Photo Picker Dialog: Recursively traverse the photo directories.

chrome/android/java/src/org/chromium/chrome/browser/photo_picker/AttrAcceptFileFilter.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.support.annotation.NonNull;
+import android.webkit.MimeTypeMap;
+
+import java.io.File;
+import java.io.FileFilter;
+import java.util.HashSet;
+import java.util.Locale;
+
+/**
+ * A file filter for handling extensions and MIME types (images/jpeg) and
+ * supertypes (images/*).
+ */
+class AttrAcceptFileFilter implements FileFilter {

[Theresa, 2017/04/10 18:01:14]

nit: I think ImageFileFilter is a better name since this is specifically
filtering for images.

[Finnur, 2017/04/11 11:30:57]

Agreed.

+    private static final String IMAGE_SUPERTYPE = "image";
+    private static final String VIDEO_SUPERTYPE = "video";
+
+    private HashSet<String> mExtensions = new HashSet<>();
+    private HashSet<String> mMimeTypes = new HashSet<>();
+    private HashSet<String> mMimeSupertypes = new HashSet<>();
+    private MimeTypeMap mMimeTypeMap;
+
+    public AttrAcceptFileFilter(@NonNull String acceptAttr) {
+        for (String field : acceptAttr.toLowerCase(Locale.US).split(",")) {
+            field = field.trim();
+            if (field.startsWith(".")) {
+                mExtensions.add(field.substring(1));
+            } else if (field.endsWith("/*")) {
+                mMimeSupertypes.add(field.substring(0, field.length() - 2));
+            } else if (field.contains("/")) {
+                mMimeTypes.add(field);
+            } else {
+                // Throw exception?
+            }
+        }
+
+        mMimeTypeMap = MimeTypeMap.getSingleton();
+    }
+
+    @Override
+    public boolean accept(@NonNull File file) {
+        if (file.isDirectory()) {
+            return true;
+        }
+
+        String uri = file.toURI().toString();
+        String ext = MimeTypeMap.getFileExtensionFromUrl(uri).toLowerCase(Locale.US);
+        if (mExtensions.contains(ext)) {
+            return true;
+        }
+
+        String mimeType = getMimeTypeFromExtension(ext);
+        if (mimeType != null) {
+            if (mMimeTypes.contains(mimeType)) {
+                return true;
+            }
+            if (mMimeSupertypes.contains(getMimeSupertype(mimeType))) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    public boolean acceptsImages() {

[Theresa, 2017/04/10 18:01:13]

nit: JavaDoc on this and other two public methods.

What are acceptsImages(), acceptsVideos() and acceptsOther() going to be used
for.

[Finnur, 2017/04/11 11:30:57]

Huh... Nothing apparently. Good catch.

+        return getAcceptedSupertypes().contains(IMAGE_SUPERTYPE);
+    }
+
+    public boolean acceptsVideos() {
+        return getAcceptedSupertypes().contains(VIDEO_SUPERTYPE);
+    }
+
+    public boolean acceptsOther() {
+        HashSet<String> supertypes = getAcceptedSupertypes();
+        supertypes.remove(IMAGE_SUPERTYPE);
+        supertypes.remove(VIDEO_SUPERTYPE);
+        return !supertypes.isEmpty();
+    }
+
+    private HashSet<String> getAcceptedSupertypes() {
+        HashSet<String> supertypes = new HashSet<>();
+        supertypes.addAll(mMimeSupertypes);
+        for (String mimeType : mMimeTypes) {
+            supertypes.add(getMimeSupertype(mimeType));
+        }
+        for (String ext : mExtensions) {
+            String mimeType = getMimeTypeFromExtension(ext);
+            if (mimeType != null) {
+                supertypes.add(getMimeSupertype(mimeType));
+            }
+        }
+        return supertypes;
+    }
+
+    private String getMimeTypeFromExtension(@NonNull String ext) {
+        String mimeType = mMimeTypeMap.getMimeTypeFromExtension(ext);

[Theresa, 2017/04/10 18:01:14]

This requires the file to have an extension type. Is that consistent with the
Android photo picker?

e.g. If I download an image called "image" with no file extension, would
Android's photo picker include "image" in the list of options?

[Finnur, 2017/04/11 11:30:57]

Yes, that is consistent. I used adb shell to rename a photo in order to drop the
extension and (after clearing the cache by rebooting) the photo stopped
appearing in the list for the stock Android picker intent.

+        return (mimeType != null) ? mimeType.toLowerCase(Locale.US) : null;
+    }
+
+    @NonNull
+    private String getMimeSupertype(@NonNull String mimeType) {
+        return mimeType.split("/", 2)[0];
+    }
+}