android - How to add a custom button state -

for instance, default button has following dependencies between states , background images:

<?xml version="1.0" encoding="utf-8"?> <selector xmlns:android="http://schemas.android.com/apk/res/android">     <item android:state_window_focused="false" android:state_enabled="true"         android:drawable="@drawable/btn_default_normal" />     <item android:state_window_focused="false" android:state_enabled="false"         android:drawable="@drawable/btn_default_normal_disable" />     <item android:state_pressed="true"          android:drawable="@drawable/btn_default_pressed" />     <item android:state_focused="true" android:state_enabled="true"         android:drawable="@drawable/btn_default_selected" />     <item android:state_enabled="true"         android:drawable="@drawable/btn_default_normal" />     <item android:state_focused="true"         android:drawable="@drawable/btn_default_normal_disable_focused" />     <item         android:drawable="@drawable/btn_default_normal_disable" /> </selector> 

how can define own custom state (smth android:state_custom), use dynamically change button visual appearance?

the solution indicated @(ted hopp) works, needs little correction: in selector, item states need "app:" prefix, otherwise inflater won't recognise namespace correctly, , fail silently; @ least happens me.

allow me report here whole solution, more details:

first, create file "res/values/attrs.xml":

<?xml version="1.0" encoding="utf-8"?> <resources>     <declare-styleable name="food">         <attr name="state_fried" format="boolean" />         <attr name="state_baked" format="boolean" />     </declare-styleable> </resources> 

then define custom class. instance, may class "foodbutton", derived class "button". have implement constructor; implement one, seems 1 used inflater:

public foodbutton(context context, attributeset attrs) {     super(context, attrs); } 

on top of derived class:

private static final int[] state_fried = {r.attr.state_fried}; private static final int[] state_baked = {r.attr.state_baked}; 

also, state variables:

private boolean misfried = false; private boolean misbaked = false; 

and couple of setters:

public void setfried(boolean isfried) {misfried = isfried;} public void setbaked(boolean isbaked) {misbaked = isbaked;} 

then override function "oncreatedrawablestate":

@override protected int[] oncreatedrawablestate(int extraspace) {     final int[] drawablestate = super.oncreatedrawablestate(extraspace + 2);     if (misfried) {         mergedrawablestates(drawablestate, state_fried);     }     if (misbaked) {         mergedrawablestates(drawablestate, state_baked);     }     return drawablestate; } 

finally, delicate piece of puzzle; selector defining statelistdrawable use background widget. file "res/drawable/food_button.xml":

<?xml version="1.0" encoding="utf-8"?> <selector xmlns:android="http://schemas.android.com/apk/res/android"     xmlns:app="http://schemas.android.com/apk/res/com.mydomain.mypackage"> <item     app:state_baked="true"     app:state_fried="false"     android:drawable="@drawable/item_baked" /> <item     app:state_baked="false"     app:state_fried="true"     android:drawable="@drawable/item_fried" /> <item     app:state_baked="true"     app:state_fried="true"     android:drawable="@drawable/item_overcooked" /> <item     app:state_baked="false"     app:state_fried="false"     android:drawable="@drawable/item_raw" /> </selector> 

notice "app:" prefix, whereas standard android states have used prefix "android:". xml namespace crucial correct interpretation inflater , depends on type of project in adding attributes. if application, replace com.mydomain.mypackage actual package name of application (application name excluded). if library must use "http://schemas.android.com/apk/res-auto" (and using tools r17 or later) or runtime errors.

a couple of notes:

• it seems don't need call "refreshdrawablestate" function, @ least solution works is, in case

• in order use custom class in layout xml file, have specify qualified name (e.g. com.mydomain.mypackage.foodbutton)

• you can weel mix-up standard states (e.g. android:pressed, android:enabled, android:selected) custom states, in order represent more complicated state combinations