SurfaceView实现写字板功能

最新推荐文章于 2021-05-31 03:27:00 发布

L .Y

最新推荐文章于 2021-05-31 03:27:00 发布

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CC 4.0 BY-SA版权

文章标签： android

本文链接：https://blog.youkuaiyun.com/alaleidd/article/details/96862615

本示例介绍了一个名为DrawingActivity的应用活动，该活动通过SurfaceView实现触摸绘画功能，并支持弹幕显示。代码展示了如何处理触摸事件来绘制路径，以及如何通过按钮添加文字到弹幕列表。

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public class DrawingActivity extends AppCompatActivity implements SurfaceHolder.Callback{

    private SurfaceView surfaceView;
    private SurfaceHolder surfaceHolder;
    private Button button;
    private EditText editText;
    private List<DanMu> list = new ArrayList<>();
    int x = 0;
    int y = 500;
    Path path = new Path();
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_drawing);
        editText = findViewById(R.id.message);
        surfaceView = findViewById(R.id.surface);
        button = findViewById(R.id.send);
        surfaceHolder = surfaceView.getHolder();
        surfaceHolder.addCallback(this);



        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String string = editText.getText().toString();
                list.add(new DanMu(string,0,150));
                editText.setText("");
            }
        });
        //触摸监听
        surfaceView.setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View v, MotionEvent event) {
            	//区分触摸类型
                switch (event.getAction()){
                   //按下
                    case MotionEvent.ACTION_DOWN:
                    //把路径移到触摸的地方
                        path.moveTo(event.getX(),event.getY());
                        break;
                    //拖动
                    case MotionEvent.ACTION_MOVE:
                        path.lineTo(event.getX(),event.getY());
                        break;
                }
                return true;
            }
        });
    }

    @Override
    public void surfaceCreated(SurfaceHolder holder) {
    //开启一个线程
        new MyThread().start();
    }

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

    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {

    }

    private class MyThread extends Thread{
        @Override
        public void run() {
        //画笔对象 设置画笔属性
            Paint paint = new Paint();
            paint.setColor(Color.RED);
            paint.setStrokeWidth(5);
            paint.setTextSize(100);
            paint.setStyle(Paint.Style.STROKE);
		//无限循环
            while (true){
            //创建画板
                Canvas canvas = surfaceHolder.lockCanvas();
                //当画板为空时 停止
                if(canvas == null){
                    break;
                }
          	
                //canvas.drawColor(Color.TRANSPARENT, PorterDuff.Mode.CLEAR);
                //弹幕
//                if(list.size() > 0){
////                    canvas.drawText(list.get(0).getText(),x+=10,y,paint);
////                }
			 //画路径
                canvas.drawPath(path,paint);
                //记得一点要关闭surfaceHolder
                surfaceHolder.unlockCanvasAndPost(canvas);
            }
        }
    }