Bug 1301718: Add StreamPageIconLayout. r=liuche

This will be used by highlights, top sites, and the AS bottom sheet to set
their icons.

I chose to use centerCrop, over centerInside, because the mocks look like they
chose to do a center crop scale pattern:
https://mozilla.invisionapp.com/share/5JCHCGXPG#/screens/224085516

To my reviewer: some of this code comes from the next commit, where it is moved
from the Highlights code to this file.

MozReview-Commit-ID: 8rtTpjW8noL

--HG--
extra : rebase_source : e0cd3213174d6cd6f42fa84e41fe7335049b6d97

mobile/android/app/src/main/res/layout/activity_stream_page_icon_layout.xml

@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+<merge xmlns:android="http://schemas.android.com/apk/res/android"
+       xmlns:gecko="http://schemas.android.com/tools">
+
+    <!-- The default visibilities are set in code. -->
+    <org.mozilla.gecko.widget.FaviconView
+            android:id="@+id/favicon_view"
+            android:layout_width="match_parent"
+            android:layout_height="match_parent"
+            gecko:enableRoundCorners="false"
+            />
+
+    <ImageView
+            android:id="@+id/image_view"
+            android:layout_width="match_parent"
+            android:layout_height="match_parent"
+            />
+
+</merge>

mobile/android/base/java/org/mozilla/gecko/activitystream/homepanel/stream/StreamPageIconLayout.java

@@ -0,0 +1,118 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package org.mozilla.gecko.activitystream.homepanel.stream;
+
+import android.content.Context;
+import android.net.Uri;
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
+import android.text.TextUtils;
+import android.util.AttributeSet;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.widget.FrameLayout;
+import android.widget.ImageView;
+import com.squareup.picasso.Picasso;
+import org.mozilla.gecko.R;
+import org.mozilla.gecko.icons.IconCallback;
+import org.mozilla.gecko.icons.IconResponse;
+import org.mozilla.gecko.icons.Icons;
+import org.mozilla.gecko.widget.FaviconView;
+
+import java.util.concurrent.Future;
+
+/**
+ * A layout that represents page icons in Activity Stream.
+ *
+ * Under the hood, it switches between multiple icon views because favicons (in FaviconView)
+ * are handled differently from other types of page images.
+ *
+ * An alternative implementation would create a flag to override FaviconView to handle non-favicon images but I
+ * found it to be more complicated: all code added to FaviconView has to be aware of which state it's in. This
+ * composable switcher layout abstracts the switching state from the FaviconView and keeps it simple, but will
+ * use slightly more resources.
+ */
+public class StreamPageIconLayout extends FrameLayout implements IconCallback {
+
+    private enum UIMode {
+        FAVICON_IMAGE, NONFAVICON_IMAGE
+    }
+
+    private FaviconView faviconView;
+    private ImageView imageView;
+
+    private @Nullable Future<IconResponse> ongoingFaviconLoad;
+
+    public StreamPageIconLayout(final Context context, final AttributeSet attrs) {
+        super(context, attrs);
+        LayoutInflater.from(context).inflate(R.layout.activity_stream_page_icon_layout, this, true);
+        initViews();
+    }
+
+    /**
+     * Updates the icon for the view. If a non-null overrideImageURL is provided, this image will be shown.
+     * Otherwise, a favicon will be retrieved for the given pageURL.
+     */
+    public void updateIcon(@NonNull final String pageURL, @Nullable final String overrideImageURL) {
+        cancelPendingRequests();
+
+        if (!TextUtils.isEmpty(overrideImageURL)) {
+            setUIMode(UIMode.NONFAVICON_IMAGE);
+
+            // TODO (bug 1322501): Optimization: since we've already navigated to these pages, there's a chance
+            // Gecko has the image in its cache: we should try to get it first before making this network request.
+            Picasso.with(getContext())
+                    .load(Uri.parse(overrideImageURL))
+                    .fit()
+                    .centerCrop()
+                    .into(imageView);
+        } else {
+            setUIMode(UIMode.FAVICON_IMAGE);
+
+            ongoingFaviconLoad = Icons.with(getContext())
+                    .pageUrl(pageURL)
+                    .skipNetwork()
+                    .build()
+                    .execute(this);
+        }
+    }
+
+    @Override
+    public void onIconResponse(final IconResponse response) {
+        faviconView.updateImage(response);
+    }
+
+    private void setUIMode(final UIMode uiMode) {
+        final View viewToShow;
+        final View viewToHide;
+        if (uiMode == UIMode.FAVICON_IMAGE) {
+            viewToShow = faviconView;
+            viewToHide = imageView;
+        } else {
+            viewToShow = imageView;
+            viewToHide = faviconView;
+        }
+
+        viewToShow.setVisibility(View.VISIBLE);
+        viewToHide.setVisibility(View.GONE);
+    }
+
+
+    private void cancelPendingRequests() {
+        Picasso.with(getContext())
+                .cancelRequest(imageView);
+
+        if (ongoingFaviconLoad != null) {
+            ongoingFaviconLoad.cancel(true);
+            ongoingFaviconLoad = null;
+        }
+    }
+
+    private void initViews() {
+        faviconView = (FaviconView) findViewById(R.id.favicon_view);
+        imageView = (ImageView) findViewById(R.id.image_view);
+        setUIMode(UIMode.FAVICON_IMAGE); // set in code to ensure state is consistent.
+    }
+}

mobile/android/base/moz.build

@@ -518,6 +518,7 @@ gbjar.sources += ['java/org/mozilla/gecko/' + x for x in [
     'activitystream/homepanel/stream/HighlightItem.java',
     'activitystream/homepanel/stream/HighlightsTitle.java',
     'activitystream/homepanel/stream/StreamItem.java',
+    'activitystream/homepanel/stream/StreamPageIconLayout.java',
     'activitystream/homepanel/stream/TopPanel.java',
     'activitystream/homepanel/stream/WelcomePanel.java',
     'activitystream/homepanel/StreamItemAnimator.java',