I have a Xamarin app that was not meant to handle the talkback functionality of android, because for it to work well it had to be build in a specific way.
My app is a little order, and I simply can't make a do-over of the whole thing.
So, what is happening?
My Xamarin app is made with non-native libs, that are not supported by the Talkback, so, when the user turns on the Talkback functionality the app effectively stops receiving the DPAD events since they are handled by the systems Accessibility Service.
That service, gets the events, and tries to handle them within my app, but, since my components are non-native, the system does not recognize them and the DPAD is wasted, hence, the illusion that the DPADs are not working.
So, what do you have to do if you just want to handle the DPADs (and nothing else) yourself with Talkback on?
The answer to this post will contain the code that describes the following behavior:
1. The talkback wont be able to 'talk' about your components
2. The DPAD events will be handled by an Accessibility Delegate
3. A virtual DPAD will handle the navigation
4. The green rectangle used for focus will be disabled, since you wont need it anyway
5. The app will look exactly the same with Talkback on and off
This post was made for educational purposes, since I had a hard time coming up with the solution, and hope the next guy finds it helpfull.
The first step is to create a class that inherits the AccessibilityDelegateCompat in order to create our own Accessibility Service.
class MyAccessibilityHelper : AccessibilityDelegateCompat
{
const string Tag = "MyAccessibilityHelper";
const int ROOT_NODE = -1;
const int INVALID_NODE = -1000;
const string NODE_CLASS_NAME = "My_Node";
public const int NODE_UP = 1;
public const int NODE_LEFT = 2;
public const int NODE_CENTER = 3;
public const int NODE_RIGHT = 4;
public const int NODE_DOWN = 5;
private class MyAccessibilityProvider : AccessibilityNodeProviderCompat
{
private readonly MyAccessibilityHelper mHelper;
public MyAccessibilityProvider(MyAccessibilityHelper helper)
{
mHelper = helper;
}
public override bool PerformAction(int virtualViewId, int action, Bundle arguments)
{
return mHelper.PerformNodeAction(virtualViewId, action, arguments);
}
public override AccessibilityNodeInfoCompat CreateAccessibilityNodeInfo(int virtualViewId)
{
var node = mHelper.CreateNode(virtualViewId);
return AccessibilityNodeInfoCompat.Obtain(node);
}
}
private readonly View mView;
private readonly MyAccessibilityProvider mProvider;
private Dictionary<int, Rect> mRects = new Dictionary<int, Rect>();
private int mAccessibilityFocusIndex = INVALID_NODE;
public MyAccessibilityHelper(View view)
{
mView = view;
mProvider = new MyAccessibilityProvider(this);
}
public override AccessibilityNodeProviderCompat GetAccessibilityNodeProvider(View host)
{
return mProvider;
}
public override void SendAccessibilityEvent(View host, int eventType)
{
Android.Util.Log.Debug(Tag, "SendAccessibilityEvent: host={0} eventType={1}", host, eventType);
base.SendAccessibilityEvent(host, eventType);
}
public void AddRect(int id, Rect rect)
{
mRects.Add(id, rect);
}
public AccessibilityNodeInfoCompat CreateNode(int virtualViewId)
{
var node = AccessibilityNodeInfoCompat.Obtain(mView);
if (virtualViewId == ROOT_NODE)
{
node.ContentDescription = "Root node";
ViewCompat.OnInitializeAccessibilityNodeInfo(mView, node);
foreach (var r in mRects)
{
node.AddChild(mView, r.Key);
}
}
else
{
node.ContentDescription = "";
node.ClassName = NODE_CLASS_NAME;
node.Enabled = true;
node.Focusable = true;
var r = mRects[virtualViewId];
node.SetBoundsInParent(r);
int[] offset = new int[2];
mView.GetLocationOnScreen(offset);
node.SetBoundsInScreen(new Rect(offset[0] + r.Left, offset[1] + r.Top, offset[0] + r.Right, offset[1] + r.Bottom));
node.PackageName = mView.Context.PackageName;
node.SetSource(mView, virtualViewId);
node.SetParent(mView);
node.VisibleToUser = true;
if (virtualViewId == mAccessibilityFocusIndex)
{
node.AccessibilityFocused = true;
node.AddAction(AccessibilityNodeInfoCompat.ActionClearAccessibilityFocus);
}
else
{
node.AccessibilityFocused = false;
node.AddAction(AccessibilityNodeInfoCompat.FocusAccessibility);
}
}
