将矢量设置为 FAB 的背景

Question

我在将矢量或 mipmap 显示为浮动操作按钮的背景时遇到问题。有谁知道这里可能出了什么问题？

xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"    

<com.google.android.material.floatingactionbutton.FloatingActionButton
                android:id="@+id/nationality"
                app:srcCompat="@drawable/flag_united_states_of_america_"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_margin="10dp"
                android:backgroundTint="@android:color/transparent"
                android:layout_alignParentRight="true" />

矢量：

<vector xmlns:android="http://schemas.android.com/apk/res/android"
    android:width="512dp"
    android:height="512dp"
    android:viewportWidth="512"
    android:viewportHeight="512">
  <path
      android:pathData="M256,256m-256,0a256,256 0,1 1,512 0a256,256 0,1 1,-512 0"
      android:fillColor="#F0F0F0"/>
  <path
      android:pathData="M244.87,256H512c0,-23.106 -3.08,-45.49 -8.819,-66.783H244.87V256z"
      android:fillColor="#D80027"/>
  <path
      android:pathData="M244.87,122.435h229.556c-15.671,-25.572 -35.708,-48.175 -59.07,-66.783H244.87V122.435z"
      android:fillColor="#D80027"/>
  <path
      android:pathData="M256,512c60.249,0 115.626,-20.824 159.356,-55.652H96.644C140.374,491.176 195.751,512 256,512z"
      android:fillColor="#D80027"/>
  <path
      android:pathData="M37.574,389.565h436.852c12.581,-20.529 22.338,-42.969 28.755,-66.783H8.819C15.236,346.596 24.993,369.036 37.574,389.565z"
      android:fillColor="#D80027"/>
  <path
      android:pathData="M118.584,39.978h23.329l-21.7,15.765l8.289,25.509l-21.699,-15.765L85.104,81.252l7.16,-22.037C73.158,75.13 56.412,93.776 42.612,114.552h7.475l-13.813,10.035c-2.152,3.59 -4.216,7.237 -6.194,10.938l6.596,20.301l-12.306,-8.941c-3.059,6.481 -5.857,13.108 -8.372,19.873l7.267,22.368h26.822l-21.7,15.765l8.289,25.509l-21.699,-15.765l-12.998,9.444C0.678,234.537 0,245.189 0,256h256c0,-141.384 0,-158.052 0,-256C205.428,0 158.285,14.67 118.584,39.978zM128.502,230.4l-21.699,-15.765L85.104,230.4l8.289,-25.509l-21.7,-15.765h26.822l8.288,-25.509l8.288,25.509h26.822l-21.7,15.765L128.502,230.4zM120.213,130.317l8.289,25.509l-21.699,-15.765l-21.699,15.765l8.289,-25.509l-21.7,-15.765h26.822l8.288,-25.509l8.288,25.509h26.822L120.213,130.317zM220.328,230.4l-21.699,-15.765L176.93,230.4l8.289,-25.509l-21.7,-15.765h26.822l8.288,-25.509l8.288,25.509h26.822l-21.7,15.765L220.328,230.4zM212.039,130.317l8.289,25.509l-21.699,-15.765l-21.699,15.765l8.289,-25.509l-21.7,-15.765h26.822l8.288,-25.509l8.288,25.509h26.822L212.039,130.317zM212.039,55.743l8.289,25.509l-21.699,-15.765L176.93,81.252l8.289,-25.509l-21.7,-15.765h26.822l8.288,-25.509l8.288,25.509h26.822L212.039,55.743z"
      android:fillColor="#0052B4"/>
</vector>

实现：

implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
implementation 'androidx.appcompat:appcompat:1.2.0-rc01'
implementation 'androidx.appcompat:appcompat-resources:1.2.0-rc01'
implementation 'com.google.android.material:material:1.3.0-alpha01'

结果：

它在 Android Studio

的查看器中的外观

它在模拟器中的样子

Answer 1

只需在 FLoating Action Button 的 xml 中将 maxImageSize 设置为 56dp:

app:maxImageSize="56dp"

将矢量设置为 FAB 的背景

Setting a vector as the background of a FAB

xml

android

vector

floating-action-button

material-ui