访问在主题和 attrs.xml android 中定义的资源

问题描述

我有一个场景，我想根据定义的主题设置 Drawable.

为了进一步解释这一点，这是我在代码中的内容:

esvaluesattrs.xml

<declare-styleable name="AppTheme"><attr name="homeIcon" format="reference"/></declare-styleable></资源>

resvaluesstyles.xml

<style name="AppTheme" parent="android:style/Theme"><item name="attr/homeIcon">@drawable/ic_home</item></风格></资源>

AndroidManifest.xml

 <application android:label="@string/app_name"android:theme="@style/AppTheme"><activity android:name=".MainActivity" android:label="@string/app_name"><意图过滤器><action android:name="android.intent.action.MAIN"/><类别 android:name="android.intent.category.LAUNCHER"/></意图过滤器></活动></应用程序>

正如您所注意到的，我正在定义一个自定义 attr homeIcon 并在 AppTheme 中设置属性值.

当我在布局 XML 中定义此属性并尝试访问它时，它工作顺利

<ImageView android:id="@+id/img"android:layout_width="wrap_content"android:layout_height="wrap_content"安卓:layout_gravity="center"android:src="?attr/homeIcon"/>

并在 ImageView 中呈现 Drawable ic_home.

但我无法弄清楚如何以编程方式访问 Drawable.

我试图通过定义一个持有者LayerList Drawable来解决这个问题，这会导致找不到资源异常:

<?xml version="1.0" encoding="utf-8"?><层列表xmlns:android="http://schemas.android.com/apk/res/android" ><项目android:drawable="?attr/homeIcon"/></层列表>

<块引用>

总结我想以编程方式访问自定义 Theme 中定义的 Drawable.

我想你可以用这段代码获得 Drawable:

TypedArray a = getTheme().obtainStyledAttributes(R.style.AppTheme, new int[] {R.attr.homeIcon});int attributeResourceId = a.getResourceId(0, 0);Drawable drawable = getResources().getDrawable(attributeResourceId);a.recycle();

I have a scenario in which I want to set a Drawable depending upon the theme defined.

To explain this further, Here is what I have in code:

esvaluesattrs.xml

<resources>
    <declare-styleable name="AppTheme">
        <attr name="homeIcon" format="reference" />
    </declare-styleable>
</resources>

resvaluesstyles.xml

<resources>
    <style name="AppTheme" parent="android:style/Theme">
        <item name="attr/homeIcon">@drawable/ic_home</item>
    </style>
</resources>

AndroidManifest.xml

    <application android:label="@string/app_name"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity" android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

So as you have noticed I am defining a custom attr homeIcon and setting the attribute value in AppTheme.

When I define this attribute in a layout XML and try to access it it works smoothly

<ImageView android:id="@+id/img"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:src="?attr/homeIcon" />

and renders the Drawable ic_home in an ImageView.

But I am not able to figure out how to access the Drawable programmatically.

I tried to do this with a work around, by defining a holder LayerList Drawable, which results in resource not found exception:

<?xml version="1.0" encoding="utf-8"?>
<layer-list
    xmlns:android="http://schemas.android.com/apk/res/android" >
    <item
        android:drawable="?attr/homeIcon" />
</layer-list>

Summary I want to access the Drawable defined in a custom defined Theme programmatically.

I think you can get the Drawable with this code:

TypedArray a = getTheme().obtainStyledAttributes(R.style.AppTheme, new int[] {R.attr.homeIcon});     
int attributeResourceId = a.getResourceId(0, 0);
Drawable drawable = getResources().getDrawable(attributeResourceId);
a.recycle();

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