return node;
}
private AccessibilityEvent CreateEvent(int virtualViewId, EventTypes eventType)
{
var e = AccessibilityEvent.Obtain(eventType);
if (virtualViewId == ROOT_NODE)
{
ViewCompat.OnInitializeAccessibilityEvent(mView, e);
}
else
{
var record = AccessibilityEventCompat.AsRecord(e);
record.Enabled = true;
record.SetSource(mView, virtualViewId);
record.ClassName = NODE_CLASS_NAME;
e.PackageName = mView.Context.PackageName;
}
return e;
}
public bool SendEventForVirtualView(int virtualViewId, EventTypes eventType)
{
if (mView.Parent == null)
return false;
var e = CreateEvent(virtualViewId, eventType);
return ViewParentCompat.RequestSendAccessibilityEvent(mView.Parent, mView, e);
}
public bool PerformNodeAction(int virtualViewId, int action, Bundle arguments)
{
if (virtualViewId == ROOT_NODE)
{
return ViewCompat.PerformAccessibilityAction(mView, action, arguments);
}
else
{
switch (action)
{
case AccessibilityNodeInfoCompat.ActionAccessibilityFocus:
if (virtualViewId != mAccessibilityFocusIndex)
{
if (mAccessibilityFocusIndex != INVALID_NODE)
{
SendEventForVirtualView(mAccessibilityFocusIndex, EventTypes.ViewAccessibilityFocusCleared);
}
mAccessibilityFocusIndex = virtualViewId;
mView.Invalidate();
SendEventForVirtualView(virtualViewId, EventTypes.ViewAccessibilityFocused);
// virtual key event
switch (virtualViewId)
{
case NODE_UP:
HandleDpadEvent(Keycode.DpadUp);
break;
case NODE_LEFT:
HandleDpadEvent(Keycode.DpadLeft);
break;
case NODE_RIGHT:
HandleDpadEvent(Keycode.DpadRight);
break;
case NODE_DOWN:
HandleDpadEvent(Keycode.DpadDown);
break;
}
// refocus center
SendEventForVirtualView(NODE_CENTER, EventTypes.ViewAccessibilityFocused);
return true;
}
break;
case AccessibilityNodeInfoCompat.ActionClearAccessibilityFocus:
mView.RequestFocus();
if (virtualViewId == mAccessibilityFocusIndex)
{
mAccessibilityFocusIndex = INVALID_NODE;
mView.Invalidate();
SendEventForVirtualView(virtualViewId, EventTypes.ViewAccessibilityFocusCleared);
return true;
}
break;
}
}
return false;
}
private void HandleDpadEvent(Keycode keycode)
{
//Here you know what DPAD was pressed
//You can create your own key event and send it to your app
//This code depends on your own application, and I wont be providing the code
//Note, it is important to handle both, the KeyDOWN and the KeyUP event for it to work
}
}
Since the code is a bit large, I'll just explain the crutal parts.
Once the talkback is active, the dictionary (from our view bellow) will be used to create a virtual tree node of our virtual DPAD. With that in mind, the function PerformNodeAction will be the most important one.
It handles the actions once a virtual node was focused by the Accessibility system, based on the provided id of the virtual element, there are two parts, the first one is the ROOT_NODE, which is the view iteslf that contains our virtual dpad, which for the most part can be ignored, but the seond part is where the handling is done.
The second part is where the actions ActionAccessibilityFocus and ActionClearAccessibilityFocus are handled. The two of witch are both important, but the first one is where we can finally handle our virtual dpad.
What is done here is that with the provided virtual ID from the dictionary, we know which DPAD was selected (virtualViewId). Based on the selected DPAD, we can perform the action we want in the HandleDpadEvent function. What is important to notice, is that after we handle the selecteds DPAD event, we will refocus our CENTER node, in order to be ready to handle the next button press. This is very important, since, you dont want to find yourself in a situation where you go DOWN, and then UP, just for the virtual dpad to focus the CENTER pad.
So, I'll epeat myself, the refocusing of the CENTER pad after the previous' DPAD event was handled needs to be done in order for us to know EXACTLY where we will be after the next DPAD button was pressed!
There is one function that I wont post here, since the code for it is very specific for my app, the function is HandleDpadEvent, there you must create a keydown and a keyup event and send it to your main activity where the function onKeyDown/Up will be triggered. Once you do that, the delegate is done.
