android 通过canvas旋转 绘制文字 竖直等不同方向的显示

package com.free.chart;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

public class DrawTextStudy extends SurfaceView implements SurfaceHolder.Callback {

SurfaceHolder holder;
public DrawTextStudy(Context context) {
super(context);
// TODO Auto-generated constructor stub
holder = this.getHolder();
holder.addCallback(this);
}

@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
// TODO Auto-generated method stub

}

@Override
public void surfaceCreated(SurfaceHolder holder) {
// TODO Auto-generated method stub
new Thread(new MyThread()).start();
}

@Override
public void surfaceDestroyed(SurfaceHolder holder) {
// TODO Auto-generated method stub

}

void drawText(Canvas canvas ,String text , float x ,float y,Paint paint ,float angle){
if(angle != 0){
canvas.rotate(angle, x, y);
}
canvas.drawText(text, x, y, paint);
if(angle != 0){
canvas.rotate(-angle, x, y);
}
}

class MyThread implements Runnable{

@Override
public void run() {
// TODO Auto-generated method stub
Canvas canvas = null;
try{
canvas = holder.lockCanvas();
Paint paint = new Paint();
paint.setColor(Color.WHITE);
paint.setTextSize(20);
canvas.drawLine(100, 100, 100, 400, paint);
drawText(canvas,"Hello", 80, 200, paint,-90);

paint.setColor(Color.RED);
paint.setTextSize(40);
drawText(canvas,"free", 150, 180, paint,-45);

paint.setColor(Color.BLUE);
drawText(canvas,"World", 150, 80, paint,0);
canvas.drawLine(100, 100, 400, 100, paint);

} catch(Exception e){

} finally {
holder.unlockCanvasAndPost(canvas);
}

}
}

}

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

setContentView(new DrawTextStudy(this));
}