画图,Shader Path

package com.javaeye.android.my;

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);  
	     }
	}
}