And once the Delegate is done, we have to make our view like this:
/**
* SimplestCustomView
*/
public class AccessibilityHelperView : View
{
private MyAccessibilityHelper mHelper;
Dictionary<int, Rect> virtualIdRectMap = new Dictionary<int, Rect>();
public AccessibilityHelperView(Context context) :
base(context)
{
Init();
}
public AccessibilityHelperView(Context context, IAttributeSet attrs) :
base(context, attrs)
{
Init();
}
public AccessibilityHelperView(Context context, IAttributeSet attrs, int defStyle) :
base(context, attrs, defStyle)
{
Init();
}
public void Init()
{
this.SetFocusable(ViewFocusability.Focusable);
this.Focusable = true;
this.FocusedByDefault = true;
setRectangle();
mHelper = new MyAccessibilityHelper(this);
ViewCompat.SetAccessibilityDelegate(this, mHelper);
foreach (var r in virtualIdRectMap)
{
mHelper.AddRect(r.Key, r.Value);
}
}
private void setRectangle()
{
virtualIdRectMap.Add(MRAccessibilityHelper.NODE_CENTER, new Rect(1, 1, 2, 2));
virtualIdRectMap.Add(MRAccessibilityHelper.NODE_LEFT, new Rect(0, 1, 1, 2));
virtualIdRectMap.Add(MRAccessibilityHelper.NODE_UP, new Rect(1, 0, 2, 1));
virtualIdRectMap.Add(MRAccessibilityHelper.NODE_RIGHT, new Rect(2, 1, 3, 2));
virtualIdRectMap.Add(MRAccessibilityHelper.NODE_DOWN, new Rect(1, 2, 2, 3));
}
protected override void OnDraw(Canvas canvas)
{
base.OnDraw(canvas);
}
}
That view looks like this:
What is to notice?
The size of the node pads is in pixels, and they will be found on the top left corner of your app.
They are set to that single pixel size, because the Talkback functionality would otherwise select the first node pad that was added to the dictionary with a green rectangle (thats standard behavior for talkback)
All the rectangles in the view are added to a dictionary that will be used in our own Accessibility Delegate, to mention here is that the CENTER pad was added first, and therefor will be in focus once the talkback is activated by default
The Init function
The Init function is crutial for this, there we will create our view, and set some talkback parameters nessessary for our virtual dpad to be recognized by the systems own Accessibility Service.
Also, there will our Accessibility Delegate be initialized and our dictionary with all the created DPADs.
Ok, so far, we made a Delegate and a View, I placed them both in the same file, so they can see each other. But it is not a must.
So what now? We must add the AccessibilityHelperView to our app, in the MainActivity.cs file
AccessibilityHelperView mAccessibilityHelperView;
In the OnCreate function, you can add the following code to initiate the view:
mAccessibilityHelperView = new AccessibilityHelperView(this);
In the OnResume function, you can check if the talkback is on or off, based on the result, you can add or remove the mAccessibilityHelperView from your mBackgroundLayout(AddView, and RemoveView).
The OnResume function should look like this:
if (TalkbackEnabled && !_isVirtualDPadShown)
{
mBackgroundLayout.AddView(mAccessibilityHelperView);
_isVirtualDPadShown = true;
}
else if (!TalkbackEnabled && _isVirtualDPadShown)
{
mBackgroundLayout.RemoveView(mAccessibilityHelperView);
_isVirtualDPadShown = false;
}
The TalkbackEnabled variable is a local one that checks if the Talkback service is on or off, like this:
public bool TalkbackEnabled
{
get
{
AccessibilityManager am = MyApp.Instance.GetSystemService(Context.AccessibilityService) as AccessibilityManager;
if (am == null) return false;
String TALKBACK_SETTING_ACTIVITY_NAME = "com.android.talkback.TalkBackPreferencesActivity";
var serviceList = am.GetEnabledAccessibilityServiceList(FeedbackFlags.AllMask);
foreach (AccessibilityServiceInfo serviceInfo in serviceList)
{
String name = serviceInfo.SettingsActivityName;
if (name.Equals(TALKBACK_SETTING_ACTIVITY_NAME))
{
Log.Debug(LogArea, "Talkback is active");
return true;
}
}
Log.Debug(LogArea, "Talkback is inactive");
return false;
}
}
That should be all you need to make it work.
