com.bumptech.glide

Class ListPreloader<T>

java.lang.Object

com.bumptech.glide.ListPreloader<T>

Type Parameters:

T - The type of the model being displayed in the list.

All Implemented Interfaces:

AbsListView.OnScrollListener

public class ListPreloader<T>
extends Object
implements AbsListView.OnScrollListener

Loads a few resources ahead in the direction of scrolling in any AbsListView so that images are in the memory cache just before the corresponding view in created in the list. Gives the appearance of an infinitely large image cache, depending on scrolling speed, cpu speed, and cache size.

Must be set using AbsListView.setOnScrollListener(android.widget.AbsListView.OnScrollListener), or have its corresponding methods called from another AbsListView.OnScrollListener to function.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	ListPreloader.PreloadModelProvider<U> An implementation of PreloadModelProvider should provide all the models that should be preloaded.
static interface	ListPreloader.PreloadSizeProvider<T> An implementation of PreloadSizeProvider should provide the size of the view in the list where the resources will be displayed.

Field Summary

Fields inherited from interface android.widget.AbsListView.OnScrollListener

SCROLL_STATE_FLING, SCROLL_STATE_IDLE, SCROLL_STATE_TOUCH_SCROLL

Constructor Summary

Constructors

Constructor and Description
ListPreloader(int maxPreload) Deprecated. Use ListPreloader(com.bumptech.glide.ListPreloader.PreloadModelProvider, com.bumptech.glide.ListPreloader.PreloadSizeProvider, int) instead. This constructor will be removed in Glide 4.0.
ListPreloader(ListPreloader.PreloadModelProvider<T> preloadModelProvider, ListPreloader.PreloadSizeProvider<T> preloadDimensionProvider, int maxPreload) Constructor for ListPreloader that accepts interfaces for providing the dimensions of images to preload, the list of models to preload for a given position, and the request to use to load images.

Method Summary

Methods

Modifier and Type	Method and Description
protected int[]	getDimensions(T item) Deprecated. Use ListPreloader.PreloadSizeProvider instead. This method will be removed in Glide 4.0.
protected List<T>	getItems(int start, int end) Deprecated. Use ListPreloader.PreloadModelProvider instead. This method will be removed in Glide 4.0.
protected GenericRequestBuilder	getRequestBuilder(T item) Deprecated. Use ListPreloader.PreloadModelProvider instead. This method will be removed in Glide 4.0.
void	onScroll(AbsListView absListView, int firstVisible, int visibleCount, int totalCount)
void	onScrollStateChanged(AbsListView absListView, int scrollState)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ListPreloader

@Deprecated
public ListPreloader(int maxPreload)

Deprecated. Use ListPreloader(com.bumptech.glide.ListPreloader.PreloadModelProvider, com.bumptech.glide.ListPreloader.PreloadSizeProvider, int) instead. This constructor will be removed in Glide 4.0.

Constructor for ListPreloader that requires users to subclass and override the getItems(int, int) and getRequestBuilder(Object) methods.

Parameters:

maxPreload - Maximum number of items to preload.

ListPreloader

public ListPreloader(ListPreloader.PreloadModelProvider<T> preloadModelProvider,
             ListPreloader.PreloadSizeProvider<T> preloadDimensionProvider,
             int maxPreload)

Constructor for ListPreloader that accepts interfaces for providing the dimensions of images to preload, the list of models to preload for a given position, and the request to use to load images.

Parameters:

preloadModelProvider - Provides models to load and requests capable of loading them.

preloadDimensionProvider - Provides the dimensions of images to load.

maxPreload - Maximum number of items to preload.

Method Detail

onScrollStateChanged

public void onScrollStateChanged(AbsListView absListView,
                        int scrollState)

Specified by:

onScrollStateChanged in interface AbsListView.OnScrollListener

onScroll

public void onScroll(AbsListView absListView,
            int firstVisible,
            int visibleCount,
            int totalCount)

Specified by:

onScroll in interface AbsListView.OnScrollListener

getDimensions

@Deprecated
protected int[] getDimensions(T item)

Deprecated. Use ListPreloader.PreloadSizeProvider instead. This method will be removed in Glide 4.0.

Returns the size of the view in the list where the resources will be displayed.

Note - The size returned here must precisely match those of the view in the list.

Parameters:

item - A model

Returns:

The size of the view where the item will be displayed

getItems

@Deprecated
protected List<T> getItems(int start,
                          int end)

Deprecated. Use ListPreloader.PreloadModelProvider instead. This method will be removed in Glide 4.0.

Returns a non null list of all models that need to be loaded for the list to display adapter items between start and end.

A list of any size can be returned so there can be multiple models per adapter position.

Parameters:

start - The smallest adapter position. Will be >= 0 && < adapter.getCount() && <= end

end - The largest adapter position. Will be >= 0 && < adapter.getCount && >= start

getRequestBuilder

@Deprecated
protected GenericRequestBuilder getRequestBuilder(T item)

Deprecated. Use ListPreloader.PreloadModelProvider instead. This method will be removed in Glide 4.0.

Returns a non null GenericRequestBuilder for a given item. Must exactly match the request used to load the resource in the list.

The target and context will be provided by the preloader.

Parameters:

item - The model to load.