For #176 - Start swipe to close gesture

CHANGELOG.md

@@ -28,6 +28,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - #1397 - Adds favicons to the history view
 - #1375 - Added setting for turning off history suggestions
 - #1139 - Resolved a 170ms delay on cold start
+- #176 - Added a swipe to delete gesture on home screen
 
 ### Changed
 - #1429 - Updated site permissions ui for MVP

app/src/main/java/org/mozilla/fenix/home/sessioncontrol/SessionControlAdapter.kt

@@ -62,7 +62,10 @@ class SessionControlAdapter(
             TabHeaderViewHolder.LAYOUT_ID -> TabHeaderViewHolder(view, actionEmitter)
             TabViewHolder.LAYOUT_ID -> TabViewHolder(view, actionEmitter, job)
             ArchiveTabsViewHolder.LAYOUT_ID -> ArchiveTabsViewHolder(view, actionEmitter)
-            PrivateBrowsingDescriptionViewHolder.LAYOUT_ID -> PrivateBrowsingDescriptionViewHolder(view, actionEmitter)
+            PrivateBrowsingDescriptionViewHolder.LAYOUT_ID -> PrivateBrowsingDescriptionViewHolder(
+                view,
+                actionEmitter
+            )
             DeleteTabsViewHolder.LAYOUT_ID -> DeleteTabsViewHolder(view, actionEmitter)
             SessionHeaderViewHolder.LAYOUT_ID -> SessionHeaderViewHolder(view)
             SessionPlaceholderViewHolder.LAYOUT_ID -> SessionPlaceholderViewHolder(view)
@@ -87,7 +90,10 @@ class SessionControlAdapter(
 
     override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int) {
         when (holder) {
-            is TabViewHolder -> holder.bindSession((items[position] as AdapterItem.TabItem).tab, position)
+            is TabViewHolder -> holder.bindSession(
+                (items[position] as AdapterItem.TabItem).tab,
+                position
+            )
             is SessionViewHolder -> holder.bind((items[position] as AdapterItem.SessionItem).session)
         }
     }

app/src/main/java/org/mozilla/fenix/home/sessioncontrol/SessionControlUIView.kt

@@ -13,6 +13,7 @@ import io.reactivex.Observer
 import io.reactivex.functions.Consumer
 import org.mozilla.fenix.R
 import org.mozilla.fenix.mvi.UIView
+import androidx.recyclerview.widget.ItemTouchHelper
 
 // Convert HomeState into a data structure HomeAdapter understands
 @SuppressWarnings("ComplexMethod")
@@ -62,6 +63,13 @@ class SessionControlUIView(
         view.apply {
             adapter = sessionControlAdapter
             layoutManager = LinearLayoutManager(container.context)
+            val itemTouchHelper =
+                ItemTouchHelper(
+                    SwipeToDeleteCallback(
+                        actionEmitter
+                    )
+                )
+            itemTouchHelper.attachToRecyclerView(this)
         }
     }
 

