Subclasses:

GridLayoutManager.DefaultSpanSizeLookup

Overview

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

Default implementation sets each item to occupy exactly 1 span.

Summary

Constructors

Methods

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

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

Parameters:

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

Sets whether the results of GridLayoutManager.SpanSizeLookup.getSpanGroupIndex(int, int) method should be cached or not. By default these values are not cached. If you are not overriding GridLayoutManager.SpanSizeLookup.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: Whether results of getGroupSpanIndex should be cached or not.

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

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

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

Returns:

True if results of GridLayoutManager.SpanSizeLookup.getSpanIndex(int, int) are cached.

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

Returns:

True if results of GridLayoutManager.SpanSizeLookup.getSpanGroupIndex(int, int) are cached.

Returns the final span index of the provided position.

If LinearLayoutManager.getOrientation() is LinearLayoutManager.VERTICAL, this is a column value. If LinearLayoutManager.getOrientation() is LinearLayoutManager.HORIZONTAL, this is a row value.

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 (GridLayoutManager.SpanSizeLookup.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 GridLayoutManager.SpanSizeLookup.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)

Returns the index of the group this position belongs.

If LinearLayoutManager.getOrientation() is LinearLayoutManager.VERTICAL, this is a row value. If LinearLayoutManager.getOrientation() is LinearLayoutManager.HORIZONTAL, this is a column value.

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