How to pass textBlock control to a Class - windows-phone-7

Question

say I have a textBlock control and I want to pass it to a class which controls the textBlock to display certain Message.
1) When I call a method in the class, I want textBlock to show message. Example " Checking connection...."
2) When the method complete the required task, the textBlock visibility become collapsed.
In the XAML : I have
a) textBlock name=textBlockMsg
b) a Button to call the class
Appreciate your help.
-- Update :
This class file inside project
public class GeoCalculation
{
public GeoCalculation() { }
public void CalculateDistance()
{
//- Begin -- want the textBlockMsg show : in progress......
--code
//-- when end-----, textBlockMsg visibility becom collapse
}
}

Answer 1

If you named you TextBox in the XAML with textBlockMsg, this will work
Edit
// I will not implement the whole INotifyPropertyChanged check how to do to it : implement
public class CalculationClass : INotifyPropertyChanged
{
public void CalculateDistance()
{
TextToBeBound = "in progress..."
--code
VisibilityToBeBound = Collapsed;
}
public string TextToBeBound
{ //... insert the implement of this property + NotifyPropertyChanged
get {...}
set {...}
}
public Visibility VisibilityToBeBound
{ //... insert the implement of this property + NotifyPropertyChanged
get {...}
set {...}
}
}
Then in the XAML add this :
<TextBlock x:Name="txtBlocMsg" Visibility={"Binding VisibilityToBeBound"} Text={Binding TextToBeBound"}/>
Don't forget to set the DataContext of the UI to your class (in my case CalculationClass
You should be good to go. If all this was new. I recommend you read about data Binding + MVVM pattern.
Edit
It's bad practice to pass UI element to model/business classes. You should use the MVVM pattern.
Hope this helps.

Answer 2

You can have a parameter to pass the TextBock:
public void CalculateDistance(TextBlock tb)
{
tb.Text = "in progress..."
--code
tb.Visibility = Visibility.Collapsed;
}
You coud use a the constructor of your class to inject the textblock it should handle
public class GeoCalculation
{
private TextBlock _tb;
public GeoCalculation(TextBlock tb)
{
_tb = tb;
}
public void CalculateDistance()
{
_tb.Text = "in progress..."
//code
_tb.Visibility = Visibility.Collapsed;
}
}
A ViewModel and using DataBinding would be better by the way!
There you could use our class (method) to provice the text for the ui (textbox)
But be aware:
There is a .net way to do this. The GeoCoordinate class contains a method "GetDistanceTo" to calculate the distance between two geo points. See http://msdn.microsoft.com/en-us/library/system.device.location.geocoordinate.getdistanceto.aspx .