ps:剛開始寫文章,有點亂,慢慢改進。
最下方項目源碼下載
github:https://github.com/nickeyCode/RoundImageViewPager
說實話不知道怎麼描述這個效果,在網頁上見得跟多,公司要求做這個效果得時候不知道怎麼用文字描述找不到對應的dome只好自己寫。
先上圖
大概效果就是這個。主要用的的知識點就是viewpager的自定義動畫。
項目目錄:
roundimg是圓形圖片,繼承ImageView的,上網好多可以搜索得到
viewpager主要分成三部分
一是viewpager本身,設置adapter,綁定監聽器等。
二是adapter,繼承PagerAdapter,用法跟listview的差不多。
三是動畫類,繼承PageTransformer。
首先看看最核心的動畫類(能做到這個效果就是根據對應的動畫變動)
HeadViewPagerTransformer.java
public class HeadViewPagerTransformer implements PageTransformer{
private static final float MIN_SCALE = 0.75f;
//主要是設置在不同位置上的VIEW的活動動畫
@Override
public void transformPage(View view, float position) {
// TODO Auto-generated method stub
int pageWidth = view.getWidth();
if (position < -1) { // [-Infinity,-1)
view.setAlpha(0);
}
else if (position <= 0) { // [-1,0]
view.setAlpha(1);
view.setTranslationX(0);
float x = -1.0f * (2f / 3f) * pageWidth * position;
view.setTranslationX(x);
float scaleFactor = MIN_SCALE + (2 - MIN_SCALE) * (1 - Math.abs(position));
view.setScaleX(scaleFactor);
view.setScaleY(scaleFactor);
} else if (position <= 1) { // (0,1]
view.setAlpha(1);
float x = -1.0f * (2f / 3f) * pageWidth * position;
view.setTranslationX(x);
float scaleFactor = MIN_SCALE + (2 - MIN_SCALE) * (1 - Math.abs(position));
view.setScaleX(scaleFactor);
view.setScaleY(scaleFactor);
}
}
}
因爲在這個類中,viewpager中view都有對應的位置編號,在正中間顯示的view位置是0
在左邊的view位置是-1,在右邊的view位置是1.(相當於一個座標軸)
只要viewpager發生滑動,就會調用tansFromPager();position之說以是float類型,是因爲如果發生滑動,位置就會有對應的變化,而變化精確到0.0001.
在函數中使用if-else來設定在不同位置區間中的view的動畫變化;
if (position < -1) { // [-Infinity,-1)
view.setAlpha(0);
}
這是負無窮到-1的區間,當然,如果你的viewpager緩存的view只有三個的話,這個就沒有作用了,因爲最多隻有三個view,多出來就銷燬了。
else if (position <= 0) { // [-1,0]
view.setAlpha(1);
view.setTranslationX(0);
float x = -1.0f * (2f / 3f) * pageWidth * position;
view.setTranslationX(x);
float scaleFactor = MIN_SCALE + (2 - MIN_SCALE) * (1 - Math.abs(position));
view.setScaleX(scaleFactor);
view.setScaleY(scaleFactor); }
這是-1到0的區間,就是左邊的view到中間或中間的view到左邊的動畫效果,這裏主要是做了兩個動畫變化,一是大小,二是位置。
這兩個變化公式是根據位置的變化與動畫數值的關係,解二元一次方程求出來的(初中數學知識。。。。)
具體方式就是balbalblabalbalb。。。。。(不多說)
同理
else if (position <= 1) { // (0,1]
view.setAlpha(1);
float x = -1.0f * (2f / 3f) * pageWidth * position;
view.setTranslationX(x);
float scaleFactor = MIN_SCALE + (2 - MIN_SCALE) * (1 - Math.abs(position)); }
0到1的區間一樣。在實際動畫設計的過程中,公式是需要變動的。
剩下的都是普通的viewpager使用,設置adapter (HeadViewPagerAdapter.java)
public class HeadViewPagerAdapter extends PagerAdapter {
private Context mContext;
private List<MyImageView> mList;
public HeadViewPagerAdapter(Context context,List<MyImageView> list){
this.mContext = context;
this.mList = list;
}
@Override
public int getCount() {
// TODO Auto-generated method stub
return mList.size();
}
@Override
public boolean isViewFromObject(View arg0, Object arg1) {
// TODO Auto-generated method stub
return arg0 == arg1;
}
//當緩存view的數量超過上限時,會銷燬最先的一個
@Override
public void destroyItem(ViewGroup container, int position, Object object) {
// TODO Auto-generated method stub
//Log.d("remove", mImageViews[position].hashCode() + "");
container.removeView(mList.get(position));
}
//添加View
@Override
public Object instantiateItem(ViewGroup container, int position) {
// TODO Auto-generated method stub
container.addView(mList.get(position),0);
return mList.get(position);
}
}
還有就是對應的綁定:HeadViewPager.java
public class HeadViewPager extends FrameLayout {
private Context mContext;
private ViewPager mViewPager;
private List<Integer> mImageIds;
private List<MyImageView> mImageViews;
private ViewGroup mViewGroup;
private List<ImageView> tips;
private int tipsChoseImgId;
private int tipsUnchoseImgId;
public HeadViewPager(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
// TODO Auto-generated constructor stub
creatView(context);
}
public HeadViewPager(Context context, AttributeSet attrs) {
