ViewPager+Fragment添加一行若干小红球滚动指示器指示当前ViewPager翻阅位置（可供第三方使用的类）

妖狐艹你老母 2023-10-16 21:01 5阅读 0赞

效果图如下：

![Center][]

ViewPager+Fragment添加一行若干小红球滚动指示器指示当前ViewPager翻阅位置（可供第三方使用的类）。

类似现在通用的新闻客户端头部，会放置几张图片供新闻阅读者翻阅，同时放置一行小圆球根据用户翻阅的位置相应的滚动，标识出当前第几页。

该项目开放出几个用以重载的方法函数供第三方使用：

protected Fragment getFragmentAt(int pos) {
    		return null;
    	}
    
    	protected int getItemsCount() {
    		return 0;
    	}
    	
    	protected	String	getDescriptionAt(int pos){
    		return	null;
    	}

测试用的主MainActivity.java （不是重点，仅仅用以测试）

package zhangphil.viewpager_fragment;
    
    import java.util.ArrayList;
    import java.util.Random;
    
    import com.example.viewpager_fragment.R;
    
    import android.graphics.Color;
    import android.os.Bundle;
    import android.support.v4.app.Fragment;
    import android.support.v4.app.FragmentActivity;
    import android.support.v4.app.FragmentTransaction;
    import android.util.Log;
    import android.view.Gravity;
    import android.view.LayoutInflater;
    import android.view.View;
    import android.view.ViewGroup;
    import android.widget.TextView;
    
    public class MainActivity extends FragmentActivity {
    
    	@Override
    	protected void onCreate(Bundle savedInstanceState) {
    		super.onCreate(savedInstanceState);
    		setContentView(R.layout.activity_main);
    
    		Fragment newFragment = new HowToUseThisView();
    		FragmentTransaction transaction = getSupportFragmentManager()
    				.beginTransaction();
    		transaction.replace(R.id.fragment, newFragment);
    		transaction.commit();
    	}
    
    	public static class HowToUseThisView extends
    			ViewPagerAndFragmentWithCircleIndicator {
    
    		private ArrayList<Fragment> mArrayList;
    
    		// 主要用以标记Fragment，没特别意义
    		private int id = 0;
    
    		// ViewPager的元素个数。
    		private int item_count = 0;
    
    		@Override
    		public void onCreate(Bundle savedInstanceState) {
    			super.onCreate(savedInstanceState);
    			mArrayList = new ArrayList<Fragment>();
    
    			// 测试用的。假设生成随机个数的Fragment。
    			Random rand = new Random();
    			item_count = rand.nextInt(10);
    		}
    
    		@Override
    		protected Fragment getFragmentAt(int pos) {
    
    			Fragment fragment = null;
    
    			try {
    				fragment = mArrayList.get(pos);
    			} catch (Exception e) {
    				Log.d(this.getClass().getName(), "队列中不存在，创建新Fragment");
    			}
    
    			if (fragment == null) {
    				fragment = new TestFragment();
    				((TestFragment) fragment).setID(id++);
    				mArrayList.add(fragment);
    			}
    
    			return fragment;
    		}
    
    		@Override
    		protected int getItemsCount() {
    			return item_count;
    		}
    
    		@Override
    		protected String getDescriptionAt(int pos) {
    			//实际使用过程中，可根据每个不同的Fragment返回不同的描述文本
    			return pos + "";
    		}
    	}
    
    	//
    	// 仅仅用于测试的Fragment，在ViewPager中加载
    	//
    	public static class TestFragment extends Fragment {
    
    		private int id = 0;
    
    		public void setID(int id) {
    			this.id = id;
    		}
    
    		public int getID() {
    			return id;
    		}
    
    		@Override
    		public View onCreateView(LayoutInflater inflater, ViewGroup container,
    				Bundle savedInstanceState) {
    
