使用主题更改Android样式

Question

I have an app with a few different Activities . The different activities have different styled buttons, texts, etc... I've set up all the components to have various styles based on their location/Activity. (Eg. style="@style/MainMenuActionBarTitle , or style="@style/MainMenuActionBarTagLine ). These styles set the background ( Drawable , MipMap , or Color ), textColor , etc...

The app will be offering some theme packs which change the colors of these various components throughout the application, and I was hoping there was a way to have Styles with the same name, but different values based on the Theme of the app. This way I can just change the Theme whenever the Activity is loaded to whatever Theme the user has chosen.

There's some good info here on how to change the standard widget look & feel using Themes, but that changes the look and feel for the standard-un-styled widgets.

Is there a way to accomplish this using Themes, or is this the wrong direction altogether? Is there a better/easier route?

Edit: After doing more research and more fiddling, I've realized what I want to do isn't far off from how I can accomplish this. What I want to do is to actually change component Styles when I set the Theme of the Activity .

Answer 1

One solution I've discovered is to use attributes which the Theme can point to different Styles .

attrs.xml

<resources>
   <!-- Attributes referencing whatever style the theme needs to set up. -->
   <attr name="main_menu_button_style_play" format="reference" />
</resources>

themes.xml

<resources>
   <!-- Base application theme. -->
   <style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
       <!-- App specific attributes -->
       <item name="@attr/main_menu_button_style_play">@style/MainMenu.Button.Play</item>
   </style>

   <!-- Blue application theme. -->
   <style name="AppTheme.Blue" parent="AppTheme">
      <!-- App specific attributes -->
      <item name="@attr/main_menu_button_style_play">@style/MainMenu.Button.Play.Blue</item>
   </style>
</resources>

styles.xml

<style name="MainMenu.Button.Play">
    <item name="android:background">#f76d3c</item>
    <item name="android:text">PLAY</item>
</style>

<style name="MainMenu.Button.Play.Blue">
    <item name="android:background">#2ca8c2</item>
</style>

activity.xml

<Button android:id="@+id/main_play_button"
        style="?attr/main_menu_button_style_play"/>

This works really well, and allows me to set the Theme in the Activity.onCreate() method.

The only annoying problem I have with this solution is that Android Studio complains that the Button is missing the layout_width and layout_height even though they're defined in the Style . I guess it doesn't follow the attribute reference back through the chosen Theme .

Another approach which is what I ended up using was to more heavily use the attributes. Creating attributes for all the properties values I want to change between themes. So, instead of main_menu_button_style_play which defines the style reference, I used main_menu_button_play_background . This approach is the same amount of work as simply specifying a style because themes can inherit, but the IDE understands it.