com.bumptech.glide.load

Interface Transformation<T>

Type Parameters:

T - The type of the resource being transformed.

All Superinterfaces:

Key

All Known Implementing Classes:

BitmapDrawableTransformation, BitmapTransformation, CenterCrop, CenterInside, CircleCrop, FitCenter, GifDrawableTransformation, MultiTransformation, RoundedCorners, UnitTransformation

public interface Transformation<T>
extends Key

A class for performing an arbitrary transformation on a resource that implements equals(Object) and hashCode()} to identify the transformation in the memory cache and Key.updateDiskCacheKey(java.security.MessageDigest)} to identify the transformation in disk caches.

Using the fully qualified class name (not Class.getName() to avoid proguard obfuscation) is an easy way to implement Key.updateDiskCacheKey(java.security.MessageDigest)} correctly.

Implementations must implement equals(Object) and hashCode().

Field Summary

Fields inherited from interface com.bumptech.glide.load.Key

CHARSET, STRING_CHARSET_NAME

Method Summary

Modifier and Type	Method and Description
boolean	equals(Object o) For caching to work correctly, implementations must implement this method and hashCode().
int	hashCode() For caching to work correctly, implementations must implement this method and equals(Object).
Resource<T>	transform(Context context, Resource<T> resource, int outWidth, int outHeight) Transforms the given resource and returns the transformed resource.

Methods inherited from interface com.bumptech.glide.load.Key

updateDiskCacheKey

Method Detail

transform

Resource<T> transform(Context context,
                      Resource<T> resource,
                      int outWidth,
                      int outHeight)

Transforms the given resource and returns the transformed resource.

If the original resource object is not returned, the original resource will be recycled and it's internal resources may be reused. This means it is not safe to rely on the original resource or any internal state of the original resource in any new resource that is created. Usually this shouldn't occur, but if absolutely necessary either the original resource object can be returned with modified internal state, or the data in the original resource can be copied into the transformed resource.

If a Transformation is updated, equals(Object), hashCode(), and Key.updateDiskCacheKey(java.security.MessageDigest) should all change. If you're using a simple String key an easy way to do this is to append a version number to your key. Failing to do so will mean users may see images loaded from cache that had the old version of the Transformation applied. Changing the return values of those methods will ensure that the cache key has changed and therefore that any cached resources will be re-generated using the updated Transformation.

During development you may need to either using DiskCacheStrategy.NONE or make sure Key.updateDiskCacheKey(java.security.MessageDigest) changes each time you make a change to the Transformation. Otherwise the resource you request may be loaded from disk cache and your Transformation may not be called.

Parameters:

context - The Application context

resource - The resource to transform.

outWidth - The width of the view or target the resource will be displayed in, or Target.SIZE_ORIGINAL to indicate the original resource width.

outHeight - The height of the view or target the resource will be displayed in, or Target.SIZE_ORIGINAL to indicate the original resource height.

Returns:

The transformed resource.

equals

boolean equals(Object o)

For caching to work correctly, implementations must implement this method and hashCode().

Specified by:

equals in interface Key

Overrides:

equals in class Object

hashCode

int hashCode()

For caching to work correctly, implementations must implement this method and equals(Object).

Specified by:

hashCode in interface Key

Overrides:

hashCode in class Object