thumbnail/app icon: use display metrics in Android instead of devicePixelRatio in Flutter

android/app/src/main/java/deckers/thibault/aves/channelhandlers/AppAdapterHandler.java

@@ -121,12 +121,16 @@ public class AppAdapterHandler implements MethodChannel.MethodCallHandler {
 
     private void getAppIcon(MethodCall call, MethodChannel.Result result) {
         String packageName = call.argument("packageName");
-        Integer size = call.argument("size");
-        if (packageName == null || size == null) {
+        Double sizeDip = call.argument("sizeDip");
+        if (packageName == null || sizeDip == null) {
             result.error("getAppIcon-args", "failed because of missing arguments", null);
             return;
         }
 
+        // convert DIP to physical pixels here, instead of using `devicePixelRatio` in Flutter
+        float density = context.getResources().getDisplayMetrics().density;
+        int size = (int) Math.round(sizeDip * density);
+
         byte[] data = null;
         try {
             int iconResourceId = context.getPackageManager().getApplicationInfo(packageName, 0).icon;

android/app/src/main/java/deckers/thibault/aves/channelhandlers/ImageFileHandler.java

@@ -21,6 +21,7 @@ public class ImageFileHandler implements MethodChannel.MethodCallHandler {
     public static final String CHANNEL = "deckers.thibault/aves/image";
 
     private Activity activity;
+    private float density;
     private MediaStoreStreamHandler mediaStoreStreamHandler;
 
     public ImageFileHandler(Activity activity, MediaStoreStreamHandler mediaStoreStreamHandler) {
@@ -28,6 +29,13 @@ public class ImageFileHandler implements MethodChannel.MethodCallHandler {
         this.mediaStoreStreamHandler = mediaStoreStreamHandler;
     }
 
+    public float getDensity() {
+        if (density == 0) {
+            density = activity.getResources().getDisplayMetrics().density;
+        }
+        return density;
+    }
+
     @Override
     public void onMethodCall(@NonNull MethodCall call, @NonNull MethodChannel.Result result) {
         switch (call.method) {
@@ -63,13 +71,20 @@ public class ImageFileHandler implements MethodChannel.MethodCallHandler {
 
     private void getThumbnail(@NonNull MethodCall call, @NonNull MethodChannel.Result result) {
         Map entryMap = call.argument("entry");
-        Integer width = call.argument("width");
-        Integer height = call.argument("height");
-        Integer defaultSize = call.argument("defaultSize");
-        if (entryMap == null || defaultSize == null) {
+        Double widthDip = call.argument("widthDip");
+        Double heightDip = call.argument("heightDip");
+        Double defaultSizeDip = call.argument("defaultSizeDip");
+
+        if (entryMap == null || widthDip == null || heightDip == null || defaultSizeDip == null) {
             result.error("getThumbnail-args", "failed because of missing arguments", null);
             return;
         }
+        // convert DIP to physical pixels here, instead of using `devicePixelRatio` in Flutter
+        float density = getDensity();
+        int width = (int) Math.round(widthDip * density);
+        int height = (int) Math.round(heightDip * density);
+        int defaultSize = (int) Math.round(defaultSizeDip * density);
+
         ImageEntry entry = new ImageEntry(entryMap);
         new ImageDecodeTask(activity).execute(new ImageDecodeTask.Params(entry, width, height, defaultSize, result));
     }

lib/services/android_app_service.dart

@@ -16,11 +16,11 @@ class AndroidAppService {
     return {};
   }
 
-  static Future<Uint8List> getAppIcon(String packageName, int size) async {
+  static Future<Uint8List> getAppIcon(String packageName, double size) async {
     try {
       final result = await platform.invokeMethod('getAppIcon', <String, dynamic>{
         'packageName': packageName,
-        'size': size,
+        'sizeDip': size,
       });
       return result as Uint8List;
     } on PlatformException catch (e) {

lib/services/image_file_service.dart

@@ -14,6 +14,7 @@ class ImageFileService {
   static const platform = MethodChannel('deckers.thibault/aves/image');
   static final StreamsChannel byteChannel = StreamsChannel('deckers.thibault/aves/imagebytestream');
   static final StreamsChannel opChannel = StreamsChannel('deckers.thibault/aves/imageopstream');
+  static const double thumbnailDefaultSize = 64.0;
 
   static Future<void> getImageEntries(SortFactor sort, GroupFactor group) async {
     try {
@@ -76,15 +77,15 @@ class ImageFileService {
     return Future.sync(() => Uint8List(0));
   }
 