Hope I could help you out.
Related
I am trying to convert my PC game code in unity to android and I am stuck on the controls change. Please help!
This is the code:
Getting the state of rocket.
enum State { Dying, Alive, Transcending }
State state = State.Alive;
// Update is called once per frame
void Update()
{
if (state == State.Alive)
{
RespondToThrustInput();
RespondToRotateInput();
}
}
When the rocket collides with anything it checks whether it's friendly or not before changing its state from alive to dead.
private void OnCollisionEnter(Collision collision)
{
if (state != State.Alive) { return; }
switch (collision.gameObject.tag)
{
case "Friendly":
break;
case "Finish":
state = State.Transcending;
audioSource.Stop();
audioSource.PlayOneShot(finishgame);
finishgameParticles.Play();
Invoke("LoadNextScene", levelloaddelay);
break;
default:
state = State.Dying;
audioSource.Stop();
audioSource.PlayOneShot(death);
deathParticles.Play();
Invoke("LoadFirstScene", levelloaddelay);
break;
}
}
private void LoadFirstScene()
{
SceneManager.LoadScene(9);
}
Loading next scene using build index.
private void LoadNextScene()
{
if (nextscenetoload > 7)
{
nextscenetoload = 0;
}
SceneManager.LoadScene(nextscenetoload);
}
Space for ignition or force and audio sources for playing sound effects.
private void RespondToThrustInput()
{
if (Input.GetKey(KeyCode.Space))
{
ApplyThrust();
}
else
{
audioSource.Stop();
mainengineParticles.Stop();
}
}
Apply thrust is the method I wrote with the logic of the rocket thrust.
private void ApplyThrust()
{
rigidbody.AddRelativeForce(Vector3.up * mainThrust * Time.deltaTime);
if (!audioSource.isPlaying)
audioSource.PlayOneShot(mainengine);
mainengineParticles.Play();
}
Rotation of the rocket or Left and right. Here I am trying to rotate the rocket using the A and D keys
void RespondToRotateInput()
{
float rotationThisFrame = rcsThrust * Time.deltaTime;
if (Input.GetKey(KeyCode.A))
{
rigidbody.freezeRotation = true;
transform.Rotate(Vector3.forward * rotationThisFrame);
rigidbody.freezeRotation = false;
}
else if (Input.GetKey(KeyCode.D))
{
rigidbody.freezeRotation = true;
transform.Rotate(-Vector3.forward * rotationThisFrame);
rigidbody.freezeRotation = false;
}
}
For PC games there is a keyboard to use to control, but for the android there are touches, you have to verify if there is a touch on the screen, like this:
if (Input.touchCount > 0)
{
Touch touch = Input.GetTouch(0);
//do something
}
also you need more work to determine where the touch is located and do you customizations... or in case you're not interested about this input handling, you can use some assets from Unity Assets Store to cover this part for you.
check this link for more information about touch control in Unity documentation:
https://docs.unity3d.com/ScriptReference/Input.GetTouch.html
I want to check that Rectangle was tapped. This mehod does the job and it works almost how I want:
private bool CheckRectangleTouch(Rectangle target)
{
var touchCollection = TouchPanel.GetState();
if (touchCollection.Count > 0)
{
foreach (var touch in touchCollection)
{
if (target.Contains(touch.Position))
{
return true;
}
}
}
return false;
}
Problem I have is that after I've tapped rectangle it keeps returning true until I release it (it can register 10-30 times for one tap) and I want it to return true just once - for the first touch.
I've tried this (replace code inside foreach):
var isFirstTouch = !touch.TryGetPreviousLocation(out _);
if (target.Contains(touch.Position) && isFirstTouch)
{
return true;
}
And this (bad one, I don't really want it to register after release):
if (target.Contains(touch.Position) && touch.State == TouchLocationState.Released)
{
return true;
}
But nothing is does it. Either logic is not consistent or doesn't work at all.
So how do I check for tap?
