删除最后一个颜色的位图撤消

Question

请我需要有关撤消方法的帮助，我试图像下面的代码一样实现它，但它不是删除最后的颜色，请帮助我解决它。

等待您的善良回应。

预先感谢。

---

MainActivity

 public class MainActivity extends AppCompatActivity implements 
 View.OnTouchListener {
Button red, blue, yellow, undo;
Paint paint;
private RelativeLayout drawingLayout;
private MyView myView;
private ArrayList<Path> paths = new ArrayList<Path>();
private ArrayList<Path> undonePaths = new ArrayList<Path>();
/**
 * Called when the activity is first created.
 */
  /*
  *
  * private ImageView imageView; private Canvas cv; private Bitmap mask,
  * original, colored; private int r,g,b; private int sG, sR, sB;
  */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    myView = new MyView(this);
    drawingLayout = (RelativeLayout) findViewById(R.id.relative_layout);
    drawingLayout.addView(myView);
    red = (Button) findViewById(R.id.btn_red);
    blue = (Button) findViewById(R.id.btn_blue);
    yellow = (Button) findViewById(R.id.btn_yellow);
    undo = (Button) findViewById(R.id.undo);
    red.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            paint.setColor(Color.RED);
        }
    });
    yellow.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            paint.setColor(Color.YELLOW);
        }
    });
    blue.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            paint.setColor(Color.BLUE);
        }
    });
    undo.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            myView.onClickUndo();
        }
    });
}
@Override
public boolean onTouch(View v, MotionEvent event) {
    // TODO Auto-generated method stub
    return false;
}

// flood fill
public class MyView extends View {
    final Point p1 = new Point();
    Bitmap mBitmap;
    ProgressDialog pd;
    Canvas canvas;
    private Path path;
    // Bitmap mutableBitmap ;
    public MyView(Context context) {
        super(context);
        paint = new Paint();
        paint.setAntiAlias(true);
        pd = new ProgressDialog(context);
        paint.setStyle(Paint.Style.STROKE);
        paint.setStrokeJoin(Paint.Join.ROUND);
        paint.setStrokeWidth(5f);
        mBitmap = BitmapFactory.decodeResource(getResources(),
                R.drawable.gp1_1).copy(Bitmap.Config.ARGB_8888, true);
        this.path = new Path();

    }
    public void onClickUndo() {
        if (paths.size() > 0) {
            undonePaths.add(paths.remove(paths.size() - 1));
            invalidate();
        } else {
            Toast.makeText(getContext(), getString(R.string.nomore), Toast.LENGTH_SHORT).show();
        }
    }
    @Override
    protected void onDraw(Canvas canvas) {
        this.canvas = canvas;
        paint.setColor(Color.GREEN);
      //   int width = drawingLayout.getWidth();
     // int height = drawingLayout.getHeight();
    // float centerX = (width - mBitmap.getWidth()) * 0.5f;
    //float centerY = (height - mBitmap.getHeight()) * 0.5f;
        canvas.drawBitmap(mBitmap, 0, 0, paint);
        ///////////////////////////////
        for (Path p : paths) {
            canvas.drawPath(p, paint);
            //////////////////////////
        }
    }
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        float x = event.getX();
        float y = event.getY();
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                p1.x = (int) x;
                p1.y = (int) y;
                final int sourceColor = mBitmap.getPixel((int) x, (int) y);
                final int targetColor = paint.getColor();
                new TheTask(mBitmap, p1, sourceColor, targetColor).execute();
                paths.add(path);
                invalidate();
        }
        return true;
    }
    public void clear() {
        path.reset();
        invalidate();
    }
    public int getCurrentPaintColor() {
        return paint.getColor();
    }
    class TheTask extends AsyncTask<Void, Integer, Void> {
        Bitmap bmp;
        Point pt;
        int replacementColor, targetColor;
        public TheTask(Bitmap bm, Point p, int sc, int tc) {
            this.bmp = bm;
            this.pt = p;
            this.replacementColor = tc;
            this.targetColor = sc;
            pd.setMessage(getString(R.string.wait));
            pd.show();
        }
        @Override
        protected void onPreExecute() {
            pd.show();
        }
        @Override
        protected void onProgressUpdate(Integer... values) {
        }
        @Override
        protected Void doInBackground(Void... params) {
            FloodFill f = new FloodFill();
            f.floodFill(bmp, pt, targetColor, replacementColor);
            return null;
        }
        @Override
        protected void onPostExecute(Void result) {
            pd.dismiss();
            invalidate();
        }
    }
}
public class FloodFill {
    public void floodFill(Bitmap image, Point node, int targetColor,
                          int replacementColor) {
        int width = image.getWidth();
        int height = image.getHeight();
        int target = targetColor;
        int replacement = replacementColor;
        if (target != replacement) {
            Queue<Point> queue = new LinkedList<Point>();
            do {
                int x = node.x;
                int y = node.y;
                while (x > 0 && image.getPixel(x - 1, y) == target) {
                    x--;
                }
                boolean spanUp = false;
                boolean spanDown = false;
                while (x < width && image.getPixel(x, y) == target) {
                    image.setPixel(x, y, replacement);
                    if (!spanUp && y > 0
                            && image.getPixel(x, y - 1) == target) {
                        queue.add(new Point(x, y - 1));
                        spanUp = true;
                    } else if (spanUp && y > 0
                            && image.getPixel(x, y - 1) != target) {
                        spanUp = false;
                    }
                    if (!spanDown && y < height - 1
                            && image.getPixel(x, y + 1) == target) {
                        queue.add(new Point(x, y + 1));
                        spanDown = true;
                    } else if (spanDown && y < height - 1
                            && image.getPixel(x, y + 1) != target) {
                        spanDown = false;
                    }
                    x++;
                }
            } while ((node = queue.poll()) != null);
        }
    }
}
  }

Answer 1

我想您的意思是撤消方法不起作用。可能的原因是没有删除画布上的先前图纸。在绘制onDraw()方法之前，请尝试清除画布。

 @Override protected void onDraw(Canvas canvas) { 
 this.canvas = canvas;   
canvas. drawColor(0,PorterDuff.Mode.CLEAR); //This clears the canvas.
 paint.setColor(Color.GREEN);
 //rest of the code
 }

Answer 2

似乎不可能返回以前的颜色，每个点都需要一个数组才能将用过的颜色存储在每个点。