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

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？

这是一个示例:

  <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 Forms版本2.1 MvvmCross版本4.1

Answer 1

即使我有同样的问题,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.有关此更多详细信息,请查看我的博客文章:http://www.appliedcodelog.com/2016/11/xamarin-form-frame-outline-color_21.html