    			TextView tv = new TextView(getActivity());
    			String str = "序号: " + getID();
    			tv.setTextColor(Color.LTGRAY);
    			tv.setText(str);
    			tv.setTextSize(60);
    			tv.setGravity(Gravity.CENTER);
    
    			return tv;
    		}
    	}
    }

MainActivity.java所要的布局文件 activity\_main.xml ：

重点是 ViewPagerAndFragmentWithCircleIndicator.java

package zhangphil.viewpager_fragment;
    
    import com.example.viewpager_fragment.R;
    
    import zhangphil.libs.view.CircleIndicatorView;
    import android.os.Bundle;
    import android.os.Handler;
    import android.os.Message;
    import android.support.v4.app.Fragment;
    import android.support.v4.app.FragmentManager;
    import android.support.v4.app.FragmentPagerAdapter;
    import android.support.v4.view.ViewPager;
    import android.view.LayoutInflater;
    import android.view.View;
    import android.view.ViewGroup;
    import android.widget.TextView;
    
    public class ViewPagerAndFragmentWithCircleIndicator extends Fragment {
    
    	private MyFragmentPagerAdapter mPagerAdapter;
    	private ViewPager mViewPager;
    	private CircleIndicatorView mCircleIndicatorView;
    	private	TextView circleIndicatorView_TextView;
    
    	private Handler handler;
    	private final int MESSAGE_WHAT_DRAW_CIRCLE = 100;
    
    	public void notifyDataSetChanged() {
    		mPagerAdapter.notifyDataSetChanged();
    	}
    
    	protected Fragment getFragmentAt(int pos) {
    		return null;
    	}
    
    	protected int getItemsCount() {
    		return 0;
    	}
    	
    	protected	String	getDescriptionAt(int pos){
    		return	null;
    	}
    	
    
    	@Override
    	public View onCreateView(LayoutInflater inflater, ViewGroup container,
    			Bundle savedInstanceState) {
    		View mView = inflater.inflate(R.layout.viewpager_fragment, null);
    
    		mViewPager = (ViewPager) mView.findViewById(R.id.viewpager);
    		mPagerAdapter = new MyFragmentPagerAdapter(getFragmentManager());
    		mViewPager.setAdapter(mPagerAdapter);
    		mViewPager
    				.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
    
    					@Override
    					public void onPageSelected(int pos) {
    						set(pos);
    					}
    
    					@Override
    					public void onPageScrolled(int arg0, float arg1, int arg2) {
    
    					}
    
    					@Override
    					public void onPageScrollStateChanged(int arg0) {
    
    					}
    				});
    
    		mCircleIndicatorView = (CircleIndicatorView) mView
    				.findViewById(R.id.circleIndicatorView);
    		mCircleIndicatorView.drawCircleView(mPagerAdapter.getCount(), 0);
    		
    		//初始化红色小圆球的 位置和文本描述
    		circleIndicatorView_TextView=(TextView) mView.findViewById(R.id.circleIndicatorView_TextView);
    		circleIndicatorView_TextView.setText(getDescriptionAt(0));
    		
    		handler = new Handler() {
    			public void handleMessage(Message msg) {
    				super.handleMessage(msg);
    				switch (msg.what) {
    				case MESSAGE_WHAT_DRAW_CIRCLE:
    					
    					mCircleIndicatorView.drawCircleView(mPagerAdapter.getCount(),mViewPager.getCurrentItem());
    					
    					break;
    				}
    			};
    		};
    
    		return mView;
    	}
    
    	private void set(int pos) {
    		mViewPager.setCurrentItem(pos, true);
    		circleIndicatorView_TextView.setText(getDescriptionAt(pos));
    		handler.sendEmptyMessage(MESSAGE_WHAT_DRAW_CIRCLE);
    	}
    	
    	private class MyFragmentPagerAdapter extends FragmentPagerAdapter {
    
    		public MyFragmentPagerAdapter(FragmentManager fm) {
    			super(fm);
    		}
    
    		@Override
    		public Fragment getItem(int pos) {
    			return	getFragmentAt(pos);
    		}
    
    		@Override
    		public int getCount() {
    			return	getItemsCount();
    		}
    
    		@Override
    		public void notifyDataSetChanged() {
    			super.notifyDataSetChanged();
    			handler.sendEmptyMessage(MESSAGE_WHAT_DRAW_CIRCLE);
    		}
    	}
    }

ViewPagerAndFragmentWithCircleIndicator.java需要的布局文件 viewpager\_fragment.xml ：

<?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical" >
        
       <FrameLayout 
        android:layout_weight="1"
        android:layout_width="match_parent"
        android:layout_height="match_parent" >
    
        <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="30dip"
            android:orientation="horizontal"
            android:layout_gravity="bottom" >
    