Update: this works but it's very hacky, has delay and gives me random phantom taps:
try
{
var tap = TouchPanel.ReadGesture(); // falls each time when no input
return tap.GestureType == GestureType.Tap && target.Contains(tap.Position);
}
catch { }
return false;
Here's what I ended up doing:
I have singleton to hold my game state (many different props updated as needed). I added to it:
public TouchCollection TouchCollection { get; set; }
Prop to hold TouchPanel.GetState result. I fill it in Games Update method once per frame, as #craftworkgames suggested:
State.TouchCollection = TouchPanel.GetState();
Also I added this prop to my game state:
public bool TouchActive { get; set; }
And this is the method to check for rectangle tap. It returns true only for the first contact in tap:
private bool CheckRectangleTap(Rectangle target)
{
if (State.TouchCollection.Count == 0)
{ // if no input
return State.TouchActive = false;
}
var targetTouched = false;
foreach (var touch in State.TouchCollection)
{
if (target.Contains(touch.Position))
{
targetTouched = true;
}
}
if (targetTouched && !State.TouchActive)
{ // if target is touched and it's first contact
return State.TouchActive = true;
}
return false;
}
It doesn't seem ideal but it works for my case.
I'm trying to determine when a screen is rotated (in Android) using the XLabs method detailed here How to handle screen rotation/orientation in Xamarin Forms? and I'm having trouble with it.
I override the OnConfigurationChanged method in MainActivity
public override void OnConfigurationChanged (Android.Content.Res.Configuration newConfig)
{
base.OnConfigurationChanged (newConfig);
var xapp = Resolver.Resolve<IXFormsApp> ();
if (xapp == null)
return;
switch (newConfig.Orientation) {
case Android.Content.Res.Orientation.Landscape:
xapp.Orientation = XLabs.Enums.Orientation.Landscape;
break;
case Android.Content.Res.Orientation.Portrait:
//xapp.Orientation = XLabs.Enums.Orientation.Portrait;
break;
default:
break;
}
}
I'm having trouble with the Orientation variable in IXFormsApp i.e. xapp.Orientation. The XLabs documentation lists this as 'protected set', as does the compiler:
MainActivity.cs(109,5,109,21): error CS0200: Property or indexer 'XLabs.Platform.Mvvm.IXFormsApp.Orientation' cannot be assigned to -- it is read only
and it doesn't get set automagically (when I check where it is used, it is always set to 'None'), so I was wondering how to make use of it, and indeed, how to use the XLabs/IXFormsApp to determine rotation?
On a related note, I was also trying to set the Rotation handler (not sure why, but I thought I'd give it a go) with unusual results.
xapp.Rotation += (sender, args) =>
{
switch (args.Value)
{
case XLabs.Enums.Orientation.Landscape:
//xapp.Orientation = XLabs.Enums.Orientation.Landscape;
...
break;
case XLabs.Enums.Orientation.Portrait:
...
break;
default:
break;
}
};
If I try in the Android code I get the following error:
MainActivity.cs(60,4,60,22): error CS0019: Operator '+=' cannot be applied to operands of type 'System.EventHandler<XLabs.EventArgs<XLabs.Enums.Orientation>>' and 'lambda expression'
however, if I set it in the Forms code (where the results are used), it is fine (altho the handler never seems to actually be called). Does anyone know whay this would be the case?
There are two different solutions I have used in the past.
The first is by making a PageBase class which all my pages inherit from, and PageBase inherits from a regular Page.
My PageBase has two abstract methods (so the children of it have to fill it in), which are UpdateLandscape and UpdatePortait. Children will fill these methods in for how to layout the page depending on whether it is being laid out in landscape or portrait mode.
Pages have a method OnSizeAllocated, as Daniel said. I made PageBase override it and make it call UpdateLandscape and UpdatePortait accordingly.
If, as you said, you are only looking to check when it has rotated, the above works just fine, as OnSizeAllocated gets called for a page whenever you rotate your phone.
If you are checking for landscape vs portait because you want your code to be able to check at any time, then the second solution below works too.
The second way I solved it is to use dependency services to fill in an IDeviceInfo interface, and write all dynamic things by checking if DeviceInfo.IsPortait() is true or false (and this way I also let DeviceInfo have a Width and Height, so I can request the screen dimensions at any point).
