简单的问题。我需要一个只有一个圆角的框架,而不是全部四个。如何仅使框架的一个角变圆(在我的情况下为右上角)?
用另一种方式表达它:如何设置框架中仅一个角的角半径?
最佳答案
它使用自定义渲染框架的另一种方法。
1.创建类名称CustomFrame,继承Frame类,在PCL中添加BindableProperty CornerRadiusProperty。
public class CustomFrame: Frame
{
public static new readonly BindableProperty CornerRadiusProperty = BindableProperty.Create(nameof(CustomFrame), typeof(CornerRadius), typeof(CustomFrame));
public CustomFrame()
{
// MK Clearing default values (e.g. on iOS it's 5)
base.CornerRadius = 0;
}
public new CornerRadius CornerRadius
{
get => (CornerRadius)GetValue(CornerRadiusProperty);
set => SetValue(CornerRadiusProperty, value);
}
}
在Android中创建CustomFrameRender。
using FrameRenderer = Xamarin.Forms.Platform.Android.AppCompat.FrameRenderer;
[assembly: ExportRenderer(typeof(CustomFrame), typeof(CustomFrameRenderer))]
namespace Demo1.Droid
{
class CustomFrameRenderer : FrameRenderer
{
public CustomFrameRenderer(Context context)
: base(context)
{
}
protected override void OnElementChanged(ElementChangedEventArgs<Frame> e)
{
base.OnElementChanged(e);
if (e.NewElement != null && Control != null)
{
UpdateCornerRadius();
}
}
protected override void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
{
base.OnElementPropertyChanged(sender, e);
if (e.PropertyName == nameof(CustomFrame.CornerRadius) ||
e.PropertyName == nameof(CustomFrame))
{
UpdateCornerRadius();
}
}
private void UpdateCornerRadius()
{
if (Control.Background is GradientDrawable backgroundGradient)
{
var cornerRadius = (Element as CustomFrame)?.CornerRadius;
if (!cornerRadius.HasValue)
{
return;
}
var topLeftCorner = Context.ToPixels(cornerRadius.Value.TopLeft);
var topRightCorner = Context.ToPixels(cornerRadius.Value.TopRight);
var bottomLeftCorner = Context.ToPixels(cornerRadius.Value.BottomLeft);
var bottomRightCorner = Context.ToPixels(cornerRadius.Value.BottomRight);
var cornerRadii = new[]
{
topLeftCorner,
topLeftCorner,
topRightCorner,
topRightCorner,
bottomRightCorner,
bottomRightCorner,
bottomLeftCorner,
bottomLeftCorner,
};
backgroundGradient.SetCornerRadii(cornerRadii);
}
}
}
}
3.使用custonframe形式。
<StackLayout>
<controls:CustomFrame
BackgroundColor="Red"
CornerRadius="0,30,0,0"
HeightRequest="100"
HorizontalOptions="Center"
VerticalOptions="Center"
WidthRequest="100" />
</StackLayout>
有关此的更多详细信息,请参阅:
https://progrunning.net/customizing-corner-radius/