Use of selector in Android

Introduction

Selector The Chinese meaning selector, which is often used as a background for components in Android, has the advantage of eliminating the use of code to control the transformation of a component's different background colors or images in different states. Very convenient to use.

Definition of Selector

Selector is the state list (statelist), which is divided into two types, a color-selector and a drawable-selector.

Color-selector

Color-selector is a list of color states that can be used with color, and colors change as the component States. The location of the file is stored in

/res/color/filename.xml

The use in Java is:R.color.filename

The use in XML is:@[package]color/filename

Grammar

<?xml version= "1.0" encoding= "Utf-8"? ><selector xmlns:android= "http://schemas.android.com/apk/res/ Android "> <Item Android:color= "Hex_color"//color value, #RGB, $ARGB, #RRGGBB, #AARRGGBBAndroid:state_pressed=["true" | "False"]//whether to touchAndroid:state_focused=["true" | "False"]//whether to get focusAndroid:state_selected=["true" | "False"]//whether it is StateAndroid:state_checkable=["true" | "False"]//is optionalAndroid:state_checked=["true" | "False"]//whether to selectAndroid:state_enabled=["true" | "False"]//is availableAndroid:state_window_focused=["true" | "False"]/>//whether the window is focused</selector>

Example

Create a new Test_color_selector.xml under the/res/color/folder

<?xml version= "1.0" encoding= "Utf-8"? ><selector xmlns:android= "http://schemas.android.com/apk/res/ Android ">    <item android:state_pressed=" true "          android:color=" #ffff0000 "/> <!-- Pressed--    <item android:state_focused= "true"          android:color= "#ff0000ff"/> <!-- Focused to    default --></selector>

Call:

<button        android:id= "@+id/bt_about"        style= "@style/button_style"        android:layout_width= "250DP"        android:layout_height= "50DP"        android:layout_margin= "5DP"        android:textcolor= "@color/test_color_ Selector "        android:text=" @string/about "/>

　　

Drawable-selector

Drawable-selector is a list of background chart states that can be used as a picture, and the background will vary depending on the state of the component. Files are stored in

/res/drawable/filename.xml

Called in Java:R.drawable.filename

Called in XML: @[package:]drawable/filename

Grammar

<?xml version= "1.0" encoding= "Utf-8"? ><selector xmlns:android= "http://schemas.android.com/apk/res/ Android "android:constantsize=[" true "| "False"]//drawable whether the size of the state changes, true indicates a change, false means no transformation, the default is False android:dither=["true" | "False"]//when the bitmap is not the same as the pixel configuration of the screen (for example, a ARGB 8888 bitmap with an RGB 555 screen) will color itself (dither). When set to False, the non-recursive color. Default true android:variablepadding=["true" | "false"] >//whether the inner margin changes, default false <item android:drawable= "@[package:]drawable/drawable_resource"//Picture Resources Android:sta Te_pressed=["true" | "False"]//whether to touch android:state_focused=["true" | "False"]//whether to get to focus android:state_hovered=["true" | "False"]//whether the cursor has passed android:state_selected=["true" | "False"]//check if android:state_checkable=["true" | "False"]//can be checked android:state_checked=["true" | "False"]//check android:state_enabled=["true" | "False"]//is available android:state_activated=["true" | "False"]//whether to activate android:state_window_focused=["true" | "false"]/>//whether the window gets focus </selector>

　　

Example

<?xml version= "1.0" encoding= "Utf-8"? ><selector xmlns:android= "http://schemas.android.com/apk/res/ Android ">    <item android:state_selected=" true "android:drawable=" @drawable/button_bg_press "/>    <item android:state_focused= "true" android:drawable= "@drawable/button_bg_press"/>    <item android: State_pressed= "true" android:drawable= "@drawable/button_bg_press"  />    <item android:drawable= "@ Drawable/button_bg_normol "  /></selector>

Call:

<button        android:id= "@+id/bt_about"        style= "@style/button_style"        android:background= "@drawable/ Button_selector "        android:layout_width=" 250DP "        android:layout_height=" 50DP "        android:layout_margin = "5DP"        android:textcolor= "@color/test_color_selector"        android:text= "@string/about"/>

　　

Summarize

Selector is a good way to achieve changes in the background and color of the view state, you can save a lot of logic code, after mastering can save a lot of Java code, but also to write some beautiful UI.

Original http://blog.csdn.net/wenwen091100304/article/details/49667293

Use of selector in Android