On Android, I filled in my Android code as so:
[assembly: Dependency (typeof(Namespace.DeviceInfoProvider))]
namespace Namespace
{
public class DeviceInfoProvider : IDeviceInfoProvider
{
public bool IsPortait () { return DeviceInfoManager.Width < DeviceInfoManager.Height; }
public int GetWidth () { return DeviceInfoManager.Width; }
public int GetHeight () { return DeviceInfoManager.Height; }
}
public static class DeviceInfoManager
{
public static MainActivity MainActivity { get; set; }
public static int Width { get { return MainActivity.GetWidth (); } }
public static int Height { get { return MainActivity.GetHeight (); } }
}
}
Then in MainActivity I gave it these methods:
public int GetWidth() {
return (int)(Resources.DisplayMetrics.WidthPixels / Resources.DisplayMetrics.Density);
}
public int GetHeight() {
return (int)(Resources.DisplayMetrics.HeightPixels / Resources.DisplayMetrics.Density);
}
And on the iOS side, I filled it in as so:
[assembly: Dependency (typeof(Namespace.DeviceInfoProvider))]
namespace Namespace {
public class DeviceInfoProvider : IDeviceInfoProvider {
public bool IsPortait() { return UIScreen.MainScreen.Bounds.Width < UIScreen.MainScreen.Bounds.Height; }
public int GetWidth() { return (int)UIScreen.MainScreen.Bounds.Width; }
public int GetHeight() { return (int)UIScreen.MainScreen.Bounds.Height; }
}
}
Personally, I am more of a fan of writing it the second way and making it check "if we are in portait mode, here are the differences". That way those things that are not different between portait and landscape only have to be written once, only the differences are written twice.
You can use OnSizeAllocated method override to detect orientation change;
double previousWidth;
double previousHeight;
protected override void OnSizeAllocated(double width, double height)
{
base.OnSizeAllocated(width, height);
if (previousWidth != width || previousHeight != height)
{
previousWidth = width;
previousHeight = height;
if (width > height)
{
// landscape mode
}
else
{
// portrait mode
}
}
}
I'm developing application that views books. There is a screen (Activity) which shows a book. It has custom view, something similar to ViewSwitcher and every page is a bitmap that is rendered by a custom View.
Now I should implement accessibility function - book should be read by the phone (audio).
I've read Accessibility section here https://developer.android.com/guide/topics/ui/accessibility/index.html but it is not clear enough.
I use SupportLibrary for accessibility management and now I have this code in ViewGroup (which manages book pages). Code 1:
private class EditionPagesViewSwitcherAccessibilityDelegate extends AccessibilityDelegateCompat {
private int mPageCount;
private double[] mPageRange;
#Override
public void onInitializeAccessibilityEvent(final View host, final AccessibilityEvent event) {
super.onInitializeAccessibilityEvent(host, event);
event.setClassName(EditionPagesViewSwitcher.class.getName());
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
event.setScrollable(canScroll());
}
if (event.getEventType() == AccessibilityEventCompat.TYPE_VIEW_SCROLLED && updatePageValues()) {
event.setItemCount(mPageCount);
// we use +1 because of user friendly numbers (from 1 not 0)
event.setFromIndex((int) (mPageRange[0] + 1));
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
event.setToIndex((int) (mPageRange[1] + 1));
}
}
}
#Override
public void onInitializeAccessibilityNodeInfo(final View host, final AccessibilityNodeInfoCompat info) {
super.onInitializeAccessibilityNodeInfo(host, info);
info.setClassName(EditionPagesViewSwitcher.class.getName());
info.setScrollable(canScroll());
info.setLongClickable(true);
if (canScrollForward()) {
info.addAction(AccessibilityNodeInfoCompat.ACTION_SCROLL_FORWARD);
}
if (canScrollBackward()) {
info.addAction(AccessibilityNodeInfoCompat.ACTION_SCROLL_BACKWARD);
}
}
#Override
public boolean performAccessibilityAction(final View host, final int action, final Bundle args) {
if (super.performAccessibilityAction(host, action, args)) {
return true;
}
switch (action) {
case AccessibilityNodeInfoCompat.ACTION_SCROLL_FORWARD: {
if (canScrollForward()) {
showNext();
return true;
}
}
return false;
case AccessibilityNodeInfoCompat.ACTION_SCROLL_BACKWARD: {
if (canScrollBackward()) {
showPrevious();
return true;
}
}
return false;
}
return false;
}
Here is code from page view Code 2:
#Override
public void onInitializeAccessibilityEvent(final View host, final AccessibilityEvent event) {
super.onInitializeAccessibilityEvent(host, event);
event.setClassName(EditionPageView.class.getName());
if (hasText()) {
event.getText().add(getPageRangeText());
final String trimText = mSurfaceUpdateData.getPageText().trim();
if (trimText.length() > MAX_TEXT_LENGTH) {
event.getText().add(trimText.substring(0, MAX_TEXT_LENGTH));
// event.getText().add(trimText.substring(MAX_TEXT_LENGTH, trimText.length()));
}
else {
event.getText().add(trimText);
}
}
}
#Override
public void onInitializeAccessibilityNodeInfo(final View host, final AccessibilityNodeInfoCompat info) {
super.onInitializeAccessibilityNodeInfo(host, info);
info.setClassName(EditionPageView.class.getName());
}
Because page text data loads asynchronous first time accessibility don't have any text while executes onInitializeAccessibilityEvent code. And then when data have been loaded I fire AccessibilityEvent.TYPE_VIEW_SELECTED and AccessibilityEvent.TYPE_VIEW_TEXT_CHANGED events. Then onInitializeAccessibilityEvent executes again and phone "read" book text.
