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) { 
} 
}); 
}