android2.3 api demo 学习系列（2）--App/Activity/Animation

1、首先学习sdk中关于Animation的说明。andorid的动画主要分为下面三种

• Property Animation

    版本要求： Android 3.0 (API level 11), property animation支持任何对象的动画效果,也是android推荐的模式。 可以很好的扩展。（因为本次demo版本为2.3 在这里不在研究，留在以后研究）

• View Animation

    View Animation 只能在Views使用. 优点是实现简单.缺点也很明显：首先只支持view，其次是他只是改变view的动画效果，并没有实际改变view，例如让一个按钮在屏幕上移动，动画效果是正确实现，但是按钮的点击位置并没有改变，需要自己另外实现。

View Animation提供了Tween和frame两种实现方式。

接下来学习Tween Animation：

动画的定义可以使用xml配置文件或者代码实现。xml配置文件定义相对于代码实现具有可读性、重用行、方便维护等特性，配置文件放置在工程的res/anim/文件内，xml配置文件必须包含下面其中一个元素：<alpha>, <scale>,<translate>, <rotate>或者 <set> ，嵌套set。例如下面的一个示例拉伸旋转view

 

<set android:shareInterpolator="false">
    <scale
        android:interpolator="@android:anim/accelerate_decelerate_interpolator"
        android:fromXScale="1.0"
        android:toXScale="1.4"
        android:fromYScale="1.0"
        android:toYScale="0.6"
        android:pivotX="50%"
        android:pivotY="50%"
        android:fillAfter="false"
        android:duration="700" />
    <set android:interpolator="@android:anim/decelerate_interpolator">
        <scale
           android:fromXScale="1.4"
           android:toXScale="0.0"
           android:fromYScale="0.6"
           android:toYScale="0.0"
           android:pivotX="50%"
           android:pivotY="50%"
           android:startOffset="700"
           android:duration="400"
           android:fillBefore="false" />
        <rotate
           android:fromDegrees="0"
           android:toDegrees="-45"
           android:toYScale="0.0"
           android:pivotX="50%"
           android:pivotY="50%"
           android:startOffset="700"
           android:duration="400" />
    </set>
</set>

  保存xml文件后在代码中调用

 

 

ImageView spaceshipImage = (ImageView) findViewById(R.id.spaceshipImage);
Animation hyperspaceJumpAnimation = AnimationUtils.loadAnimation(this, R.anim.xml配置文件);
spaceshipImage.startAnimation(hyperspaceJumpAnimation);

 

 接下来看看每一个的属性

set：

android:interpolator：可以使用平台提供的属性 如下图所示

如果你觉得平台定义的不符合需求，可以更改他们（定义的时候名字强制使用小写） 

各个Interpolator的属性如下

 

<accelerateDecelerateInterpolator>

没有属性

<accelerateInterpolator>

The rate of change starts out slowly, then accelerates.

attributes:

android:factor

Float. The acceleration rate (default is 1).

<anticipateInterpolator>

The change starts backward then flings forward.

attributes:

android:tension

Float. The amount of tension to apply (default is 2).

<anticipateOvershootInterpolator>

The change starts backward, flings forward and overshoots the target value, then settles at the final value.

attributes:

android:tension

Float. The amount of tension to apply (default is 2).

android:extraTension

Float. The amount by which to multiply the tension (default is 1.5).

<bounceInterpolator>

The change bounces at the end.

No attributes

<cycleInterpolator>

Repeats the animation for a specified number of cycles. The rate of change follows a sinusoidal pattern.

attributes:

android:cycles

Integer. The number of cycles (default is 1).

<decelerateInterpolator>

The rate of change starts out quickly, then decelerates.

attributes:

android:factor

Float. The deceleration rate (default is 1).

<linearInterpolator>

The rate of change is constant.

No attributes.

<overshootInterpolator>

The change flings forward and overshoots the last value, then comes back.

attributes:

android:tension

Float. The amount of tension to apply (default is 2).

 

修改时例如下面的xml定义

 

<?xml version="1.0" encoding="utf-8"?>
<overshootInterpolator xmlns:android="http://schemas.android.com/apk/res/android"
    android:tension="7.0"
    />

xml文件保存在res/anim文件夹内

 

  同事别的动画配置文件可以引用interpolator 例如

 

<scale xmlns:android="http://schemas.android.com/apk/res/android"
    android:interpolator="@anim/预先定义的interpolator"
    android:fromXScale="1.0"
    android:toXScale="3.0"
    android:fromYScale="1.0"
    android:toYScale="3.0"
    android:pivotX="50%"
    android:pivotY="50%"
    android:duration="700" />

 set的另外一个属性 android:shareInterpolator：true向所有的子元素共享interpolator

 

 

 

<alpha>

A fade-in or fade-out animation. Represents an  AlphaAnimation.

attributes:

android:fromAlpha

Float. Starting opacity offset, where 0.0 is transparent and 1.0 is opaque.

android:toAlpha

Float. Ending opacity offset, where 0.0 is transparent and 1.0 is opaque.

<scale>

A resizing animation. You can specify the center point of the image from which it grows outward (or inward) by specifying  pivotX and  pivotY. For example, if these values are 0, 0 (top-left corner), all growth will be down and to the right. Represents a  ScaleAnimation.

attributes:

android:fromXScale

Float. Starting X size offset, where 1.0 is no change.

android:toXScale

Float. Ending X size offset, where 1.0 is no change.

android:fromYScale

Float. Starting Y size offset, where 1.0 is no change.

android:toYScale

Float. Ending Y size offset, where 1.0 is no change.

android:pivotX

Float. The X coordinate to remain fixed when the object is scaled.

android:pivotY

Float. The Y coordinate to remain fixed when the object is scaled.

