我尝试使用矢量图像作为按钮的背景。它需要在API 19+上得到支持，所以我添加了Xamarin.Android.Support.v7.AppCompat NuGet包和Xamarin.Android.Support.VectorDrawable：
<package id="Xamarin.Android.Support.Animated.Vector.Drawable" version="25.1.0" targetFramework="monoandroid70" />
<package id="Xamarin.Android.Support.Compat" version="25.1.0" targetFramework="monoandroid70" />
<package id="Xamarin.Android.Support.Core.UI" version="25.1.0" targetFramework="monoandroid70" />
<package id="Xamarin.Android.Support.Core.Utils" version="25.1.0" targetFramework="monoandroid70" />
<package id="Xamarin.Android.Support.Fragment" version="25.1.0" targetFramework="monoandroid70" />
<package id="Xamarin.Android.Support.Media.Compat" version="25.1.0" targetFramework="monoandroid70" />
<package id="Xamarin.Android.Support.Percent" version="25.1.0" targetFramework="monoandroid70" />
<package id="Xamarin.Android.Support.v4" version="25.1.0" targetFramework="monoandroid70" />
<package id="Xamarin.Android.Support.v7.AppCompat" version="25.1.0" targetFramework="monoandroid70" />
<package id="Xamarin.Android.Support.Vector.Drawable" version="25.1.0" targetFramework="monoandroid70" />
矢量定义文件（resources/drawable/key_visual.xml）如下：
<?xml version="1.0" encoding="utf-8"?>
<vector xmlns:android="http://schemas.android.com/apk/res/android"
android:width="135.08dp"
android:height="141.35dp"
android:viewportWidth="135.08"
android:viewportHeight="141.35">
<path
android:fillColor="#004e9a"
android:pathData="M64,140.83 A25.66,25.66,0,0,1,45.51,132.93 L37.2,124.22
A18.2,18.2,0,0,0,33.8,121.42 L32.44,120.55 A56.79,56.79,0,0,1,0.52,69.29
C0.52,39.87,22.52,14.93,51.75,11.99 L51.9,11.99 L69.77,3.39
A26.45,26.45,0,0,1,100.43,8.24 L126.85,34.66 A26.34,26.34,0,0,1,131.71,65.32
L126.81,74.94 C126.66,75.52,126.54,75.94,126.4,76.43 L123,88
A18.4,18.4,0,0,0,122.28,92.35 L121.75,104.35 A25.64,25.64,0,0,1,102.26,128
L90.56,130.84 A18.09,18.09,0,0,0,86.43,132.39 L75.75,138
A25.55,25.55,0,0,1,64,140.83 Z" />
<path
android:fillColor="#fdb71a"
android:pathData="M115.9,47.29 L108.69,42.69 A57.62,57.62,0,0,1,32.16,121 L33.53,121.87
A17.69,17.69,0,0,1,36.84,124.59 L45.15,133.3 A26.07,26.07,0,0,0,76,138.42
L86.68,132.87 A17.6,17.6,0,0,1,90.68,131.37 L102.38,128.53
A26.08,26.08,0,0,0,122.25,104.38 L122.78,92.38 A17.9,17.9,0,0,1,123.48,88.16
L126.87,76.61 C127.01,76.14,127.13,75.67,127.24,75.2
A26.08,26.08,0,0,0,115.9,47.29 Z" />
<path
android:fillColor="#86bae4"
android:pathData="M81.73,0 A26.84,26.84,0,0,0,69.53,2.93 L51.74,12 A58,58,0,0,1,57.59,11.71
L57.59,11.71 A57.59,57.59,0,0,1,108.69,42.71 L115.9,47.31
A26.08,26.08,0,0,1,127.25,75.19 L132.15,65.57 A27,27,0,0,0,127.15,34.31
L100.79,7.88 A27,27,0,0,0,81.73,0" />
<path
android:fillColor="#7275b7"
android:pathData="M91.19,113.54 A26.87,26.87,0,0,1,86.99,113.21 L50.09,107.36
A27,27,0,0,1,27.72,85 L21.87,48.09 A26.93,26.93,0,0,1,36.24,19.89 L51.74,12
A57.6,57.6,0,1,0,94.74,113.31 A26.77,26.77,0,0,1,91.19,113.54 Z" />
</vector>
以下是我如何使用它：
...
