Java tutorial
/* Copyright 2017 Andrew Dawson * * This file is a part of Tusky. * * This program is free software; you can redistribute it and/or modify it under the terms of the * GNU General Public License as published by the Free Software Foundation; either version 3 of the * License, or (at your option) any later version. * * Tusky is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even * the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General * Public License for more details. * * You should have received a copy of the GNU General Public License along with Tusky; if not, * see <http://www.gnu.org/licenses>. */ package com.keylesspalace.tusky.fragment; import android.animation.Animator; import android.animation.AnimatorListenerAdapter; import android.content.Context; import android.os.Bundle; import android.support.annotation.NonNull; import android.support.annotation.Nullable; import android.support.v4.view.ViewCompat; import android.text.TextUtils; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.ImageView; import android.widget.TextView; import com.github.chrisbanes.photoview.PhotoView; import com.github.chrisbanes.photoview.PhotoViewAttacher; import com.keylesspalace.tusky.R; import com.keylesspalace.tusky.ViewMediaActivity; import com.keylesspalace.tusky.entity.Attachment; import com.squareup.picasso.Callback; import com.squareup.picasso.NetworkPolicy; import com.squareup.picasso.Picasso; import java.util.Objects; import kotlin.jvm.functions.Function0; public final class ViewMediaFragment extends BaseFragment { public interface PhotoActionsListener { void onBringUp(); void onDismiss(); void onPhotoTap(); } private PhotoViewAttacher attacher; private PhotoActionsListener photoActionsListener; private View rootView; private PhotoView photoView; private TextView descriptionView; private boolean showingDescription; private boolean isDescriptionVisible; private Function0 toolbarVisibiltyDisposable; private static final String ARG_START_POSTPONED_TRANSITION = "startPostponedTransition"; private static final String ARG_ATTACHMENT = "attach"; private static final String ARG_AVATAR_URL = "avatarUrl"; public static ViewMediaFragment newInstance(@NonNull Attachment attachment, boolean shouldStartPostponedTransition) { Bundle arguments = new Bundle(2); ViewMediaFragment fragment = new ViewMediaFragment(); arguments.putParcelable(ARG_ATTACHMENT, attachment); arguments.putBoolean(ARG_START_POSTPONED_TRANSITION, shouldStartPostponedTransition); fragment.setArguments(arguments); return fragment; } public static ViewMediaFragment newAvatarInstance(@NonNull String avatarUrl) { Bundle arguments = new Bundle(2); ViewMediaFragment fragment = new ViewMediaFragment(); arguments.putString(ARG_AVATAR_URL, avatarUrl); arguments.putBoolean(ARG_START_POSTPONED_TRANSITION, true); fragment.setArguments(arguments); return fragment; } @Override public void onAttach(Context context) { super.onAttach(context); photoActionsListener = (PhotoActionsListener) context; } @Override public View onCreateView(@NonNull LayoutInflater inflater, final ViewGroup container, Bundle savedInstanceState) { rootView = inflater.inflate(R.layout.fragment_view_media, container, false); photoView = rootView.findViewById(R.id.view_media_image); descriptionView = rootView.findViewById(R.id.tv_media_description); final Bundle arguments = Objects.requireNonNull(getArguments(), "Empty arguments"); final Attachment attachment = arguments.getParcelable(ARG_ATTACHMENT); final String url; if (attachment != null) { url = attachment.getUrl(); @Nullable final String description = attachment.getDescription(); descriptionView.setText(description); showingDescription = !TextUtils.isEmpty(description); isDescriptionVisible = showingDescription; } else { url = arguments.getString(ARG_AVATAR_URL); if (url == null) { throw new IllegalArgumentException("attachment or avatar url has to be set"); } showingDescription = false; isDescriptionVisible = false; } // Setting visibility without animations so it looks nice when you scroll images //noinspection ConstantConditions descriptionView.setVisibility( showingDescription && (((ViewMediaActivity) getActivity())).isToolbarVisible() ? View.VISIBLE : View.GONE); attacher = new PhotoViewAttacher(photoView); // Clicking outside the photo closes the viewer. attacher.setOnOutsidePhotoTapListener(imageView -> photoActionsListener.onDismiss()); attacher.setOnClickListener(v -> onMediaTap()); /* A vertical swipe motion also closes the viewer. This is especially useful when the photo * mostly fills the screen so clicking outside is difficult. */ attacher.setOnSingleFlingListener((e1, e2, velocityX, velocityY) -> { if (Math.abs(velocityY) > Math.abs(velocityX)) { photoActionsListener.onDismiss(); return true; } return false; }); ViewCompat.setTransitionName(photoView, url); // If we are the view to be shown initially... if (arguments.getBoolean(ARG_START_POSTPONED_TRANSITION)) { // Try to load image from disk. Picasso.with(getContext()).load(url).noFade().networkPolicy(NetworkPolicy.OFFLINE).into(photoView, new Callback() { @Override public void onSuccess() { // if we loaded image from disk, we should check that view is attached. if (ViewCompat.isAttachedToWindow(photoView)) { finishLoadingSuccessfully(); } else { // if view is not attached yet, wait for an attachment and // start transition when it's finally ready. photoView.addOnAttachStateChangeListener(new View.OnAttachStateChangeListener() { @Override public void onViewAttachedToWindow(View v) { finishLoadingSuccessfully(); photoView.removeOnAttachStateChangeListener(this); } @Override public void onViewDetachedFromWindow(View v) { } }); } } @Override public void onError() { // if there's no image in cache, load from network and start transition // immediately. photoActionsListener.onBringUp(); loadImageFromNetwork(url, photoView); } }); } else { // if we're not initial page, don't bother. loadImageFromNetwork(url, photoView); } toolbarVisibiltyDisposable = ((ViewMediaActivity) getActivity()) .addToolbarVisibilityListener(this::onToolbarVisibilityChange); return rootView; } @Override public void onDestroyView() { if (toolbarVisibiltyDisposable != null) toolbarVisibiltyDisposable.invoke(); super.onDestroyView(); } private void onMediaTap() { photoActionsListener.onPhotoTap(); } private void onToolbarVisibilityChange(boolean visible) { isDescriptionVisible = showingDescription && visible; final int visibility = isDescriptionVisible ? View.VISIBLE : View.INVISIBLE; int alpha = isDescriptionVisible ? 1 : 0; descriptionView.animate().alpha(alpha).setListener(new AnimatorListenerAdapter() { @Override public void onAnimationEnd(Animator animation) { descriptionView.setVisibility(visibility); animation.removeListener(this); } }).start(); } @Override public void onDetach() { super.onDetach(); Picasso.with(getContext()).cancelRequest(photoView); } private void loadImageFromNetwork(String url, ImageView photoView) { Picasso.with(getContext()).load(url).noPlaceholder().networkPolicy(NetworkPolicy.NO_STORE).into(photoView, new Callback() { @Override public void onSuccess() { finishLoadingSuccessfully(); } @Override public void onError() { rootView.findViewById(R.id.view_media_progress).setVisibility(View.GONE); } }); } private void finishLoadingSuccessfully() { rootView.findViewById(R.id.view_media_progress).setVisibility(View.GONE); attacher.update(); photoActionsListener.onBringUp(); } }