绘制折线图

package com.example.canvas.view;

import java.util.ArrayList;
import java.util.List;
import java.util.Random;

import android.annotation.SuppressLint;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Handler;
import android.os.Message;
import android.util.AttributeSet;
import android.view.View;

@SuppressLint({ "DrawAllocation", "HandlerLeak" })
public class MyView extends View {
    private int XPoint = 60;
    private int YPoint = 260;
    private int XScale = 8; // 刻度长度
    private int YScale = 40;
    private int XLength = 380;
    private int YLength = 240;

    private int MaxDataSize = XLength / XScale;

    private List<Integer> data = new ArrayList<Integer>();

    private String[] YLabel = new String[YLength / YScale];

    private Handler handler = new Handler() {
        public void handleMessage(Message msg) {
            if (msg.what == 0x1234) {
                MyView.this.invalidate();
            }
        };
    };

    public MyView(Context context, AttributeSet attrs) {
        super(context, attrs);
        // TODO Auto-generated constructor stub
        for (int i = 0; i < YLabel.length; i++) {
            YLabel[i] = (i + 1) + "M/s";
        }

        new Thread(new Runnable() {
            @Override
            public void run() {
                while (true) {
                    try {
                        Thread.sleep(1000);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    if (data.size() >= MaxDataSize) {
                        data.remove(0);
                    }
                    data.add(new Random().nextInt(4) + 1);
                    handler.sendEmptyMessage(0x1234);
                }
            }
        }).start();

    }

    /*
     * (non-Javadoc)
     * 
     * @see android.view.View#onDraw(android.graphics.Canvas)
     * 
     * if(data.size() > 1){ Path path = new Path(); path.moveTo(XPoint, YPoint -
     * data.get(0) * YScale); for(int i=1; i<data.size(); i++){
     * path.lineTo(XPoint + i * XScale, YPoint - data.get(i) * YScale); }
     * canvas.drawPath(path, paint); }
     */
    @Override
    protected void onDraw(Canvas canvas) {
        // TODO Auto-generated method stub
        super.onDraw(canvas);

        Paint paint = new Paint();
        paint.setStyle(Paint.Style.STROKE);
        paint.setAntiAlias(true); // 去锯齿
        paint.setColor(Color.BLUE);

        // 画Y轴
        canvas.drawLine(XPoint, YPoint - YLength, XPoint, YPoint, paint);

        // Y轴箭头
        canvas.drawLine(XPoint, YPoint - YLength, XPoint - 3, YPoint - YLength
                + 6, paint); // 箭头
        canvas.drawLine(XPoint, YPoint - YLength, XPoint + 3, YPoint - YLength
                + 6, paint);

        // 添加刻度和文字
        for (int i = 0; i * YScale < YLength; i++) {
            canvas.drawLine(XPoint, YPoint - i * YScale, XPoint + 5, YPoint - i
                    * YScale, paint); // 刻度

            canvas.drawText(YLabel[i], XPoint - 50, YPoint - i * YScale, paint);// 文字
        }

        // 画X轴
        canvas.drawLine(XPoint, YPoint, XPoint + XLength, YPoint, paint);
        System.out.println("Data.size = " + data.size());
        if (data.size() > 1) {
            for (int i = 1; i < data.size(); i++) {
                canvas.drawLine(XPoint + (i - 1) * XScale,
                        YPoint - data.get(i - 1) * YScale, XPoint + i * XScale,
                        YPoint - data.get(i) * YScale, paint);
            }
        }

    }

}