Issue mozilla-mobile#6827: Move Thumbnails into its own browser compo…

…nent

.buildconfig.yml

@@ -212,6 +212,10 @@ projects:
     path: components/browser/tabstray
     description: 'A tabs tray component for browsers.'
     publish: true
+  browser-thumbnails:
+    path: components/browser/thumbnails
+    description: 'A component for loading and storing website thumbnails.'
+    publish: true
   browser-toolbar:
     path: components/browser/toolbar
     description: 'A customizable toolbar for browsers.'

components/browser/thumbnails/README.md

@@ -0,0 +1,19 @@
+# [Android Components](../../../README.md) > Browser > Thumbnails
+
+A component for loading and storing website thumbnails (screenshot of the website).
+
+## Usage
+
+### Setting up the dependency
+
+Use Gradle to download the library from [maven.mozilla.org](https://maven.mozilla.org/) ([Setup repository](../../../README.md#maven-repository)):
+
+```Groovy
+implementation "org.mozilla.components:browser-thumbnails:{latest-version}"
+```
+
+## License
+
+    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/

components/browser/thumbnails/build.gradle

@@ -0,0 +1,47 @@
+/* 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/. */
+
+apply plugin: 'com.android.library'
+apply plugin: 'kotlin-android'
+
+android {
+    compileSdkVersion config.compileSdkVersion
+
+    defaultConfig {
+        minSdkVersion config.minSdkVersion
+        targetSdkVersion config.targetSdkVersion
+        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
+    }
+
+    buildTypes {
+        release {
+            minifyEnabled false
+            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
+        }
+    }
+
+    packagingOptions {
+        exclude 'META-INF/proguard/androidx-annotations.pro'
+    }
+}
+
+dependencies {
+    implementation project(':support-ktx')
+    implementation project(':concept-engine')
+    implementation project(':browser-session')
+
+    implementation Dependencies.androidx_annotation
+
+    testImplementation project(':support-test')
+
+    testImplementation Dependencies.androidx_test_junit
+    testImplementation Dependencies.testing_mockito
+
+    androidTestImplementation Dependencies.androidx_test_core
+    androidTestImplementation Dependencies.androidx_test_runner
+    androidTestImplementation Dependencies.androidx_test_rules
+}
+
+apply from: '../../../publish.gradle'
+ext.configurePublish(config.componentsGroupId, archivesBaseName, project.ext.description)

components/browser/thumbnails/proguard-rules.pro

@@ -0,0 +1,21 @@
+# Add project specific ProGuard rules here.
+# You can control the set of applied configuration files using the
+# proguardFiles setting in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}
+
+# Uncomment this to preserve the line number information for
+# debugging stack traces.
+#-keepattributes SourceFile,LineNumberTable
+
+# If you keep the line number information, uncomment this to
+# hide the original source file name.
+#-renamesourcefileattribute SourceFile

components/browser/thumbnails/src/main/AndroidManifest.xml

@@ -0,0 +1,5 @@
+<!-- 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/. -->
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="mozilla.components.browser.thumbnails" />

components/browser/thumbnails/src/main/java/mozilla/components/browser/thumbnails/BrowserThumbnails.kt

@@ -0,0 +1,72 @@
+/* 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 mozilla.components.browser.thumbnails
+
+import android.content.Context
+import androidx.annotation.VisibleForTesting
+import mozilla.components.browser.session.SelectionAwareSessionObserver
+import mozilla.components.browser.session.Session
+import mozilla.components.browser.session.SessionManager
+import mozilla.components.concept.engine.EngineView
+import mozilla.components.support.base.feature.LifecycleAwareFeature
+import mozilla.components.support.ktx.android.content.isOSOnLowMemory
+
+/**
+ * Feature implementation for automatically taking thumbnails of sites.
+ * The feature will take a screenshot when the page finishes loading,
+ * and will add it to the [Session.thumbnail] property.
+ *
+ * If the OS is under low memory conditions, the screenshot will be not taken.
+ * Ideally, this should be used in conjunction with [SessionManager.onLowMemory] to allow
+ * free up some [Session.thumbnail] from memory.
+ */
+class BrowserThumbnails(
+    private val context: Context,
+    private val engineView: EngineView,
+    sessionManager: SessionManager
+) : LifecycleAwareFeature {
+
+    private val observer = ThumbnailsRequestObserver(sessionManager)
+
+    /**
+     * Starts observing the selected session to listen for when a session finish loading.
+     */
+    override fun start() {
+        observer.observeSelected()
+    }
+
+    /**
+     * Stops observing the selected session.
+     */
+    override fun stop() {
+        observer.stop()
+    }
+
+    internal inner class ThumbnailsRequestObserver(
+        sessionManager: SessionManager
+    ) : SelectionAwareSessionObserver(sessionManager) {
+
+        override fun onLoadingStateChanged(session: Session, loading: Boolean) {
+            if (!loading) {
+                requestScreenshot(session)
+            }
+        }
+    }
+
+    private fun requestScreenshot(session: Session) {
+        if (!isLowOnMemory()) {
+            engineView.captureThumbnail {
+                session.thumbnail = it
+            }
+        } else {
+            session.thumbnail = null
+        }
+    }
+
+    @VisibleForTesting
+    internal var testLowMemory = false
+
+    private fun isLowOnMemory() = testLowMemory || context.isOSOnLowMemory()
+}

components/browser/thumbnails/src/test/java/mozilla/components/browser/thumbnails/BrowserThumbnailsTest.kt

