SurfaceView啓發代碼

時間 2019-12-08

標籤 surfaceview 啓發代碼欄目 Microsoft Surface 简体版

原文原文鏈接

import java.util.Random;

import Android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceHolder.Callback;
import android.view.SurfaceView;
import android.view.Window;
import android.view.WindowManager;

public class BallActivity extends Activity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //設置全屏
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
                WindowManager.LayoutParams.FLAG_FULLSCREEN);

        setContentView(new BallSurfaceView(this));
    }

    class BallSurfaceView extends SurfaceView implements Callback,Runnable{
        private int screenW;        //屏幕寬度
        private int screenH;        //屏幕高度
        private Paint paint;        //定義畫筆
        private float cx = 50;      //圓點默認X座標
        private float cy = 50;      //圓點默認Y座標
        private int radius = 20;
        //定義顏色數組
        private int colorArray[] = {Color.BLACK,Color.BLACK,Color.GREEN,Color.YELLOW, Color.RED};
        private int paintColor = colorArray[0]; //定義畫筆默認顏色
        private Canvas canvas = null; //定義畫布
        private Thread th = null;     //定義線程
        private SurfaceHolder sfh = null;

        public BallSurfaceView(Context context){
            super(context);
            /*備註1：在此處獲取屏幕高、寬值爲0，覺得此時view還未被建立，
             * 在接口Callback的surfaceCreated方法中view才被建立
             */
            /*screenW = getWidth();
            screenH = getHeight();*/

            //初始化畫筆
            initPaint();
            sfh = getHolder();
            sfh.addCallback(this);
            th = new Thread(this);
        }

        @Override
        public void surfaceCreated(SurfaceHolder holder) {
            //獲取屏幕寬度
            screenW = getWidth();
            //獲取屏幕高度
            screenH = getHeight();
            //啓動繪圖線程
            th.start();
        }

        private void initPaint(){
            paint = new Paint();
            //設置消除鋸齒
            paint.setAntiAlias(true);
            //設置畫筆顏色
            paint.setColor(paintColor);
        }

        @Override
        public void run() {
            while(true){
                try{
                    myDraw();
                    Thread.sleep(100);
                }catch(InterruptedException e){
                    e.printStackTrace();
                }
            }
        }

        /*備註2：切記，在自定SurfaceView中定義的myDraw方法，自定義View（繼承自View的子類）中的onDraw方法
         * 徹底是兩碼事：
         * 1）自定義View（繼承自View的子類）中的onDraw方法是重寫父類的onDraw方法，在調用postInvalidate後會自動回調該onDraw()方法。
         * 2）此處的myDraw方法須要手動調用，因此此處故意將方法命名爲myDraw，突出爲該方法是本身寫的，非重寫父類的方法。
         *
         */
        //重寫onDraw方法實現繪圖操做
        protected void myDraw() {
            //獲取canvas實例
            canvas = sfh.lockCanvas();
            //將屏幕設置爲白色
            canvas.drawColor(Color.WHITE);
            //修正圓點座標
            revise();
            //隨機設置畫筆顏色
            setPaintRandomColor();
            //繪製小圓做爲小球
            canvas.drawCircle(cx, cy, radius, paint);
            //將畫好的畫布提交
            sfh.unlockCanvasAndPost(canvas);
        }

        //爲畫筆設置隨機顏色
        private void setPaintRandomColor(){
            Random rand = new Random();
            int randomIndex = rand.nextInt(colorArray.length);
            paint.setColor(colorArray[randomIndex]);
        }

        //修正圓點座標
        private void revise(){
            if(cx <= radius){
                cx = radius;
            }else if(cx >= (screenW-radius)){
                cx = screenW-radius;
            }
            if(cy <= radius){
                cy = radius;
            }else if(cy >= (screenH-radius)){
                cy = screenH-radius;
            }
        }

        @Override
        public boolean onTouchEvent(MotionEvent event) {
            switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                // 按下
                cx = (int) event.getX();
                cy = (int) event.getY();
                break;
            case MotionEvent.ACTION_MOVE:
                // 移動
                cx = (int) event.getX();
                cy = (int) event.getY();
                break;
            case MotionEvent.ACTION_UP:
                // 擡起
                cx = (int) event.getX();
                cy = (int) event.getY();
                break;
            }

            /*
             * 備註1：次處必定要將return super.onTouchEvent(event)修改成return true，緣由是：
             * 1）父類的onTouchEvent(event)方法可能沒有作任何處理，可是返回了false。
             * 2)一旦返回false，在該方法中不再會收到MotionEvent.ACTION_MOVE及MotionEvent.ACTION_UP事件。
             */
            //return super.onTouchEvent(event);
            return true;
        }

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

        }

        @Override
        public void surfaceDestroyed(SurfaceHolder holder) {

        }

    }
} java