开源项目：SubstepView

1 <org.warnier.zhang.widget.SubstepView
2 　　android:layout_width="match_parent"
3 　　android:layout_height="wrap_content" />

  1 package org.warnier.zhang.widget;
  2 
  3 import android.content.Context;
  4 import android.graphics.Canvas;
  5 import android.graphics.Color;
  6 import android.graphics.Paint;
  7 import android.support.v4.view.ViewPager;
  8 import android.util.AttributeSet;
  9 import android.util.DisplayMetrics;
 10 import android.view.View;
 11 import android.view.WindowManager;
 12 
 13 public class SubstepView extends View implements ViewPager.OnPageChangeListener {
 14     private ViewPager mViewPager;
 15     private Paint mPaint;
 16     private Paint mPaintSelected;
 17     private Paint mPaintText;
 18     private int mCurrentPage;
 19     private float mWidth;
 20 
 21     public SubstepView(Context context) {
 22         this(context, null);
 23     }
 24 
 25     public SubstepView(Context context, AttributeSet attrs) {
 26         this(context, attrs, 0);
 27     }
 28 
 29     public SubstepView(Context context, AttributeSet attrs, int defStyleAttr) {
 30         super(context, attrs, defStyleAttr);
 31 
 32         //Retrieve the style attributes.
 33 
 34         //Customize the paint.
 35         mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
 36         mPaint.setStrokeWidth(8);
 37         mPaint.setColor(Color.parseColor("#B6B6B6"));
 38         mPaintSelected = new Paint(Paint.ANTI_ALIAS_FLAG);
 39         mPaintSelected.setStrokeWidth(8);
 40         mPaintSelected.setColor(Color.parseColor("#4CAF50"));
 41         mPaintText = new Paint(Paint.ANTI_ALIAS_FLAG);
 42         mPaintText.setTextSize(48);
 43         mPaintText.setColor(Color.WHITE);
 44 
 45         //Retrieve the width of screen.
 46         WindowManager windowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
 47         DisplayMetrics displayMetrics = new DisplayMetrics();
 48         windowManager.getDefaultDisplay().getMetrics(displayMetrics);
 49         mWidth = displayMetrics.widthPixels;
 50     }
 51 
 52     @Override
 53     protected void onDraw(Canvas canvas) {
 54         super.onDraw(canvas);
 55         if (mViewPager == null) {
 56             return;
 57         }
 58         final int count = mViewPager.getAdapter().getCount();
 59         if (count == 0) {
 60             return;
 61         }
 62         float width = mWidth / (count + 1);
 63         float height = 48;
 64         for (int i = 0; i < count; i++) {
 65             if (i > 0) {
 66                 canvas.drawLine(width * i + height, height, width * (i + 1), height, (mCurrentPage >= i) ? mPaintSelected : mPaint);
 67             }
 68             canvas.drawCircle(width * (i + 1), height, height, (mCurrentPage >= i) ? mPaintSelected : mPaint);
 69             //It does‘t work well when trying to draw text in the center of circle.
 70             canvas.drawText("" + (i + 1), width * (i + 1) - 12, height + 12, mPaintText);
 71         }
 72     }
 73 
 74     public void setViewPager(ViewPager viewPager) {
 75         if (mViewPager == viewPager) {
 76             return;
 77         }
 78         if (mViewPager != null) {
 79             mViewPager.setOnPageChangeListener(null);
 80         }
 81         if (mViewPager.getAdapter() == null) {
 82             throw new IllegalStateException("ViewPager does‘t have an adapter instance.");
 83         }
 84         mViewPager = viewPager;
 85         mViewPager.setOnPageChangeListener(this);
 86         invalidate();
 87     }
 88 
 89     /**
 90      * Add the custom implementation of ViewPager.OnPageChangeListener.
 91      */
 92     @Override
 93     public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
 94         //Do some operations if need.
 95     }
 96 
 97     @Override
 98     public void onPageSelected(int position) {
 99         mCurrentPage = position;
100         invalidate();
101     }
102 
103     @Override
104     public void onPageScrollStateChanged(int state) {
105         //Do some operations if need.
106     }
107 }