效果圖:
代碼實現:
佈局文件
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="200dp">
<!--存放圖片的ViewPager-->
<android.support.v4.view.ViewPager
android:id="@+id/viewpager"
android:layout_width="match_parent"
android:layout_height="match_parent" />
<LinearLayout
android:layout_width="match_parent"
android:layout_height="40dp"
android:layout_alignParentBottom="true"
android:background="#66000000"
android:gravity="center_horizontal"
android:orientation="vertical"
android:padding="5dp">
<!--標題-->
<TextView
android:id="@+id/tv_desc"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:singleLine="true"
android:text="標題"
android:textColor="@android:color/white" />
<!--存放小圓點的容器-->
<LinearLayout
android:id="@+id/ll_point_container"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="5dp"
android:orientation="horizontal" />
</LinearLayout>
</RelativeLayout>
</RelativeLayout>
MainActivity.java
public class Main2Activity extends Activity implements ViewPager.OnPageChangeListener {
private ViewPager viewPager;
private int[] imageResIds;
private ArrayList<ImageView> imageViewList;
private LinearLayout ll_point_container;
private String[] contentDescs;
private TextView tv_desc;
private int previousSelectedPosition = 0;
boolean isRunning = false;
private Timer timer;
private @SuppressLint("HandlerLeak")
Handler handler;
MyRunnable runnable = new MyRunnable();
@RequiresApi(api = Build.VERSION_CODES.M)
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main2);
viewPager = (ViewPager) findViewById(R.id.viewpager);
// 設置頁面更新監聽
viewPager.addOnPageChangeListener(this);
ll_point_container = (LinearLayout) findViewById(R.id.ll_point_container);
tv_desc = (TextView) findViewById(R.id.tv_desc);
// Model數據
initData();
// Controller 控制器
initAdapter();
// 開啓輪詢
startLooper2();
}
@SuppressLint("HandlerLeak")
private void startLooper2() {
handler = new Handler();
handler.postDelayed(runnable,3000);
}
class MyRunnable implements Runnable{
@Override
public void run() {
viewPager.setCurrentItem(viewPager.getCurrentItem() + 1);
handler.postDelayed(runnable,3000);
}
}
private void startLooper() {
new Thread() {
@Override
public void run() {
isRunning = true;
while (isRunning) {
try {
Thread.sleep(2000);
} catch (InterruptedException e) {
e.printStackTrace();
}
// 往下跳一位
runOnUiThread(new Runnable() {
@Override
public void run() {
viewPager.setCurrentItem(viewPager.getCurrentItem() + 1);
}
});
}
}
}.start();
}
/**
* 初始化要顯示的數據
*/
private void initData() {
// 圖片資源id數組
imageResIds = new int[]{R.drawable.aa, R.drawable.bb, R.drawable.cc, R.drawable.dd, R.drawable.ee};
// 文本描述
contentDescs = new String[]{
"我是第零張圖片",
"我是第一張圖片",
"我是第二張圖片",
"我是第三張圖片",
"我是第四張圖片"
};
// 初始化要展示的5個ImageView
imageViewList = new ArrayList<ImageView>();
ImageView imageView;
View pointView;
LinearLayout.LayoutParams layoutParams;
for (int i = 0; i < imageResIds.length; i++) {
// 初始化要顯示的圖片對象
imageView = new ImageView(this);
imageView.setBackgroundResource(imageResIds[i]);
imageViewList.add(imageView);
// 加小白點, 指示器
pointView = new View(this);
pointView.setBackgroundResource(R.drawable.ic_launcher_background);
layoutParams = new LinearLayout.LayoutParams(5, 5);
if (i != 0) {
layoutParams.leftMargin = 10;
}
// 設置默認所有都不可用
pointView.setEnabled(false);
ll_point_container.addView(pointView, layoutParams);
}
}
@RequiresApi(api = Build.VERSION_CODES.M)
private void initAdapter() {
ll_point_container.getChildAt(0).setEnabled(true);
ll_point_container.getChildAt(previousSelectedPosition).setBackgroundColor(Color.WHITE);
tv_desc.setText(contentDescs[0]);
previousSelectedPosition = 0;
// 設置適配器
viewPager.setAdapter(new MyAdapter());
//設置界面切換動畫
viewPager.setPageTransformer(true, (ViewPager.PageTransformer) new DepthPageTransformer());
// 默認設置到中間的某個位置
int pos = Integer.MAX_VALUE / 2 - (Integer.MAX_VALUE / 2 % imageViewList.size());
// 2147483647 / 2 = 1073741823 - (1073741823 % 5)
// 設置到某個位置
viewPager.setCurrentItem(pos);
}
class MyAdapter extends PagerAdapter {
@Override
public int getCount() {
return Integer.MAX_VALUE;
}
// 3. 指定複用的判斷邏輯, 固定寫法
@Override
public boolean isViewFromObject(View view, Object object) {
// 當劃到新的條目, 又返回來, view是否可以被複用.
