Android自定义控件（实现视图树绘制指示器）

<!--小红点，小圆点的滑动，具体布局在代码里面写的--> <?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"> <android.support.v4.view.ViewPager android:id="@+id/vp_pager" android:layout_width="match_parent" android:layout_height="match_parent"/> <Button android:id="@+id/btn_start" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentBottom="true" android:layout_centerHorizontal="true" android:layout_marginBottom="60dp" android:background="#FFF107" android:paddingLeft="10dp" android:paddingRight="10dp" android:textSize="20sp" android:text="开始体验" android:visibility="gone"/> <!--小红点，小圆点的滑动，具体布局在代码里面写的--> <RelativeLayout android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentBottom="true" android:layout_centerHorizontal="true" android:layout_marginBottom="20dp"> <LinearLayout android:id="@+id/ll_point_group" android:layout_width="wrap_content" android:layout_height="wrap_content" android:orientation="horizontal"> </LinearLayout> <View android:id="@+id/view_red_point" android:layout_width="10dp" android:layout_height="10dp" android:background="@drawable/shape_guide_point_selected"/> </RelativeLayout> </RelativeLayout> <!--普通的圆点--> <?xml version="1.0" encoding="utf-8"?> <shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="oval" > <solid android:color="@android:color/darker_gray" /> </shape> <!--小红点的圆点--> <?xml version="1.0" encoding="utf-8"?> <shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="oval" > <solid android:color="#f00" /> </shape> 

/** * 初始化viewpager的数据 */ private void initView() { int[] icons = {R.mipmap.guide1,R.mipmap.guide2,R.mipmap.guide3,R.mipmap.guide4}; mList = new ArrayList<>(); for (int i = 0; i < icons.length; i++) { ImageView view = new ImageView(this); view.setBackgroundResource(icons[i]); //只有设置了背景才能填充满屏幕 mList.add(view); //设置，灰色的小圆点，表示滑动时候的状态 View point = new View(this); point.setBackgroundResource(R.drawable.shape_guide_point_default); //设置背景 LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(DensityUtils.dp2px(this,10), DensityUtils.dp2px(this,10)); point.setLayoutParams(params); if (i != 0) { params.leftMargin = DensityUtils.dp2px(this, 10); } llpointGroup.addView(point); } } 

/** * 初始化小红点之间的距离 */ private void initPoint() { // measure -> layout -> draw viewRedPoint.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() { //完成布局后回调该方法，该方法有可能被多次回调 @Override public void onGlobalLayout() { viewRedPoint.getViewTreeObserver().removeGlobalOnLayoutListener(this); mPointWidth = llpointGroup.getChildAt(1).getLeft() - llpointGroup.getChildAt(0).getLeft(); } }); } 

/** * viewpager的页面滑动的监听 */ private void initScrollListen() { viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() { //当页面被滑动的时候 //参数一：当前页面的位置 参数二：偏移的百分比 参数三：偏移的距离 @Override public void onPageScrolled(int position,float positionOffset,int positionOffsetPixels) { int leftMargin = (int) (mPointWidth * (position + positionOffset)); RelativeLayout.LayoutParams lp = (RelativeLayout.LayoutParams) viewRedPoint.getLayoutParams(); lp.leftMargin = leftMargin; viewRedPoint.setLayoutParams(lp); } //当页面被选择 @Override public void onPageSelected(int position) { } //当页面状态改变的时候 @Override public void onPageScrollStateChanged(int state) { } }); }