app/src/main/java/org/mozilla/fenix/home/sessioncontrol/SwipeToDeleteCallback.kt

@@ -0,0 +1,152 @@
+/* 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.fenix.home.sessioncontrol
+
+import android.content.Context
+import android.content.res.Resources
+import android.graphics.Canvas
+import android.graphics.Paint
+import androidx.core.content.ContextCompat
+import androidx.recyclerview.widget.ItemTouchHelper
+import androidx.recyclerview.widget.RecyclerView
+import io.reactivex.Observer
+import org.mozilla.fenix.DefaultThemeManager
+import org.mozilla.fenix.R
+import org.mozilla.fenix.home.sessioncontrol.viewholders.SessionViewHolder
+import org.mozilla.fenix.home.sessioncontrol.viewholders.TabViewHolder
+import android.graphics.drawable.Drawable
+
+class SwipeToDeleteCallback(
+    val actionEmitter: Observer<SessionControlAction>
+) : ItemTouchHelper.SimpleCallback(0, ItemTouchHelper.LEFT or ItemTouchHelper.RIGHT) {
+    override fun onMove(
+        recyclerView: RecyclerView,
+        viewHolder: RecyclerView.ViewHolder,
+        target: RecyclerView.ViewHolder
+    ): Boolean {
+        // We don't support drag and drop so this method will never be called
+        return false
+    }
+
+    override fun onSwiped(viewHolder: RecyclerView.ViewHolder, direction: Int) {
+        if (viewHolder is TabViewHolder) {
+            actionEmitter.onNext(TabAction.Close(viewHolder.tab?.sessionId!!))
+        }
+        if (viewHolder is SessionViewHolder) {
+            viewHolder.session?.apply { actionEmitter.onNext(ArchivedSessionAction.Delete(this)) }
+        }
+    }
+
+    override fun onChildDraw(
+        c: Canvas,
+        recyclerView: RecyclerView,
+        viewHolder: RecyclerView.ViewHolder,
+        dX: Float,
+        dY: Float,
+        actionState: Int,
+        isCurrentlyActive: Boolean
+    ) {
+        super.onChildDraw(c, recyclerView, viewHolder, dX, dY, actionState, isCurrentlyActive)
+        val icon = ContextCompat.getDrawable(recyclerView.context, R.drawable.ic_delete)
+        val background = ContextCompat.getDrawable(
+            recyclerView.context,
+            R.drawable.session_background
+        )
+
+        background?.let {
+            icon?.let {
+                val itemView = viewHolder.itemView
+                val iconLeft: Int
+                val iconRight: Int
+                val margin = convertDpToPixel(MARGIN.toFloat())
+                val iconWidth = icon.intrinsicWidth
+                val iconHeight = icon.intrinsicHeight
+                val cellHeight = itemView.bottom - itemView.top
+                val iconTop = itemView.top + (cellHeight - iconHeight) / 2
+                val iconBottom = iconTop + iconHeight
+
+                when {
+                    dX > 0 -> { // Swiping to the right
+                        iconLeft = itemView.left + margin
+                        iconRight = itemView.left + margin + iconWidth
+                        background.setBounds(
+                            itemView.left, itemView.top,
+                            (itemView.left + dX).toInt() + BACKGROUND_CORNER_OFFSET,
+                            itemView.bottom
+                        )
+                        icon.setBounds(iconLeft, iconTop, iconRight, iconBottom)
+                        draw(background, icon, c, recyclerView.context, iconLeft, iconBottom)
+                    }
+                    dX < 0 -> { // Swiping to the left
+                        iconLeft = itemView.right - margin - iconWidth
+                        iconRight = itemView.right - margin
+                        background.setBounds(
+                            (itemView.right + dX).toInt() - BACKGROUND_CORNER_OFFSET,
+                            itemView.top, itemView.right, itemView.bottom
+                        )
+                        icon.setBounds(iconLeft, iconTop, iconRight, iconBottom)
+                        draw(background, icon, c, recyclerView.context, iconLeft, iconBottom)
+                    }
+                    else -> { // View not swiped
+                        background.setBounds(0, 0, 0, 0)
+                        icon.setBounds(0, 0, 0, 0)
+                    }
+                }
+            }
+        }
+    }
+
+    override fun getSwipeDirs(
+        recyclerView: RecyclerView,
+        viewHolder: RecyclerView.ViewHolder
+    ): Int {
+        return if (viewHolder is TabViewHolder || viewHolder is SessionViewHolder) super.getSwipeDirs(
+            recyclerView,
+            viewHolder
+        ) else 0
+    }
+
+    companion object {
+        const val BACKGROUND_CORNER_OFFSET = 40
+        const val MARGIN = 32
+        const val TEXT_MARGIN = 12
+        const val TEXT_SIZE = 36f
+        const val TEXT_MARGIN_X = 14
+        const val DENSITY_CONVERSION = 160f
+
+        @Suppress("LongParameterList")
+        private fun draw(
+            background: Drawable,
+            icon: Drawable,
+            c: Canvas,
+            context: Context,
+            iconLeft: Int,
+            iconBottom: Int
+        ) {
+            background.draw(c)
+            icon.draw(c)
+            val textPaint = Paint()
+            textPaint.color = ContextCompat.getColor(
+                context,
+                DefaultThemeManager.resolveAttribute(R.attr.deleteColor, context)
+            )
+            textPaint.textSize = TEXT_SIZE
+            val textX = iconLeft - TEXT_MARGIN_X
+            val textY = iconBottom + convertDpToPixel(TEXT_MARGIN.toFloat())
+            c.drawText(
+                context.getString(R.string.current_session_delete),
+                textX.toFloat(),
+                textY.toFloat(),
+                textPaint
+            )
+        }
+
+        private fun convertDpToPixel(dp: Float): Int {
+            val metrics = Resources.getSystem().displayMetrics
+            val px = dp * (metrics.densityDpi / DENSITY_CONVERSION)
+            return Math.round(px)
+        }
+    }
+}

app/src/main/java/org/mozilla/fenix/home/sessioncontrol/viewholders/SessionViewHolder.kt

@@ -89,7 +89,7 @@ class SessionViewHolder(
     private val actionEmitter: Observer<SessionControlAction>,
     override val containerView: View? = view
 ) : RecyclerView.ViewHolder(view), LayoutContainer {
-    private var session: ArchivedSession? = null
+    internal var session: ArchivedSession? = null
 
     init {
         session_item.setOnClickListener {

app/src/main/res/drawable/session_background.xml

@@ -3,9 +3,8 @@
    - 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/. -->
 
-<shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle" >
-    <solid android:color="@color/photonGrey40" />
-    <corners
-        android:bottomLeftRadius="8dp"
-        android:bottomRightRadius="8dp" />
-</shape>
+<shape xmlns:android="http://schemas.android.com/apk/res/android"
+    android:shape="rectangle">
+    <corners android:radius="8dp" />
+    <solid android:color="@color/photonGrey30" />
+</shape>