Android 畫曲線音頻示意圖

package com.huluo.testwaveformfigure;  
  
import java.util.ArrayList;  
import java.util.Iterator;  
  
import android.content.Context;  
import android.graphics.Canvas;  
import android.graphics.Color;  
import android.graphics.Paint;  
import android.graphics.Point;  
import android.graphics.PointF;  
import android.util.AttributeSet;  
import android.util.Log;  
import android.view.View;  
  
public class HLWaveFormFigure extends View{  
  
    private Paint m_Paint = null;  
      
    //private Point m_WaveformFigure[] = new Point[1000];  
    private ArrayList<PointF> m_WaveformFigure =  new ArrayList<PointF>();  
    private int kMaxKeyPoints  = 1000;  
    private int  kHillSegmentWidth = 10;  
    PointF pt0;  
    PointF pt1;  
    public HLWaveFormFigure(Context context, AttributeSet attrs) {  
        super(context, attrs);  
        // TODO Auto-generated constructor stub  
         pt0 = new PointF();  
         pt1 = new PointF();  
          
          
    generatePoint();  
        m_Paint = new Paint();  
        m_Paint.setColor(Color.RED);  
    }  
      
    @Override  
    protected void onDraw(Canvas canvas) {  
        // TODO Auto-generated method stub  
        super.onDraw(canvas);  
          
        //canvas.drawColor(Color.RED);  
        //canvas.save();  
        for (int i = 1; i < kMaxKeyPoints; i++) {  
              
            PointF p0 = (PointF)m_WaveformFigure.get(i-1);  
            PointF p1 = (PointF)m_WaveformFigure.get(i);  
              
          
            double hSegments = Math.floor((double)(p1.x - p0.x) / kHillSegmentWidth);//Math.floor((double)((p1.x - p0.x) / kHillSegmentWidth));  
            float dx = (p1.x - p0.x) / (float)hSegments;  
            float da = (float)(Math.PI / hSegments);  
            float ymid = (p0.y + p1.y) / 2;  
            float ampl = (p0.y - p1.y) / 2;  
              
              
            pt0.set(p0.x, p0.y);  
            for (int j = 0; j < hSegments + 1; ++j) {  
                pt1.set(p0.x + j * dx, (float)(ymid + ampl * Math.cos(da * j)));  
                  
                canvas.drawLine(pt0.x, pt0.y, pt1.x, pt1.y, m_Paint);  
                pt0.set(pt1.x, pt1.y);  
                  
                  
            }  
              
              
              
              
              
              
              
              
              
              
        }  
//        
      
        canvas.restore();  
    }  
      
      
      
    private void generatePoint()  
    {  
        float minDX = 50;  
        float minDY = 30;  
        float rangeDX = 10;  
        float rangeDY = 40;  
          
        float x = -minDX;  
        float y = 197.5f;  
        float dy= 0f,ny=0f;  
        float sign = 1;  
        float paddingTop = 0;  
        float paddingBottom = 0;  
        for (int i = 0; i < kMaxKeyPoints; i++) {  
            m_WaveformFigure.add(new PointF(x, y));  
            if (i == 0) {  
                x = 0;  
                y = 97.5f / 2;  
                  
            }  
            else {  
                x += Math.random() % rangeDX + minDX ;  
                while (true) {  
                    dy = (float)Math.random() % rangeDY + minDY;  
                    ny = y + dy * sign;  
                    if (ny < 480f- paddingTop && ny > paddingBottom) {  
                        break;  
                    }  
                }  
                y = ny;  
            }  
            sign *= -1;  
        }  
    }  
}