How to set corner radius for button in xamarin uwp by programatically? - xamarin

Question

I am having an grid holding in Button. I want to set corner radius for this button by programmatically in xamarin.uwp. If it possible means i want to set corner radius for Bottom left alone. Please suggest your ideas for this query.

Answer 1

For your requirement, you could custom BottomLeft BindableProperty. then use it in your custom button render like the following.
Custom Forms buttom
public class MyButton : Button
{
public static readonly BindableProperty BottomLeftProperty = BindableProperty.Create(
propertyName: "BottomLeft",
returnType: typeof(int),
declaringType: typeof(MyButton),
defaultValue: default(int));
public int BottomLeft
{
get { return (int)GetValue(BottomLeftProperty); }
set { SetValue(BottomLeftProperty, value); }
}
}
CustomButtonRenderer.cs
public class CustomButtonRenderer : ButtonRenderer
{
Windows.UI.Xaml.Controls.ContentPresenter _contentPresenter;
MyButton _myElement;
protected override void OnElementChanged(ElementChangedEventArgs<Button> e)
{
base.OnElementChanged(e);
if (Control == null)
{
SetNativeControl(new FormsButton());
}
if (e.NewElement != null)
{
Control.Loaded += Control_Loaded;
_myElement = Element as MyButton;
}
}
protected override void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
{
base.OnElementPropertyChanged(sender, e);
if (e.PropertyName == MyButton.BottomLeftProperty.PropertyName)
{
UpdateBottomLeftBorderRadius(_myElement.BottomLeft);
}
}
private void Control_Loaded(object sender, Windows.UI.Xaml.RoutedEventArgs e)
{
_contentPresenter = MyFindChildByName(Control, "ContentPresenter") as Windows.UI.Xaml.Controls.ContentPresenter;
if (_myElement.IsSet(MyButton.BottomLeftProperty) && _myElement.BottomLeft != (int)MyButton.BottomLeftProperty.DefaultValue)
{
UpdateBottomLeftBorderRadius(_myElement.BottomLeft);
}
}
private void UpdateBottomLeftBorderRadius(int bottomLeft)
{
if (_contentPresenter != null)
{
_contentPresenter.CornerRadius = new CornerRadius(0, 0, 0, bottomLeft);
}
}
public static DependencyObject MyFindChildByName(DependencyObject parant, string ControlName)
{
int count = VisualTreeHelper.GetChildrenCount(parant);
for (int i = 0; i < count; i++)
{
var MyChild = VisualTreeHelper.GetChild(parant, i);
if (MyChild is FrameworkElement && ((FrameworkElement)MyChild).Name == ControlName)
return MyChild;
var FindResult = MyFindChildByName(MyChild, ControlName);
if (FindResult != null)
return FindResult;
}
return null;
}
}
Usage
<local:MyButton x:Name="Hello" Text="hello"
WidthRequest="100"
HeightRequest="100"
Margin="0,100,0,0"
BottomLeft="15"
VerticalOptions="Center"
HorizontalOptions="Center"
Clicked="MyButton_Clicked"/>
For edit the bottom left property programatically.
HelloBtn.BottomLeft = 30;