Package 

Class GridLayoutManager.SpanSizeLookup

  • 
public abstract class GridLayoutManager.SpanSizeLookup

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

    Default implementation sets each item to occupy exactly 1 span.

    • Method Detail

      • getSpanSize

         abstract int getSpanSize(int position)

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

        Parameters:
        position - The adapter position of the item

      • setSpanIndexCacheEnabled

         void setSpanIndexCacheEnabled(boolean cacheSpanIndices)

        Sets whether the results of getSpanIndex method should be cached ornot. By default these values are not cached. If you are not overriding getSpanIndex with something highly performant, you should set thisto true for better performance.

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

      • setSpanGroupIndexCacheEnabled

         void setSpanGroupIndexCacheEnabled(boolean cacheSpanGroupIndices)

        Sets whether the results of getSpanGroupIndex method should be cachedor not. By default these values are not cached. If you are not overriding getSpanGroupIndex with something highly performant, and you are usingspans to calculate scrollbar offset and range, you should set this to true for betterperformance.

        Parameters:
        cacheSpanGroupIndices - Whether results of getGroupSpanIndex should be cached ornot.

      • invalidateSpanIndexCache

         void invalidateSpanIndexCache()

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

      • invalidateSpanGroupIndexCache

         void invalidateSpanGroupIndexCache()

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

      • getSpanIndex

         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 overridethis method. Otherwise, you should enable span index cache(setSpanIndexCacheEnabled) for better performance. When caching isdisabled, default implementation traverses all items from 0 toposition. When caching is enabled, it calculates from the closest cachedvalue before the position.

        If you override this method, you need to make sure it is consistent with getSpanSize. GridLayoutManager does not call this method foreach item. It is called only for the reference item and rest of the itemsare assigned to spans based on the reference item. For example, you cannot assign aposition 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

      • getSpanGroupIndex

         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 indexfor 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