How do I set a binding value as a parameter on a behavior in Xamarin Forms?
When I do this I get: Error. No property, bindable property, or event found for 'InputValue', or mismatching type between value and property.
XAML:
<Label Grid.Column="0" x:Name="player" FontSize="Small" VerticalOptions="CenterAndExpand" HorizontalOptions="CenterAndExpand"
Text="{Binding FormattedName}" >
<Label.Behaviors>
<local:ColorTextLabelBehavior MaxInputValue="100" MinInputValue="0" InputValue="{Binding Happiness}" />
</Label.Behaviors>
</Label>
C#:
public class ColorTextLabelBehavior : Behavior<Label>
{
public static readonly BindableProperty MaxValue = BindableProperty.Create("MaxValue", typeof(int), typeof(ColorTextLabelBehavior), defaultValue: 100);
public static readonly BindableProperty MinValue = BindableProperty.Create("MinValue", typeof(int), typeof(ColorTextLabelBehavior), defaultValue: 0);
public static readonly BindableProperty ActualValue = BindableProperty.Create("ActualValue", typeof(int), typeof(ColorTextLabelBehavior), defaultValue: 100);
public int MaxInputValue
{
get { return (int)GetValue(MaxValue); }
set { SetValue(MaxValue, value); }
}
public int MinInputValue
{
get { return (int)GetValue(MinValue); }
set { SetValue(MinValue, value); }
}
public int InputValue
{
get { return (int)GetValue(ActualValue); }
set { SetValue(ActualValue, value); }
}
void HandleTextChanged(object sender, PropertyChangedEventArgs e)
{
try
{
float percent = ((float)InputValue - (float)MinInputValue) / ((float)MaxInputValue - (float)MinInputValue);
double resultRed = Color.Red.R + percent * (Color.Green.R - Color.Red.R);
double resultGreen = Color.Red.G + percent * (Color.Green.G - Color.Red.G);
double resultBlue = Color.Red.B + percent * (Color.Green.B - Color.Red.B);
((Label)sender).TextColor = new Color(resultRed, resultGreen, resultBlue);
}
catch (Exception)
{
}
}
protected override void OnAttachedTo(BindableObject bindable)
{
bindable.PropertyChanged += HandleTextChanged;
}
protected override void OnDetachingFrom(BindableObject bindable)
{
bindable.PropertyChanged += HandleTextChanged;
}
}
If I hard code a value for 'InputValue' this works, but I want to be able to send a binding so that it will auto color the text.
Note this is in a listview if that matters.
Please help, I've been stuck on this and can't find any answers. I'm open to other alternatives to implementing this as well.
Thanks!!
I believe that the exact naming is important and that the BindableProperty
has to have the name of the actual property with "Property" appended to the end. From the docs:
The naming convention for bindable properties is that the bindable property identifier must match the property name specified in the Create method, with "Property" appended to it.
So I believe you want something like this:
public static readonly BindableProperty MaxInputValueProperty = BindableProperty.Create(nameof(MaxInputValue), typeof(int), typeof(ColorTextLabelBehavior), defaultValue: 100);
public static readonly BindableProperty MinInputValueProperty = BindableProperty.Create(nameof(MinInputValue), typeof(int), typeof(ColorTextLabelBehavior), defaultValue: 0);
public static readonly BindableProperty InputValueProperty = BindableProperty.Create(nameof(InputValue), typeof(int), typeof(ColorTextLabelBehavior), defaultValue: 100);
public int MaxInputValue
{
get { return (int)GetValue(MaxValue); }
set { SetValue(MaxValue, value); }
}
public int MinInputValue
{
get { return (int)GetValue(MinValue); }
set { SetValue(MinValue, value); }
}
public int InputValue
{
get { return (int)GetValue(ActualValue); }
set { SetValue(ActualValue, value); }
}