public class DrawableTransformation extends Object implements Transformation<Drawable>
Bitmap Transformation to Drawables by first attempting to
convert the Drawable to a Bitmap and then running the Transformation
on the converted Bitmap.
This class is relatively efficient for BitmapDrawable where the Bitmap is
readily accessible. For non-Bitmap based Drawables, this class must first try to
draw the Drawable to a Bitmap using Canvas, which is
less efficient. Drawables that implement Animatable
will fail with an exception. Drawables that return <= 0 for
Drawable.getIntrinsicHeight() and/or Drawable.getIntrinsicWidth() will fail
with an exception if the requested size is
Target.SIZE_ORIGINAL. Drawables without
intrinsic dimensions are drawn using the dimensions provided in
Transformation.transform(Context, Resource, int, int). As a result, they may be
transformed incorrectly or in unexpected ways.
CHARSET, STRING_CHARSET_NAME| Constructor and Description |
|---|
DrawableTransformation(Transformation<Bitmap> wrapped,
boolean isRequired) |
| Modifier and Type | Method and Description |
|---|---|
Transformation<BitmapDrawable> |
asBitmapDrawable() |
boolean |
equals(Object o)
For caching to work correctly, implementations must implement this method and
Transformation.hashCode(). |
int |
hashCode()
For caching to work correctly, implementations must implement this method and
Transformation.equals(Object). |
Resource<Drawable> |
transform(Context context,
Resource<Drawable> resource,
int outWidth,
int outHeight)
Transforms the given resource and returns the transformed resource.
|
void |
updateDiskCacheKey(MessageDigest messageDigest)
Adds all uniquely identifying information to the given digest.
|
public DrawableTransformation(Transformation<Bitmap> wrapped, boolean isRequired)
public Transformation<BitmapDrawable> asBitmapDrawable()
public Resource<Drawable> transform(Context context, Resource<Drawable> resource, int outWidth, int outHeight)
TransformationIf 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, Transformation.equals(Object), Transformation.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.
transform in interface Transformation<Drawable>context - The Application contextresource - 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.public boolean equals(Object o)
TransformationTransformation.hashCode().public int hashCode()
TransformationTransformation.equals(Object).public void updateDiskCacheKey(MessageDigest messageDigest)
Key Note - Using MessageDigest.reset() inside of this method will result
in undefined behavior.
updateDiskCacheKey in interface Key