ContentResolverResourceProvider should handle document Uris correctly (#808)

vtm-android/src/org/oscim/android/theme/ContentResolverResourceProvider.java

@@ -15,6 +15,7 @@
 package org.oscim.android.theme;
 
 import android.content.ContentResolver;
+import android.content.Intent;
 import android.database.Cursor;
 import android.net.Uri;
 import android.os.Build;
@@ -40,6 +41,7 @@ public class ContentResolverResourceProvider implements XmlThemeResourceProvider
 
     private final ContentResolver contentResolver;
     private final Uri relativeRootUri;
+    private final boolean isDocumentUri;
 
     private final Map<String, Uri> resourceUriCache = new HashMap<>();
 
@@ -55,9 +57,34 @@ public class ContentResolverResourceProvider implements XmlThemeResourceProvider
         }
     }
 
-    public ContentResolverResourceProvider(ContentResolver contentResolver, Uri treeUri) {
+    /**
+     * Creates a new content resolver resource provider.
+     *
+     * @param contentResolver content resolver used to read content.
+     * @param relativeRootUri uri pointing to a directory.
+     *                        Uri is assumed to be a pure tree Uri (as e.g. returned by {@link Intent#ACTION_OPEN_DOCUMENT_TREE}).
+     */
+    public ContentResolverResourceProvider(ContentResolver contentResolver, Uri relativeRootUri) {
+        this(contentResolver, relativeRootUri, false);
+    }
+
+    /**
+     * Creates a new content resolver resource provider.
+     *
+     * @param contentResolver content resolver used to read content.
+     * @param relativeRootUri uri pointing to a directory.
+     * @param isDocumentUri   Uris as returned e.g. by {@link Intent#ACTION_OPEN_DOCUMENT_TREE}) cannot directly be used to scan directories and read content.
+     *                        They must be converted to document uris first using {@link DocumentsContract#buildChildDocumentsUriUsingTree(Uri, String)}.
+     *                        However, in some situations this conversion was done previously by caller (e.g. if root dir should be subdirectory of a directory returned by {@link Intent#ACTION_OPEN_DOCUMENT_TREE}).
+     *                        In these cases, converted Uri will point to original root directory which is not always the wanted behaviour.
+     *                        Thus, this parameter allows caller to control whether conversion should be done or not.
+     *                        If set to true, then given Uri is considered to be a document uri already and no conversion is done.
+     *                        If set to false, uri is considered to be a pure tree uri as returned e.g. by {@link Intent#ACTION_OPEN_DOCUMENT_TREE}) and it is converted.
+     */
+    public ContentResolverResourceProvider(ContentResolver contentResolver, Uri relativeRootUri, boolean isDocumentUri) {
         this.contentResolver = contentResolver;
-        this.relativeRootUri = treeUri;
+        this.relativeRootUri = relativeRootUri;
+        this.isDocumentUri = isDocumentUri;
 
         refreshCache();
     }
@@ -140,7 +167,11 @@ public class ContentResolverResourceProvider implements XmlThemeResourceProvider
             return;
         }
 
-        Uri dirUri = DocumentsContract.buildDocumentUriUsingTree(relativeRootUri, DocumentsContract.getTreeDocumentId(relativeRootUri));
+        Uri dirUri = relativeRootUri;
+        if (!isDocumentUri) {
+            // Convert "tree uri" to a "document uri"
+            dirUri = DocumentsContract.buildDocumentUriUsingTree(dirUri, DocumentsContract.getTreeDocumentId(dirUri));
+        }
         buildCacheLevel(CanvasAdapter.PREFIX_FILE, dirUri);
     }
 }