So my questions:
Is my Accessibility implementation right? May be it is design wrong? Because I didn't find any good tutorial about this feature.
Why I need to use SDK versions checks in Support implementations in Code 1? Why support implementation doesn't handle it correctly?
Is firing TYPE_VIEW_SELECTED and TYPE_VIEW_TEXT_CHANGED really needed? Or may be some other code should be implemented?
The main question. In Code 2 there is commented code line. This code statement substring text to be less then MAX_TEXT_LENGTH (it's 3800) because if text is bigger nothing is played. Nothing. Is it accessibility restriction? Any other text that is less then this value is played well.
Does anyone know where I can find any good tutorial? (yes I saw samples).
Does anyone have any custom realizations to look through?
UPDATED
Well. Here is some answers:
As I can see TYPE_VIEW_SELECTED and TYPE_VIEW_TEXT_CHANGED events are not needed if you don't want this text to be read as soon as you get it.
On Nexus 7 all large text is played well (text up to 8000 symbols), so this issue doesn't reproduce on it, but on Samsung Galaxy Tab 10.1 (Android 4.0.4) and Genymotion emulator of Tab 10.1 with Android 4.3 does. And this is strange...
4.. According to the documentation of String.substring()
The first argument you pass is the start index in the original string, the second argument is the end index in the original string.
Example:
String text = "Hello";
partOfText = text.substring(2,text.length() - 1);
partOfText equals to "llo" (the first char is index 0)
So by putting your constant MAX_TEXT_LENGTH as a first argument, it would start at index 3800 to take out the substring.
http://developer.android.com/reference/java/lang/String.html#substring(int)
You are right MAX_TEXT_LENGTH is 3800.
About your doubt,
this code:
event.getText().add(trimText.substring(MAX_TEXT_LENGTH, trimText.length()));
}
you are trying to substring "trimText" from MAX_TEXT_LENGTH to trimText.length() !
Supposing that trimText = "STACK", trimText.length() = 5, then trimText.substring(3800,5) is going to be ?
At first, this doesn't have sense, using correctly would be like this:
trimText.substring(0,2) = "ST";
I have a NumberPicker that has a formatter that formats the displayed numbers either when the NumberPicker spins or when a value is entered manually. This works fine, but when the NumberPicker is first shown and I initialize it with setValue(0) the 0 does not get formatted (it should display as "-" instead of 0). As soon as I spin the NumberPicker from that point on everything works.
How can I force the NumberPicker to format always - Both on first rendering and also when I enter a number manually with the keyboard?
This is my formatter
public class PickerFormatter implements Formatter {
private String mSingle;
private String mMultiple;
public PickerFormatter(String single, String multiple) {
mSingle = single;
mMultiple = multiple;
}
#Override
public String format(int num) {
if (num == 0) {
return "-";
}
if (num == 1) {
return num + " " + mSingle;
}
return num + " " + mMultiple;
}
}
I add my formatter to the picker with setFormatter(), this is all I do to the picker.
picker.setMaxValue(max);
picker.setMinValue(min);
picker.setFormatter(new PickerFormatter(single, multiple));
picker.setWrapSelectorWheel(wrap);
dgel's solution doesn't work for me: when I tap on the picker, formatting disappears again. This bug is caused by input filter set on EditText inside NumberPicker when setDisplayValues isn't used. So I came up with this workaround:
Field f = NumberPicker.class.getDeclaredField("mInputText");
f.setAccessible(true);
EditText inputText = (EditText)f.get(mPicker);
inputText.setFilters(new InputFilter[0]);
I also encountered this annoying little bug. Used a technique from this answer to come up with a nasty but effective fix.
