Android新手之旅(9) 自定义的折线图

　　希望实现一个折线图，但没有找到合适的控件或者代码，只有一个基本样子的，在它的基础上，进行了一些改进，改得比较灵活，可以传递参数，可以设置位置，坐标轴长度，刻度长度等。

　　自定义的ChartView.java

package jetz.common;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.view.View;

public class ChartView extends View{
    public int XPoint=40;    //原点的X坐标
    public int YPoint=260;     //原点的Y坐标
    public int XScale=55;     //X的刻度长度
    public int YScale=40;     //Y的刻度长度
    public int XLength=380;        //X轴的长度
    public int YLength=240;        //Y轴的长度
    public String[] XLabel;    //X的刻度
    public String[] YLabel;    //Y的刻度
    public String[] Data;      //数据
    public String Title;    //显示的标题
    public ChartView(Context context)
    {
        super(context);
    }
    public void SetInfo(String[] XLabels,String[] YLabels,String[] AllData,String strTitle)
    {
        XLabel=XLabels;
        YLabel=YLabels;
        Data=AllData;
        Title=strTitle;
    }
    @Override
    protected void onDraw(Canvas canvas){
        super.onDraw(canvas);//重写onDraw方法

        //canvas.drawColor(Color.WHITE);//设置背景颜色
        Paint paint= new Paint();
        paint.setStyle(Paint.Style.STROKE);
        paint.setAntiAlias(true);//去锯齿
        paint.setColor(Color.BLUE);//颜色
        Paint paint1=new Paint();
        paint1.setStyle(Paint.Style.STROKE);
        paint1.setAntiAlias(true);//去锯齿
        paint1.setColor(Color.DKGRAY);
        paint.setTextSize(12);  //设置轴文字大小
        //设置Y轴
        canvas.drawLine(XPoint, YPoint-YLength, XPoint, YPoint, paint);   //轴线
        for(int i=0;i*YScale<YLength ;i++)               
        {
            canvas.drawLine(XPoint,YPoint-i*YScale, XPoint+5, YPoint-i*YScale, paint);  //刻度
            try
            {
                canvas.drawText(YLabel[i] , XPoint-22, YPoint-i*YScale+5, paint);  //文字
            }
            catch(Exception e)
            {
            }
        }
        canvas.drawLine(XPoint,YPoint-YLength,XPoint-3,YPoint-YLength+6,paint);  //箭头
        canvas.drawLine(XPoint,YPoint-YLength,XPoint+3,YPoint-YLength+6,paint);           
        //设置X轴
        canvas.drawLine(XPoint,YPoint,XPoint+XLength,YPoint,paint);   //轴线
        for(int i=0;i*XScale<XLength;i++)   
        {
            canvas.drawLine(XPoint+i*XScale, YPoint, XPoint+i*XScale, YPoint-5, paint);  //刻度
            try
            {
                canvas.drawText(XLabel[i] , XPoint+i*XScale-10, YPoint+20, paint);  //文字
                //数据值
                    if(i>0&&YCoord(Data[i-1])!=-999&&YCoord(Data[i])!=-999)  //保证有效数据
                        canvas.drawLine(XPoint+(i-1)*XScale, YCoord(Data[i-1]), XPoint+i*XScale, YCoord(Data[i]), paint);
                    canvas.drawCircle(XPoint+i*XScale,YCoord(Data[i]), 2, paint);
           }
            catch(Exception e)
            {
            }
        }
        canvas.drawLine(XPoint+XLength,YPoint,XPoint+XLength-6,YPoint-3,paint);    //箭头
        canvas.drawLine(XPoint+XLength,YPoint,XPoint+XLength-6,YPoint+3,paint); 
        paint.setTextSize(16);
        canvas.drawText(Title, 150, 50, paint);
    }
    private int YCoord(String y0)  //计算绘制时的Y坐标，无数据时返回-999
    {
        int y;
        try
        {
            y=Integer.parseInt(y0);
        }
        catch(Exception e)
        {
            return -999;    //出错则返回-999
        }
        try
        {
            return YPoint-y*YScale/Integer.parseInt(YLabel[1]);
        }
        catch(Exception e)
        {
        }
        return y;
    }
}

--------------------------------------------------------------------------------------------

调用方法：

ChartView myView=new ChartView(this);
myView.SetInfo(
        new String[]{"7-11","7-12","7-13","7-14","7-15","7-16","7-17"},   //X轴刻度
        new String[]{"","50","100","150","200","250"},   //Y轴刻度
        new int[]{15,23,10,36,45,40,12},  //数据
        "图标的标题"
);

效果：