Android新手之旅(9) 自訂的折線圖

　　希望實現一個折線圖，但沒有找到合適的控制項或者代碼，只有一個基本樣子的，在它的基礎上，進行了一些改進，改得比較靈活，可以傳遞參數，可以設定位置，座標軸長度，刻度長度等。

　　自訂的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;    //原點的X座標
    public int YPoint=260;     //原點的Y座標
    public int XScale=55;     //X的刻度長度
    public int YScale=40;     //Y的刻度長度
    public int XLength=380;        //X軸的長度
    public int YLength=240;        //Y軸的長度
    public String[] XLabel;    //X的刻度
    public String[] YLabel;    //Y的刻度
    public String[] Data;      //資料
    public String Title;    //顯示的標題
    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);//重寫onDraw方法

        //canvas.drawColor(Color.WHITE);//設定背景顏色
        Paint paint= new Paint();
        paint.setStyle(Paint.Style.STROKE);
        paint.setAntiAlias(true);//去鋸齒
        paint.setColor(Color.BLUE);//顏色
        Paint paint1=new Paint();
        paint1.setStyle(Paint.Style.STROKE);
        paint1.setAntiAlias(true);//去鋸齒
        paint1.setColor(Color.DKGRAY);
        paint.setTextSize(12);  //設定軸文字大小
        //設定Y軸
        canvas.drawLine(XPoint, YPoint-YLength, XPoint, YPoint, paint);   //軸線
        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);  //箭頭
        canvas.drawLine(XPoint,YPoint-YLength,XPoint+3,YPoint-YLength+6,paint);           
        //設定X軸
        canvas.drawLine(XPoint,YPoint,XPoint+XLength,YPoint,paint);   //軸線
        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
                //資料值
                    if(i>0&&YCoord(Data[i-1])!=-999&&YCoord(Data[i])!=-999)  //保證有效資料
                        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);    //箭頭
        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)  //計算繪製時的Y座標，無資料時返回-999
    {
        int y;
        try
        {
            y=Integer.parseInt(y0);
        }
        catch(Exception e)
        {
            return -999;    //出錯則返回-999
        }
        try
        {
            return YPoint-y*YScale/Integer.parseInt(YLabel[1]);
        }
        catch(Exception e)
        {
        }
        return y;
    }
}

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

調用方法：

ChartView myView=new ChartView(this);
myView.SetInfo(
        new String[]{"7-11","7-12","7-13","7-14","7-15","7-16","7-17"},   //X軸刻度
        new String[]{"","50","100","150","200","250"},   //Y軸刻度
        new int[]{15,23,10,36,45,40,12},  //資料
        "表徵圖的標題"
);

效果：