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Android Selector Drawable doesnt work with attributes

Posted by: admin June 16, 2020 Leave a comment

Questions:

I am using attr to create a selector drawable for my project so that once i change theme colors, i dont have to make any change in the drawable file. I am using following libs:

compile 'com.android.support:appcompat-v7:+'
compile 'com.android.support:cardview-v7:+'
compile 'com.android.support:design:22.2.0'

Here is the source code for drawable:

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:drawable="?attr/colorPrimary" android:state_enabled="true" android:state_window_focused="false"/>
    <item android:drawable="?attr/colorPrimaryDark" android:state_pressed="true"/>
    <item android:drawable="@android:color/darker_gray" android:state_enabled="false"/>
    <item android:drawable="?attr/colorPrimary"/>
</selector>

in this same code, if i replace attributes with colors defined in colors.xml file, the same drawable works.

Sample drawable with colors:

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:drawable="@color/color_primary" android:state_enabled="true" android:state_window_focused="false"/>
    <item android:drawable="@color/color_primary_dark" android:state_pressed="true"/>
    <item android:drawable="@android:color/darker_gray" android:state_enabled="false"/>
    <item android:drawable="@color/color_primary"/>
</selector>

Thanks in advance!

How to&Answers:

Finally, found the problem. There is a bug in android [pre-lollipop] OS which doesnt allow you to use attr in drawable. Here is the link to bug:

https://code.google.com/p/android/issues/detail?id=26251

Android dev team has released a fix but it works on android L and above.For workaround to this problem, refer to following solution:

How to reference style attributes from a drawable?

Answer:

I dunno if it’s still relevant to you, but I was struggling with the same thing and I think I have found a workaround (kinda). The direct use of ?attr/ is not working (working on api 21 and up, but even then it’s not working with color selectors (only with drawables).

So I did it like this (giving you my own example).
Create an atribute in attr.xml

<attr name="nav_item_color_selector" format="reference|color"/>

Then in all the themes you’re using, add the attribute like so (f.e. for the Light Theme):

<item name="nav_item_color_selector">@color/text_color_selector_light</item>

or for the dark theme(default):

<item name="nav_item_color_selector">@color/text_color_selector</item>

Now my text_color_selector.xml (both) look like this:

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:state_selected="true"
      android:color="@color/myAccentColor" />
<item android:state_selected="false" 
      android:color = "@color/myTextPrimaryColor"/>
<item android:color="@color/myTextPrimaryColor" />

and when I want to use them, f.e in tinting my custom image view, I use:

    <com.yourdomain.yourpackage.NavDrawerIcon
    android:layout_width="24dp"
    android:layout_height="24dp"
    android:layout_gravity="center_vertical"
    android:src="@mipmap/ic_launcher"
    android:id="@+id/nav_item_icon"
    android:layout_margin="24dp"
    android:tint = "?attr/nav_item_color_selector"
    android:tintMode="src_atop"/>

You can also reitieve it programmatically by using TypedValue, like so:

    TypedValue typedValue = new TypedValue();
    Resources.Theme theme = context.getTheme();
    theme.resolveAttribute(R.attr.nav_item_color_selector, typedValue, true);
    XmlResourceParser parser = viewGroup.getContext().getResources().getXml(typedValue.resourceId);
    try {
        ColorStateList sl = ColorStateList.createFromXml(viewGroup.getContext().getResources(), parser);
        viewHolder.textView.setTextColor(sl);

    } catch (Exception e) {  }

I hope this helps 🙂

Answer:

I encountered the same problem and as of 2019 it hasn’t been resolved so you can’t have an attribute referenced in a selector as a drawable. I will share the solution I got for the problem as I don’t see it posted in here. I found it in the last comment of the bug report also referred by mudit in his answer.

The workaround is basically create a drawable resource that will be the one referring the attribute value.

To illustrate your case the solution would be instead of:

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:drawable="?attr/colorPrimary" android:state_enabled="true" android:state_window_focused="false"/>
    <item android:drawable="?attr/colorPrimaryDark" android:state_pressed="true"/>
    <item android:drawable="@android:color/darker_gray" android:state_enabled="false"/>
    <item android:drawable="?attr/colorPrimary"/>
</selector>

you would replace the ?attr/* for a drawable resource:

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:drawable="@drawable/colorPrimaryDrawable" android:state_enabled="true" android:state_window_focused="false"/>
    <item android:drawable="@drawable/colorPrimaryDarkDrawable" android:state_pressed="true"/>
    <item android:drawable="@android:color/darker_gray" android:state_enabled="false"/>
    <item android:drawable="@drawable/colorPrimaryDrawable"/>
</selector>

The drawables would be defined as:

drawable/colorPrimaryDrawable

<shape xmlns:android="http://schemas.android.com/apk/res/android"android:shape="rectangle">
    <solid android:color="?attr/colorPrimary" />
</shape>

drawable/colorPrimaryDarkDrawable

<shape xmlns:android="http://schemas.android.com/apk/res/android"android:shape="rectangle">
    <solid android:color="?attr/colorPrimaryDark" />
</shape>

Hope it helps!!

Answer:

In stead of putting a “?” Change it to “@”