<android.support.v7.widget.AppCompatButton
local:srcCompat="@drawable/key_visual"
android:layout_gravity="bottom|center_horizontal"
android:layout_height="wrap_content"
android:layout_width="wrap_content"
android:layout_weight=".75"
android:textColor="#FFFFFF"
android:text="open the door"
android:id="@+id/doorOpen"
local:MvxBind="Click MyCommand"/>
...
当我在模拟器上运行它时（在虚拟化的win10，Android 4.4 API19上）没有显示任何按钮，我在调试器控制台上收到以下错误：
02-07 13:32:01.689 I/dalvikvm( 1988): Could not find method android.content.res.Resources.getDrawable, referenced from method android.support.v7.widget.ResourcesWrapper.getDrawable
02-07 13:32:01.689 W/dalvikvm( 1988): VFY: unable to resolve virtual method 563: Landroid/content/res/Resources;.getDrawable (ILandroid/content/res/Resources$Theme;)Landroid/graphics/drawable/Drawable;
02-07 13:32:01.689 D/dalvikvm( 1988): VFY: replacing opcode 0x6e at 0x0002
02-07 13:32:01.689 I/dalvikvm( 1988): Could not find method android.content.res.Resources.getDrawableForDensity, referenced from method android.support.v7.widget.ResourcesWrapper.getDrawableForDensity
02-07 13:32:01.689 W/dalvikvm( 1988): VFY: unable to resolve virtual method 565: Landroid/content/res/Resources;.getDrawableForDensity (IILandroid/content/res/Resources$Theme;)Landroid/graphics/drawable/Drawable;
02-07 13:32:01.689 D/dalvikvm( 1988): VFY: replacing opcode 0x6e at 0x0002
02-07 13:32:01.693 I/dalvikvm( 1988): Could not find method android.content.res.TypedArray.getChangingConfigurations, referenced from method android.support.v7.widget.TintTypedArray.getChangingConfigurations
02-07 13:32:01.693 W/dalvikvm( 1988): VFY: unable to resolve virtual method 600: Landroid/content/res/TypedArray;.getChangingConfigurations ()I
02-07 13:32:01.693 D/dalvikvm( 1988): VFY: replacing opcode 0x6e at 0x0002
02-07 13:32:01.693 I/dalvikvm( 1988): Could not find method android.content.res.TypedArray.getType, referenced from method android.support.v7.widget.TintTypedArray.getType
02-07 13:32:01.693 W/dalvikvm( 1988): VFY: unable to resolve virtual method 622: Landroid/content/res/TypedArray;.getType (I)I
02-07 13:32:01.693 D/dalvikvm( 1988): VFY: replacing opcode 0x6e at 0x0008
02-07 13:32:01.693 I/dalvikvm( 1988): Could not find method android.content.Context.getColorStateList, referenced from method android.support.v7.content.res.AppCompatResources.getColorStateList
02-07 13:32:01.693 W/dalvikvm( 1988): VFY: unable to resolve virtual method 374: Landroid/content/Context;.getColorStateList (I)Landroid/content/res/ColorStateList;
02-07 13:32:01.693 D/dalvikvm( 1988): VFY: replacing opcode 0x6e at 0x0006
02-07 13:32:01.693 D/Mono ( 1988): Assembly Ref addref Xamarin.Android.Support.v7.AppCompat[0xb96b8190] -> Xamarin.Android.Support.Compat[0xb96aff20]: 2
我试图重新安装所有软件包，但没有运气。有什么想法可能是什么？