怎么在android中绘制一个几何图形

public class MyView extends View 
{ 
  public MyView(Context context, AttributeSet set) 
  { 
    super(context, set); 
  } 
  @Override 
  // 重写该方法，进行绘图 
  protected void onDraw(Canvas canvas) 
  { 
    super.onDraw(canvas); 
    // 把整张画布绘制成白色 
    canvas.drawColor(Color.WHITE); 
    Paint paint = new Paint();//创建一个画笔对象 
    // 去锯齿 
    paint.setAntiAlias(true); 
    paint.setColor(Color.BLUE);//设置画笔颜色为蓝色 
    paint.setStyle(Paint.Style.STROKE);//设置样式 
    paint.setStrokeWidth(3);//设置样式的宽度 
    // 绘制圆形 
    canvas.drawCircle(40, 40, 30, paint); 
    // 绘制正方形 
    canvas.drawRect(10, 80, 70, 140, paint); 
    // 绘制矩形 
    canvas.drawRect(10, 150, 70, 190, paint); 
    RectF re1 = new RectF(10, 200, 70, 230); 
    // 绘制圆角矩形 
    canvas.drawRoundRect(re1, 15, 15, paint); 
    RectF re11 = new RectF(10, 240, 70, 270); 
    // 绘制椭圆 
    canvas.drawOval(re11, paint);     
    // 定义一个Path对象，封闭成一个三角形。 
    Path path2 = new Path(); 
    path2.moveTo(10, 340);//将路径点设置到10，340位置 
    path2.lineTo(70, 340);//将起始路径点连接都70,340位置 
    path2.lineTo(40, 290);//将第二连接点连接到40,290位置 
    path2.close();//关闭路径的绘制 
    // 根据Path进行绘制，绘制三角形 
    canvas.drawPath(path2, paint); 
    // 定义一个Path对象，封闭成一个五角形。 
    Path path3 = new Path(); 
    path3.moveTo(26, 360); 
    path3.lineTo(54, 360); 
    path3.lineTo(70, 392); 
    path3.lineTo(40, 420); 
    path3.lineTo(10, 392); 
    path3.close(); 
    // 根据Path进行绘制，绘制五角形 
    canvas.drawPath(path3, paint); 
    // ----------设置填充风格后绘制---------- 
    paint.setStyle(Paint.Style.FILL); 
    paint.setColor(Color.RED); 
    canvas.drawCircle(120, 40, 30, paint); 
    //绘制正方形 
    canvas.drawRect(90, 80, 150, 140, paint); 
    //绘制矩形 
    canvas.drawRect(90, 150, 150, 190, paint); 
    RectF re2 = new RectF(90, 200, 150, 230); 
    //绘制圆角矩形 
    canvas.drawRoundRect(re2, 15, 15, paint); 
    RectF re21 = new RectF(90, 240, 150, 270); 
    // 绘制椭圆 
    canvas.drawOval(re21, paint);     
    Path path4 = new Path(); 
    path4.moveTo(90, 340); 
    path4.lineTo(150, 340); 
    path4.lineTo(120, 290); 
    path4.close(); 
    //绘制三角形 
    canvas.drawPath(path4, paint); 
    Path path5 = new Path(); 
    path5.moveTo(106, 360); 
    path5.lineTo(134, 360); 
    path5.lineTo(150, 392); 
    path5.lineTo(120, 420); 
    path5.lineTo(90, 392); 
    path5.close(); 
    //绘制五角形 
    canvas.drawPath(path5, paint); 
    // ----------设置渐变器后绘制---------- 
    // 为Paint设置渐变器 
    Shader mShader = new LinearGradient(0, 0, 40, 60 
      , new int[] { 
      Color.RED, Color.GREEN, Color.BLUE, Color.YELLOW } 
      , null , Shader.TileMode.REPEAT); 
    paint.setShader(mShader); 
    //设置阴影 
    paint.setShadowLayer(45 , 10 , 10 , Color.GRAY); 
    // 绘制圆形 
    canvas.drawCircle(200, 40, 30, paint); 
    // 绘制正方形 
    canvas.drawRect(170, 80, 230, 140, paint); 
    // 绘制矩形 
    canvas.drawRect(170, 150, 230, 190, paint); 
    RectF re3 = new RectF(170, 200, 230, 230); 
    // 绘制圆角矩形 
    canvas.drawRoundRect(re3, 15, 15, paint); 
    RectF re31 = new RectF(170, 240, 230, 270); 
    // 绘制椭圆 
    canvas.drawOval(re31, paint);     
    Path path6 = new Path(); 
    path6.moveTo(170, 340); 
    path6.lineTo(230, 340); 
    path6.lineTo(200, 290); 
    path6.close(); 
    // 根据Path进行绘制，绘制三角形 
    canvas.drawPath(path6, paint); 
    Path path7 = new Path(); 
    path7.moveTo(186, 360); 
    path7.lineTo(214, 360); 
    path7.lineTo(230, 392); 
    path7.lineTo(200, 420); 
    path7.lineTo(170, 392); 
    path7.close(); 
    // 根据Path进行绘制，绘制五角形 
    canvas.drawPath(path7, paint); 
    // ----------设置字符大小后绘制---------- 
    paint.setTextSize(24); 
    paint.setShader(null); 
    // 绘制7个字符串 
    canvas.drawText(getResources().getString(R.string.circle), 240, 50, 
      paint); 
    canvas.drawText(getResources().getString(R.string.square), 240, 120, 
      paint); 
    canvas.drawText(getResources().getString(R.string.rect), 240, 175, 
      paint); 
    canvas.drawText(getResources().getString(R.string.round_rect), 230, 
      220, paint); 
    canvas.drawText(getResources().getString(R.string.oval), 240, 
      260, paint);     
    canvas.drawText(getResources().getString(R.string.triangle), 240, 325, 
      paint); 
    canvas.drawText(getResources().getString(R.string.pentagon), 240, 390, 
      paint); 
  } 
}