Limit number of ClipData items for a quick viewer to 1000.

Bug: 20822219
Change-Id: I774be914ddeea0335dc646000a1d5c997ea73fd4

1 files changed, 73 insertions, 33 deletions

diff --git a/packages/DocumentsUI/src/com/android/documentsui/QuickViewIntentBuilder.java b/packages/DocumentsUI/src/com/android/documentsui/QuickViewIntentBuilder.java
index c34cec0d57bb..a77a9b3559dc 100644
--- a/packages/DocumentsUI/src/com/android/documentsui/QuickViewIntentBuilder.java
+++ b/packages/DocumentsUI/src/com/android/documentsui/QuickViewIntentBuilder.java
@@ -33,16 +33,19 @@ import android.provider.DocumentsContract.Document;
 import android.support.annotation.Nullable;
 import android.text.TextUtils;
 import android.util.Log;
+import android.util.Range;
 
 import com.android.documentsui.dirlist.Model;
 import com.android.documentsui.model.DocumentInfo;
 
+import java.util.ArrayList;
 import java.util.List;
 
 /**
  * Provides support for gather a list of quick-viewable files into a quick view intent.
  */
 final class QuickViewIntentBuilder {
+    private static final int MAX_CLIP_ITEMS = 1000;
 
     private final DocumentInfo mDocument;
     private final Model mModel;
@@ -50,9 +53,6 @@ final class QuickViewIntentBuilder {
     private final PackageManager mPkgManager;
     private final Resources mResources;
 
-    private ClipData mClipData;
-    private int mDocumentLocation;
-
     public QuickViewIntentBuilder(
             PackageManager pkgManager,
             Resources resources,
@@ -80,12 +80,28 @@ final class QuickViewIntentBuilder {
             intent.setFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
             intent.setPackage(trustedPkg);
             if (hasRegisteredHandler(intent)) {
-                List<String> siblingIds = mModel.getModelIds();
-                for (int i = 0; i < siblingIds.size(); i++) {
-                    onNextItem(i, siblingIds);
+                final ArrayList<Uri> uris = new ArrayList<Uri>();
+                final int documentLocation = collectViewableUris(uris);
+                final Range<Integer> range = computeSiblingsRange(uris, documentLocation);
+
+                ClipData clipData = null;
+                ClipData.Item item;
+                Uri uri;
+                for (int i = range.getLower(); i <= range.getUpper(); i++) {
+                    uri = uris.get(i);
+                    item = new ClipData.Item(uri);
+                    if (DEBUG) Log.d(TAG, "Including file: " + uri);
+                    if (clipData == null) {
+                        clipData = new ClipData(
+                                "URIs", new String[] { ClipDescription.MIMETYPE_TEXT_URILIST },
+                                item);
+                    } else {
+                        clipData.addItem(item);
+                    }
                 }
-                intent.putExtra(Intent.EXTRA_INDEX, mDocumentLocation);
-                intent.setClipData(mClipData);
+
+                intent.putExtra(Intent.EXTRA_INDEX, documentLocation);
+                intent.setClipData(clipData);
 
                 return intent;
             } else {
@@ -96,39 +112,63 @@ final class QuickViewIntentBuilder {
         return null;
     }
 
-    private boolean hasRegisteredHandler(Intent intent) {
-        // Try to resolve the intent. If a matching app isn't installed, it won't resolve.
-        return intent.resolveActivity(mPkgManager) != null;
-    }
+    private int collectViewableUris(ArrayList<Uri> uris) {
+        final List<String> siblingIds = mModel.getModelIds();
+        uris.ensureCapacity(siblingIds.size());
 
-    private void onNextItem(int index, List<String> siblingIds) {
-        final Cursor cursor = mModel.getItem(siblingIds.get(index));
+        int documentLocation = 0;
+        Cursor cursor;
+        String mimeType;
+        String id;
+        String authority;
+        Uri uri;
 
-        if (cursor == null) {
-            return;
-        }
+        // Cursor's are not guaranteed to be immutable. Hence, traverse it only once.
+        for (int i = 0; i < siblingIds.size(); i++) {
+            cursor = mModel.getItem(siblingIds.get(i));
 
-        String mimeType = getCursorString(cursor, Document.COLUMN_MIME_TYPE);
-        if (Document.MIME_TYPE_DIR.equals(mimeType)) {
-            return;
-        }
+            mimeType = getCursorString(cursor, Document.COLUMN_MIME_TYPE);
+            if (Document.MIME_TYPE_DIR.equals(mimeType)) {
+                continue;
+            }
+
+            id = getCursorString(cursor, Document.COLUMN_DOCUMENT_ID);
+            authority = getCursorString(cursor, RootCursorWrapper.COLUMN_AUTHORITY);
+            uri = DocumentsContract.buildDocumentUri(authority, id);
 
-        String id = getCursorString(cursor, Document.COLUMN_DOCUMENT_ID);
-        String authority = getCursorString(cursor, RootCursorWrapper.COLUMN_AUTHORITY);
-        Uri uri = DocumentsContract.buildDocumentUri(authority, id);
-        if (DEBUG) Log.d(TAG, "Including file[" + id + "] @ " + uri);
+            if (id.equals(mDocument.documentId)) {
+                if (DEBUG) Log.d(TAG, "Found starting point for QV. " + i);
+                documentLocation = i;
+            }
 
-        if (id.equals(mDocument.documentId)) {
-            if (DEBUG) Log.d(TAG, "Found starting point for QV. " + index);
-            mDocumentLocation = index;
+            uris.add(uri);
         }
 
-        ClipData.Item item = new ClipData.Item(uri);
-        if (mClipData == null) {
-            mClipData = new ClipData(
-                    "URIs", new String[]{ClipDescription.MIMETYPE_TEXT_URILIST}, item);
+        return documentLocation;
+    }
+
+    private static Range<Integer> computeSiblingsRange(List<Uri> uris, int documentLocation) {
+        // Restrict number of siblings to avoid hitting the IPC limit.
+        // TODO: Remove this restriction once ClipData can hold an arbitrary number of
+        // items.
+        int firstSibling;
+        int lastSibling;
+        if (documentLocation < uris.size() / 2) {
+            firstSibling = Math.max(0, documentLocation - MAX_CLIP_ITEMS / 2);
+            lastSibling = Math.min(uris.size() - 1, firstSibling + MAX_CLIP_ITEMS - 1);
         } else {
-            mClipData.addItem(item);
+            lastSibling = Math.min(uris.size() - 1, documentLocation + MAX_CLIP_ITEMS / 2);
+            firstSibling = Math.max(0, lastSibling - MAX_CLIP_ITEMS + 1);
         }
+
+        if (DEBUG) Log.d(TAG, "Copmuted siblings from index: " + firstSibling
+                + " to: " + lastSibling);
+
+        return new Range(firstSibling, lastSibling);
+    }
+
+    private boolean hasRegisteredHandler(Intent intent) {
+        // Try to resolve the intent. If a matching app isn't installed, it won't resolve.
+        return intent.resolveActivity(mPkgManager) != null;
     }
 }