-  static Future<Uint8List> getThumbnail(ImageEntry entry, int width, int height, {Object taskKey, int priority}) {
+  static Future<Uint8List> getThumbnail(ImageEntry entry, double width, double height, {Object taskKey, int priority}) {
     return servicePolicy.call(
       () async {
         try {
           final result = await platform.invokeMethod('getThumbnail', <String, dynamic>{
             'entry': entry.toMap(),
-            'width': width,
-            'height': height,
-            'defaultSize': 256,
+            'widthDip': width,
+            'heightDip': height,
+            'defaultSizeDip': thumbnailDefaultSize,
           });
           return result as Uint8List;
         } on PlatformException catch (e) {

lib/widgets/common/image_providers/app_icon_image_provider.dart

@@ -21,7 +21,7 @@ class AppIconImage extends ImageProvider<AppIconImageKey> {
   Future<AppIconImageKey> obtainKey(ImageConfiguration configuration) {
     return SynchronousFuture<AppIconImageKey>(AppIconImageKey(
       packageName: packageName,
-      sizePixels: (size * configuration.devicePixelRatio).round(),
+      size: size,
       scale: scale,
     ));
   }
@@ -38,28 +38,28 @@ class AppIconImage extends ImageProvider<AppIconImageKey> {
   }
 
   Future<ui.Codec> _loadAsync(AppIconImageKey key, DecoderCallback decode) async {
-    final bytes = await AndroidAppService.getAppIcon(key.packageName, key.sizePixels);
+    final bytes = await AndroidAppService.getAppIcon(key.packageName, key.size);
     return await decode(bytes ?? Uint8List(0));
   }
 }
 
 class AppIconImageKey {
   final String packageName;
-  final int sizePixels;
+  final double size;
   final double scale;
 
   const AppIconImageKey({
     @required this.packageName,
-    @required this.sizePixels,
+    @required this.size,
     this.scale,
   });
 
   @override
   bool operator ==(Object other) {
     if (other.runtimeType != runtimeType) return false;
-    return other is AppIconImageKey && other.packageName == packageName && other.sizePixels == sizePixels && other.scale == scale;
+    return other is AppIconImageKey && other.packageName == packageName && other.size == size && other.scale == scale;
   }
 
   @override
-  int get hashCode => hashValues(packageName, sizePixels, scale);
+  int get hashCode => hashValues(packageName, size, scale);
 }

lib/widgets/common/image_providers/thumbnail_provider.dart

@@ -34,7 +34,6 @@ class ThumbnailProvider extends ImageProvider<ThumbnailProviderKey> {
   ThumbnailProviderKey _buildKey(ImageConfiguration configuration) => ThumbnailProviderKey(
         entry: entry,
         extent: extent,
-        devicePixelRatio: configuration.devicePixelRatio,
         scale: scale,
       );
 
@@ -50,8 +49,7 @@ class ThumbnailProvider extends ImageProvider<ThumbnailProviderKey> {
   }
 
   Future<ui.Codec> _loadAsync(ThumbnailProviderKey key, DecoderCallback decode) async {
-    final dimPixels = (extent * key.devicePixelRatio).round();
-    final bytes = await ImageFileService.getThumbnail(key.entry, dimPixels, dimPixels, taskKey: _cancellationKey);
+    final bytes = await ImageFileService.getThumbnail(key.entry, extent, extent, taskKey: _cancellationKey);
     return await decode(bytes ?? Uint8List(0));
   }
 
@@ -67,13 +65,11 @@ class ThumbnailProvider extends ImageProvider<ThumbnailProviderKey> {
 class ThumbnailProviderKey {
   final ImageEntry entry;
   final double extent;
-  final double devicePixelRatio; // do not include configuration in key hashcode or == operator
   final double scale;
 
   const ThumbnailProviderKey({
     @required this.entry,
     @required this.extent,
-    @required this.devicePixelRatio,
     this.scale,
   });