如何在没有xml的条形图中添加按钮？

GraphViewDemo.java

public class GraphViewDemo  extends Activity {

public static String graphreturn;



@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    float[] values = new float[] { 2.0f,3.0f,5.0f,1.0f,6.0f,4.0f,7.0f };
    String[] verlabels = new String[] { "7","6","5","4","3","2","1" };
    String[] horlabels = new String[] {"jan20","jan21","jan22","jan23","jan24","jan25","jan26"};
  GraphView graphView = new GraphView(this,values,"GraphViewDemo",horlabels,verlabels,GraphView.BAR);
  setContentView(graphView);}}

GraphView.java

public class GraphView extends View{

public static boolean BAR = true;
public static boolean LINE = false;

private Paint paint;
private float[] values;
private String[] horlabels;
private String[] verlabels;
private String title;
private boolean type;
Context context;
private Drawable mDrawable;
private Runnable in ;


public GraphView(Context context,float[] values,String title,String[] horlabels,String[] verlabels,boolean type) {

    super(context);
    if (values == null)
        values = new float[0];
    else
        this.values = values;
    if (title == null)
        title = "";
    else
        this.title = title;
    if (horlabels == null)
        this.horlabels = new String[0];
    else
        this.horlabels = horlabels;
    if (verlabels == null)
        this.verlabels = new String[0];
    else
        this.verlabels = verlabels;
    this.type = type;
    paint = new Paint();
}

@Override
protected void onDraw(final Canvas canvas) {
    context=getContext();
    float border = 20;
    float horstart = border * 2;
    float height = getHeight()-50;
    float width = getWidth();
    float max = getMax();
    Log.w("max",""+max);
    float min = getMin();
    Log.w("min",""+min);
    float diff = max - min;
    float graphheight = height - (2 * border);
    float graphwidth = width - (2 * border);

    paint.setTextAlign(Align.LEFT);
    int vers = verlabels.length - 1;
    for (int i = 0; i < verlabels.length; i++) {
        paint.setColor(Color.DKGRAY);
        float y = ((graphheight / vers) * i) + border;
        canvas.drawLine(horstart,y,width,paint);
        paint.setColor(Color.WHITE);
        canvas.drawText(verlabels[i],paint);
    }
    int hors = horlabels.length;
    for (int i = 0; i < horlabels.length; i++) {
        paint.setColor(Color.DKGRAY);
        float x = ((graphwidth / hors) * i) + horstart;
        canvas.drawLine(x,height - border,x,border,paint);
        paint.setTextAlign(Align.CENTER);
        if (i==horlabels.length+5)
            paint.setTextAlign(Align.RIGHT);
        if (i==0)
            paint.setTextAlign(Align.LEFT);
        paint.setColor(Color.WHITE);
        canvas.drawText(horlabels[i],height - 4,paint);
    }

    paint.setTextAlign(Align.CENTER);
    canvas.drawText(title,(graphwidth / 2) + horstart,border - 4,paint);


    int x = 0;
    int y = 0;
    Paint paint = new Paint();
    Paint paint1 = new Paint();
    paint.setStyle(Paint.Style.FILL);
    String str2rotate = "Rotated!";
    // draw bounding rect before rotating text
    Rect rect = new Rect();
    paint.getTextBounds(str2rotate,str2rotate.length(),rect);
    canvas.translate(x,y);
    paint.setColor(Color.GREEN);
    paint.setStyle(Paint.Style.FILL);
    paint.setStrokeWidth(1);

    paint.setStyle(Paint.Style.STROKE);

    paint1.setColor(Color.RED);
    canvas.drawText("!Rotated",paint1);


    mDrawable = context.getResources().getDrawable(R.drawable.previousi);
    mDrawable.setBounds(getWidth()/2-40,getHeight()-40,getWidth()/2+30,getHeight()-20);
    mDrawable.draw(canvas);

    mDrawable.scheduleSelf(in,0);

    //....................
    in = new Runnable() {
        public void run() {

                try {


                    //canvas.restore();
                     mDrawable.setBounds(getWidth()/2,getHeight(),getWidth(),getHeight()-20);
                        mDrawable.draw(canvas);




                } 
                 catch (Exception e) { 
                        e.printStackTrace();
                    }



            } 

    };

    Thread thread = new Thread(null,in,"graphview");
    thread.start();






    if (max != min) {
        paint.setColor(Color.BLUE);
        paint.setStyle(Paint.Style.FILL);

        if (type == BAR) {
            float datalength = values.length;
            float colwidth = (width - (2 * border)) / datalength;
            for (int i = 0; i < values.length; i++) {
                float val = values[i] - min;
                float rat = val / diff;
                float h = graphheight * rat;
                canvas.drawRect((i * colwidth) + horstart,(border - h) + graphheight,((i * colwidth) + horstart) + (colwidth - 1),height - (border - 1),paint);                     

            }
        } else {
            float datalength = values.length;
            float colwidth = (width - (2 * border)) / datalength;
            float halfcol = colwidth / 2;
            float lasth = 0;
            for (int i = 0; i < values.length; i++) {
                float val = values[i] - min;
                float rat = val / diff;
                float h = graphheight * rat;
                if (i > 0)
                    canvas.drawLine(((i - 1) * colwidth) + (horstart + 1) + halfcol,(border - lasth) + graphheight,(i * colwidth) + (horstart + 1) + halfcol,paint);
                lasth = h;
            }
        }
    }
}



private float getMax() {
    float largest = Integer.MIN_VALUE;
    for (int i = 0; i < values.length; i++)
        if (values[i] > largest)
            largest = values[i];
    return largest;
}

private float getMin() {
    float smallest = Integer.MAX_VALUE;
    for (int i = 0; i < values.length; i++)
        if (values[i] < smallest)
            smallest = values[i];
    return smallest;
}


}