Android drawable resource learning (5) and statelistdrawable

A statelistdrawable is defined in an XML file. Based on the different states of the object, several different images are used to represent the same image. For example, a button has multiple states, such as getting focus, losing focus, and clicking. statelistdrawable can provide different backgrounds based on different states.

Describe these statuses in the XML file. Under the unique <selector> label, the <item> label is used to represent a graph. Each <item> tag uses various attributes to describe the drawable resources required for its status.

When the status changes again, the status list will be traversed from top to bottom, and the first matching will be used ------- instead of selecting the most suitable match.

File Location：

res/drawable/filename.xmlThe filename is used as the resource ID.

Compile Data Type:

Pointer to statelistdrawable


Resource reference:

In Java: R.drawable.filenameIn XML: @[package:]drawable/filename

Syntax:

    <?xml version="1.0" encoding="utf-8"?>    <selector xmlns:android="http://schemas.android.com/apk/res/android"        android:constantSize=["true" | "false"]        android:dither=["true" | "false"]        android:variablePadding=["true" | "false"] >        <item            android:drawable="@[package:]drawable/drawable_resource"            android:state_pressed=["true" | "false"]            android:state_focused=["true" | "false"]            android:state_hovered=["true" | "false"]            android:state_selected=["true" | "false"]            android:state_checkable=["true" | "false"]            android:state_checked=["true" | "false"]            android:state_enabled=["true" | "false"]            android:state_activated=["true" | "false"]            android:state_window_focused=["true" | "false"] />    </selector>

Element:

<Selector>: required. It must be the root element and contain one or more <item> elements.

Attribute

xmlns:android

String. Required.The namespace must be "http://schemas.android.com/apk/res/android".

android:constantSize

Boolean value. Whether the internal size (the largest among all States) is reported when it is changed. The default value is false.

android:dither

Boolean value. Whether to allow jitter if the bitmap and the screen pixel configuration are different (for example, the pixel setting of a bitmap is argb 8888, but the screen setting is RGB 565)

android:variablePadding

Boolean value. The default value is false. Whether to fill the drawing. (Not clear)

<item>

Defines a drawable for a State, which must be a child element of <selector>.

Attribute:

android:drawable

Mandatory, pointing to a drawable Resource

android:state_pressed

Boolean. Press or not

android:state_focused

Boolean. Get focus?

android:state_hovered

Boolean. Move the mouse over it. Normally, the same drawable as state_focused

Added after api14

android:state_selected

Boolean. Selected?

android:state_checkable

Boolean. Checkable ). It can only be used on the control that can be selected

android:state_checked

Boolean. Checked or not

android:state_enabled

Boolean. Available or not

android:state_activated

Boolean. Whether it is activated and persistent

Added after api11

android:state_window_focused

Boolean. Whether the current application gets the focus

Note: The Android system selects the first item that matches the current state .. Therefore, if the first item list contains all the State attributes, it only uses the State attributes each time. This is why your default value should be placed at the end.

Example:

Implementation of XML files:

<? XML version = "1.0" encoding = "UTF-8"?> <Selector xmlns: Android = "http://schemas.android.com/apk/res/android"> <item Android: state_focused = "true" Android: drawable = "@ drawable/botton_add"/> <item Android: state_pressed = "true" Android: drawable = "@ drawable/botton_add_down"/> <item Android: state_selected = "true" Android: drawable = "@ drawable/botton_add"/> <item Android: drawable = "@ drawable/botton_add"/> // default </selector>

<Button         android:background="@drawable/statelist"        android:layout_width="wrap_content"        android:layout_height="wrap_content"/>

Java code implementation:

Button BTN = (button) findviewbyid (R. id. BTN); statelistdrawable drawable = new statelistdrawable (); // if you want to set the mo item to false, add a negative sign in front, such as Android. r. ATTR. state_focesed flag is true,-android. r. ATTR. state_focesed indicates false drawable. addstate (New int [] {android. r. ATTR. state_focused}, this. getresources (). getdrawable (R. drawable. botton_add); drawable. addstate (New int [] {android. r. ATTR. state_pressed}, this. getresources (). getdrawable (R. drawable. botton_add_down); drawable. addstate (New int [] {android. r. ATTR. state_selected}, this. getresources (). getdrawable (R. drawable. botton_add); drawable. addstate (New int [] {}, this. getresources (). getdrawable (R. drawable. botton_add); // The default value is BTN. setbackgrounddrawable (drawable );

<Button        android:id="@+id/btn"         android:layout_width="wrap_content"        android:layout_height="wrap_content"/>

Example:

Http://www.apkbus.com/forum.php? MoD = viewthread & tid = 52722.