Support the special asset uri syntax

plugin/android/src/main/kotlin/com/nkming/nc_photos/plugin/BitmapUtil.kt

@@ -4,6 +4,7 @@ import android.content.Context
 import android.graphics.Bitmap
 import android.graphics.BitmapFactory
 import android.net.Uri
+import java.io.InputStream
 
 fun Bitmap.aspectRatio() = width / height.toFloat()
 
@@ -113,10 +114,20 @@ interface BitmapUtil {
 			}
 		}
 
+		private fun openUriInputStream(
+			context: Context, uri: Uri
+		): InputStream? {
+			return if (UriUtil.isAssetUri(uri)) {
+				context.assets.open(UriUtil.getAssetUriPath(uri))
+			} else {
+				context.contentResolver.openInputStream(uri)
+			}
+		}
+
 		private fun loadImageBounds(
 			context: Context, uri: Uri
 		): BitmapFactory.Options {
-			context.contentResolver.openInputStream(uri)!!.use {
+			openUriInputStream(context, uri)!!.use {
 				val opt = BitmapFactory.Options().apply {
 					inJustDecodeBounds = true
 				}
@@ -128,7 +139,7 @@ interface BitmapUtil {
 		private fun loadImage(
 			context: Context, uri: Uri, opt: BitmapFactory.Options
 		): Bitmap {
-			context.contentResolver.openInputStream(uri)!!.use {
+			openUriInputStream(context, uri)!!.use {
 				return BitmapFactory.decodeStream(it, null, opt)!!
 			}
 		}

plugin/android/src/main/kotlin/com/nkming/nc_photos/plugin/ContentUriChannelHandler.kt

@@ -31,10 +31,15 @@ class ContentUriChannelHandler(context: Context) :
 	private fun readUri(uri: String, result: MethodChannel.Result) {
 		val uriTyped = Uri.parse(uri)
 		try {
-			val bytes =
+			val bytes = if (UriUtil.isAssetUri(uriTyped)) {
+				context.assets.open(UriUtil.getAssetUriPath(uriTyped)).use {
+					it.readBytes()
+				}
+			} else {
 				context.contentResolver.openInputStream(uriTyped)!!.use {
 					it.readBytes()
 				}
+			}
 			result.success(bytes)
 		} catch (e: FileNotFoundException) {
 			result.error("fileNotFoundException", e.toString(), null)

plugin/android/src/main/kotlin/com/nkming/nc_photos/plugin/UriUtil.kt

@@ -28,6 +28,24 @@ interface UriUtil {
 			}
 		}
 
+		/**
+		 * Asset URI is a non-standard Uri that points to an asset file.
+		 *
+		 * An asset URI is formatted as file:///android_asset/path/to/file
+		 *
+		 * @param uri
+		 * @return
+		 */
+		fun isAssetUri(uri: Uri): Boolean {
+			return uri.scheme == "file" && uri.path?.startsWith(
+				"/android_asset/"
+			) == true
+		}
+
+		fun getAssetUriPath(uri: Uri): String {
+			return uri.path!!.substring("/android_asset/".length)
+		}
+
 		private const val TAG = "UriUtil"
 	}
 }