Android PathEffect 效果使用

本文内容摘自《疯狂Android讲义第3版》

Android系统有以下6种PathEffect效果：

• ComposePathEffect
• CornerPathEffect
• DiscretePathEffect
• DiscretePathEffect
• PathDashPathEffect
• SumPathEffect

示例代码

package shortcut.song.com.myapplication;import android.content.Context;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.ComposePathEffect;import android.graphics.CornerPathEffect;import android.graphics.DashPathEffect;import android.graphics.DiscretePathEffect;import android.graphics.Paint;import android.graphics.Path;import android.graphics.PathDashPathEffect;import android.graphics.PathEffect;import android.graphics.SumPathEffect;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.view.View;public class PathEffectActivity extends AppCompatActivity {    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        //setContentView(R.layout.activity_path_effect);        setContentView(new MyPathEffect(this));    }    class MyPathEffect extends View {        float phase;        PathEffect[] effects = new PathEffect[7];        int[] colors;        private Paint paint;        Path  path;        public MyPathEffect(Context context) {            super(context);            paint = new Paint();            paint.setStyle(Paint.Style.STROKE);            paint.setStrokeWidth(4);            path = new Path();            path.moveTo(0, 0);            for (int i = 1; i <= 40; i++)            {                path.lineTo(i * 20, (float)Math.random() * 60);  ;            }            path.close();            colors = new int[]{Color.BLACK, Color.BLUE, Color.CYAN, Color.GREEN, Color.MAGENTA,Color.RED, Color.YELLOW};        }        @Override        protected void onDraw(Canvas canvas) {            //super.onDraw(canvas);            canvas.drawColor(Color.WHITE);            effects[0] = null;            effects[1] = new CornerPathEffect(10);            effects[2] = new DiscretePathEffect(3.0f, 5.0f);            effects[3] = new DashPathEffect(new float[]{20, 10, 5, 10}, phase);            Path p = new Path();            p.addRect(0,0,8,8, Path.Direction.CCW);            effects[4] = new PathDashPathEffect(p, 12, phase, PathDashPathEffect.Style.MORPH);            effects[5] = new ComposePathEffect(effects[2], effects[4]);            effects[6] = new SumPathEffect(effects[4], effects[3]);            //将画布移动至（8，8）处开始绘制；            canvas.translate(8, 8);            for(int i = 0; i < effects.length; i++ )            {                paint.setPathEffect(effects[i]);                paint.setColor(colors[i]);                canvas.drawPath(path, paint);                canvas.translate(0, 60);            }            phase += 1;//改变phase的值，形成动画效果            invalidate();        }    }}

程序运行效果图：