ANDROID画图PATH的使用

import android.app.Activity;  
import android.os.Bundle;  
import android.view.View;  
import android.content.Context;  
import android.graphics.Canvas;  
import android.graphics.Color;  
import android.graphics.Paint;  
import android.graphics.RectF;  
import android.graphics.Path;  
import android.graphics.Shader;  
import android.graphics.LinearGradient;  
//主程序中继承自Android.view.View的 MyView类，重写 MyView的onDraw（）方法，  
//一开始就会运行绘制的工作，在onDraw（）中以Paint将几何图形绘制在Canvas上，  
//以 paint.setColor() 改变图形颜色、以 paint.setStyle()的设置来控制画出的的  
//图形是空心还是实心。程序的最后一段，就是直接在Canvas写上文字，随着Paint对  
//象里的属性设置，也会有不同的外观模式。
public class GraphicesActivity extends Activity {  
    /** Called when the activity is first created. */ 
    @Override 
    public void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        /*设置ContentView为自定义的MyVieW*/ 
        MyView myView=new MyView(this);  
        setContentView(myView);  
    }  
       
    /* 自定义继承View 的MyView*/ 
    private class MyView extends View {  
         public MyView(Context context){  
            super(context) ;  
         }  
           
         /*重写onDraw（）*/ 
         @Override 
         protected void onDraw(Canvas canvas)  
         {     
              super.onDraw(canvas);  
              /*设置背景为白色*/ 
              canvas.drawColor(Color.WHITE);  
                 
              Paint paint=new Paint();  
              /*去锯齿*/ 
              paint.setAntiAlias(true);  
              /*设置paint的颜色*/ 
              paint.setColor(Color.RED);  
              /*设置paint的 style 为STROKE：空心*/ 
              paint.setStyle(Paint.Style.STROKE);  
              /*设置paint的外框宽度*/ 
              paint.setStrokeWidth(3);  
                 
              /*画一个空心圆形*/ 
              canvas.drawCircle(40, 40, 30, paint);  
              /*画一个空心正方形*/ 
              canvas.drawRect(10, 90, 70, 150, paint);  
              /*画一个空心长方形*/ 
              canvas.drawRect(10, 170, 70,200, paint);  
              /*画一个空心椭圆形*/ 
              canvas.drawOval(new RectF(10,220,70,250), paint);  
              /*画一个空心三角形*/ 
              Path path=new Path();  
              path.moveTo(10, 330);  
              path.lineTo(70,330);  
              path.lineTo(40,270);  
              path.close();  
              canvas.drawPath(path, paint);  
              /*画一个空心梯形*/ 
              Path path1=new Path();  
              path1.moveTo(10, 410);  
              path1.lineTo(70,410);  
              path1.lineTo(55,350);  
              path1.lineTo(25, 350);  
              path1.close();  
              canvas.drawPath(path1, paint);  
                 
              /*设置paint的颜色*/ 
              paint.setColor(Color.BLUE);  
              /*设置paint 的style为 FILL：实心*/ 
              paint.setStyle(Paint.Style.FILL);  
              /*画一个实心圆*/ 
              canvas.drawCircle(120,40,30, paint);  
              /*画一个实心正方形*/ 
              canvas.drawRect(90, 90, 150, 150, paint);  
              /*画一个实心长方形*/ 
              canvas.drawRect(90, 170, 150,200, paint);  
              /*画一个实心椭圆*/ 
              RectF re2=new RectF(90,220,150,250);  
              canvas.drawOval(re2, paint);  
              /*画一个实心三角形*/ 
              Path path2=new Path();  
              path2.moveTo(90, 330);  
              path2.lineTo(150,330);  
              path2.lineTo(120,270);  
              path2.close();  
              canvas.drawPath(path2, paint);  
              /*画一个实心梯形*/ 
              Path path3=new Path();  
              path3.moveTo(90, 410);  
              path3.lineTo(150,410);  
              path3.lineTo(135,350);  
              path3.lineTo(105, 350);  
              path3.close();  
              canvas.drawPath(path3, paint);  
                 
              /*设置渐变色*/ 
              Shader mShader=new LinearGradient(0,0,100,100,  
                      new int[]{Color.RED,Color.GREEN,Color.BLUE,Color.YELLOW},  
                      null,Shader.TileMode.REPEAT);  
              //Shader.TileMode三种模式  
              //REPEAT:沿着渐变方向循环重复  
              //CLAMP:如果在预先定义的范围外画的话，就重复边界的颜色  
              //MIRROR:与REPEAT一样都是循环重复，但这个会对称重复  
              paint.setShader(mShader);//用Shader中定义定义的颜色来话  
              
              /*画一个渐变色圆*/ 
              canvas.drawCircle(200,40,30, paint);  
              /*画一个渐变色正方形*/ 
              canvas.drawRect(170, 90, 230, 150, paint);  
              /*画一个渐变色长方形*/ 
              canvas.drawRect(170, 170, 230,200, paint);  
              /*画一个渐变色椭圆*/ 
              RectF re3=new RectF(170,220,230,250);  
              canvas.drawOval(re3, paint);  
              /*画一个渐变色三角形*/ 
              Path path4=new Path();  
              path4.moveTo(170,330);  
              path4.lineTo(230,330);  
              path4.lineTo(200,270);  
              path4.close();  
              canvas.drawPath(path4, paint);  
              /*画一个渐变色梯形*/ 
              Path path5=new Path();  
              path5.moveTo(170, 410);  
              path5.lineTo(230,410);  
              path5.lineTo(215,350);  
              path5.lineTo(185, 350);  
              path5.close();  
              canvas.drawPath(path5, paint);  
                 
              /*写字*/ 
              paint.setTextSize(24);  
              canvas.drawText("圆形", 240, 50, paint);  
              canvas.drawText("正方形", 240, 120, paint);  
              canvas.drawText("长方形", 240, 190, paint);  
              canvas.drawText("椭圆形", 240, 250, paint);  
              canvas.drawText("三角形", 240, 320, paint);  
              canvas.drawText("梯形", 240, 390, paint);    
         }  
    }  
}