WIP

ground/src/main/java/com/google/android/ground/Config.kt

@@ -26,7 +26,7 @@ object Config {
 
   // Local db settings.
   // TODO(#128): Reset version to 1 before releasing.
-  const val DB_VERSION = 103
+  const val DB_VERSION = 104
   const val DB_NAME = "ground.db"
 
   // Firebase Cloud Firestore settings.

ground/src/main/java/com/google/android/ground/repository/OfflineAreaRepository.kt

@@ -114,4 +114,10 @@ constructor(
   private fun getFirstTileSourceUrl() =
     surveyRepository.activeSurvey?.tileSources?.firstOrNull()?.url
       ?: error("Survey has no tile sources")
+
+  suspend fun estimateSizeOnDisk(bounds: Bounds): Int {
+    val client = getMogClient()
+    val requests = client.buildTilesRequests(bounds.toGoogleMapsObject())
+    return requests.sumOf { it.totalBytes }
+  }
 }

ground/src/main/java/com/google/android/ground/ui/offlinebasemap/selector/OfflineAreaSelectorViewModel.kt

@@ -17,6 +17,7 @@ package com.google.android.ground.ui.offlinebasemap.selector
 
 import androidx.lifecycle.MutableLiveData
 import androidx.lifecycle.viewModelScope
+import com.google.android.ground.R
 import com.google.android.ground.coroutines.IoDispatcher
 import com.google.android.ground.model.imagery.TileSource
 import com.google.android.ground.repository.LocationOfInterestRepository
@@ -30,12 +31,17 @@ import com.google.android.ground.ui.common.BaseMapViewModel
 import com.google.android.ground.ui.common.Navigator
 import com.google.android.ground.ui.common.SharedViewModel
 import com.google.android.ground.ui.map.Bounds
+import com.google.android.ground.ui.map.CameraPosition
 import com.google.android.ground.ui.map.Map
 import com.google.android.ground.ui.map.MapType
 import javax.inject.Inject
+import kotlin.math.round
 import kotlinx.coroutines.CoroutineDispatcher
 import kotlinx.coroutines.launch
 
+private const val MIN_DOWNLOAD_ZOOM_LEVEL = 10
+private const val MAX_AREA_DOWNLOAD_SIZE_MB = 50
+
 /** States and behaviors of Map UI used to select areas for download and viewing offline. */
 @SharedViewModel
 class OfflineAreaSelectorViewModel
@@ -67,6 +73,9 @@ internal constructor(
   val isDownloadProgressVisible = MutableLiveData(false)
   val downloadProgressMax = MutableLiveData(0)
   val downloadProgress = MutableLiveData(0)
+  val sizeOnDisk = MutableLiveData<String>(null)
+  val visibleBottomTextView = MutableLiveData<Int>(null)
+  val downloadButtonEnabled = MutableLiveData(false)
 
   init {
     tileSources = surveyRepository.activeSurvey!!.tileSources
@@ -81,11 +90,11 @@ internal constructor(
     isDownloadProgressVisible.value = true
     downloadProgress.value = 0
     viewModelScope.launch(ioDispatcher) {
-      offlineAreaRepository.downloadTiles(viewport!!).collect { (byteDownloaded, totalBytes) ->
+      offlineAreaRepository.downloadTiles(viewport!!).collect { (bytesDownloaded, totalBytes) ->
         // Set total bytes / max value on first iteration.
         if (downloadProgressMax.value != totalBytes) downloadProgressMax.postValue(totalBytes)
         // Add number of bytes downloaded to progress.
-        downloadProgress.postValue(byteDownloaded)
+        downloadProgress.postValue(bytesDownloaded)
       }
       isDownloadProgressVisible.postValue(false)
       navigator.navigateUp()
@@ -97,4 +106,31 @@ internal constructor(
     tileSources.forEach { map.addTileOverlay(it) }
     disposeOnClear(cameraBoundUpdates.subscribe { viewport = it })
   }
+
+  override fun onMapCameraMoved(newCameraPosition: CameraPosition) {
+    super.onMapCameraMoved(newCameraPosition)
+    val (_, zoomLevel, _, bounds) = newCameraPosition
+    if (bounds == null || zoomLevel == null) return
+    if (zoomLevel < MIN_DOWNLOAD_ZOOM_LEVEL) {
+      visibleBottomTextView.value = R.id.area_too_large_text_view
+      downloadButtonEnabled.value = false
+    } else {
+      sizeOnDisk.value = "…"
+      visibleBottomTextView.value = R.id.size_on_disk_text_view
+      viewModelScope.launch(ioDispatcher) {
+        val size = offlineAreaRepository.estimateSizeOnDisk(bounds) / (1024f * 1024f)
+        if (size > MAX_AREA_DOWNLOAD_SIZE_MB) {
+          visibleBottomTextView.postValue(R.id.area_too_large_text_view)
+          downloadButtonEnabled.postValue(false)
+        } else {
+          if (size < 1f) {
+            sizeOnDisk.postValue("<1")
+          } else {
+            sizeOnDisk.postValue(round(size).toInt().toString())
+          }
+          downloadButtonEnabled.postValue(true)
+        }
+      }
+    }
+  }
 }

