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Saturday, 16 December 2017

Displaying Images with the Glide Library

Overview

Glide is an Image Loader Library for Android developed by bumptech and is a library that is recommended by Google. It has been used in many Google open source projects including Google I/O 2014 official application. It provides animated GIF support and handles image loading/caching.

Setup

Add to your app/build.gradle file:
dependencies {
  compile 'com.github.bumptech.glide:glide:3.8.0'
}

Basic Usage

Glide.with(context)
    .load("http://via.placeholder.com/300.png")
    .into(ivImg);

Advanced Usage

Resizing images with:
Glide.with(context)
    .load("http://via.placeholder.com/300.png")
    .override(300, 200)
    .into(ivImg);
Placeholder and error images:
Glide.with(context)
    .load("http://via.placeholder.com/300.png")
    .placeholder(R.drawable.placeholder)
    .error(R.drawable.imagenotfound)
    .into(ivImg);
Cropping images with:
Glide.with(context)
    .load("http://via.placeholder.com/300.png")
    .centerCrop()
    .into(ivImg);

Configuration

You can configure Glide by creating a GlideConfiguration.java file:
public class GlideConfiguration implements GlideModule {

    @Override
    public void applyOptions(Context context, GlideBuilder builder) {
        // Apply options to the builder here.
        // Glide default Bitmap Format is set to RGB_565 since it 
        // consumed just 50% memory footprint compared to ARGB_8888.
        // Increase memory usage for quality with:
        builder.setDecodeFormat(DecodeFormat.PREFER_ARGB_8888);
    }

    @Override
    public void registerComponents(Context context, Glide glide) {
        // register ModelLoaders here.
    }
}
And then define it as meta-data inside AndroidManifest.xml:
<meta-data android:name="my.app.namespace.utils.GlideConfiguration"
            android:value="GlideModule"/>

Resizing

Ideally, an image's dimensions would match exactly those of the ImageView in which it is being displayed, but as this is often not the case, care must be taken to resize and/or scale the image appropriately. Android's native support for this isn't robust, especially when displaying very large images (such as bitmaps returned from the camera) in smaller image views, which can often lead to errors (see Troubleshooting).
Glide automatically limits the size of the image it holds in memory to the ImageView dimensions. Picasso has the same ability, but requires a call to fit(). With Glide, if you don't want the image to be automatically fitted to the ImageView, you can call override(horizontalSize, verticalSize). This will resize the image before displaying it in the ImageView but without respect to the image's aspect ratio:
Glide.with(context)
    .load("http://via.placeholder.com/300.png")
    .override(100, 200) // resizes the image to 100x200 pixels but does not respect aspect ratio
    .into(ivImg);
Resizing images in this way without respect to the original aspect ratio will often make the image appear skewed or distorted. In most cases, this should be avoided, and Glide offers two standard scaling transformation options to prevent this: centerCrop and fitCenter.
If you only want to resize one dimension, use Target.SIZE_ORIGINAL as a placeholder for the other dimension:
Glide.with(context)
    .load("http://via.placeholder.com/300.png")
    .override(100, Target.SIZE_ORIGINAL) // resizes width to 100, preserves original height, does not respect aspect ratio
    .into(ivImg);

centerCrop()

Calling centerCrop() scales the image so that it fills the requested bounds of the ImageView and then crops the extra. The ImageView will be filled completely, but the entire image might not be displayed.
Glide.with(context)
    .load("http://via.placeholder.com/300.png")
    .override(100, 200) 
    .centerCrop() // scale to fill the ImageView and crop any extra
    .into(ivImg);

fitCenter()

Calling fitCenter() scales the image so that both dimensions are equal to or less than the requested bounds of the ImageView. The image will be displayed completely, but might not fill the entire ImageView.
Glide.with(context)
    .load("http://via.placeholder.com/300.png")
    .override(100, 200) 
    .fitCenter() // scale to fit entire image within ImageView
    .into(ivImg);

Troubleshooting

OutOfMemoryError Loading Errors

If an image or set of images aren't loading, make sure to check the Android monitor log in Android Studio. There's a good chance you might see an java.lang.OutOfMemoryError "Failed to allocate a [...] byte allocation with [...] free bytes" or a Out of memory on a 51121168-byte allocation.. This is quite common and means that you are loading one or more large imagesthat have not been properly resized.
First, you have to find which image(s) being loaded are likely causing this error. For any given Glide call, we can fix this by one or more of the following approaches:
  • Add an explicit width or height to the ImageView by setting layout_width=500dp in the layout file.
  • Call .override(width, height) during the Glide load and explicitly set a width or height for the image such as: Glide.with(...).load(imageUri).override(500, 500).into(...).
  • Try removing android:adjustViewBounds="true" from your ImageView if present and if you not calling .override()
  • Open up your static placeholder or error images and make sure their dimensions are relatively small (< 500px width). If not, resize those static images and save them back to your project.
Applying these tips to all of your Glide image loads should resolve any out of memory issues. As a fallback, you might want to open up your AndroidManifest.xml and then add android:largeHeapto your manifest:
<application
        android:name=".MyApplication"
        ...
        android:largeHeap="true"
        ...
Note that this is not generally a good idea, but can be used temporarily to trigger fewer out of memory errors.

