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authorSvetoslav Ganov <svetoslavganov@google.com>2012-03-20 11:51:39 -0700
committerSvetoslav Ganov <svetoslavganov@google.com>2012-04-13 19:05:24 -0700
commit4213804541a8b05cd0587b138a2fd9a3b7fd9350 (patch)
tree6b19718ddbc60229cd4f2e059feea8021225c5e6 /core/tests
parentdbed083ff07f4e6fa727ea22cdd7d758291630c1 (diff)
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Accessibility focus - framework
Usefulness: Keep track of the current user location in the screen when traversing the it. Enabling structural and directional navigation over all elements on the screen. This enables blind users that know the application layout to efficiently locate desired elements as opposed to try touch exploring the region where the the element should be - very tedious. Rationale: There are two ways to implement accessibility focus One is to let accessibility services keep track of it since they have access to the screen content, and another to let the view hierarchy keep track of it. While the first approach would require almost no work on our part it poses several challenges which make it a sub-optimal choice. Having the accessibility focus in the accessibility service would require that service to scrape the window content every time it changes to sync the view tree state and the accessibility focus location. Pretty much the service will have to keep an off screen model of the screen content. This could be quite challenging to get right and would incur performance cost for the multiple IPCs to repeatedly fetch the screen content. Further, keeping virtual accessibility focus (i.e. in the service) would require sync of the input and accessibility focus. This could be challenging to implement right as well. Also, having an unlimited number of accessibility services we cannot guarantee that they will have a proper implementation, if any, to allow users to perform structural navigation of the screen content. Assuming two accessibility services implement structural navigation via accessibility focus, there is not guarantee that they will behave similarly by default, i.e. provide some standard way to navigate the screen content. Also feedback from experienced accessibility researchers, specifically T.V Raman, provides evidence that having virtual accessibility focus creates many issues and it is very hard to get right. Therefore, keeping accessibility focus in the system will avoid keeping an off-screen model in accessibility services, it will always be in sync with the state of the view hierarchy and the input focus. Also this will allow having a default behavior for traversing the screen via this accessibility focus that is consistent in all accessibility services. We provide accessibility services with APIs to override this behavior but all of them will perform screen traversal in a consistent way by default. Behavior: If accessibility is enabled the accessibility focus is the leading one and the input follows it. Putting accessibility focus on a view moves the input focus there. Clearing the accessibility focus of a view, clears the input focus of this view. If accessibility focus is on a view that cannot take input focus, then no other view should have input focus. In accessibility mode we initially give accessibility focus to the topmost view and no view has input focus. This ensures consistent behavior accross all apps. Note that accessibility focus can move hierarchically in the view tree and having it at the root is better than putting it where the input focus would be - at the first input focusable which could be at an arbitrary depth in the view tree. By default not all views are reported for accessibility, only the important ones. A view may be explicitly labeled as important or not for accessibility, or the system determines which one is such - default. Important views for accessibility are all views that are not dumb layout managers used only to arrange their chidren. Since the same content arrangement can be obtained via different combintation of layout managers, such managers cannot be used to reliably determine the application structure. For example, a user should see a list as a list view with several list items and each list item as a text view and a button as opposed to seeing all the layout managers used to arrange the list item's content. By default only important for accessibility views are regared for accessibility purposes. View not regarded for accessibility neither fire accessibility events, nor are reported being on the screen. An accessibility service may request the system to regard all views. If the target SDK of an accessibility services is less than JellyBean, then all views are regarded for accessibility. Note that an accessibility service that requires all view to be ragarded for accessibility may put accessibility focus on any view. Hence, it may implement any navigational paradigm if desired. Especially considering the fact that the system is detecting some standard gestures and delegates their processing to an accessibility service. The default implementation of an accessibility services performs the defualt navigation. bug:5932640 bug:5605641 Change-Id: Ieac461d480579d706a847b9325720cb254736ebe
Diffstat (limited to 'core/tests')
-rw-r--r--core/tests/coretests/src/android/widget/focus/ListOfButtonsTest.java7
1 files changed, 4 insertions, 3 deletions
diff --git a/core/tests/coretests/src/android/widget/focus/ListOfButtonsTest.java b/core/tests/coretests/src/android/widget/focus/ListOfButtonsTest.java
index 3dba4e5..1968a32 100644
--- a/core/tests/coretests/src/android/widget/focus/ListOfButtonsTest.java
+++ b/core/tests/coretests/src/android/widget/focus/ListOfButtonsTest.java
@@ -19,7 +19,7 @@ package android.widget.focus;
import android.widget.focus.ListOfButtons;
import com.android.frameworks.coretests.R;
-import android.test.ActivityInstrumentationTestCase;
+import android.test.ActivityInstrumentationTestCase2;
import android.test.suitebuilder.annotation.MediumTest;
import android.widget.ListAdapter;
import android.widget.Button;
@@ -31,7 +31,7 @@ import android.view.View;
* Tests that focus works as expected when navigating into and out of
* a {@link ListView} that has buttons in it.
*/
-public class ListOfButtonsTest extends ActivityInstrumentationTestCase<ListOfButtons> {
+public class ListOfButtonsTest extends ActivityInstrumentationTestCase2<ListOfButtons> {
private ListAdapter mListAdapter;
private Button mButtonAtTop;
@@ -39,7 +39,7 @@ public class ListOfButtonsTest extends ActivityInstrumentationTestCase<ListOfBut
private ListView mListView;
public ListOfButtonsTest() {
- super("com.android.frameworks.coretests", ListOfButtons.class);
+ super(ListOfButtons.class);
}
@Override
@@ -47,6 +47,7 @@ public class ListOfButtonsTest extends ActivityInstrumentationTestCase<ListOfBut
super.setUp();
ListOfButtons a = getActivity();
+ getInstrumentation().waitForIdleSync();
mListAdapter = a.getListAdapter();
mButtonAtTop = (Button) a.findViewById(R.id.button);
mListView = a.getListView();