Question

目前我正在使用MvvmCross开发Xamarin Forms Android项目。关于Frame我有一个奇怪的问题。每当我设置OutlineColor时，它仅在iOS中显示，而不在Android中显示。我已尝试使用不同的Xamarin Forms项目，并且两个平台都显示它没有任何问题。我没有任何迹象表明为什么会这样。 MvvmCross能否以某种方式与此问题相关？

以下是一个示例：

  <core:BasePage
        xmlns="http://xamarin.com/schemas/2014/forms"
        xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
        xmlns:core="clr-namespace:Core.Base.Views;assembly=Core"
        x:Class="Views.TestPage"
        BackgroundImage="background_secret.png"
        Title="Test">

        <ContentPage.Content>
            <Grid
                HorizontalOptions="FillAndExpand"
                Padding="12,20,12,20"
                VerticalOptions="FillAndExpand">
                <Frame
                    HasShadow="false"
                    VerticalOptions="Fill"
                    BackgroundColor="White"
                    OutlineColor="#1961ac">
                    <StackLayout>
                        <Frame
                                VerticalOptions="Start"
                                Padding="8,4,8,4"
                                HasShadow="false"
                                OutlineColor="#9DB0BB">
                                <Label Text="Test"></Label>
                            </Frame>
                    </StackLayout>
        </Frame>
            </Grid>
        </ContentPage.Content>
    </core:BasePage>

Xamarin表格版本2.1 MvvmCross版本4.1

Answer 1

即使我遇到了同样的问题，为了解决这个问题，我已经为Frame控件添加了自定义渲染器。在framerenderer中需要重写方法Draw和私有方法DrawOutline如下，

public override void Draw(ACanvas canvas)
{
    base.Draw(canvas);
    DrawOutline(canvas, canvas.Width, canvas.Height, 4f);//set corner radius
}
void DrawOutline(ACanvas canvas, int width, int height, float cornerRadius)
{
    using (var paint = new Paint { AntiAlias = true })
    using (var path = new Path())
    using (Path.Direction direction = Path.Direction.Cw)
    using (Paint.Style style = Paint.Style.Stroke)
    using (var rect = new RectF(0, 0, width, height))
    {
        float rx = Forms.Context.ToPixels(cornerRadius);
        float ry = Forms.Context.ToPixels(cornerRadius);
        path.AddRoundRect(rect, rx, ry, direction);

        paint.StrokeWidth = 2f;  //set outline stroke
        paint.SetStyle(style);
        paint.Color = Color.ParseColor("#A7AE22");//set outline color //_frame.OutlineColor.ToAndroid(); 
        canvas.DrawPath(path, paint);
    }
}

在另一种方法中，您还可以考虑使用圆角的android选择器xml作为后台资源。有关此问题的更多详细信息，请查看我的博文：http://www.appliedcodelog.com/2016/11/xamarin-form-frame-outline-color_21.html

Answer 2

Suchith的答案是正确的，可以在这里解决我的问题，但是0自Xamarin 2.5版以来已经过时了。

现在，更好的方法是使用Xamarin.Forms.Forms.Context，所以这就是现在的代码。

Android.App.Application.Context

在此link中，我们对为什么应该使用这种新方法以及为什么public override void Draw(Canvas canvas) { base.Draw(canvas); DrawOutline(canvas, canvas.Width, canvas.Height, 4f);//set corner radius } void DrawOutline(Canvas canvas, int width, int height, float cornerRadius) { using (var paint = new Paint { AntiAlias = true }) using (var path = new Path()) using (Path.Direction direction = Path.Direction.Cw) using (Paint.Style style = Paint.Style.Stroke) using (var rect = new RectF(0, 0, width, height)) { float rx = Android.App.Application.Context.ToPixels(cornerRadius); float ry = Android.App.Application.Context.ToPixels(cornerRadius); path.AddRoundRect(rect, rx, ry, direction); paint.StrokeWidth = 2f; //set outline stroke paint.SetStyle(style); paint.Color = Android.Graphics.Color.ParseColor("#FFFFFF");//set outline color //_frame.OutlineColor.ToAndroid(); canvas.DrawPath(path, paint); } }已经过时有了很好的解释。

Answer 3

MyCustomRenderer，见到你;）

using Xamarin.Forms.Platform.Android;
using Android.Graphics;
using Android.Graphics.Drawables;

[assembly: ExportRenderer(typeof(Frame), typeof(YourProject.Droid.Renderers.BorderFrameRenderer))]
namespace YourProject.Droid.Renderers
{
public class BorderFrameRenderer : FrameRenderer
{
    public override void Draw(Canvas canvas)
    {
        base.Draw(canvas);
        using (var strokePaint = new Paint())
     using (var rect = new RectF(0, 0, canvas.Width, canvas.Height))
     {

          // stroke
         strokePaint.SetStyle(Paint.Style.Stroke);
          strokePaint.Color = Element.OutlineColor.ToAndroid();
         strokePaint.StrokeWidth = 5;

           canvas.DrawRoundRect(rect, Element.CornerRadius * 2, Element.CornerRadius * 2, strokePaint);  // stroke
        }
    }

 public BorderFrameRenderer(Context context) : base(context)
    {
    }

 protected override void OnElementChanged(ElementChangedEventArgs<Frame> e)
    {
        base.OnElementChanged(e);
    }
  }
}

使用MvvmCross在Xamarin Forms Android Project中不显示Frame的轮廓颜色

3 个答案: