android Tween动画四种动画效果的实现步骤教程

tween animation:通过预先定义一组指令，指令指定了图形变幻的类型、触发时间、持续时间，对场景里的对象不断平移、缩放、旋转等变幻来产生动画效果。

animation是以xml格式定义的，定义好的xml文件放在"res/anim"目录中。

在xml文件中，tween动画主要包括以下四种动画效果：(箭头后是与之对应的java代码方法)

alpha:渐变透明-------------->alphaanimation

scale:伸缩 --------------->scaleanimation

translate:移动--------------->translateanimation

rotate:旋转 ---------------->rotateanimation

实现步骤：

1.定义animation对象

2.设置动画的属性

3.通过startanimation()方法开始动画

例子：

1.java代码：

public class mainactivity extends appcompatactivity implements view.onclicklistener{


 /**定义alpha动画*/
 private animation animalpha=null;

 /**定义scale动画*/
 private animation animscale=null;

 /**定义translate动画*/
 private animation animtranslate=null;

 /**定义rotate动画*/
 private animation animrotate=null;

 private imageview img;
 private textview alpha,scale,translate,rotate;

 @override
 protected void oncreate(bundle savedinstancestate) {
  super.oncreate(savedinstancestate);
  setcontentview(r.layout.activity_main);

  img=findviewbyid(r.id.iv_animation);
  alpha=findviewbyid(r.id.alpha);
  scale=findviewbyid(r.id.scale);
  translate=findviewbyid(r.id.translate);
  rotate=findviewbyid(r.id.rotate);

  alpha.setonclicklistener(this);
  scale.setonclicklistener(this);
  translate.setonclicklistener(this);
  rotate.setonclicklistener(this);
 }

 @override
 public void onclick(view v) {
  switch (v.getid()){
case r.id.alpha:
 /**创建alpha动画*/
 animalpha=new alphaanimation(0.1f,1.0f);
 /**设置动画时间*/
 animalpha.setduration(3000);
 /**开始播放动画*/
 img.startanimation(animalpha);
 break;
case r.id.scale:
 /**创建scale动画*/
 animscale=new scaleanimation(0.0f,1.0f,0.0f,1.0f,
animation.relative_to_self,animation.relative_to_self);
 /**设置动画时间*/
 animscale.setduration(5000);
 /**开始播放动画*/
 img.startanimation(animscale);
 break;
case r.id.translate:
 /**创建translate动画*/
 animtranslate=new translateanimation(10,100,10,100);
 /**设置动画时间*/
 animtranslate.setduration(1000);
 /**开始播放动画*/
 img.startanimation(animtranslate);
 break;
case r.id.rotate:
 /**创建translate动画*/
 animrotate=new rotateanimation(0.0f,+360.0f,
animation.relative_to_self,0.5f,
animation.relative_to_self,0.5f);
 /**设置动画时间*/
 animrotate.setduration(1000);
 /**开始播放动画*/
 img.startanimation(animrotate);
 break;
  }
 }
}

效果：
alpha: scale: 


translate:rotate:


=======================================================================================

/**
 * constructor to use when building an alphaanimation from code
 * 
 * @param fromalpha starting alpha value for the animation, where 1.0 means
 *  fully opaque and 0.0 means fully transparent.
 * @param toalpha ending alpha value for the animation.
 */
public alphaanimation(float fromalpha, float toalpha) {
 mfromalpha = fromalpha;
 mtoalpha = toalpha;
}

/**
 * constructor to use when building a scaleanimation from code
 * 
 * @param fromx horizontal scaling factor to apply at the start of the
 *  animation
 * @param tox horizontal scaling factor to apply at the end of the animation
 * @param fromy vertical scaling factor to apply at the start of the
 *  animation
 * @param toy vertical scaling factor to apply at the end of the animation
 * @param pivotx the x coordinate of the point about which the object is
 *  being scaled, specified as an absolute number where 0 is the left
 *  edge. (this point remains fixed while the object changes size.)
 * @param pivoty the y coordinate of the point about which the object is
 *  being scaled, specified as an absolute number where 0 is the top
 *  edge. (this point remains fixed while the object changes size.)
 */
public scaleanimation(float fromx, float tox, float fromy, float toy,
  float pivotx, float pivoty) {
 mresources = null;
 mfromx = fromx;
 mtox = tox;
 mfromy = fromy;
 mtoy = toy;

 mpivotxtype = absolute;
 mpivotytype = absolute;
 mpivotxvalue = pivotx;
 mpivotyvalue = pivoty;
 initializepivotpoint();
}

=====================================================================================

/**
 * constructor to use when building a translateanimation from code
 *
 * @param fromxdelta change in x coordinate to apply at the start of the
 *  animation
 * @param toxdelta change in x coordinate to apply at the end of the
 *  animation
 * @param fromydelta change in y coordinate to apply at the start of the
 *  animation
 * @param toydelta change in y coordinate to apply at the end of the
 *  animation
 */
public translateanimation(float fromxdelta, float toxdelta, float fromydelta, float toydelta) {
 mfromxvalue = fromxdelta;
 mtoxvalue = toxdelta;
 mfromyvalue = fromydelta;
 mtoyvalue = toydelta;

 mfromxtype = absolute;
 mtoxtype = absolute;
 mfromytype = absolute;
 mtoytype = absolute;
}

/**
 * constructor to use when building a rotateanimation from code
 * 
 * @param fromdegrees rotation offset to apply at the start of the
 *  animation.
 * 
 * @param todegrees rotation offset to apply at the end of the animation.
 * 
 * @param pivotxtype specifies how pivotxvalue should be interpreted. one of
 *  animation.absolute, animation.relative_to_self, or
 *  animation.relative_to_parent.
 * @param pivotxvalue the x coordinate of the point about which the object
 *  is being rotated, specified as an absolute number where 0 is the
 *  left edge. this value can either be an absolute number if
 *  pivotxtype is absolute, or a percentage (where 1.0 is 100%)
 *  otherwise.
 * @param pivotytype specifies how pivotyvalue should be interpreted. one of
 *  animation.absolute, animation.relative_to_self, or
 *  animation.relative_to_parent.
 * @param pivotyvalue the y coordinate of the point about which the object
 *  is being rotated, specified as an absolute number where 0 is the
 *  top edge. this value can either be an absolute number if
 *  pivotytype is absolute, or a percentage (where 1.0 is 100%)
 *  otherwise.
 */
public rotateanimation(float fromdegrees, float todegrees, int pivotxtype, float pivotxvalue,
  int pivotytype, float pivotyvalue) {
 mfromdegrees = fromdegrees;
 mtodegrees = todegrees;

 mpivotxvalue = pivotxvalue;
 mpivotxtype = pivotxtype;
 mpivotyvalue = pivotyvalue;
 mpivotytype = pivotytype;
 initializepivotpoint();
}