Loading Errors

If you experience errors loading images, you can create a RequestListener<String, GlideDrawable> and pass it in via Glide.listener() to intercept errors:
Glide.with(context)
        .load("http://via.placeholder.com/300.png")
        .placeholder(R.drawable.placeholder)
        .error(R.drawable.imagenotfound)
        .listener(new RequestListener<String, GlideDrawable>() {
            @Override
            public boolean onException(Exception e, String model, Target<GlideDrawable> target, boolean isFirstResource) {
                // log exception
                Log.e("TAG", "Error loading image", e);
                return false; // important to return false so the error placeholder can be placed
            }

            @Override
            public boolean onResourceReady(GlideDrawable resource, String model, Target<GlideDrawable> target, boolean isFromMemoryCache, boolean isFirstResource) {
                return false;
            }
        })
        .into(ivImg);

Transformations

Transformations are supported by an additional third-party library, glide-transformations. First, add the dependencies:
dependencies {
    compile 'jp.wasabeef:glide-transformations:2.0.2'
    // If you want to use the GPU Filters
    compile 'jp.co.cyberagent.android.gpuimage:gpuimage-library:1.4.1'
}

Rounded Corners

int radius = 30; // corner radius, higher value = more rounded
int margin = 10; // crop margin, set to 0 for corners with no crop
Glide.with(this)
        .load("http://via.placeholder.com/300.png")
        .bitmapTransform(new RoundedCornersTransformation(context, radius, margin))
        .into(ivImg);

Crop

Circle crop:
Glide.with(this)
        .load("http://via.placeholder.com/300.png")
        .bitmapTransform(new CropCircleTransformation(context))
        .into(ivImg);

Effects

Blur:
Glide.with(this)
        .load("http://via.placeholder.com/300.png")
        .bitmapTransform(new BlurTransformation(context))
        .into(ivImg);
Multiple transforms:
Glide.with(this)
        .load("http://via.placeholder.com/300.png")
        .bitmapTransform(new BlurTransformation(context, 25), new CropCircleTransformation(context))
        .into(ivImg);

Advanced Usages

Showing a ProgressBar

Add a ProgressBar or otherwise handle callbacks for an image that is loading:
progressBar.setVisibility(View.VISIBLE);

Glide.with(this)
        .load("http://via.placeholder.com/300.png")
        .listener(new RequestListener<String, GlideDrawable>() {
            @Override
            public boolean onException(Exception e, String model, Target<GlideDrawable> target, boolean isFirstResource) {
                progressBar.setVisibility(View.GONE);
                return false; // important to return false so the error placeholder can be placed
            }

            @Override
            public boolean onResourceReady(GlideDrawable resource, String model, Target<GlideDrawable> target, boolean isFromMemoryCache, boolean isFirstResource) {
                progressBar.setVisibility(View.GONE);
                return false;
            }
        })
        .into(ivImg);

Adjusting Image Size Dynamically

To readjust the ImageView size after the image has been retrieved, first define a SimpleTarget<Bitmap> object to intercept the Bitmap once it is loaded:
private SimpleTarget target = new SimpleTarget<Bitmap>() {  
    @Override
    public void onResourceReady(Bitmap bitmap, GlideAnimation glideAnimation) {
        // do something with the bitmap
        // set it to an ImageView
        imageView.setImageBitmap(bitmap);
    }
};
Next, pass the SimpleTarget to Glide via into():
Glide.with(context)
        .load("http://via.placeholder.com/300.png")
        .asBitmap()
        .into(target);
Note: The SimpleTarget object must be stored as a member field or method and cannot be an anonymous class otherwise this won't work as expected. The reason is that Glide accepts this parameter as a weak memory reference, and because anonymous classes are eligible for garbage collection when there are no more references, the network request to fetch the image may finish after this anonymous class has already been reclaimed. See this Stack Overflow discussion for more details.
In other words, you cannot do this all inline Glide.with(this).load("url").into(new SimpleTarget<Bitmap>() { ... }) as in other scenarios.

Networking

By default, Glide uses the Volley networking library.

Using with OkHttp

There is a way to use Glide to use OkHttp instead, which may be useful if you need to do authenticated requests. First, add the okhttp3-integration library as a dependency:
dependencies {
    compile 'com.github.bumptech.glide:okhttp3-integration:1.4.0@aar'
}
Next, you can configure Glide to use OkHttp in XML or through Java. The Java approach is useful especially if you already have a shared instance of OkHttpClient:
OkHttpClient okHttpClient = new OkHttpClient();
Glide.get(application).register(GlideUrl.class, InputStream.class, new OkHttpUrlLoader.Factory(okHttpClient));
Alternatively, you can declare Glide to use OkHttp by declaring it in your AndroidManifest.xml file:
<meta-data
    android:name="com.bumptech.glide.integration.okhttp3.OkHttpGlideModule"
    android:value="GlideModule" />
Review this section if are configuring Glide for use with ProGuard.

References

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