public
static
abstract
class
GridLayoutManager.SpanSizeLookup
extends Object
| java.lang.Object | |
| ↳ | android.support.v7.widget.GridLayoutManager.SpanSizeLookup |
 Known Direct Subclasses
|
A helper class to provide the number of spans each item occupies.
Default implementation sets each item to occupy exactly 1 span.
See also:
Public constructors | |
|---|---|
GridLayoutManager.SpanSizeLookup()
|
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Public methods | |
|---|---|
int
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getSpanGroupIndex(int adapterPosition, int spanCount)
Returns the index of the group this position belongs. |
int
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getSpanIndex(int position, int spanCount)
Returns the final span index of the provided position. |
abstract
int
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getSpanSize(int position)
Returns the number of span occupied by the item at |
void
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invalidateSpanIndexCache()
Clears the span index cache. |
boolean
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isSpanIndexCacheEnabled()
Returns whether results of |
void
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setSpanIndexCacheEnabled(boolean cacheSpanIndices)
Sets whether the results of |
Inherited methods | |
|---|---|
From
class
java.lang.Object
| |
GridLayoutManager.SpanSizeLookup ()
Developers
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 |
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)
|
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 |
void invalidateSpanIndexCache ()
Clears the span index cache. GridLayoutManager automatically calls this method when adapter changes occur.
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.
|
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 |
boolean:
Whether results of getSpanIndex should be cached or not.
|