@@ -0,0 +1,88 @@
+/* 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 mozilla.components.browser.thumbnails
+
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import mozilla.components.browser.session.Session
+import mozilla.components.browser.session.SessionManager
+import mozilla.components.concept.engine.Engine
+import mozilla.components.concept.engine.EngineView
+import mozilla.components.support.test.any
+import mozilla.components.support.test.mock
+import mozilla.components.support.test.robolectric.testContext
+import org.junit.Assert.assertNull
+import org.junit.Before
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.mockito.Mockito.never
+import org.mockito.Mockito.spy
+import org.mockito.Mockito.verify
+
+@RunWith(AndroidJUnit4::class)
+class BrowserThumbnailsTest {
+
+    private lateinit var mockSessionManager: SessionManager
+    private lateinit var mockEngineView: EngineView
+    private lateinit var thumbnails: BrowserThumbnails
+
+    @Before
+    fun setup() {
+        val engine = mock<Engine>()
+        mockSessionManager = spy(SessionManager(engine))
+        mockEngineView = mock()
+        thumbnails = BrowserThumbnails(testContext, mockEngineView, mockSessionManager)
+    }
+
+    @Test
+    fun `when feature is stop must not capture thumbnail when a site finish loading`() {
+        thumbnails.start()
+        thumbnails.stop()
+
+        val session = getSelectedSession()
+
+        session.notifyObservers {
+            onLoadingStateChanged(session, false)
+        }
+
+        verify(mockEngineView, never()).captureThumbnail(any())
+    }
+
+    @Test
+    fun `feature must capture thumbnail when a site finish loading`() {
+        thumbnails.start()
+
+        val session = getSelectedSession()
+
+        session.notifyObservers {
+            onLoadingStateChanged(session, false)
+        }
+
+        verify(mockEngineView).captureThumbnail(any())
+    }
+
+    @Test
+    fun `when a page is loaded and the os is in low memory condition none thumbnail should be captured`() {
+        thumbnails.start()
+
+        val session = getSelectedSession()
+        session.thumbnail = mock()
+
+        thumbnails.testLowMemory = true
+
+        session.notifyObservers {
+            onLoadingStateChanged(session, false)
+        }
+
+        verify(mockEngineView, never()).captureThumbnail(any())
+        assertNull(session.thumbnail)
+    }
+
+    private fun getSelectedSession(): Session {
+        val session = Session("https://www.mozilla.org")
+        mockSessionManager.add(session)
+        mockSessionManager.select(session)
+        return session
+    }
+}

samples/browser/build.gradle

@@ -73,6 +73,7 @@ dependencies {
     implementation project(':browser-session')
     implementation project(':browser-state')
     implementation project(':browser-tabstray')
+    implementation project(':browser-thumbnails')
     implementation project(':browser-toolbar')
     implementation project(':browser-menu')
     implementation project(':browser-storage-memory')

samples/browser/src/main/java/org/mozilla/samples/browser/BrowserFragment.kt

@@ -9,10 +9,10 @@ import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
 import kotlinx.android.synthetic.main.fragment_browser.view.*
+import mozilla.components.browser.thumbnails.BrowserThumbnails
 import mozilla.components.feature.awesomebar.AwesomeBarFeature
 import mozilla.components.feature.awesomebar.provider.SearchSuggestionProvider
 import mozilla.components.feature.search.SearchFeature
-import mozilla.components.feature.session.ThumbnailsFeature
 import mozilla.components.feature.tabs.WindowFeature
 import mozilla.components.feature.tabs.toolbar.TabsToolbarFeature
 import mozilla.components.feature.toolbar.ToolbarAutocompleteFeature
@@ -26,7 +26,7 @@ import org.mozilla.samples.browser.integration.ReaderViewIntegration
  * Fragment used for browsing the web within the main app.
  */
 class BrowserFragment : BaseBrowserFragment(), UserInteractionHandler {
-    private val thumbnailsFeature = ViewBoundFeatureWrapper<ThumbnailsFeature>()
+    private val thumbnailsFeature = ViewBoundFeatureWrapper<BrowserThumbnails>()
     private val readerViewFeature = ViewBoundFeatureWrapper<ReaderViewIntegration>()
     private val webExtToolbarFeature = ViewBoundFeatureWrapper<WebExtensionToolbarFeature>()
     private val searchFeature = ViewBoundFeatureWrapper<SearchFeature>()
@@ -81,7 +81,7 @@ class BrowserFragment : BaseBrowserFragment(), UserInteractionHandler {
         )
 
         thumbnailsFeature.set(
-            feature = ThumbnailsFeature(requireContext(), layout.engineView, components.sessionManager),
+            feature = BrowserThumbnails(requireContext(), layout.engineView, components.sessionManager),
             owner = this,
             view = layout
         )