Photo Picker Dialog: Recursively traverse the photo directories.

chrome/android/java/src/org/chromium/chrome/browser/photo_picker/PickerCategoryView.java

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.chrome.browser.photo_picker;
 
 import android.app.Activity;
 import android.content.Context;
 import android.graphics.Rect;
 import android.support.v7.widget.GridLayoutManager;
 import android.support.v7.widget.RecyclerView;
 import android.support.v7.widget.Toolbar.OnMenuItemClickListener;
 import android.util.AttributeSet;
 import android.view.LayoutInflater;
 import android.view.MenuItem;
 import android.view.View;
 import android.widget.RelativeLayout;
 
 import org.chromium.chrome.R;
 import org.chromium.chrome.browser.widget.selection.SelectableListLayout;
 import org.chromium.chrome.browser.widget.selection.SelectionDelegate;
 import org.chromium.ui.PhotoPickerListener;
 
-import java.util.ArrayList;
 import java.util.List;
 
 /**
  * A class for keeping track of common data associated with showing photos in
  * the photo picker, for example the RecyclerView and the bitmap caches.
  */
-public class PickerCategoryView extends RelativeLayout implements OnMenuItemClickListener {
+public class PickerCategoryView extends RelativeLayout
+        implements FileEnumWorkerTask.FilesEnumeratedCallback, OnMenuItemClickListener {
     // The dialog that owns us.
     private PhotoPickerDialog mDialog;
 
     // The view containing the RecyclerView and the toolbar, etc.
     private SelectableListLayout<PickerBitmap> mSelectableListLayout;
 
     // Our context.
     private Context mContext;
 
     // The list of images on disk, sorted by last-modified first.
@@ skipping 20 matching lines @@
      * are a mix).
      */
     private int mColumns;
 
     // The padding between columns. See also comment for mColumns.
     private int mPadding;
 
     // The size of the bitmaps (equal length for width and height).
     private int mImageSize;
 
+    // A worker task for asynchronously enumerating files off the main thread.
+    private FileEnumWorkerTask mWorkerTask;
+
     public PickerCategoryView(Context context) {
         super(context);
         postConstruction(context);
     }
 
     public PickerCategoryView(Context context, AttributeSet attrs) {
         super(context, attrs);
         postConstruction(context);
     }
 
@@ skipping 44 matching lines @@
      */
     public void initialize(
             PhotoPickerDialog dialog, PhotoPickerListener listener, boolean multiSelectionAllowed) {
         // TODO(finnur): Change selection delegate to support single-selection.
 
         mDialog = dialog;
         mMultiSelectionAllowed = multiSelectionAllowed;
         mListener = listener;
     }
 
+    // FileEnumWorkerTask.FilesEnumeratedCallback:
+
+    @Override
+    public void filesEnumeratedCallback(List<PickerBitmap> files) {
+        mPickerBitmaps = files;
+        if (files != null && files.size() > 0) {
+            mPickerAdapter.notifyDataSetChanged();
+        }
+    }
+
     // OnMenuItemClickListener:
 
     @Override
     public boolean onMenuItemClick(MenuItem item) {
         if (item.getItemId() == R.id.close_menu_id) {
             mListener.onPickerUserAction(PhotoPickerListener.Action.CANCEL, null);
             mDialog.dismiss();
             return true;
         } else if (item.getItemId() == R.id.selection_mode_done_menu_id) {
             notifyPhotosSelected();
@@ skipping 49 matching lines @@
         // Make sure columns and padding are either both even or both odd.
         if (((mColumns % 2) == 0) != ((mPadding % 2) == 0)) {
             mPadding++;
         }
     }
 
     /**
      * Prepares bitmaps for loading.
      */
     private void prepareBitmaps() {
-        // TODO(finnur): Use worker thread to fetch bitmaps instead of hard-coding.
-        mPickerBitmaps = new ArrayList<>();
-        mPickerBitmaps.add(0, new PickerBitmap("", 0, PickerBitmap.GALLERY));
-        mPickerBitmaps.add(0, new PickerBitmap("", 0, PickerBitmap.CAMERA));
-        mPickerBitmaps.add(new PickerBitmap("foo/bar1.jpg", 1, PickerBitmap.PICTURE));
-        mPickerBitmaps.add(new PickerBitmap("foo/bar2.jpg", 2, PickerBitmap.PICTURE));
-        mPickerBitmaps.add(new PickerBitmap("foo/bar3.jpg", 3, PickerBitmap.PICTURE));
-        mPickerBitmaps.add(new PickerBitmap("foo/bar4.jpg", 4, PickerBitmap.PICTURE));
-        mPickerAdapter.notifyDataSetChanged();
+        if (mWorkerTask != null) {
+            mWorkerTask.cancel(true);

[Theresa, 2017/04/11 15:44:49]

Should we also cancel the work task when the dialog is closed if we haven't
received a callback yet?

[Finnur, 2017/04/11 16:25:23]

Not a bad idea. Done.

+        }
+
+        mWorkerTask = new FileEnumWorkerTask(this, new ImageFileFilter("image/*"));

[Theresa, 2017/04/11 15:44:49]

I think the name ImageFileFilter indicates that only images will be accepted.
Should we move the "image/*" in-line there until there's a need for for
ImageFileFilter to be more generic? Or perhaps my last comment to rename
ImageFileFilter was misguided and the class should be more generic now?

[Finnur, 2017/04/11 16:25:23]

How about MimeTypeFileFilter?

[Theresa, 2017/04/11 17:01:28]

Sounds good to me.

+        mWorkerTask.execute();
     }
 
     /**
      * Notifies any listeners that one or more photos have been selected.
      */
     private void notifyPhotosSelected() {
         List<PickerBitmap> selectedFiles = mSelectionDelegate.getSelectedItems();
         String[] photos = new String[selectedFiles.size()];
         int i = 0;
         for (PickerBitmap bitmap : selectedFiles) {
             photos[i++] = bitmap.getFilePath();
         }
 
         mListener.onPickerUserAction(PhotoPickerListener.Action.PHOTOS_SELECTED, photos);
     }
 }