tachiyomi/app/src/main/java/eu/kanade/mangafeed/ui/fragment/ReaderPageFragment.java

package eu.kanade.mangafeed.ui.fragment;

import android.os.Bundle;
import android.support.annotation.Nullable;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.LinearLayout;
import android.widget.ProgressBar;
import android.widget.TextView;

import com.davemorrissey.labs.subscaleview.ImageSource;
import com.davemorrissey.labs.subscaleview.SubsamplingScaleImageView;

import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;

import butterknife.Bind;
import butterknife.ButterKnife;
import eu.kanade.mangafeed.R;
import eu.kanade.mangafeed.data.models.Page;
import eu.kanade.mangafeed.ui.activity.ReaderActivity;
import eu.kanade.mangafeed.ui.fragment.base.BaseFragment;
import rx.Observable;
import rx.Subscription;
import rx.android.schedulers.AndroidSchedulers;
import rx.schedulers.Schedulers;
import rx.subjects.PublishSubject;

public class ReaderPageFragment extends BaseFragment {

    @Bind(R.id.page_image_view) SubsamplingScaleImageView imageView;
    @Bind(R.id.progress_container) LinearLayout progressContainer;
    @Bind(R.id.progress) ProgressBar progressBar;
    @Bind(R.id.progress_text) TextView progressText;
    @Bind(R.id.image_error) TextView errorText;

    private Page page;
    private Subscription progressSubscription;
    private Subscription statusSubscription;

    public static ReaderPageFragment newInstance(Page page) {
        ReaderPageFragment fragment = new ReaderPageFragment();
        fragment.setPage(page);
        return fragment;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setRetainInstance(true);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_page, container, false);
        ButterKnife.bind(this, view);

        imageView.setDoubleTapZoomStyle(SubsamplingScaleImageView.ZOOM_FOCUS_FIXED);
        imageView.setPanLimit(SubsamplingScaleImageView.PAN_LIMIT_INSIDE);
        imageView.setMinimumScaleType(SubsamplingScaleImageView.SCALE_TYPE_CENTER_INSIDE);
        imageView.setOnTouchListener((v, motionEvent) ->
                ((ReaderActivity) getActivity()).onImageSingleTap(motionEvent));

        return view;
    }

    public void onStart() {
        super.onStart();
        observeStatus();
    }

    @Override
    public void onStop() {
        unsubscribeProgress();
        unsubscribeStatus();
        super.onStop();
    }

    public void setPage(Page page) {
        this.page = page;
    }

    private void showImage() {
        if (page == null || page.getImagePath() == null)
            return;

        imageView.setImage(ImageSource.uri(page.getImagePath()).tilingDisabled());
        progressContainer.setVisibility(View.GONE);
    }

    private void showDownloading() {
        progressText.setVisibility(View.VISIBLE);
    }

    private void showLoading() {
        progressText.setVisibility(View.VISIBLE);
        progressText.setText(R.string.downloading);
    }

    private void showError() {
        progressContainer.setVisibility(View.GONE);
        errorText.setVisibility(View.VISIBLE);
    }

    private void processStatus(int status) {
        switch (status) {
            case Page.LOAD_PAGE:
                showLoading();
                break;
            case Page.DOWNLOAD_IMAGE:
                observeProgress();
                showDownloading();
                break;
            case Page.READY:
                showImage();
                unsubscribeProgress();
                unsubscribeStatus();
                break;
            case Page.ERROR:
                showError();
                unsubscribeProgress();
                break;
        }
    }

    private void observeStatus() {
        if (page == null || statusSubscription != null)
            return;

        PublishSubject<Integer> statusSubject = PublishSubject.create();
        page.setStatusSubject(statusSubject);

        statusSubscription = statusSubject
                .startWith(page.getStatus())
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe(this::processStatus);
    }

    private void observeProgress() {
        if (progressSubscription != null)
            return;

        final AtomicInteger currentValue = new AtomicInteger(-1);

        progressSubscription = Observable.interval(75, TimeUnit.MILLISECONDS)
                .subscribeOn(Schedulers.io())
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe(tick -> {
                    // Refresh UI only if progress change
                    if (page.getProgress() != currentValue.get()) {
                        currentValue.set(page.getProgress());
                        progressText.setText(getString(R.string.download_progress, page.getProgress()));
                    }
                });
    }

    private void unsubscribeStatus() {
        if (statusSubscription != null) {
            page.setStatusSubject(null);
            statusSubscription.unsubscribe();
            statusSubscription = null;
        }
    }

    private void unsubscribeProgress() {
        if (progressSubscription != null) {
            progressSubscription.unsubscribe();
            progressSubscription = null;
        }
    }

}