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Android动画效果之自定义ViewGroup添加布局动画(五)

  • 时间:2020-11-18 22:36 编辑: 来源: 阅读:
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摘要:Android动画效果之自定义ViewGroup添加布局动画(五)
前言: 前面几篇文章介绍了补间动画、逐帧动画、属性动画,大部分都是针对View来实现的动画,那么该如何为了一个ViewGroup添加动画呢?今天结合自定义ViewGroup来学习一下布局动画。本文将通过对自定义图片选择控件设置动画为例来学习布局动画。 自定义一个显示多行图片的ViewGroup: 这里不再对自定义控件做解说,想了解的可以看下以下几篇文章  •Android自定义控件之基本原理(一)  •Android自定义控件之自定义属性(二)  •Android自定义控件之自定义组合控件(三)  •Android自定义控件之自定义ViewGroup实现标签云(四)  声明几个属性值:
  <declare-styleable name="GridImageViewGroup">
  <attr name="childVerticalSpace" format="dimension"/>
  <attr name="childHorizontalSpace" format="dimension"/>
  <attr name="columnNum" format="integer"/>
 </declare-styleable>
GridImageViewGroup.java 代码
public class GridImageViewGroup extends ViewGroup {
 private int childVerticalSpace = 0;
 private int childHorizontalSpace = 0;
 private int columnNum = 3;
 private int childWidth = 0;
 private int childHeight = 0;


 public GridImageViewGroup(Context context, AttributeSet attrs) {
  super(context, attrs);
  TypedArray attributes = context.obtainStyledAttributes(attrs, R.styleable.GridImageViewGroup);
  if (attributes != null) {
   childVerticalSpace = attributes.getDimensionPixelSize(R.styleable.GridImageViewGroup_childVerticalSpace, 0);
   childHorizontalSpace = attributes.getDimensionPixelSize(R.styleable.GridImageViewGroup_childHorizontalSpace, 0);
   columnNum = attributes.getInt(R.styleable.GridImageViewGroup_columnNum, 3);
   attributes.recycle();
  }
 }

 @Override
 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
  super.onMeasure(widthMeasureSpec, heightMeasureSpec);
  int rw = MeasureSpec.getSize(widthMeasureSpec);
  int rh = MeasureSpec.getSize(heightMeasureSpec);
  int childCount = getChildCount();
  if (childCount > 0) {
   childWidth = (rw - (columnNum - 1) * childHorizontalSpace) / columnNum;

   childHeight = childWidth;

   int vw = rw;
   if (childCount < columnNum) {
    vw = childCount * (childHeight + childVerticalSpace);
   }
   int rowCount = childCount / columnNum + (childCount % columnNum != 0 ? 1 : 0);

   int vh = rowCount * childHeight + (rowCount > 0 ? rowCount - 1 : 0) * childVerticalSpace;

   setMeasuredDimension(vw, vh);
  }
 }

 @Override
 protected void onLayout(boolean changed, int l, int t, int r, int b) {
  int left = 0;
  int top = 0;
  int count = getChildCount();
  for (int i = 0; i < count; i++) {
   View child = getChildAt(i);
   left = (i % columnNum) * (childWidth + childHorizontalSpace);
   top = (i / columnNum) * (childHeight + childVerticalSpace);
   child.layout(left, top, left + childWidth, top + childHeight);
  }
 }

在xml中引用: 
<com.whoislcj.animation.GridImageViewGroup
   android:id="@+id/image_layout"
   android:layout_width="match_parent"
   android:layout_height="wrap_content"
   android:layout_margin="10dp"
   android:animateLayoutChanges="true"
   lee:childHorizontalSpace="10dp"
   lee:childVerticalSpace="10dp"
   lee:columnNum="3"/>



在Activity中调用:
private void initViews() {
  mImageViewGroup = (GridImageViewGroup) findViewById(R.id.image_layout);
  ImageView imageView = new ImageView(this);
  imageView.setImageResource(R.mipmap.add_image);
  imageView.setOnClickListener(new View.OnClickListener() {
   @Override
   public void onClick(View v) {
    addImageView();
   }
  });
  mImageViewGroup.addView(imageView);
 }

 public void addImageView() {
  final ImageView imageView = new ImageView(MainActivity4.this);
  imageView.setImageResource(R.mipmap.lottery);
  imageView.setOnClickListener(new View.OnClickListener() {
   @Override
   public void onClick(View v) {
    mImageViewGroup.removeView(imageView);
   }
  });
  mImageViewGroup.addView(imageView, 0);
 }

实现效果如下:  [img]http://files.jb51.net/file_images/article/201608/201682592850415.jpg?201672592916[/img] [b]布局动画产生的背景:[/b] 凡事总要问个明白,为何要引入布局动画呢?其实通过上面的实现效果可以看出,在添加和删除图片时都显得很突兀,不知道该用什么语言形容了,总之就是感觉不舒服。其实我平时在开发中调用View.setVisibility()方法时也会有这种感受,这也是布局动画产生的一个背景吧。  [b]布局动画:[/b] 布局动画是指ViewGroup在布局时产生的动画效果 。实现布局动画有如下几种方式  [b]第一种方式:[/b]在xml中,对ViewGrope设置android:animateLayoutChanges="true"属性: 
<com.whoislcj.animation.GridImageViewGroup
   android:id="@+id/image_layout"
   android:layout_width="match_parent"
   android:layout_height="wrap_content"
   android:layout_margin="10dp"
   android:animateLayoutChanges="true"
   lee:childHorizontalSpace="10dp"
   lee:childVerticalSpace="10dp"
   lee:columnNum="3"/>

