Shape drawable in layer-list rendered incorrectly for APIs below 23

问题

Yesterday, I've switched to Android Studio version 2.1.3. Today, I've re-opened one of my projects and tried to add some layer-list drawables for use with an ImageView. For example this one:

<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:width="80px" android:height="80px"
        android:top="0px" android:left="0px" 
        android:right="0px" android:bottom="0px">
        <shape android:shape="rectangle">
            <solid android:color="@color/deep_orange"/>
        </shape>
    </item>
    <item android:width="60px" android:height="60px"
        android:top="10px" android:left="10px" 
        android:right="10px" android:bottom="10px">
        <shape android:shape="oval">
            <solid android:color="@color/light_yellow"/>
        </shape>
    </item>
</layer-list>

This is what I used to get before upgrading my Android Studio version, and this is what I get now in the Preview if I choose 23 as "Android version to use when rendering layouts in the IDE".

However, if I choose any version below 23, I get just the square:

Unfortunately, I also get nothing but the square when running the app on an emulator (Lollipop 22) or a device (Jellybean 18).

Just in case this is helpful:

• compileSdkVersion 23
• buildToolsVersion "23.0.3"
• minSdkVersion 11
• targetSdkVersion 23
• nothing for buildType debug
• dependencies: compile 'com.android.support:appcompat-v7:23.0.1'
• the Activity extends AppCompatActivity

I think the problem is somehow related to the use of top, left, right and bottom for the upper layer. Because if I simply place a circle on top of a square, the preview as well as the "real thing" work as expected for all API levels.

EDIT I also started a brand new project with the same code/ xml and the following (automatically created) build.gradle:

• compileSdkVersion 24
• buildToolsVersion "24.0.2"
• minSdkVersion 15
• targetSdkVersion 24
• nothing for buildType debug
• dependencies: compile 'com.android.support:appcompat-v7:24.2.0'
• the Activity extends AppCompatActivity

The same behaviour here: the upper layer is not rendered for API leves <= 22 if I use top, left, right and bottom with values != 0.

---

So my question is: how can I create shape drawables "with insets" for all API levels using Android Studio 2.1.3?

回答1:

First of all, I'd like to thank @pskink for helping me to analyse the problem :)

The xml in the question worked for API level 23+, because

it is possible to set width and height right within the "item" tag

like @android developer states in this SO post

It did not work for lower versions, because there one needs to set width and height attributes for a ShapeDrawable using the size tag.

I suppose Android needs the size to figure out how to scale the drawable (-> aspect ratio!) while taking into account the insets (top, left, right, bottom).

And as is sometimes the case with malformed (for a specific API level) xml, Android failed silently and simply did not draw the shape.

So the solution is:

<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:width="80px" android:height="80px"
        android:top="0px" android:left="0px" 
        android:right="0px" android:bottom="0px">
        <shape android:shape="rectangle">
            <solid android:color="@color/deep_orange"/>
        </shape>
    </item>
    <item android:width="60px" android:height="60px"
        android:top="10px" android:left="10px" 
        android:right="10px" android:bottom="10px">
        <shape android:shape="oval">
            <solid android:color="@color/light_yellow"/>
            <size android:height="60px" android:width="60px"/>
        </shape>
    </item>
</layer-list>

来源：https://stackoverflow.com/questions/39410568/shape-drawable-in-layer-list-rendered-incorrectly-for-apis-below-23