexCacheEnabled(boolean cacheSpanIndices)
Sets whether the results of getSpanIndex(int, int) method should be cached or not.
[Expand]
Inherited Methods
From class java.lang.Object

Public Constructors

public GridLayoutManager.SpanSizeLookup ()

Public Methods

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 The position in adapter
spanCount The total number of spans in the grid
Returns
  • The index of the span group including the item at the given adapter position

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 The position of the item
spanCount The total number of spans in the grid
Returns
  • The final span position of the item. Should be between 0 (inclusive) and spanCount(exclusive)

public abstract int getSpanSize (int position)

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

Parameters
position The adapter position of the item
Returns
  • The number of spans occupied by the item at the provided position

public void invalidateSpanIndexCache ()

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

public boolean isSpanIndexCacheEnabled ()

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

Returns

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), you should set this to true for better performance.

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