<translate>

A vertical and/or horizontal motion. Supports the following attributes in any of the following three formats: values from -100 to 100 ending with "%", indicating a percentage relative to itself; values from -100 to 100 ending in "%p", indicating a percentage relative to its parent; a float value with no suffix, indicating an absolute value. Represents a  TranslateAnimation.

attributes:

android:fromXDelta

Float or percentage. Starting X offset. Expressed either: in pixels relative to the normal position (such as  "5"), in percentage relative to the element width (such as  "5%"), or in percentage relative to the parent width (such as  "5%p").

android:toXDelta

Float or percentage. Ending X offset. Expressed either: in pixels relative to the normal position (such as  "5"), in percentage relative to the element width (such as  "5%"), or in percentage relative to the parent width (such as  "5%p").

android:fromYDelta

Float or percentage. Starting Y offset. Expressed either: in pixels relative to the normal position (such as  "5"), in percentage relative to the element height (such as  "5%"), or in percentage relative to the parent height (such as  "5%p").

android:toYDelta

Float or percentage. Ending Y offset. Expressed either: in pixels relative to the normal position (such as  "5"), in percentage relative to the element height (such as  "5%"), or in percentage relative to the parent height (such as  "5%p").

<rotate>

A rotation animation. Represents a  RotateAnimation.

attributes:

android:fromDegrees

Float. Starting angular position, in degrees.

android:toDegrees

Float. Ending angular position, in degrees.

android:pivotX

Float or percentage. The X coordinate of the center of rotation. Expressed either: in pixels relative to the object's left edge (such as  "5"), in percentage relative to the object's left edge (such as  "5%"), or in percentage relative to the parent container's left edge (such as  "5%p").

android:pivotY

Float or percentage. The Y coordinate of the center of rotation. Expressed either: in pixels relative to the object's top edge (such as  "5"), in percentage relative to the object's top edge (such as  "5%"), or in percentage relative to the parent container's top edge (such as  "5%p").

 

上述<alpha>, <scale>, <translate>, <rotate>同样拥有下图中得属性

介绍完了tween animation  接下来看看 frame animation的内容

frame animation主要是定义显示一系列图片的动画，xml配置文件保存在res/drawable/ xml的语法如下：

 

<?xml version="1.0" encoding="utf-8"?>
<animation-list xmlns:android="http://schemas.android.com/apk/res/android"
    android:oneshot=["true" | "false"] >
    <item
        android:drawable="@[package:]drawable/图片资源引用"
        android:duration="integer持续时间" />
</animation-list>

 在按照语法定义完后 xml可以保存在 res/anim or drawable文件夹下面

 

调用代码如下 为什么在这个方法里面调用 请看注释不多解释

 

@Override
	public void onWindowFocusChanged(boolean hasFocus) {
		// TODO Auto-generated method stub
		super.onWindowFocusChanged(hasFocus);
		//图片背景置换 frame animation
		//此段代码为什么放在 onWindowFocusChanged
		//因为当我们在onCreate中调用AnimationDrawable的start方法时，窗口Window对象还没有完全初始化，
		//AnimationDrawable不能完全追加到窗口Window对象中，那么该怎么办呢？我们需要把这段代码放在onWindowFocusChanged方法中，
		//当Activity展示给用户时，onWindowFocusChanged方法就会被调用，我们正是在这个时候实现我们的动画效果。
		//当然，onWindowFocusChanged是在onCreate之后被调用的
		ImageView changeImage = (ImageView) findViewById(R.id.animation_frame_img);
		changeImage.setBackgroundResource(R.anim.animation_frame);//xml配置文件
		AnimationDrawable changeAnimation = (AnimationDrawable) changeImage.getBackground();
		changeAnimation.start();
	}

 如果用纯代码实现frame animation 代码示如下

 

AnimationDrawable anim = new AnimationDrawable();  
for (int i = 1; i <= 4; i++) {  
    int id = getResources().getIdentifier("animation_frame_" + i, "drawable", getPackageName());  
    Drawable drawable = getResources().getDrawable(id);  
    anim.addFrame(drawable, 300);  
}  
anim.setOneShot(false);  
image.setBackgroundDrawable(anim);  
anim.start();  

 

• Drawable Animation

 见上文 frame animation

 

最后说一下 apidemo的activity的淡入淡出和放大缩小动画入场

1.淡入淡出 配置文件

 

<alpha xmlns:android="http://schemas.android.com/apk/res/android"
       android:interpolator="@android:anim/accelerate_interpolator"
       android:fromAlpha="0.0" android:toAlpha="1.0"
       android:duration="@android:integer/config_longAnimTime" />

 

 

<translate xmlns:android="http://schemas.android.com/apk/res/android"
       android:interpolator="@android:anim/accelerate_interpolator"
       android:fromXDelta="0" android:toXDelta="0"
       android:duration="@android:integer/config_longAnimTime" />

 代码中调用 

 

 

startActivity(new Intent(Animation.this, ApiDemosStudyActivity.class));
overridePendingTransition(R.anim.animation_fade,R.anim.animation_hold);

 其中关于overridePendingTransition方法 sdk中有如下说明

Call immediately after one of the flavors of startActivity(Intent) or finish to specify an explicit transition animation to perform next.

2.zoom效果同样 只是xml配置有区别