android ShapeDrawable实例

  今天看了一下api中的画图，遇到了一个新的类，Shader类介绍，android中提供了Shader类专门来渲染图像已经一些几何图形，shader 下面包括几个直接子类，分别是BitmapShaper，ComposeShader，LinerGradient,RadialGradient,SweepGradient.BitmapShader主要用来渲染图像，Shader类的使用，先构造Shdaer对象，然后通过Paint的setShader方法来设置渲染对象，然后再绘制使用这个Paint对象既可。

import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapShader;
import android.graphics.Canvas;
import android.graphics.ComposePathEffect;
import android.graphics.CornerPathEffect;
import android.graphics.DiscretePathEffect;
import android.graphics.LinearGradient;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.PathEffect;
import android.graphics.RectF;
import android.graphics.Shader;
import android.graphics.SweepGradient;
import android.graphics.drawable.Drawable;
import android.graphics.drawable.ShapeDrawable;
import android.graphics.drawable.shapes.ArcShape;
import android.graphics.drawable.shapes.OvalShape;
import android.graphics.drawable.shapes.PathShape;
import android.graphics.drawable.shapes.RectShape;
import android.graphics.drawable.shapes.RoundRectShape;
import android.graphics.drawable.shapes.Shape;
import android.os.Bundle;
import android.view.View;

public class ShapeDrawble1 extends Activity {
    /** Called when the activity is first created. */
	

	    @Override
	    protected void onCreate(Bundle savedInstanceState) {
	        super.onCreate(savedInstanceState);
	        setContentView(new SampleView(this));
	    }
	    
	    private static class SampleView extends View {
	        private ShapeDrawable[] mDrawables;
	        
	        private static Shader makeSweep() {
	        	/* SweepGradient 是继承于Shader的，它是以中心点（150，25）
	        	 * 按照下列四种颜色进行变化的*/
	            return new SweepGradient(0, 0,
	                new int[] { 0xFFFF0000, 0xFF00FF00, 0xFF0000FF, 0xFFFF0000 },
	                null);// null 表示均衡变化
	        }
	        
	        private static Shader makeLinear() {
	        	//颜色按照直线线性变化的着色器
	            return new LinearGradient(100, 100, 0, 0,
	                              new int[] { 0xFFFF0000, 0xFF00FF00, 0xFF0000FF },
	                              null, Shader.TileMode.MIRROR);
	        }
	        
	        private static Shader makeTiling() {
	            int[] pixels = new int[] { 0xFFFF0000, 0xFF00FF00, 0xFF0000FF, 0};
	            Bitmap bm = Bitmap.createBitmap(pixels, 1, 1,
	                                            Bitmap.Config.ARGB_8888);
	            /**
	             * BitmapShader 是一个位图着色器，这个着色器是通过
	             * 在x，y方向重复位图bm的像素来着色的
	             *
	             */
	            return new BitmapShader(bm, Shader.TileMode.REPEAT,
	                                        Shader.TileMode.REPEAT);
	        }
	        /**
	         * ShapeDrawable 是绘制各种几何体的类。它注入想要绘制的形状shap
	         * 类，就可以绘制出我们想要的集合体，这个类最寒心的就是draw（canvas）
	         * 和onDraw（Shape，Canvas，Paint）这个方法调用
	         *
	         */
	        private static class MyShapeDrawable extends ShapeDrawable {
	        	//Paint.ANTI_ALIAS_FLAG代表这个画笔的图形是光滑的
	            private Paint mStrokePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
	            
	            public MyShapeDrawable(Shape s) {
	                super(s);
	                mStrokePaint.setStyle(Paint.Style.STROKE);
	            }
	            
	            public Paint getStrokePaint() {
	                return mStrokePaint;
	            }
	            
	            @Override protected void onDraw(Shape s, Canvas c, Paint p) {
	                //绘制填充效果的图形
	            	s.draw(c, p);
	            	//绘制黑边
	                s.draw(c, mStrokePaint);
	            }
	        }
	        
	        public SampleView(Context context) {
	            super(context);
	            setFocusable(true);
                //外部圆角矩形的圆角圆半径，上面俩个角是圆
	            float[] outerR = new float[] { 12, 12, 12, 12, 0, 0, 0, 0 };
	            //内部矩形
	            RectF   inset = new RectF(6, 6, 6, 6);
	            //内部圆角矩形的圆角是圆半径，左上角和右下角是圆角矩形
	            float[] innerR = new float[] { 12, 12, 0, 0, 12, 12, 0, 0 };
	            //绘制一个顶点为下列四个点的棱形
	            Path path = new Path();
	            path.moveTo(50, 0);
	            path.lineTo(0, 50);
	            path.lineTo(50, 100);
	            path.lineTo(100, 50);
	            //封闭前面点所绘制的路径
	            path.close();
	            
	            mDrawables = new ShapeDrawable[7];
	            //绘制矩形
	            mDrawables[0] = new ShapeDrawable(new RectShape());
	            //绘制椭圆
	            mDrawables[1] = new ShapeDrawable(new OvalShape());
	            //绘制上面俩个角是圆角的矩形
	            mDrawables[2] = new ShapeDrawable(new RoundRectShape(outerR, null,
	                                                                 null));
	            //绘制上面俩角是圆角，并且有一个内嵌的矩形
	            mDrawables[3] = new ShapeDrawable(new RoundRectShape(outerR, inset,
	                                                                 null));
	           ////绘制上面俩角是圆角，并且有一个内嵌的矩形且左上角和右下角是圆形矩形环
	            mDrawables[4] = new ShapeDrawable(new RoundRectShape(outerR, inset,
	                                                                 innerR));
	            //绘制指定路径的集合体
	            mDrawables[5] = new ShapeDrawable(new PathShape(path, 100, 100));
	           // 用自定的ShapDrawble绘制开始弧度45扫过弧度-270的椭圆
	            mDrawables[6] = new MyShapeDrawable(new ArcShape(45, -270));
	            
	            mDrawables[0].getPaint().setColor(0xFFFF0000);
	            mDrawables[1].getPaint().setColor(0xFF00FF00);
	            mDrawables[2].getPaint().setColor(0xFF0000FF);
	            mDrawables[3].getPaint().setShader(makeSweep());
	            mDrawables[4].getPaint().setShader(makeLinear());
	            mDrawables[5].getPaint().setShader(makeTiling());
	            mDrawables[6].getPaint().setColor(0x88FF8844);
	            //DiscretePathEffect是一个折线路径效果，分割长度是10，偏差时4
	            PathEffect pe = new DiscretePathEffect(10, 4);
	            //CornerPathEffect是将2个路径效果合并后的路径效果
	            PathEffect pe2 = new CornerPathEffect(4);
	            mDrawables[3].getPaint().setPathEffect(
	                                                new ComposePathEffect(pe2, pe));
	        
	            MyShapeDrawable msd = (MyShapeDrawable)mDrawables[6];
	            //设置笔画宽度等于4
	            msd.getStrokePaint().setStrokeWidth(4);
	        }
	        
	        @Override protected void onDraw(Canvas canvas) {
	            
	            int x = 10;
	            int y = 10;
	            int width = 300;
	            int height = 50;
	            //循环绘制
	            for (Drawable dr : mDrawables) {
	                dr.setBounds(x, y, x + width, y + height);
	                dr.draw(canvas);                
	                y += height + 5;
	            }
	        }
	    }
	}