Change format for specific loads and still get transition drawable

[eicm]

Is it possible to change the load format between ARGB and RGB_565 for specific loads and still load a drawable to get the transition effect between thumbnail and actual image?

[TWiStErRob]

You're essentially asking to do .asBitmap().crossFade(), right?

Remember that you can always do your own animation with .animate() or .listener(). I found a way to do something like this a few weeks ago for v4, I'll check tomorrow off I can backport it.

Update: here's the v4 version I was talking about:

.transition(new GenericTransitionOptions<PaletteBitmap>().transition(CROSS_FADE_FACTORY))

private static final TransitionFactory<PaletteBitmap> CROSS_FADE_FACTORY = new TransitionFactory<PaletteBitmap>() {
    private final TransitionFactory<Drawable> realFactory = new DrawableCrossFadeFactory();

    @Override public Transition<PaletteBitmap> build(DataSource dataSource, boolean isFirstResource) {
        final Transition<Drawable> transition = realFactory.build(dataSource, isFirstResource);
        return new Transition<PaletteBitmap>() {
            @Override
            public boolean transition(PaletteBitmap current, ViewAdapter adapter) {
                Resources resources = adapter.getView().getResources();
                Drawable currentBitmap = new BitmapDrawable(resources, current.bitmap);
                return transition.transition(currentBitmap, adapter);
            }
        };
    }
};

I made it for PaletteBitmap, but it's easy to adapt it to any custom transcoded type that has a Bitmap or Drawable.

[TWiStErRob]

This response is outdated, since 3.8.0 it's possible to do .asBitmap().crossFade(), see #1007.

The heart of all is a custom factory:

private static final GlideAnimationFactory<Bitmap> CROSS_FADE_FACTORY = new GlideAnimationFactory<Bitmap>() {
    private final GlideAnimationFactory<Drawable> realFactory = new DrawableCrossFadeFactory<>();
    @Override public GlideAnimation<Bitmap> build(boolean isFromMemoryCache, boolean isFirstResource) {
        final GlideAnimation<Drawable> transition = realFactory.build(isFromMemoryCache, isFirstResource);
        return new GlideAnimation<Bitmap>() {
            @Override public boolean animate(Bitmap current, ViewAdapter adapter) {
                Resources resources = adapter.getView().getResources();
                Drawable currentBitmap = new BitmapDrawable(resources, current);
                return transition.animate(currentBitmap, adapter);
            }
        };
    }
};

This can be exploded into several classes and realFactory can be anything, most notably DrawableCrossFadeFactory has several constructor overloads.

Assuming you have something like this (you'll see later why I extracted the local variable):

BitmapRequestBuilder<String, Bitmap> request = Glide
    .with(context)
    .load(fullUrl)
    .asBitmap()
    .format(DecodeFormat.PREFER_ARGB_8888)
    .thumbnail(Glide
        .with(context)
        .load(thumbUrl)
        .asBitmap()
    )
;

you have two options, both of them are weird because GenericRequestBuilder.animate(GlideAnimationFactory) is package private.
@sjudd I think it could be made public in 3.7.0 if ever released since v4 already made it public. Also let's use this issue to track the addition of built-in crossFade for asBitmap().

The proper

... yet ugly: I don't like listeners to do stuff, though they were designed that way.

request
    .dontAnimate() // turn off defaults since we're handling it
    .listener(new BitmapCrossfadeListener<>())
    .into(imageView)
;

public class BitmapCrossfadeListener<ModelType> implements RequestListener<ModelType, Bitmap> {
    // CROSS_FADE_FACTORY here
    @Override public boolean onException(Exception e, ModelType model, Target<Bitmap> target, boolean isFirstResource) {
        return false;
    }
    @Override public boolean onResourceReady(Bitmap resource, ModelType model, Target<Bitmap> target, boolean isFromMemoryCache, boolean isFirstResource) {
        return CROSS_FADE_FACTORY
            .build(isFromMemoryCache, isFirstResource)
            .animate(resource, (ViewAdapter)target)
        ;
    }
}

The hacky

but would-be nicer: equivalent to calling .animate(CROSS_FADE_FACTORY).into(imageView) if it was public, see #1007

GlideRequestBuilderAccessor.animate(request, CROSS_FADE_FACTORY);
request.into(imageView);

package com.bumptech.glide;
public class GlideRequestBuilderAccessor {
    public static <T> void animate(GenericRequestBuilder<?, ?, ?, T> request, GlideAnimationFactory<T> factory) {
        request.animate(factory);
    }
}

or, depending on your preferred style, an alternative:

GlideRequestBuilderAccessor.animate(request, CROSS_FADE_FACTORY).into(imageView);

public static <ModelType, DataType, ResourceType, TranscodeType>
GenericRequestBuilder<ModelType, DataType, ResourceType, TranscodeType> animate(
        GenericRequestBuilder<ModelType, DataType, ResourceType, TranscodeType> request,
        GlideAnimationFactory<TranscodeType> factory
    ) {
    return request.animate(factory);
}

[TWiStErRob]

Just noticed that #605 is the same and has a simpler solution, which is essentially the total inlining of the core of CROSS_FADE_FACTORY.

[eicm]

Thanks for the reply.

[sjudd]

Agree, pull requests welcome :)