Glide: What It Is, Image Library, and Usage in Android

What is Glide?

Glide is a library for fast and efficient loading of images, animated GIFs, and video frames in Android applications. The project is developed by Bumptech under the umbrella of Google and is widely used in official Google applications.

The internal architecture of Glide is built on a component-based approach: the Engine manages request execution, DecodeJob handles decoding, and ResourceDecoder converts raw data into Bitmap or Drawable. Each stage can be customized through modules and registries, making Glide an extremely flexible library for non-standard image formats.

Unlike many competitors, Glide was designed from the start with Android specifics in mind: Activity and Fragment lifecycle, screen rotations, configuration changes. The library automatically pauses and resumes loading depending on the component state.

According to Android Developers, Glide is the recommended library for image loading in Google official documentation. It is used in Google Play, Google Maps, and other company products, confirming its reliability and performance.

The key difference between Glide and alternatives is automatic image scaling to fit ImageView size. While Picasso loads an image at full resolution and then scales it, Glide decodes the file directly to the required size. This reduces peak memory consumption and speeds up display in lists with different cell sizes.

Key Glide Features

Glide provides a wide range of functions for working with images, covering both simple and complex content loading scenarios.

GIF and Animated WebP Support

GIF and animated WebP are loaded and displayed by Glide as easily as static images. The library automatically detects the format by MIME type and decodes the animation, displaying frames in a background thread. asGif and asBitmap methods are available for playback control.

Lifecycle Integration

Glide automatically binds to the lifecycle of Activity, Fragment, and View. When an Activity is paused, loading is suspended; when destroyed, it is canceled. This prevents memory leaks and loading images for already closed screens. Integration works through LifecycleOwner support.

Video Frame Loading

Glide can extract frames from video by URL or local path. The asBitmap() method in combination with load() is used for video URIs. Glide automatically selects a key frame or a frame at a specified timestamp. This is useful for displaying video thumbnails.

Generating and Configuring GlideApp

GlideApp is a generated class that provides an extended API based on AppGlideModule configuration. It allows using methods unavailable in standard Glide.with: loading with custom default options, integration with libraries, and preset transformations. Generation requires the @GlideModule annotation in a class extending AppGlideModule.

How Does Glide Work?

Glide uses a multi-layered architecture with an engine, decoders, transformations, and cache. Each request passes through a chain of handlers that optimize loading for a specific ImageView.

Architecture and Pipeline

When into(view) is called, Glide checks the cache: active resources, memory cache, disk cache, and only then the network. The image is automatically scaled to the target ImageView size taking into account screen density and scaleType. This reduces memory usage — a key advantage of Glide.

Glide.with(context)
    .load("https://example.com/image.jpg")
    .placeholder(R.drawable.loading)
    .error(R.drawable.error)
    .override(400, 300)
    .centerCrop()
    .into(imageView)

Installing and Configuring Glide

Installation of Glide is done via Gradle. The library requires configuration through AppGlideModule for API generation. The minimum Android API version is 21.

Adding Dependencies

In build.gradle, add Glide with kapt annotation processor for GlideApp API generation. For Kotlin, use kapt instead of annotationProcessor. Glide version 4.16+ works stably with Android Gradle Plugin 8.x.

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

// Use kapt for Kotlin
// kapt "com.github.bumptech.glide:compiler:4.16.0"

Creating AppGlideModule

AppGlideModule is a required component for configuring Glide. It allows setting cache size, custom HttpStack, and registering custom decoders. The module is scanned by Glide at application startup. The @GlideModule annotation registers it automatically.

@GlideModule
public class MyGlideModule extends AppGlideModule {
    @Override
    public void applyOptions(Context context, GlideBuilder builder) {
        int diskCacheSize = 250 * 1024 * 1024;
        builder.setDiskCache(
            new DiskLruCacheFactory(cacheDir.getPath(), diskCacheSize)
        );
    }
}

Glide Usage Examples

Examples below demonstrate typical scenarios: image loading, working with GIFs, and video frame extraction.

Loading an Image with Placeholder

Basic loading via Glide.with().load().into() — minimal code for displaying an image from the network. Glide automatically adjusts to ImageView size. Placeholder is shown during loading, and error is shown on failure.

Glide.with(fragment)
    .load("https://example.com/photo.jpg")
    .placeholder(R.drawable.placeholder)
    .error(R.drawable.error)
    .skipMemoryCache(true)
    .diskCacheStrategy(DiskCacheStrategy.NONE)
    .into(imageView)

Loading a GIF Image

GIF is loaded the same way as a static image — Glide automatically detects the format by content type. For forced loading as a static image, use asBitmap(); for GIF, use asGif(). Glide efficiently decodes only visible frames.

Glide.with(context)
    .asGif()
    .load("https://example.com/animation.gif")
    .into(imageView)

// Load the first frame of a GIF as a static image
Glide.with(context)
    .asBitmap()
    .load("https://example.com/animation.gif")
    .into(imageView)

Loading a Video Frame

A video frame is extracted by Glide from a local or remote video URI. By default, Glide loads the key frame. To specify a specific timestamp, use frameMillis. This is convenient for displaying previews in a video gallery.

String videoUrl = "https://example.com/video.mp4";

Glide.with(context)
    .asBitmap()
    .load(videoUrl)
    .override(200, 200)
    .into(imageView)

Optimizing Glide for Large Lists

Optimizing Glide for RecyclerView is a critical skill when developing applications with a large number of images. Proper configuration prevents lag and OOM errors.

One of Glide key features is RecyclerView integration via RecyclerViewPreloader. This component analyzes scroll speed and direction, preloading images that will appear on screen in a few items. To use the preloader, you need to implement the PreloadSizeProvider interface and pass it to the constructor along with the target ImageView.

Using the override() method with exact ImageView dimensions significantly speeds up loading. When Glide knows the exact target size, it can decode the image directly at the required resolution, skipping the scaling step. This reduces decoding time and peak memory consumption by 30–40%.

For feeds with heterogeneous content, use different RequestOptions for each item type. For example, for large banner images, you can set override(1200, 600) and RGB_565 quality, while for avatars — override(200, 200) and rounding via transform. This approach optimally uses resources for each content type.

Error Handling

Glide provides flexible error handling options through error images and custom RequestListener. RequestListener allows reacting to successful loading or failure — logging errors or sending analytics. You can also configure a fallback — an image shown when load() receives null instead of a URL.

Use RecyclerViewPreloader to preload images before the user scrolls to them. Glide supports RecyclerView integration through a preloader that analyzes scroll speed and loads images in advance.

Thumbnail multiplication allows showing a reduced version of the image first, then loading the full version. Calling thumbnail(0.25f) loads a 25% size version displayed immediately, while the full-size image loads later. This creates the impression of instant loading.

For list adapters, use .override() with exact ImageView dimensions so Glide does not scale the image every time. This reduces CPU load and memory consumption. Cache size is selected experimentally, but 250 MB for disk and 20% of available memory is a good starting point.