ground/src/main/res/color/color_states_chip_button.xml

@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="utf-8"?>
+
+<!--
+  ~ Copyright 2023 Google LLC
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     https://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+<selector xmlns:android="http://schemas.android.com/apk/res/android">
+  <item android:state_enabled="false" android:color="@color/md_theme_primary" />
+  <item android:color="@color/md_theme_on_surface_disabled" />
+</selector>

ground/src/main/res/layout/offline_base_map_selector_frag.xml

@@ -20,6 +20,8 @@
   xmlns:app="http://schemas.android.com/apk/res-auto">
 
   <data>
+    <import type="com.google.android.ground.R" />
+    <import type="android.view.View" />
     <variable
       name="viewModel"
       type="com.google.android.ground.ui.offlinebasemap.selector.OfflineAreaSelectorViewModel" />
@@ -70,10 +72,43 @@
           app:backgroundTint="@color/colorMapAccent"
           app:chipIcon="@drawable/ic_area_download"
           app:icon="@drawable/ic_area_download"
+          android:enabled="@{viewModel.downloadButtonEnabled}"
           app:layout_constraintBottom_toBottomOf="parent"
           app:layout_constraintEnd_toEndOf="parent"
           app:useCompatPadding="true" />
       </com.google.android.ground.ui.common.TwoLineToolbar>
+      <TextView
+        android:id="@+id/size_on_disk_text_view"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintLeft_toLeftOf="parent"
+        app:layout_constraintRight_toRightOf="parent"
+        android:textAlignment="center"
+        android:textSize="20sp"
+        android:textColor="@color/textOverMap"
+        android:fontFamily="Google Sans Text"
+        android:layout_marginLeft="16sp"
+        android:layout_marginRight="16sp"
+        android:layout_marginBottom="24sp"
+        android:visibility="@{viewModel.visibleBottomTextView == R.id.size_on_disk_text_view ? View.VISIBLE : View.GONE}"
+        android:text="@{@string/selected_area_size_on_disk(viewModel.sizeOnDisk)}"/>
+      <TextView
+        android:id="@+id/area_too_large_text_view"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintLeft_toLeftOf="parent"
+        app:layout_constraintRight_toRightOf="parent"
+        android:textAlignment="center"
+        android:textSize="20sp"
+        android:textColor="@color/textOverMap"
+        android:fontFamily="Google Sans Text"
+        android:layout_marginLeft="16sp"
+        android:layout_marginRight="16sp"
+        android:layout_marginBottom="24sp"
+        android:visibility="@{viewModel.visibleBottomTextView == R.id.area_too_large_text_view ? View.VISIBLE : View.GONE}"
+        android:text="@string/selected_area_too_large"/>
     </androidx.constraintlayout.widget.ConstraintLayout>
   </FrameLayout>
 </layout>

ground/src/main/res/values/colors.xml

@@ -20,6 +20,7 @@
   <color name="colorMapAccent">#ff9131</color>
   <color name="clusterColor">#6DDD81</color>
   <color name="polyLineColor">#55ffffff</color>
+  <color name="textOverMap">#FCFDF7</color>
 
   <!-- Updated Color palette -->
   <color name="md_theme_primary">#006E2C</color>

ground/src/main/res/values/strings.xml

@@ -163,4 +163,6 @@
   <string name="contact_survey_organizer_to_obtain_access">Contact your system administrator to request access</string>
   <string name="close_app">Close app</string>
   <string name="warning_sign_out">Warning: If you sign out, all unsaved data will be lost </string>
+  <string name="selected_area_size_on_disk">The selected area may take up to %s\u00A0MB of space on your device</string>
+  <string name="selected_area_too_large">Zoom in and select a smaller area to download to your device</string>
 </resources>

ground/src/main/res/values/styles.xml

@@ -134,7 +134,8 @@
   </style>
 
   <style name="ChipButton" parent="Widget.MaterialComponents.Chip.Action">
-    <item name="chipBackgroundColor">?attr/colorPrimary</item>
+
+    <item name="backgroundTint">@color/color_states_chip_button</item>
     <item name="chipCornerRadius">@dimen/chip_button_corner_radius</item>
     <item name="chipStartPadding">@dimen/chip_button_padding</item>
     <item name="chipEndPadding">@dimen/chip_button_padding</item>