            <TextView
                android:id="@+id/circleIndicatorView_TextView"
                android:layout_width="0dip"
                android:layout_height="match_parent"
                android:gravity="left"
                android:textColor="#FF0000"
                android:layout_weight="1"
                android:singleLine="true"
                android:text="" />
            
            <zhangphil.libs.view.CircleIndicatorView
                android:id="@+id/circleIndicatorView"
                android:layout_width="0dip"
                android:layout_height="match_parent"
                android:layout_weight="0.382"/>
            
        </LinearLayout>
    
    </FrameLayout>
    
    </LinearLayout>

以及用以绘制红色小圆球的 CircleIndicatorView.java

package zhangphil.libs.view;
    
    import android.content.Context;
    import android.graphics.Canvas;
    import android.graphics.Color;
    import android.graphics.Paint;
    import android.util.AttributeSet;
    import android.view.View;
    
    public class CircleIndicatorView extends View { 
    	
        public CircleIndicatorView(Context context, AttributeSet attrs){   
        	       super(context, attrs);  
        }
        
        private	int	gap=20;//各个横向排列的小球间距
    	public	void	setCirlceGap(int gap){
    	    	this.gap=gap;
    	}
    	public	int	getCirlceGap(){
    	    	return	gap;
    	}
        
        private	int	padding=20;
        public	void	setPadding(int padding){
        	this.padding=padding;
        }
        public	int	getPadding(){
        	return	padding;
        }
        
        private	int	circle_normal_radius=5; //普通小球半径
        public	void	setNormalCircleRadius(int radius){
        	this.circle_normal_radius=radius;
        }
        public	int	getNormalCircleRadius(){
        	return	circle_normal_radius;
        }
        
        private	int	circle_selected_radius=7; //被选择的小球半径
        public	void setSelectedCircleRadius(int radius){
        	this.circle_selected_radius=radius;
        } 
        public	int	getSelectedCircleRadius(){
        	return	circle_selected_radius;
        }
        
        private	int	count=0;
        public	void	setCircleCount(int count){
        	this.count=count;
        }
        public	int	getCircleCount(){
        	return	count;
        }
    
        private	int	pos=0;
        public	void	setCircleSelectedPosition(int pos){
        	this.pos=pos;
        }
        public	int	getCircleSelectedPosition(){
        	return	pos;
        }
        
        public	void	drawCircleView(){
        	this.invalidate();
        }
        
        public	void	drawCircleView(int count,int circleSelectedPosition){
        	setCircleCount(count);
        	setCircleSelectedPosition(circleSelectedPosition);
        	
        	this.invalidate();
        }
        
        private	int	circleSelectedColor=Color.RED;
        public	void	setCircleSelectedColor(int color){
        	circleSelectedColor=color;
        }
        public	int	getCircleSelectedColor(){
        	return	circleSelectedColor;
        }
        
        private	int	circleUnSelectedColor=Color.LTGRAY;
        public	void	setCircleUnSelectedColor(int color){
        	circleUnSelectedColor=color;
        }
        public	int	getCircleUnSelectedColor(){
        	return	circleUnSelectedColor;
        }
    
        
        @Override  
        protected void onDraw(Canvas canvas) {  
            super.onDraw(canvas); 
            
            Paint p = new Paint();  
            p.setAntiAlias(true);
            
            int w=this.getWidth();
            int h=this.getHeight();
            
            //因为是自右往左绘制小圆圈，需要转化pos的位置。
          int translate_pos=getCircleCount()-getCircleSelectedPosition()-1;
           
          //如果居中绘制则使用start_x，但需要依次递加x坐标轴位置值。
          //int start_x=(w-(CIRCLE_GAP*(getCircleCount()-1)))/2;
            
            for(int i=0;i<getCircleCount();i++){
            	int r=getNormalCircleRadius();
            	
            	if(i==translate_pos){
            		r=getSelectedCircleRadius();
            		p.setColor(getCircleSelectedColor());
            	}
            	else{
            		r=getNormalCircleRadius();
            		p.setColor(getCircleUnSelectedColor()); 
            	}
            	
            	//自右向左绘制。从最右边往左边绘制小球
            	//如果从该自定制的View左边绘制，直接将 x=0即可。
            	canvas.drawCircle(w-i*getCirlceGap()-getPadding(), h/2, r, p);
            }
        } 
    }

[Center]: https://img-blog.csdn.net/20150211113259383?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQvemhhbmdwaGls/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center