android画图----ShapeDrawable和shader

在这个例程中主要讲述了ShapeDrawable，以及各种Gradient
首先初始化了 mDrawables = new ShapeDrawable[7];默认的是矩形，
当然还有其他形状：
  mDrawables[0] = new ShapeDrawable(new RectShape());
            mDrawables[1] = new ShapeDrawable(new OvalShape());
mDrawables[4] = new ShapeDrawable(new RoundRectShape(outerR, inset,
                                                                 innerR));
            mDrawables[5] = new ShapeDrawable(new PathShape(path, 100, 100));
float[] outerR = new float[] { 12, 12, 12, 12, 0, 0, 0, 0 };
            RectF   inset = new RectF(20, 20, 20, 20);
            float[] innerR = new float[] { 12, 12, 0, 0, 12, 12, 0, 0 };
           
            Path path = new Path();
            path.moveTo(50, 0);
            path.lineTo(0, 50);
            path.lineTo(50, 100);
            path.lineTo(100, 50);
            path.close();

实例化ShapeDrawable后就可以对他们进行设置：
设置渐变
mDrawables[0].getPaint().setShader(makeTiling());
设置颜色
            mDrawables[1].getPaint().setColor(0xFF00FF00);
设置影响 影响呢有很多 可以设置单个 也可以用组合
PathEffect pe = new DiscretePathEffect(10, 2);
            PathEffect pe2 = new CornerPathEffect(8);
            mDrawables[3].getPaint().setPathEffect(
                                                new SumPathEffect(pe2, pe));
其中渐变又包括：
private static Shader makeSweep() {
           return new SweepGradient(150, 25, new int[] { 0xFFFF0000, 0xFF00FF00, 0xFF0000FF, 0xFFFF0000 }, null);
        //return new SweepGradient(150, 25, new int[] { 0xFFFF0000, 0xFF00FF00, 0xFF0000FF }, new float[]{0.9f,0.1f,0.9f});
        }
       
        private static Shader makeLinear() {
            return new LinearGradient(0, 0, 50, 50,
                              new int[] { 0xFFFF0000, 0xFF00FF00, 0xFF0000FF },
                              null, Shader.TileMode.REPEAT);
        }
       
        private  Shader makeTiling() {
            int[] pixels = new int[] { 0xFFFF0000, 0xFF00FF00, 0xFF0000FF, 0};
          
          Bitmap bm = Bitmap.createBitmap(pixels, 2, 2,  Bitmap.Config.ARGB_8888);
           // Bitmap bm = Bitmap.createBitmap(mBitmap, 60, 45,  Bitmap.Config.ARGB_8888);
           
            return new BitmapShader(bm, Shader.TileMode.REPEAT,
                                        Shader.TileMode.REPEAT);
        }

最后在这个实例中 可以自定义一个ShapeDrawable
private static class MyShapeDrawable extends ShapeDrawable {
            private Paint mStrokePaint = new Paint(Paint.LINEAR_TEXT_FLAG);
           
            public MyShapeDrawable(Shape s) {
                super(s);
                mStrokePaint.setStyle(Paint.Style.STROKE);
                mStrokePaint.setColor(Color.GREEN);
            }
           
            public Paint getStrokePaint() {
                return mStrokePaint;
            }
           
            @Override protected void onDraw(Shape s, Canvas c, Paint p) {
//第一个调用父类的p，第二个调用自己刚才设置的p，如果你不想使用默认的父类，默认的颜色为黑了          
    s.draw(c, p);
                s.draw(c, mStrokePaint);
            }

mDrawables[6] = new MyShapeDrawable(new ArcShape(45, 360));
MyShapeDrawable msd = (MyShapeDrawable)mDrawables[6];
            msd.getStrokePaint().setStrokeWidth(1);
        }