Xamarin Forms - Get the size of an AbsoluteLayout - height

Question

I cannot find the way to get the Width and the Height of a Xamarin.Forms.View.
I have this object:
public class SquareLayout : View
{
public static readonly BindableProperty ScalingBaseProperty =
BindableProperty.Create(nameof(ScalingBase), typeof(ScalingBaseType), typeof(SquareLayout), ScalingBaseType.Average,
propertyChanged: OnScalingBasePropertyChanged);
public ScalingBaseType ScalingBase
{
get { return (ScalingBaseType)GetValue(ScalingBaseProperty); }
set { SetValue(ScalingBaseProperty, value); }
}
public enum ScalingBaseType
{
Average,
Height,
Width
}
public static void OnScalingBasePropertyChanged(BindableObject bindable, object oldValue, object newValue)
{
SquareLayout sq = ((SquareLayout)bindable);
Debug.WriteLine("|Width = {0}|Height = {1}|", sq.Bounds.Width, sq.Bounds.Height);
switch (sq.ScalingBase)
{
case ScalingBaseType.Average:
double size = (sq.Bounds.Width + sq.Bounds.Height) / 2;
sq.WidthRequest = size;
sq.HeightRequest = size;
break;
case ScalingBaseType.Height:
sq.WidthRequest = sq.Bounds.Height;
break;
case ScalingBaseType.Width:
sq.HeightRequest = sq.Bounds.Width;
break;
}
Debug.WriteLine("|Width = {0}|Height = {1}|", sq.Bounds.Width, sq.Bounds.Height);
}
}
Basically, you declare somewhere this SquareLayout and then, based on an Enum, the layout is resized as a Square.
So, I then have this XAML part
<ContentPage.Content>
<AbsoluteLayout BackgroundColor="White">
...
<AbsoluteLayout x:Name="ToolsLayout" BackgroundColor="Red"
AbsoluteLayout.LayoutBounds="0.5, 0.05, 0.9, 0.075"
AbsoluteLayout.LayoutFlags="All">
<control:SquareLayout BackgroundColor="White" ScalingBase="Height"
AbsoluteLayout.LayoutBounds="0, 0.5, 0.1, 1"
AbsoluteLayout.LayoutFlags="All">
</control:SquareLayout>
<control:SquareLayout BackgroundColor="White" ScalingBase="Height"
AbsoluteLayout.LayoutBounds="1, 0.5, 0.1, 1"
AbsoluteLayout.LayoutFlags="All">
</control:SquareLayout>
</AbsoluteLayout>
...
</AbsoluteLayout>
</ContentPage.Content>
Which would give me a Rectangle with two Square around.. But nothing !
I tried to display the Width and the Height but nothing.. I tried the Bounds as well as you can see in the example, but nothing one more time..
The only values I get are -1
Does someone can help me? Thank in advance !

Answer 1

Xamarin has very less documentation for newbies , took some time to figure this out , basically during design time the the width and height property have a default value of -1 , which indicates auto , there is no way of knowing during design time what the values will be , hence you need to use 'events' to get the width and height property in this case you will use SizeChanged event , when the layout bounds are set during runtime this event will trigger.
In your xaml codebehind use this event to get your widh and height of yourlayout , i have used a lambda function , this can be implemented in many ways i just find this method easy.
yourlayout.SizeChanged+=(sender,e)=>
{
//Add your child objects here and set its values using yourlayout.Height etc
};
Instead of adding your children within this function you can use it to return a value and use that instead.
NOTE:I am not sure if this is the best practice for MVVM or otherwise