android - 方向改变时如何在 Canvas 中重绘绘图

Question

在 table 或设备旋转之前，我的代码工作正常。旋转时绘图被清除，我了解到它会发生，因为当设备旋转时， Activity 会重新启动。 我的问题是如何重绘并将数据保存到 onSaveInstanceState。 许多人说我必须使用 onSaveInstanceState 来保存绘图，但是当我必须保存的数据类型是 Path 时，我不知道该怎么做。

这是我的代码 fragment

public class MyDrawView extends View implements OnTouchListener {
    MyDrawView drawView;
    float prevX = 0;
    float prevY = 0;

    private Bitmap mBitmap;
    private Canvas mCanvas;
    private Path mPath;
    private Paint mBitmapPaint;
    private Paint mPaint;
    private int w,h;
    private ArrayList<Path> paths = new ArrayList<Path>();
    private ArrayList<Paint> bitPaints = new ArrayList<Paint>();
    private ArrayList<Paint> pathPaints = new ArrayList<Paint>();
    Paint tempPaint;
    private String filename="";

    public MyDrawView(Context c,String filename) {
        super(c);
        mPath = new Path();
        mBitmapPaint = new Paint(Paint.DITHER_FLAG);


        this.filename=filename;
        setFocusable(true);
        setFocusableInTouchMode(true);
        this.setOnTouchListener(this);
        mPaint = new Paint();
        mPaint.setAntiAlias(true);
        mPaint.setDither(true);
        mPaint.setColor(Color.RED);
        mPaint.setStyle(Paint.Style.STROKE);
        mPaint.setStrokeJoin(Paint.Join.ROUND);
        mPaint.setStrokeCap(Paint.Cap.ROUND);
        mPaint.setStrokeWidth(6);
        tempPaint=new Paint(mPaint);
        mCanvas = new Canvas();
        mPath = new Path();
        if (rotated){
            setDefaultDrawing();
        }

    }
    public void setDefaultDrawing()
    {

    }
    public Bitmap getBitmap(){
        return this.mBitmap;
    }
    public void setStrokeWidth(float width){
        mPaint.setStrokeWidth(width);
    }
    public void setColor(int color){
        mPaint.setColor(color);
    }
    public String getFileName(){
        return this.filename;
    }
    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
        this.w=w;
        this.h=h;
        mBitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
        mCanvas = new Canvas(mBitmap);
        Path tempPath=new Path(mPath);
        paths.add(tempPath);
        Paint tempPaint=new Paint(mPaint);
        pathPaints.add(tempPaint);
        Paint tempBitPaint=new Paint(mBitmapPaint);
        bitPaints.add(tempBitPaint);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint);

        canvas.drawPath(mPath, mPaint);
    }

Answer 1

我想通了，因为 Path 是一个自定义对象，我创建了一个类对象来保存 Path，这样，我就可以将类对象保存在我的 onSaveInstanceState 中，并使用相同的类对象检索它。