This question is the same as How to set a top margin only in XAML? but regarding Xamarin instead of WPF.
How can I set an individual margin on a view from XAML?
The linked Q&A indicates that the default implementation always sets all unspecified Margins to 0, even from code.
The solution is to create an AttachedProperty :
using System;
using Xamarin.Forms;
namespace Sample.Utils
{
/// <summary>
/// Allows setting Top,Left,Right,Bottom Margin independently from each other.
/// The default implementation does not allow that, even from code. This
/// attached property remembers the previously set margins and only modifies what you intend to modify.
/// </summary>
public static class Margin
{
public static readonly BindableProperty LeftProperty = BindableProperty.CreateAttached(
propertyName: "Left",
returnType: typeof(double),
declaringType: typeof(Margin),
propertyChanged: LeftPropertyChanged,
defaultValue: 0.0d);
private static void LeftPropertyChanged(BindableObject bindable, object oldValue, object newValue)
{
SetLeft(bindable, (double)newValue);
}
public static void SetLeft(BindableObject element, double value)
{
var view = element as View;
if (view != null)
{
Thickness currentMargin = (Xamarin.Forms.Thickness)view.GetValue(View.MarginProperty);
view.Margin = new Thickness(value, currentMargin.Top, currentMargin.Right, currentMargin.Bottom);
}
}
public static double GetLeft(BindableObject element)
{
View view = element as View;
if (view != null)
{
Thickness margin = (Xamarin.Forms.Thickness)view.GetValue(View.MarginProperty);
return margin.Left;
}
return (double)LeftProperty.DefaultValue;
}
}
}
Declare this in the same way for Bottom
, Top
, and Right
. Then use it in XAML like this:
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:utils="using:Sample.Utils"
x:Class="Sample.MyContentPage">
<StackLayout
Orientation="Vertical"
utils:Margin.Left="{StaticResource InnerPageContentMarginLeft}">
</StackLayout>
</ContentPage>
Sources:
* https://forums.xamarin.com/discussion/66026/use-attached-bindable-property-in-xaml
* https://stackoverflow.com/a/32408461/2550406
Unless I'm missing something, it's just a matter of specifying the Margin as follows:
<Label
Margin = "0,20,0,0"
Text = "Hello World!" />
The Margin is specified as left , top , right , bottom values.
Maybe try a valueConverter where you can send a value to converter through binding and return a Thickness object. Somewhat like
Margin ={{Binding Marginleft, Converter={StaticResource stringToThicknessConverter}}
where you pass a string and get back a thickness object like new thickness(0,marginleft,0,0)
.
Also you could directly bind to a thickness type object in viewModel but that's a bad practice as it would create a View dependency in ViewModel which defeats the purpose of MVVM
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