Android动画详解之第一话：帧动画（Frame动画）

1. 表现形式
2. 使用方法
3. 官方文档详解

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1.表现形式
暂时没有截图

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2.使用方法

1. 官方方法（基础演示）
   The simplest way to create a frame-by-frame animation is to define the animation in an XML file, placed in the res/drawable/ folder, and set it as the background to a View object. Then, call start() to run the animation.（作为View的背景，在xml中或者setBackground都可以实现，启动动画用start()方法）
   An AnimationDrawable defined in XML consists of a single element, and a series of nested tags. Each item defines a frame of the animation. See the example below.
   spin_animation.xml file in res/drawable/ folder（放置的目录）:
   文件资源中的定义：

   Java代码中的实现启动动画：
   // Load the ImageView that will host the animation and
   // set its background to our AnimationDrawable XML resource.
   ImageView img = (ImageView)findViewById(R.id.spinning_wheel_image);
   img.setBackgroundResource(R.drawable.spin_animation);

   // Get the background, which has been compiled to an AnimationDrawable object.
   AnimationDrawable frameAnimation = (AnimationDrawable) img.getBackground();

   // Start the animation (looped playback by default).
   frameAnimation.start();

2. 小小的实验
   首先定义资源文件

   
<animation-list xmlns:android="http://schemas.android.com/apk/res/android">
   <item android:drawable="@drawable/gaoyuanyuan_01" android:duration="500"/>

    <item android:drawable="@drawable/gaoyuanyuan_02" android:duration="500"/>
    <item android:drawable="@drawable/gaoyuanyuan_03" android:duration="500"/>
    <item android:drawable="@drawable/gaoyuanyuan_04" android:duration="500"/>

animation-list>

在java代码中动态添加

public class FrameAnimActivity extends BaseActivity {
private ImageView _imgTest = null;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.frame_test_layout);
findViewById();
initViewListener();
} @Override
public void findViewById() {
_imgTest =(ImageView)findViewById(R.id.img_anim_frame_test);
try{
_imgTest.setImageDrawable(getResources().getDrawable(R.drawable.gaoyuanyuan_04));
AnimationDrawable animationDrawable = (AnimationDrawable)_imgTest.getBackground();
animationDrawable.start();
}catch(Exception e){
e.printStackTrace();
}

}

@Override
public void initViewListener() {

}

}

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3.官方文档详解

XML Attributes
android:drawable

Reference to a drawable resource to use for the frame. If not given, the drawable must be defined by the first child tag.

Must be a reference to another resource, in the form “@[+][package:]type:name” or to a theme attribute in the form “?[package:][type:]name”.

This corresponds to the global attribute resource symbol drawable.
Related Methods

android:duration（动画持续时间，时间必须为整数）

Amount of time (in milliseconds) to display this frame.

Must be an integer value, such as “100”.

This may also be a reference to a resource (in the form “@[package:]type:name”) or theme attribute (in the form “?[package:][type:]name”) containing a value of this type.

This corresponds to the global attribute resource symbol duration.
Related Methods

android:oneshot（是否只执行一次动画，如果为false则进行循环执行—）

If true, the animation will only run a single time and then stop. If false (the default), it will continually run, restarting at the first frame after the last has finished.

Must be a boolean value, either “true” or “false”.

This may also be a reference to a resource (in the form “@[package:]type:name”) or theme attribute (in the form “?[package:][type:]name”) containing a value of this type.

This corresponds to the global attribute resource symbol oneshot.
Related Methods

android:variablePadding

If true, allows the drawable’s padding to change based on the current state that is selected. If false, the padding will stay the same (based on the maximum padding of all the states). Enabling this feature requires that the owner of the drawable deal with performing layout when the state changes, which is often not supported.

Must be a boolean value, either “true” or “false”.

This may also be a reference to a resource (in the form “@[package:]type:name”) or theme attribute (in the form “?[package:][type:]name”) containing a value of this type.

This corresponds to the global attribute resource symbol variablePadding.
Related Methods

android:visible

Provides initial visibility state of the drawable; the default value is false. See setVisible(boolean, boolean).

Must be a boolean value, either “true” or “false”.

This may also be a reference to a resource (in the form “@[package:]type:name”) or theme attribute (in the form “?[package:][type:]name”) containing a value of this type.

This corresponds to the global attribute resource symbol visible.
Related Methods

Public Constructors
public AnimationDrawable ()
Added in API level 1

Public Methods
public void addFrame (Drawable frame, int duration)
Added in API level 1

Add a frame to the animation
Parameters
frame The frame to add
duration How long in milliseconds the frame should appear
public int getDuration (int i)
Added in API level 1

Returns

The duration in milliseconds of the frame at the specified index 

public Drawable getFrame (int index)
Added in API level 1

Returns

The Drawable at the specified frame index 

public int getNumberOfFrames ()
Added in API level 1

Returns

The number of frames in the animation 

public void inflate (Resources r, XmlPullParser parser, AttributeSet attrs, Resources.Theme theme)
Added in API level 21

Inflate this Drawable from an XML resource optionally styled by a theme.
Parameters
r Resources used to resolve attribute values
parser XML parser from which to inflate this Drawable
attrs Base set of attribute values
theme Theme to apply, may be null
Throws
XmlPullParserException
IOException
public boolean isOneShot ()
Added in API level 1

Returns

True of the animation will play once, false otherwise 

public boolean isRunning ()
Added in API level 1

Indicates whether the animation is currently running or not.

Returns

true if the animation is running, false otherwise 

public Drawable mutate ()
Added in API level 3

Make this drawable mutable. This operation cannot be reversed. A mutable drawable is guaranteed to not share its state with any other drawable. This is especially useful when you need to modify properties of drawables loaded from resources. By default, all drawables instances loaded from the same resource share a common state; if you modify the state of one instance, all the other instances will receive the same modification. Calling this method on a mutable Drawable will have no effect.
Returns

This drawable.

public void run ()
Added in API level 1

This method exists for implementation purpose only and should not be called directly. Invoke start() instead.

See Also

start()

public void setOneShot (boolean oneShot)
Added in API level 1

Sets whether the animation should play once or repeat.
Parameters
oneShot Pass true if the animation should only play once
public boolean setVisible (boolean visible, boolean restart)
Added in API level 1

Sets whether this AnimationDrawable is visible.

When the drawable becomes invisible, it will pause its animation. A subsequent change to visible with restart set to true will restart the animation from the first frame. If restart is false, the animation will resume from the most recent frame.
Parameters
visible true if visible, false otherwise
restart when visible, true to force the animation to restart from the first frame
Returns

true if the new visibility is different than its previous state 

public void start ()
Added in API level 1

Starts the animation, looping if necessary. This method has no effect if the animation is running. Do not call this in the onCreate(Bundle) method of your activity, because the AnimationDrawable is not yet fully attached to the window. If you want to play the animation immediately, without requiring interaction, then you might want to call it from the onWindowFocusChanged(boolean) method in your activity, which will get called when Android brings your window into focus.

See Also

isRunning()
stop()

public void stop ()
Added in API level 1

Stops the animation. This method has no effect if the animation is not running.

See Also

isRunning()
start()

public void unscheduleSelf (Runnable what)
Added in API level 1

Use the current Drawable.Callback implementation to have this Drawable unscheduled. Does nothing if there is no Callback attached to the Drawable.
Parameters
what The runnable that you no longer want called.
Protected Methods
protected void setConstantState (DrawableContainer.DrawableContainerState state)
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