The question is published on by Tutorial Guruji team.
I’m trying to load images asynchronously into a CardPresenter in Leanback like this.
public interface CustomImageModel {
String requestCustomUrl(int width, int height);
}
public static class CustomImageModelGrabber implements CustomImageModel {
public CustomImageModelGrabber() {
}
@Override
public String requestCustomUrl(int width, int height) {
OkHttpClient client = new OkHttpClient;
Request request = new Request.Builder().url(image_url).build();
return client.newCall(request).execute().body().string();
}
}
public static class CustomImageUrlLoader extends BaseGlideUrlLoader<CustomImageModel> {
public CustomImageUrlLoader(Context context) {
super( context );
}
@Override
protected String getUrl(CustomImageModel model, int width, int height) {
return model.requestCustomUrl();
}
}
In CardPresenter.java
@Override
public void onBindViewHolder(Presenter.ViewHolder viewHolder, Object item) {
CustomImageModel customImageRequest = new CustomImageModelGrabber();
Glide
.with( context )
.using( new CustomImageUrlLoader( context ) )
.load( customImageRequest )
.into( imageView1 );
}
Unfortunately this doesn’t work as expected. Only a few images are loaded correctly into the card presenter, but most of them are not, and the following error is thrown:
android.os.NetworkOnMainThreadException android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1303)
It’s totally random which work and which don’t.
I also tried setting the strict mode in MainActivity.java.
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build(); StrictMode.setThreadPolicy(policy);
While this solution loads all images correctly and doesn’t throw any NetworkOnMainThreadException errors, it comes with huge performance issues. The scrolling becomes slow and laggy, showing me the following message:
I/Choreographer: Skipped 182 frames! The application may be doing too much work on its main thread.
Is there any solution to make the images load asynchronously while still maintaining a smooth and good performance?
Answer
My approach was totally wrong. I thought that BaseGlideUrlLoader runs on a background-thread, but it doesn’t.
So the code to go is the following:
@Override
public void onBindViewHolder(Presenter.ViewHolder viewHolder, Object item) {
final ImageCardView cardView = (ImageCardView) viewHolder.view;
OkHttpClient client = new OkHttpClient;
Request request = new Request.Builder().url(image_url).build();
client.newCall(request).enqueue(new Callback() {
@Override public void onFailure(Call call, IOException e) {
e.printStackTrace();
}
@Override public void onResponse(Call call, Response response) throws IOException {
try (ResponseBody responseBody = response.body()) {
if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);
String imageFromResponse = responseBody.string();
// do whatever is needed to get the image (i.e JSON-handling)
Handler mainHandler = new Handler(Looper.getMainLooper());
Runnable myRunnable = new Runnable() {
@Override
public void run() {
Glide.with(cardView.getContext())
.load(imagefromResponse)
.error(mDefaultCardImage)
.into(cardView.getMainImageView());
}
};
}
});
}