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SurfaceView的基本使用
Android截屏SurfaceView黑屏问题解决办法

目录

1. 创建SurfaceView
2. 使用SurfaceView

1.创建SurfaceView

public class FirstSurfaceView extends SurfaceView implements SurfaceHolder.Callback, Runnable {

    //SurfaceHolder
    private SurfaceHolder mHolder;
    //用于绘图的Canvas
    private Canvas mCanvas;
    //子线程标志位
    private boolean mIsDrawing;
    //画笔
    private Paint mPaint;
    //路径
    private Path mPath;


    public FirstSurfaceView(Context context) {
        super(context);
        initView();
    }

    public FirstSurfaceView(Context context, AttributeSet attrs) {
        super(context, attrs);
        initView();
    }

    public FirstSurfaceView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        initView();
    }

    private void initView() {
        mHolder = getHolder();

        //添加回调
        mHolder.addCallback(this);

        mPath = new Path();
        //初始化画笔
        mPaint = new Paint();
        mPaint.setStyle(Paint.Style.STROKE);
        mPaint.setStrokeWidth(6);
        mPaint.setAntiAlias(true);
        mPaint.setColor(Color.RED);

        setFocusable(true);
        setFocusableInTouchMode(true);
        this.setKeepScreenOn(true);
    }

    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        mIsDrawing = true;
        new Thread(this).start();
    }

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

    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        mIsDrawing = false;
    }

    @Override
    public void run() {
        long start = System.currentTimeMillis();
        while (mIsDrawing) {
            try {
                //锁定画布并返回画布对象
                mCanvas = mHolder.lockCanvas();
                //接下去就是在画布上进行一下draw
                drawIt(mCanvas);

            } catch (Exception e) {
            } finally {
                //当画布内容不为空时，才post，避免出现黑屏的情况。
                if (mCanvas != null)
                    mHolder.unlockCanvasAndPost(mCanvas);
            }


            long end = System.currentTimeMillis();
            if (end - start < 100) {
                try {
                    Thread.sleep(100 - end + start);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    private void drawIt(Canvas canvas) {
        canvas.drawColor(Color.WHITE);
        canvas.drawPath(mPath, mPaint);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        int x = (int) event.getX();
        int y = (int) event.getY();
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                mPath.moveTo(x, y);
                break;
            case MotionEvent.ACTION_MOVE:
                mPath.lineTo(x, y);
                break;
            case MotionEvent.ACTION_UP:
                break;
        }
        return true;
    }

    /**
     * 清屏
     *
     * @return true
     */
    public boolean reDraw() {
        mPath.reset();
        return true;
    }

    public Bitmap getBitmap() {
        Bitmap bitmap = Bitmap.createBitmap(getWidth(), getHeight(), Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(bitmap);
        drawIt(canvas);
        return bitmap;
    }
}

2. 使用SurfaceView

新建一个activity

布局：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <xxx.lulu.view.FirstSurfaceView
        android:id="@+id/view_surfaceview"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1" />

    <Button
        android:id="@+id/btn_clear"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@color/purple"
        android:text="clear"
        android:textColor="@color/white" />
</LinearLayout>

java文件：

public class SurfaceViewActivity extends BaseActivity {
    private static final int PERMISSION_EXTERNAL = 1;
    @BindView(R.id.view_surfaceview)
    FirstSurfaceView viewSurfaceview;
    @BindView(R.id.btn_clear)
    Button btnClear;
    @BindView(R.id.btn_save)
    Button btnSave;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_surfaceview, "surfaceview");
        ButterKnife.bind(this);

    }

    @OnClick({R.id.btn_clear, R.id.btn_save})
    public void onViewClicked(View view) {
        switch (view.getId()) {
            case R.id.btn_clear:
                viewSurfaceview.reDraw();
                break;
            case R.id.btn_save:
                if (ContextCompat.checkSelfPermission(SurfaceViewActivity.this, Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
                    //没有授权，则申请授权
                    //ActivityCompat.requestPermissions() 参数一：context 参数二：申请的权限名数组 参数三：请求码，要求唯一值
                    ActivityCompat.requestPermissions(SurfaceViewActivity.this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, PERMISSION_EXTERNAL);
                } else {
                    save();
                }
                break;
        }
    }

    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        switch (requestCode) {
            case PERMISSION_EXTERNAL:
                if (resultCode != Activity.RESULT_OK) return;
                save();
                break;
        }
    }

    private void save() {
/*        View dView = getWindow().getDecorView();
        dView.setDrawingCacheEnabled(true);
        dView.buildDrawingCache();*/
        Bitmap bitmap = viewSurfaceview.getBitmap();
        if (bitmap != null) {
            try {
                // 获取内置SD卡路径
                File dir = Environment.getExternalStorageDirectory();
                // 图片文件路径
                File file = new File(dir, "123.png");
                FileOutputStream os = new FileOutputStream(file);
                bitmap.compress(Bitmap.CompressFormat.PNG, 100, os);
                os.flush();
                os.close();
                Toast.makeText(this, "存储完成", Toast.LENGTH_SHORT).show();
            } catch (Exception e) {
             
            }
        }
    }

}