super(context, attrs);
// TODO Auto-generated constructor stub
creatView(context);
}
public HeadViewPager(Context context) {
super(context);
// TODO Auto-generated constructor stub
creatView(context);
}
public HeadViewPager(Context context,List<MyImageView> imgageList) {
super(context);
// TODO Auto-generated constructor stub
creatView(context,imgageList);
}
public void creatView(Context context){
this.mContext = context;
LayoutInflater.from(context).inflate(R.layout.head_view_pager, this);
mViewPager = (ViewPager)findViewById(R.id.viewpager);
mViewGroup = (ViewGroup)findViewById(R.id.viewgroup);
mImageViews = new ArrayList<MyImageView>();
mImageIds = new ArrayList<Integer>();
tips = new ArrayList<ImageView>();
tipsChoseImgId = R.drawable.img_bg_chose;
tipsUnchoseImgId = R.drawable.img_bg_unchose;
build();
}
public void creatView(Context context,List<MyImageView> imgageList){
this.mContext = context;
LayoutInflater.from(context).inflate(R.layout.head_view_pager, this);
mViewPager = (ViewPager)findViewById(R.id.viewpager);
mViewGroup = (ViewGroup)findViewById(R.id.viewgroup);
mImageViews = imgageList;
mImageIds = new ArrayList<Integer>();
tips = new ArrayList<ImageView>();
tipsChoseImgId = R.drawable.img_bg_chose;
tipsUnchoseImgId = R.drawable.img_bg_unchose;
build();
}
public void build(){
buildTips();
mViewPager.setAdapter(new HeadViewPagerAdapter(mContext,mImageViews));
//設置默認顯示頁面爲第0頁
mViewPager.setCurrentItem(0);
//設置選擇頁面時的動畫
mViewPager.setPageTransformer(true, new HeadViewPagerTransformer());
//設置緩存View的個數,默認是3個,這表示緩存了5個
mViewPager.setOffscreenPageLimit(4);
//頁面發生改變的監聽器
mViewPager.setOnPageChangeListener(new OnPageChangeListener() {
//選擇發生改變
@Override
public void onPageSelected(int arg0) {
// TODO Auto-generated method stub
changeTips(arg0);
}
//有滑動操作
@Override
public void onPageScrolled(int arg0, float arg1, int arg2) {
// TODO Auto-generated method stub
}
//滑動操作或選擇改變
@Override
public void onPageScrollStateChanged(int arg0) {
// TODO Auto-generated method stub
}
});
}
//初始化底部導航圓點條
public void buildTips(){
for (int i = 0 ; i < mImageViews.size() ; i ++){
ImageView imageView = new ImageView(mContext);
imageView.setLayoutParams(new LayoutParams(10,10));
if(i == 0){
imageView.setBackgroundResource(tipsChoseImgId);
}else{
imageView.setBackgroundResource(tipsUnchoseImgId);
}
LinearLayout.LayoutParams layoutParams = new LinearLayout.LayoutParams(new ViewGroup.LayoutParams(12,12));
layoutParams.leftMargin = 5;
layoutParams.rightMargin = 5;
tips.add(imageView);
mViewGroup.addView(imageView, layoutParams);
}
}
//當選定的頁面發生改變時,導航條也對應改變
public void changeTips(int index){
for (int i = 0 ; i < tips.size() ; i ++){
if(i == index){
tips.get(i).setBackgroundResource(tipsChoseImgId);
}else{
tips.get(i).setBackgroundResource(tipsUnchoseImgId);
}
}
}
public Context getmContext() {
return mContext;
}
public void setmContext(Context mContext) {
this.mContext = mContext;
}
public ViewPager getmViewPager() {
return mViewPager;
}
public void setmViewPager(ViewPager mViewPager) {
this.mViewPager = mViewPager;
}
public List<MyImageView> getmImageViews() {
return mImageViews;
}
//改變圖片隊列時,要更新整個viewPager
public void setmImageViews(List<MyImageView> mImageViews) {
this.mImageViews = mImageViews;
this.mViewPager.notify();
this.mViewPager.setCurrentItem(0);
}
public ViewGroup getmViewGroup() {
return mViewGroup;
}
public void setmViewGroup(ViewGroup mViewGroup) {
this.mViewGroup = mViewGroup;
}
public int getTipsChoseImgId() {
return tipsChoseImgId;
}
public void setTipsChoseImgId(int tipsChoseImgId) {
this.tipsChoseImgId = tipsChoseImgId;
}
public int getTipsUnchoseImgId() {
return tipsUnchoseImgId;
}
public void setTipsUnchoseImgId(int tipsUnchoseImgId) {
this.tipsUnchoseImgId = tipsUnchoseImgId;
}
}
樣例項目資源:
http://download.csdn.net/detail/nickey_1314/8932807