NumberPicker picker = (NumberPicker)view.findViewById(id.picker);
picker.setMinValue(1);
picker.setMaxValue(5);
picker.setWrapSelectorWheel(false);
picker.setFormatter(new NumberPicker.Formatter() {
#Override
public String format(int value) {
return my_formatter(value);
}
});
try {
Method method = picker.getClass().getDeclaredMethod("changeValueByOne", boolean.class);
method.setAccessible(true);
method.invoke(picker, true);
} catch (NoSuchMethodException e) {
e.printStackTrace();
} catch (IllegalArgumentException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (InvocationTargetException e) {
e.printStackTrace();
}
Calling that private changeValueByOne method immediately after instantiating my number picker seems to kick the formatter enough to behave how it should. The number picker comes up nice and clean with the first value formatted correctly. Like I said, nasty but effective.
I had the same problem and I used the setDisplayedValues() method instead.
int max = 99;
String[] values = new String[99];
values[0] = “-” + mSingle
values[1] =
for(int i=2; i<=max; i++){
makeNames[i] = String.valueOf(i) + mMultiple;
}
picker.setMinValue(0);
picker.setMaxValue(max);
picker.setDisplayedValues(values)
This doesn't allow the user to set the value manually in the picker though.
The following solution worked out for me for APIs 18-26 without using reflection, and without using setDisplayedValues().
It consists of two steps:
Make sure the first element shows by setting it's visibility to invisible (I used Layout Inspector to see the difference with when it shows, it's not logical but View.INVISIBLE actually makes the view visible).
private void initNumberPicker() {
// Inflate or create your BugFixNumberPicker class
// Do your initialization on bugFixNumberPicker...
bugFixNumberPicker.setFormatter(new NumberPicker.Formatter() {
#Override
public String format(final int value) {
// Format to your needs
return aFormatMethod(value);
}
});
// Fix for bug in Android Picker where the first element is not shown
View firstItem = bugFixNumberPicker.getChildAt(0);
if (firstItem != null) {
firstItem.setVisibility(View.INVISIBLE);
}
}
Subclass NumberPicker and make sure no click events go through so the glitch where picker elements disapear on touch can't happen.
public class BugFixNumberPicker extends NumberPicker {
public BugFixNumberPicker(Context context) {
super(context);
}
public BugFixNumberPicker(Context context, AttributeSet attrs) {
super(context, attrs);
}
public BugFixNumberPicker(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
#Override
public boolean performClick() {
return false;
}
#Override
public boolean performLongClick() {
return false;
}
#Override
public boolean onInterceptTouchEvent(MotionEvent event) {
return false;
}
}
Here's my solution based on answers by torvin and Sebastian. You don't have to subclass anything or use reflection.
View editView = numberPicker.getChildAt(0);
if (editView instanceof EditText) {
// Remove default input filter
((EditText) editView).setFilters(new InputFilter[0]);
}
Calling the private method changeValueByOne() via reflection as described in an earlier answer works for me on API Level 16 (Android 4.1.2 and up), but it does not seem to help on API Level 15 (Android 4.0.3), however!
What works for me on API Level 15 (and up) is to use your own custom formatter to create String array and pass that with the method setDisplayedValues() to the number picker.
See also: Android 3.x and 4.x NumberPicker Example
The answer provided by NoActivity worked for me but I only had to do:
View firstItem = bugFixNumberPicker.getChildAt(0);
if (firstItem != null) {
firstItem.setVisibility(View.INVISIBLE);
}
to fix the issue. I did not need to subclass NumberPicker. I did not see the issue where picker elements disappear on touch.
Kotlin version based on Nikolai's answer
private fun initNumberPicker() {
nrPicker.children.iterator().forEach {
if (it is EditText) it.filters = arrayOfNulls(0) // remove default input filter
}
}
I managed to fix it by calling
picker.invalidate();
just after setting the formatter.
Improved Nikolai answer if selected index is not 0. Not to great for performances but fix the problem..
for(index in numberPicker.minValue..numberPicker.maxValue) {
val editView = numberPicker.getChildAt(index-numberPicker.minValue)
if (editView != null && editView is EditText) {
// Remove default input filter
(editView as EditText).filters = arrayOfNulls(0)
}
}