Border being ignored on Android - Xamarin.Forms

问题

I am attempting to build a circular button with a green border using Xamarin.Forms, using a method that I have used on previous projects by adding a BorderRadius, BorderColour etc values to the Button element.

Please consider the following code:

Button goButton = new Button
{
    Text = "GO!",
    TextColor = Color.White,
    FontSize = 75,
    HeightRequest = 200,
    WidthRequest = 200,
    BorderRadius = 100,
    BorderWidth = 10,
    BorderColor = Color.Green,
    BackgroundColor = Color.Red
};

The above code gives me the following, undesired output:

I have tried re-writing in XAML and had the same issue, I have also checked that my version of Xamarin (and NuGet Xamarin.forms packages) are up to date. However on the iOS version, everything looks correct (first time for everything I suppose!)

Any assistance in finding the problem and fixing this issue would be greatly appreciated.

Suggested Edit:

Please find below my styles.xml

<?xml version="1.0" encoding="utf-8" ?>
<resources>
    <style name="MainTheme" parent="MainTheme.Base">
    </style>

    <!-- Base theme applied no matter what API -->
    <style name="MainTheme.Base" parent="Theme.AppCompat.Light.DarkActionBar">

        <!--If you are using revision 22.1 please use just windowNoTitle. Without android:-->
        <item name="windowNoTitle">true</item>

        <!--We will be using the toolbar so no need to show ActionBar-->
        <item name="windowActionBar">false</item>

        <!-- Set theme colors from http://www.google.com/design/spec/style/color.html#color-color-palette -->

        <!-- colorPrimary is used for the default action bar background -->
        <item name="colorPrimary">#2196F3</item>

        <!-- colorPrimaryDark is used for the status bar -->
        <item name="colorPrimaryDark">#1976D2</item>

        <!-- colorAccent is used as the default value for     colorControlActivated
     which is used to tint widgets -->
        <item name="colorAccent">#FF4081</item>

        <!-- You can also set colorControlNormal, colorControlActivated
     colorControlHighlight and colorSwitchThumbNormal. -->
        <item name="windowActionModeOverlay">true</item>

        <item name="android:datePickerDialogTheme">@style/AppCompatDialogStyle</item>
    </style>

    <style name="AppCompatDialogStyle" parent="Theme.AppCompat.Light.Dialog">
        <item name="colorAccent">#FF4081</item>
    </style>

</resources>

回答1:

Bordered Buttons work fine for me... maybe try some more reasonable values:

Button button = new Button {
    BorderWidth = 1,
    BorderColor = Color.Green,
    BackgroundColor = Color.Transparent,
    Text = "GO!",
    TextColor = Color.White,
}

That is all I have in my Buttons and the border shows up ok. Wondering if the BackgroundColor = Color.Transparent will make a difference for you.

*Edit: Adding comment as answer. According to this post, adding a completely empty custom renderer for the Button may help:

[assembly: ExportRenderer(typeof(Xamarin.Forms.Button), typeof(GenericButtonRenderer))]

namespace Express.CustomRenderers {
    public class GenericButtonRenderer : Xamarin.Forms.Platform.Android.ButtonRenderer { }
}

来源：https://stackoverflow.com/questions/40868466/border-being-ignored-on-android-xamarin-forms

标签

android

Xamarin

xamarin.android

xamarin.forms