就这么简单的一句话实现的效果就可以实现了,看看效果如何  [img]http://files.jb51.net/file_images/article/201608/201682592936466.jpg?201672592946[/img] 这种方式虽然简单但是实现的布局动画比较单一,下面看第二种方式。  [b]第二种方式:[/b]LayoutTransition实现 
 LayoutTransition mLayoutTransition = new LayoutTransition();

  //设置每个动画持续的时间
  mLayoutTransition.setStagger(LayoutTransition.CHANGE_APPEARING, 50);
  mLayoutTransition.setStagger(LayoutTransition.CHANGE_DISAPPEARING, 50);
  mLayoutTransition.setStagger(LayoutTransition.APPEARING, 50);
  mLayoutTransition.setStagger(LayoutTransition.DISAPPEARING, 50);

  PropertyValuesHolder appearingScaleX = PropertyValuesHolder.ofFloat("scaleX", 0.5f, 1.0f);
  PropertyValuesHolder appearingScaleY = PropertyValuesHolder.ofFloat("scaleY", 0.5f, 1.0f);
  PropertyValuesHolder appearingAlpha = PropertyValuesHolder.ofFloat("alpha", 0f, 1f);
  ObjectAnimator mAnimatorAppearing = ObjectAnimator.ofPropertyValuesHolder(this, appearingAlpha, appearingScaleX, appearingScaleY);
  //为LayoutTransition设置动画及动画类型
  mLayoutTransition.setAnimator(LayoutTransition.APPEARING, mAnimatorAppearing);


  PropertyValuesHolder disappearingAlpha = PropertyValuesHolder.ofFloat("alpha", 1f, 0f);
  PropertyValuesHolder disappearingRotationY = PropertyValuesHolder.ofFloat("rotationY", 0.0f, 90.0f);
  ObjectAnimator mAnimatorDisappearing = ObjectAnimator.ofPropertyValuesHolder(this, disappearingAlpha, disappearingRotationY);
  //为LayoutTransition设置动画及动画类型
  mLayoutTransition.setAnimator(LayoutTransition.DISAPPEARING, mAnimatorDisappearing);


  ObjectAnimator mAnimatorChangeDisappearing = ObjectAnimator.ofFloat(null, "alpha", 1f, 0f);
  //为LayoutTransition设置动画及动画类型
  mLayoutTransition.setAnimator(LayoutTransition.CHANGE_DISAPPEARING, mAnimatorChangeDisappearing);

  ObjectAnimator mAnimatorChangeAppearing = ObjectAnimator.ofFloat(null, "alpha", 1f, 0f);
  //为LayoutTransition设置动画及动画类型
  mLayoutTransition.setAnimator(LayoutTransition.CHANGE_APPEARING, mAnimatorChangeAppearing);

  //为mImageViewGroup设置mLayoutTransition对象
  mImageViewGroup.setLayoutTransition(mLayoutTransition);

上面通过自定义LayoutTransition 修改系统提高的默认动画效果,如果不需要自定义的动画效果的话,不调用mLayoutTransition.setAnimator(LayoutTransition.DISAPPEARING, mAnimatorDisappearing);就行了。  LayoutTransition 提供了以下几种过渡类型:  •APPEARING —— 元素在容器中显现时需要动画显示。  •CHANGE_APPEARING —— 由于容器中要显现一个新的元素,其它元素的变化需要动画显示。  •DISAPPEARING —— 元素在容器中消失时需要动画显示。  •CHANGE_DISAPPEARING —— 由于容器中某个元素要消失,其它元素的变化需要动画显示。  看下修改过的动画效果:  [img]http://files.jb51.net/file_images/article/201608/201682592958166.jpg?20167259307[/img] [b]第三种方式:[/b]通过设置LayoutAnimation来实现布局动画
 AlphaAnimation alphaAnimation = new AlphaAnimation(0f, 1f);
  alphaAnimation.setDuration(200);
  LayoutAnimationController animationController = new LayoutAnimationController(alphaAnimation, 0.5f);
  animationController.setOrder(LayoutAnimationController.ORDER_NORMAL);
  mImageViewGroup.setLayoutAnimation(animationController); 
 显示顺序有以下几种:  • ORDER_NORMAL;//顺序显示  • ORDER_REVERSE;//反显示  • ORDER_RANDOM//随机显示  也可以通过xml实现 
<?xml version="1.0" encoding="utf-8"?>
<layoutAnimation
 xmlns:android="http://schemas.android.com/apk/res/android"
 android:delay="0.5"
 android:animationOrder="normal"
 android:animation="@anim/alpha"
 />

ViewGroup xml添加android:layoutAnimation属性 
 <com.whoislcj.animation.GridImageViewGroup
   android:id="@+id/image_layout"
   android:layout_width="match_parent"
   android:layout_height="wrap_content"
   android:layout_margin="10dp"
   android:layoutAnimation="@anim/layoutanimation"
   lee:childHorizontalSpace="10dp"
   lee:childVerticalSpace="10dp"
   lee:columnNum="3"/>
由于这种方式采用的是补间动画,个人不再推荐使用这种方式,原因很简单实现的动画效果相对单一。 [b]总结: [/b] 本篇学习了布局动画,自此Android的动画学习也将告一段落了,接下来准备总结一下学习动画的过程中遇见的编程知识,比如链式编程,TreadLocal等。
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