Glide images

Glide 4 Image Loading (Java)

Instructions

Glide is the default image loader. It handles lifecycle, memory cache, disk cache, and decoding off the main thread. Prefer Glide over Picasso for new code; prefer it over Coil when the project must stay Java.

1. Setup

dependencies {
    implementation 'com.github.bumptech.glide:glide:4.16.0'
    annotationProcessor 'com.github.bumptech.glide:compiler:4.16.0'
}

With the annotation processor you get a generated GlideApp class. Register a module for app-wide defaults:

@GlideModule
public class AppGlideModule extends com.bumptech.glide.module.AppGlideModule {

    @Override
    public void applyOptions(@NonNull Context context, @NonNull GlideBuilder builder) {
        builder.setDefaultRequestOptions(new RequestOptions()
                .format(DecodeFormat.PREFER_RGB_565)
                .diskCacheStrategy(DiskCacheStrategy.AUTOMATIC));
        builder.setMemoryCache(new LruResourceCache(1024L * 1024L * 40L)); // 40MB
    }

    @Override
    public boolean isManifestParsingEnabled() { return false; }
}

2. Basic Load

Always pass a lifecycle-aware scope: pass this for Activity, this (Fragment), or the View.

Glide.with(imageView)
     .load(article.imageUrl())
     .placeholder(R.drawable.placeholder_article)
     .error(R.drawable.error_article)
     .into(imageView);

Never call Glide.with(getApplicationContext()) — it disables lifecycle cancellation and leaks.

3. Transformations

Glide.with(imageView)
     .load(user.avatarUrl())
     .transform(new CenterCrop(), new RoundedCorners(16))
     .into(imageView);

Common transformations:

• CenterCrop, CenterInside, FitCenter
• RoundedCorners(px)
• CircleCrop() for avatars
• Custom BitmapTransformation for effects (blur, grayscale) — override transform() and return a new Bitmap.

4. Thumbnails (fast perceived load)

RequestBuilder<Drawable> fullSize = Glide.with(imageView).load(article.imageUrl());
RequestBuilder<Drawable> thumb    = Glide.with(imageView).load(article.thumbUrl());

fullSize.thumbnail(thumb).into(imageView);

Or a fractional thumbnail of the same URL:

Glide.with(imageView)
     .load(url)
     .thumbnail(0.25f)
     .into(imageView);

5. RecyclerView

Cancel outstanding loads on view recycle:

@Override
public void onBindViewHolder(VH h, int pos) {
    Article a = getItem(pos);
    Glide.with(h.b.image)
         .load(a.imageUrl())
         .centerCrop()
         .placeholder(R.color.image_placeholder)
         .into(h.b.image);
}

@Override
public void onViewRecycled(@NonNull VH h) {
    super.onViewRecycled(h);
    Glide.with(h.b.image).clear(h.b.image);
}

Set fixed sizes (android:layout_width, android:layout_height) so Glide downsamples to the correct resolution. Avoid wrap_content on image views.

6. Preloading

For paging / detail screens, preload upcoming images:

RecyclerViewPreloader<Article> preloader = new RecyclerViewPreloader<>(
        Glide.with(this),
        new ListPreloader.PreloadModelProvider<>() {
            @Override public List<Article> getPreloadItems(int position) {
                return List.of(adapter.getItem(position));
            }
            @Override public RequestBuilder<?> getPreloadRequestBuilder(Article a) {
                return Glide.with(recyclerView).load(a.imageUrl());
            }
        },
        new ViewPreloadSizeProvider<>(),
        10);
recyclerView.addOnScrollListener(preloader);

7. Disk / Memory Cache

• DiskCacheStrategy.AUTOMATIC (default) is correct for most apps.
• Use DiskCacheStrategy.NONE for one-off blobs (e.g. captchas).
• Use DiskCacheStrategy.ALL for assets served with stable URLs.
• .skipMemoryCache(true) for debug overlays.

Clear caches on sign-out:

new Thread(() -> Glide.get(context).clearDiskCache()).start();
Glide.get(context).clearMemory();

Checklist

• Glide.with(...) is called with a lifecycle-bound owner, not applicationContext.
• Every ImageView has a fixed size or explicit constraint so Glide can downsample.
• Placeholders and error drawables are set for network loads.
• Glide.with(view).clear(view) is called in onViewRecycled for long lists.
• Avatars use CircleCrop(), not a rounded background + mask hack.
• AppGlideModule sets reasonable cache sizes and default DecodeFormat.