How does Android implement a fuzzy translucent window?

This example uses a custom theme style to implement a fuzzy translucent Activity.

1. Define the inventory file (AndroidManifest. xml)

<? Xml version = "1.0" encoding = "UTF-8"?>

<Manifest xmlns: android = "http://schemas.android.com/apk/res/android"

Package = "my. android. test"

Android: versionCode = "1"

Android: versionName = "1.0" type = "codeph" text = "/codeph">

<! -- Use the android: theme attribute to set the theme style for the Activity -->

<Application android: icon = "@ drawable/icon" android: label = "@ string/app_name">

<Activity android: name = ". TranslucentBlur"

Android: label = "@ string/app_name"

Android: theme = "@ style/Theme. Transparent">

<Intent-filter>

<Action android: name = "android. intent. action. MAIN"/>

<Category android: name = "android. intent. category. LAUNCHER"/>

</Intent-filter>

</Activity>

</Application>

<Uses-sdk android: minSdkVersion = "9"/>

</Manifest>

2. Define string resources (values/strings. xml)

<? Xml version = "1.0" encoding = "UTF-8"?>

<Resources>

<String name = "hello"> Hello World, TranslucentBlur! </String>

<String name = "app_name"> TranslucentBlur </string>

<String name = "translucent_background"> Example of how you can make

Activity have a translucent background, compositing over

Whatever is behind it. </string>

</Resources>

3. Define the color resource used for plotting (values/colors. xml)

<? Xml version = "1.0" encoding = "UTF-8"?>

<Resources>

<Drawable name = "transparent_background"> #00000000 </drawable>

</Resources>

4. Define a fuzzy translucent theme style (values/styles. xml)

<? Xml version = "1.0" encoding = "UTF-8"?>

<Resources>

<! -- Apply the default theme style -->

<Style name = "Theme" parent = "android: Theme">

</Style>

<! -- Modify the theme style of the application so that the Activity has a background with transparent effects.

In this example, the Android built-in translucent theme is not used, but a fully customized translucent theme style is used.

-->

<Style name = "Theme. Transparent">

<! -- Set to allow window transparency -->

<Item name = "android: javaswistranslucent"> true </item>

<! -- Reference the animated translucent style of the Android System -->

<Item name = "android: windowAnimationStyle"> @ android: style/Animation. Translucent </item>

<! -- Set the background color of the window -->

<Item name = "android: windowBackground"> @ drawable/transparent_background </item>

<! -- Hide the window title bar -->

<Item name = "android: windowNoTitle"> true </item>

<! -- Set the text foreground -->

<Item name = "android: colorForeground"> # fff </item>

</Style>

</Resources>

5. Define the layout (translucent_blackground.xml)

<? Xml version = "1.0" encoding = "UTF-8"?>

<! -- Used to display the sample text -->

<TextView xmlns: android = "http://schemas.android.com/apk/res/android" android: id = "@ + id/text"

Android: layout_width = "match_parent" android: layout_height = "match_parent"

Android: gravity = "center_vertical | center_horizontal"

Android: text = "@ string/translucent_background"/>

6. Define the Activity class (TranslucentBlur. java)

Package my. android. test;

 

Import android. app. Activity;

Import android. OS. Bundle;

Import android. view. WindowManager;

 

Publicclass TranslucentBlur extends Activity {

/** Call this callback method when the Activity is created for the first time */

@ Override

Publicvoid onCreate (Bundle savedInstanceState ){

Super. onCreate (savedInstanceState );

/**

* The getWindow () method gets the Window object of the current Activity. With this object, you can directly access the Window class

* API interface. In this example, the setFlags () method is called to set the layout parameter FLAG_BLUR_BEHIND to blur every component in the window.

*/

GetWindow (). setFlags (WindowManager. LayoutParams. FLAG_BLUR_BEHIND, WindowManager. LayoutParams. FLAG_BLUR_BEHIND );

// Fill in the Activity Layout

SetContentView (R. layout. translucent_background );

}

}

From FireOfStar's column