// 返回判斷規則
return view == object;
}
// 1. 返回要顯示的條目內容, 創建條目
@Override
public Object instantiateItem(ViewGroup container, int position) {
System.out.println("instantiateItem初始化: " + position);
// container: 容器: ViewPager
// position: 當前要顯示條目的位置 0 -> 4
// newPosition = position % 5
int newPosition = position % imageViewList.size();
ImageView imageView = imageViewList.get(newPosition);
// a. 把View對象添加到container中
container.addView(imageView);
// b. 把View對象返回給框架, 適配器
// 必須重寫, 否則報異常
return imageView;
}
// 2. 銷燬條目
@Override
public void destroyItem(ViewGroup container, int position, Object object) {
// object 要銷燬的對象
container.removeView((View) object);
}
}
@Override
public void onPageScrolled(int position, float positionOffset,
int positionOffsetPixels) {
// 滾動時調用
}
@Override
public void onPageSelected(int position) {
// 新的條目被選中時調用
int newPosition = position % imageViewList.size();
//設置文本
tv_desc.setText(contentDescs[newPosition]);
// 把之前的禁用, 把最新的啓用, 更新指示器
ll_point_container.getChildAt(previousSelectedPosition).setEnabled(false);
ll_point_container.getChildAt(previousSelectedPosition).setBackgroundResource(R.drawable.ic_launcher_background);
ll_point_container.getChildAt(newPosition).setEnabled(true);
ll_point_container.getChildAt(newPosition).setBackgroundColor(Color.WHITE);
// 記錄之前的位置
previousSelectedPosition = newPosition;
}
@Override
public void onPageScrollStateChanged(int state) {
// 滾動狀態變化時調用
}
@Override
protected void onDestroy() {
super.onDestroy();
isRunning = false;
}
}
- 切換動畫
public class DepthPageTransformer implements ViewPager.PageTransformer {
private static final float MIN_SCALE = 0.75f;
@Override
public void transformPage(View view, float position) {
int pageWidth = view.getWidth();
if (position < -1) { // [-Infinity,-1)
// This page is way off-screen to the left.
view.setAlpha(0);
} else if (position <= 0) { // [-1,0]
// Use the default slide transition when moving to the left page
view.setAlpha(1);
view.setTranslationX(0);
view.setScaleX(1);
view.setScaleY(1);
} else if (position <= 1) { // (0,1]
// Fade the page out.
view.setAlpha(1 - position);
// Counteract the default slide transition
view.setTranslationX(pageWidth * -position);
// Scale the page down (between MIN_SCALE and 1)
float scaleFactor = MIN_SCALE
+ (1 - MIN_SCALE) * (1 - Math.abs(position));
view.setScaleX(scaleFactor);
view.setScaleY(scaleFactor);
} else { // (1,+Infinity]
// This page is way off-screen to the right.
view.setAlpha(0);
}
}
}
其它
小紅點的移動
引言
當我們滑動頁面時,小紅點也是隨着滑動的。如何控制小紅點的移動呢?
此時,同樣要監聽ViewPager的滑動了。我們知道,ViewPager的滑動監聽,有三個
回調方法,監聽哪個方法呢?在哪個方法中,來控制小紅點的移動距離呢?
好! 這裏我們通過監聽:
onPageScrolled(int position, float positionOffset,int positionOffsetPixels)
參數說明:
Position:頁面滑動的索引
positionOffset:頁面滑動的百分比
positionOffsetPixels: 頁面滑動的像素
實現思路
計算小紅點的移動距離,首先監聽ViewPager的滑動事件:
setOnPageChangeListener
onPageScrolled(int position, float positionOffset,int positionOffsetPixels)
計算當前小紅點根據移動的百分百,更改它的位置
小紅點移動原理:
-
獲取第一個小灰點的左邊距離
containerGrayPoint.getChildAt(0).getLeft() -
獲取第二個小灰點的左邊距離
containerGrayPoint.getChildAt(1).getLeft() -
兩點之間的距離 = 第二點的左邊距離 - 第一個點的左邊距離
containerGrayPoint.getChildAt(1).getLeft()- llContainer.getChildAt(0).getLeft(); -
根據移動的百分百,計算小紅點當前移動之後的左邊距
根據當前的ViewPager移動的索引*小紅點移動的距離 + 小紅點移動距離 * 滑動百分比
代碼實現:
佈局中:
<RelativeLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_alignParentBottom="true"
android:layout_marginBottom="20dp">
<LinearLayout
android:id="@+id/container_gray_point"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal">
<!--在代碼中動態的添加灰色的點-->
</LinearLayout>
<!--紅色的點-->
<View
android:id="@+id/red_point"
android:layout_width="10dp"
android:layout_height="10dp"
android:background="@drawable/point_red_bg"/>
</RelativeLayout>
Java中:
//動態的創建灰色的點
private void initGrayPoint() {
for (int resId : imgs) {
View view = new View(this);
view.setBackgroundResource(R.drawable.point_gray_bg);
LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(10,10);
params.rightMargin = 20;//設置右邊距
containerGrayPoint.addView(view,params);
}
}
//小灰點之間的寬度
private int width;
//position:當前滑動頁面的下標 positionOffset:頁面的滑動比率 positionOffsetPixels:頁面滑動的實際像素
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
MyLogger.i(TAG,"position:"+position+",positionOffset:"+positionOffset+",positionOffsetPixels:"+positionOffsetPixels);
if(width == 0){
width = containerGrayPoint.getChildAt(1).getLeft() - containerGrayPoint.getChildAt(0).getLeft();
MyLogger.i(TAG,"width:"+width);
}
//修改小紅點與相對佈局的左邊距
RelativeLayout.LayoutParams params = (RelativeLayout.LayoutParams) redPoint.getLayoutParams();
params.leftMargin = (int)(position*width + width*positionOffset);
redPoint.setLayoutParams(params);
}
shape:
<?xml version="1.0" encoding="UTF-8"?>
<shape android:shape="oval" xmlns:android="http://schemas.android.com/apk/res/android">
<solid android:color="#666"/>
</shape>