android：实现共享首选项

Question

我正在创建一个应用程序，我必须在画布中绘制图像，然后以共享首选项保存该图像，然后在下一个屏幕中显示。任何帮助将不胜感激

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(new DrawingPanel(this));
    mPaint = new Paint();
    mPaint.setDither(true);


//    mPaint.setColor(0xFF FF FF FF);
    System.out.println("hello1");
    mPaint.setColor(Color.BLACK);
    System.out.println("hello2");

    mPaint.setStyle(Paint.Style.STROKE);
    mPaint.setStrokeJoin(Paint.Join.ROUND);
    mPaint.setStrokeCap(Paint.Cap.ROUND);
    mPaint.setStrokeWidth(3);


}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.game_menu, menu);
    return true;
}
@SuppressWarnings("null")
@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle item selection
    switch (item.getItemId()) {
        case R.id.create_new: // **ON THIS CLICK I WANT TO SAVE IMAGE**

            System.out.println("hii");
        //  name = cur.getString(cur.getColumnIndex(MediaStore.Images.Media.DATA));
            System.out.println("hii1");
            date1 = currentTimeString;
            System.out.println("hii2");
        //  cur = context.getContentResolver().query(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, null, null, null, null);
            System.out.println("hii3");
        //  File f1=new File("/sdcard/" + date1 + ".png");
            System.out.println("hii4");

          //  FileSave fs = null;
        //  fs.Save(f1);
            // Add a new record without the bitmap, but with the values just set.
            // insert() returns the URI of the new record.
        //  Uri uri = getContentResolver().insert(Media.EXTERNAL_CONTENT_URI, values);

            // Now get a handle to the file for that record, and save the data into it.
            // Here, sourceBitmap is a Bitmap object representing the file to save to the database.
            try {
                //   FileOutputStream out = new FileOutputStream(path);
                   bmp.compress(Bitmap.CompressFormat.PNG, 90, out);
            } catch (Exception e) {
                   e.printStackTrace();
            }




            return true;

        case R.id.erase:
        System.out.println("new2");
              mPaint.setColor(-1);
             mPaint.setAlpha(0);
             mPaint.setAntiAlias(true);
             mPaint.setStyle(Paint.Style.STROKE);
             mPaint.setStrokeCap(Paint.Cap.ROUND);
             mPaint.setStrokeWidth(1);


                Intent intent1 = new Intent(getApplicationContext(), CanvasDrawingActivity.class);
                intent1.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
                startActivity(intent1);
                finish();


            return true;


        default:
            return super.onOptionsItemSelected(item);
    }
}



class DrawingPanel extends SurfaceView implements SurfaceHolder.Callback {
    private DrawingThread _thread;
    private Path path;

    public DrawingPanel(Context context) {
        super(context);
        getHolder().addCallback(this);
        _thread = new DrawingThread(getHolder(), this);
    }




    @Override
    protected void onAttachedToWindow() {
        // TODO Auto-generated method stub
        super.onAttachedToWindow();
        System.out.println("hello");
         Save=(Button)findViewById(R.id.Save);
         System.out.println("hello2");
    }




    public boolean onTouchEvent(MotionEvent event) {
        synchronized (_thread.getSurfaceHolder()) {
        if(event.getAction() == MotionEvent.ACTION_DOWN){
        path = new Path();
        path.moveTo(event.getX(), event.getY());
        path.lineTo(event.getX(), event.getY());
        }else if(event.getAction() == MotionEvent.ACTION_MOVE){
        path.lineTo(event.getX(), event.getY());
        _graphics.add(path);
        path = new Path();
        path.moveTo(event.getX(), event.getY());
        }else if(event.getAction() == MotionEvent.ACTION_UP){
        path.lineTo(event.getX(), event.getY());
        _graphics.add(path);
        }

        return true;
        }
        }

    @Override
    public void onDraw(Canvas canvas) {
        canvas.drawColor(Color.WHITE);
        for (Path path : _graphics) {
            //canvas.drawPoint(graphic.x, graphic.y, mPaint);
            canvas.drawPath(path, mPaint);
            canvas.drawPath(path, mPaint);
        }
    }

    public void surfaceChanged(SurfaceHolder holder, int format, int width,
                               int height) {
        // TODO Auto-generated method stub

    }

    public void surfaceCreated(SurfaceHolder holder) {
        // TODO Auto-generated method stub
        _thread.setRunning(true);
        _thread.start();
    }

    public void surfaceDestroyed(SurfaceHolder holder) {
        // TODO Auto-generated method stub
        boolean retry = true;
        _thread.setRunning(false);
        while (retry) {
            try {
                _thread.join();
                retry = false;
            } catch (InterruptedException e) {
                // we will try it again and again...
            }
        }
    }
}

class DrawingThread extends Thread {
    private SurfaceHolder _surfaceHolder;
    private DrawingPanel _panel;
    private boolean _run = false;

    public DrawingThread(SurfaceHolder surfaceHolder, DrawingPanel panel) {
        _surfaceHolder = surfaceHolder;
        _panel = panel;
    }

    public void setRunning(boolean run) {
        _run = run;
    }

    public SurfaceHolder getSurfaceHolder() {
        return _surfaceHolder;
    }

    @Override
    public void run() {
        Canvas c;
        while (_run) {
            c = null;
            try {
                c = _surfaceHolder.lockCanvas(null);
                synchronized (_surfaceHolder) {
                    _panel.onDraw(c);
                }
            } finally {
                // do this in a finally so that if an exception is thrown
                // during the above, we don't leave the Surface in an
                // inconsistent state
                if (c != null) {
                    _surfaceHolder.unlockCanvasAndPost(c);
                }
            }
        }
    }
}

}

我希望将此图片保存在共享首选项中，并在下一个屏幕中使用缩略图

打开

Answer 1

如果您在SurfaceView上启用了绘图缓存，则可以使用View的getDrawingCache（）方法获取最后一个缓存的Bitmap。

Bitmap对象实现了Parcelable;这意味着您可以直接将它放入使用Intent.putExtra（键，位图）启动下一个Activity的Intent。

Answer 2

您可以从位图中获取字节数组，并将其转换为字符串以保存在共享首选项中。

但我认为在sqlite数据库中保存更好。

Answer 3

可以使用图像的base64字符串表示，然后以共享首选项保存字符串，也可以将图像路径保存为共享首选项。

Answer 4

你是否只是在另一个活动中使用sharedPreference，然后你滥用一个功能，尝试传递位图，或者使用静态变量，虽然我不建议使用静态变量。