xamarin binding byte array to grid labels - xamarin

Question

I want to binding a byte[] to difference label in grid view but it is weird when I change the value in a timer event,the onPropertyChanged() don't call,turns out the label didn't update with the byte[].Pls help me out where is the mistake in my code.I can binding a byte with the code I list,but seems not work with byte[].Thanks!
System.Timers.Timer testtimer;
Grid gridView;
byte[] _recvdata;
byte testbyte;
public byte[] RecvData
{
get
{
return _recvdata;
}
set
{
if (_recvdata != value)
{
_recvdata = value;
OnPropertyChanged("RecvData");
}
}
}
public event PropertyChangedEventHandler PropertyChanged;
protected override void OnPropertyChanged(string propertyName)
{
var changed = PropertyChanged;
if (changed != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
public DevicePage(IDevice currDevice)
{
device = currDevice;
this.Title = "Status";
testtimer = new System.Timers.Timer();
testtimer.Interval = 1000;
testtimer.Elapsed += OnTimedEvent;
testtimer.Enabled = true;
gridView = new Grid();
RecvData = new byte[40];
for (byte i = 0; i < 40;i++)
{
string st;
var lb = new Label ();
st = "RecvData[" + i + "]";
lb.SetBinding(Label.TextProperty, st);
lb.BindingContext = this;
gridView.Children.Add(lb, 0, i);
}
this.Content = gridView;
}
private void OnTimedEvent(object sender, System.Timers.ElapsedEventArgs e)
{
byte i;
testbyte += 1;
for (i = 0; i < 40; i++)
{
RecvData[i] = testbyte;
}
}

Answer 1

The setter of RecvData property is not called when you just change it using [indexer]. You have two options I see:
1) manually call OnPropertyChanged after you change the byte array using indexer:
private void OnTimedEvent(object sender, System.Timers.ElapsedEventArgs e)
{
byte i;
testbyte += 1;
for (i = 0; i < 40; i++)
{
RecvData[i] = testbyte;
}
OnPropertyChanged("RecvData");
}
2) create a wrapper for byte array which would call OnPropertyChanged automatically when you change an array using the indexer:
public class ByteArrayWrapper : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
byte[] _array;
public byte[] Array
{
get
{
return _array;
}
set
{
if (_array != value)
{
_array = value;
OnPropertyChanged("Array");
}
}
}
public byte this[int index]
{
get
{
return _array[index];
}
set
{
_array[index] = value;
OnPropertyChanged("Array");
}
}
protected void OnPropertyChanged(string propertyName)
{
var changed = PropertyChanged;
if (changed != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
}
then instead of operating on your byte array like this:
public byte[] RecvData
{
// get/set
}
you should use an instance of above class:
public ByteArrayWrapper RecvData
{
// get/set
}
Other code should be just fine. If the binding doesn't work, maybe you'd need to bind to RecvData.Array[i] instead of RecvData[i], please let me know if that works as I'm not able to test right now.