SurfaceView 绘制分形图

之前一直做的是应用类，这次抽时间，参考网上资料实践了下SurfaceView。目标是在页面上画一个科赫曲线的分形图。

代码如下：

package com.example.fredric.demo02;

import android.content.Context;

import android.graphics.Canvas;

import android.graphics.Color;

import android.graphics.Paint;

import android.graphics.Rect;

import android.os.Bundle;

import android.support.design.widget.FloatingActionButton;

import android.support.design.widget.Snackbar;

import android.support.v7.app.AppCompatActivity;

import android.support.v7.widget.Toolbar;

import android.view.Surface;

import android.view.SurfaceHolder;

import android.view.SurfaceView;

import android.view.View;

import android.view.Menu;

import android.view.MenuItem;

import android.view.WindowManager;

public class MainActivity extends AppCompatActivity {

    private int width;

    private int height;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        WindowManager wm = (WindowManager) getSystemService(Context.WINDOW_SERVICE);

        width = wm.getDefaultDisplay().getWidth();

        height = wm.getDefaultDisplay().getHeight();

        setContentView(new MyView(this));

    }

    //知识点备注：

    //1、Surface:原始图像缓冲区的句柄，通过该接口可以获取原始缓冲区中的数据；

    //Surface 中包含canvas对象

    //2、SurfaceView:继承至View，

    // 2.1 提供了一个运行在渲染线程的surface

    // 2.2 SurfaceView 和 SurfaceHolder.Callback的方法都应该在主线程（UI线程）里面调用

    //3、SurfaceHolder:控制surface的一个抽象接口

    //4、SurfaceHolder.Callback: 监听Surface改变的接口

    class MyView extends SurfaceView implements SurfaceHolder.Callback {

        private SurfaceHolder holder;

        private MyThread myThread;

        public MyView(Context context) {

            super(context);

            // TODO Auto-generated constructor stub

            holder = this.getHolder();

            holder.addCallback(this);

            myThread = new MyThread(holder);

        }

        @Override

        public void surfaceCreated(SurfaceHolder holder) {

            myThread.isRun = true;

            myThread.start();

        }

        @Override

        public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {

        }

        @Override

        public void surfaceDestroyed(SurfaceHolder holder) {

            myThread.isRun = false;

        }

        class MyThread extends Thread {

            private SurfaceHolder holder;

            public boolean isRun;

            public MyThread(SurfaceHolder holder) {

                this.holder = holder;

                isRun = true;

            }

            @Override

            public void run() {

                int count = 0;

                while (isRun) {

                    Canvas c = null;

                    c = this.holder.lockCanvas();

                    try {

                        synchronized (holder) {

                            if (null != c){

                                c.drawColor(Color.WHITE);

                                Paint p = new Paint();

                                p.setColor(Color.BLUE);

                                p.setStrokeWidth((float) 5.0);

                                draw(c, p, 0, 0, width, height, 6);

                                Thread.sleep(1000);

                                isRun = false;

                            }

                        }

                    } catch (Exception e) {

                        e.printStackTrace();

                    } finally {

                        if (c != null) {

                            // 此时才提交绘画结果

                            holder.unlockCanvasAndPost(c);

                        }

                    }

                }

            }

        }//class MyThread extends Thread {

        public void draw(Canvas c, Paint p, int x1, int y1, int x2, int y2,int depth) {

            c.drawLine(x1, y1, x2, y2, p);

            if (depth <= 1) {

                return;

            }

            else {//得到三等分点

                double x11 = (x1 * 2  + x2)  / 3;

                double y11 = (y1 * 2  + y2)  / 3;

                double x22 = (x1 + x2 * 2) / 3;

                double y22 = (y1 + y2 * 2) / 3;

                double x33 = (x11 + x22) / 2 - (y11 - y22) * Math.sqrt(3) / 2;

                double y33 = (y11 + y22) / 2 - (x22 - x11) * Math.sqrt(3) / 2;

                c.drawLine(x1, y1, x2, y2, p);

                draw(c, p, x1, y1, (int) x11, (int) y11, depth - 1);

                draw(c, p, (int) x11, (int) y11, (int) x33, (int) y33, depth - 1);

                draw(c, p, (int) x22, (int) y22, x2, y2, depth - 1);

                draw(c, p, (int) x33, (int) y33, (int) x22, (int) y22, depth - 1);

            }

        }

    }

}

结果：