Android layer-list 中图片被拉伸问题

无图无真相，先上图：

其中 item 1~5 是正正常的，后面本来应该显示在右下角的icon 都被拉伸了。
代码如下：

<selector xmlns:android="http://schemas.android.com/apk/res/android" xmlns:reader="http://schemas.android.com/apk/res-auto">

    <item reader:state_chapter_download_accomplish="true">
        <layer-list>
            <item>
                <shape android:shape="rectangle">
                    <solid android:color="@color/text_color_comic_e" />
                    <stroke android:width="0.5dp" android:color="@color/text_color_comic_g" />
                    <corners android:radius="20dp" />
                shape>

            item>
            
            <item>
                <bitmap android:src="@drawable/reader_select_to_download_item_status_accomplish" android:gravity="bottom|right"/>
            item>
            
            
        layer-list>
    item>

 
    <item reader:state_chapter_download_loading="true">
        <layer-list>
            <item >
                <shape android:shape="rectangle">
                    <solid android:color="@color/text_color_comic_e" />
                    <stroke android:width="0.5dp" android:color="@color/text_color_comic_g"/>
                    <corners android:radius="20dp" />
                shape>

            item>
            <item android:drawable="@drawable/reader_select_to_download_item_status_loading" android:gravity="bottom|right"/>
        layer-list>
    item>




    <item android:state_checked="true" reader:state_chapter_need_pay ="true" >
        <layer-list>
            <item >
                <shape android:shape="rectangle">
                    <solid android:color="@color/text_color_comic_k" />
                    <stroke android:width="0.5dp" android:color="@color/text_color_comic_g"/>
                    <corners android:radius="20dp" />
                shape>

            item>
            <item android:drawable="@drawable/reader_select_to_download_item_status_buy" android:gravity="bottom|right">
            item>
        layer-list>
    item>

    <item android:state_checked="false" reader:state_chapter_need_pay ="true" >
        <layer-list>
            <item >
                <shape android:shape="rectangle">
                    <solid android:color="@color/text_color_comic_e" />
                    <stroke android:width="0.5dp" android:color="@color/text_color_comic_g"/>
                    <corners android:radius="20dp" />
                shape>

            item>
            <item android:drawable="@drawable/reader_select_to_download_item_status_buy" android:gravity="bottom|right">
            item>
        layer-list>
    item>


    <item android:state_checked="true" reader:state_chapter_need_pay ="false" >
        <layer-list>
            <item >
                <shape android:shape="rectangle">
                    <solid android:color="@color/text_color_comic_k" />
                    <stroke android:width="0.5dp" android:color="@color/text_color_comic_g"/>
                    <corners android:radius="20dp" />
                shape>

            item>
        layer-list>
    item>

    <item>
        <shape android:shape="rectangle">
            <solid android:color="@color/text_color_comic_e" />
            <corners android:radius="20dp" />
            <stroke android:width="0.5dp" android:color="@color/text_color_comic_g" />
        shape>
    item>
selector>