自定义View绘制字符串

import android.app.Activity;  
import android.os.Bundle;  
import android.view.Display;  
import android.view.View;  
import android.content.Context;  
import android.graphics.Canvas;  
import android.graphics.Color;  
import android.graphics.Paint;  
import android.graphics.Paint.FontMetrics;  


public class MainActivity extends Activity {  
      
    public int nScreenWidth = 0;  
    public int nScreenHeight = 0;  
    Paint paint = null;  
      
    @Override  
    protected void onCreate(Bundle savedInstanceState) {  
  
        //  获取屏幕宽高  
        Display display = getWindowManager().getDefaultDisplay();  
        nScreenWidth = display.getWidth();  
        nScreenHeight = display.getHeight();  
          
        super.onCreate(savedInstanceState);  
        setContentView(new FontView(this));  
    }  
      
    //  自定义的View  
    class FontView extends View {  
        public final static String STR_WIDTH = "获取字符宽度为：";  
        public final static String STR_HEIGHT = "获取字符高度为：";  
  
        public FontView(Context context) {  
            super(context);  
            // TODO Auto-generated constructor stub  
            paint = new Paint();  
        }  
          
        @Override  
        protected void onDraw(Canvas canvas) {  
            super.onDraw(canvas);  
            //  设置背景色  
            setBackgroundColor(Color.BLACK);  
              
            //  设置字符串颜色  
            paint.setColor(Color.WHITE);  
            canvas.drawText("当前屏幕宽"+nScreenWidth, 0, 30, paint);  
            canvas.drawText("当前屏幕高"+nScreenHeight, 0, 60, paint);  
              
            //  设置字体大小  
            paint.setColor(Color.RED);  
            paint.setTextSize(18);  
            canvas.drawText("字体大小为18", 0, 90, paint);  
              
            //  消除字体锯齿  
            paint.setFlags(Paint.ANTI_ALIAS_FLAG);  
            canvas.drawText("消除字体锯齿", 0, 120, paint);  
              
            //  获取字符串宽度  
            canvas.drawText(STR_WIDTH + getStringWidth(STR_WIDTH), 0, 150, paint);  
              
            //  获取字体高度  
            canvas.drawText(STR_HEIGHT + getFontHeight() , 0, 180, paint);  
              
        }  
          
        //  获取字体串宽度  
        private int getStringWidth(String str) {  
            return (int) paint.measureText(str);  
        }  
          
        //  获取字体高度  
        private int getFontHeight() {  
            FontMetrics fm = paint.getFontMetrics();  
            return (int) Math.ceil(fm.descent - fm.top) + 2;  
        }  
    }  
}