如何在Android的绘画应用中实现撤消功能？

我想在我的应用程序中做撤消功能..为此我搜索了我的网发现，采取x，y点，我已经做了下面的代码我arraylist我无法撤消图纸？如何在Android的绘画应用中实现撤消功能？

public Drawview(Context context, float x, float y, int r) { 
      super(context); 


      mBitmap = Bitmap.createBitmap(800, 1200, Bitmap.Config.ARGB_8888); 
      // mainbitmap.add(mBitmap); 
      //System.out.println("**mBitmapPaint***"+mBitmapPaint); 
      mCanvas = new Canvas(mBitmap); 
      mPath = new Path(); 
      mBitmapPaint = new Paint(Paint.DITHER_FLAG); 



     } 

     @Override 
     protected void onSizeChanged(int w, int h, int oldw, int oldh) { 
      super.onSizeChanged(w, h, oldw, oldh); 
     } 

     @Override 
     protected void onDraw(Canvas canvas) { 

      System.out.println("***Drawinglines****"+Drawinglines); 

       canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint); 
       canvas.drawPath(mPath, mPaint); 



     } 


     private float mX, mY; 
     private static final float TOUCH_TOLERANCE = 4; 

     private void touch_start(float x, float y) { 
      mPath.reset(); 
      mPath.moveTo(x, y); 
      mX = x; 
      mY = y; 
     } 

     private void touch_move(float x, float y) { 
      float dx = Math.abs(x - mX); 
      float dy = Math.abs(y - mY); 
      if (dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE) { 
       mPath.quadTo(mX, mY, (x + mX)/2, (y + mY)/2); 
       mX = x; 
       mY = y; 
      } 
     } 

     private void touch_up() { 


      mPath.lineTo(mX, mY); 
      mCanvas.drawPath(mPath, mPaint); 
     /// path. 
      //graphics.add(mPath); 
      mPath.reset(); 
     } 

     // events when touching the screen 
     public boolean onTouchEvent(MotionEvent event) { 

      event.getAction(); 
      int eventaction = event.getAction(); 

      int X = (int)event.getX(); 
      int Y = (int)event.getY(); 

      switch (eventaction) { 

      case MotionEvent.ACTION_DOWN: 

      { 
       touch_start(X, Y); 
       } 
       invalidate(); 
       break; 


      case MotionEvent.ACTION_MOVE: 

       System.out.println("***ACTION_MOVE**************"+X+"************"+Y); 
       if((Drawinglines.equals("Pen"))||(Drawinglines.equals("Erase"))) 
       { 
        touch_move(X, Y); 
        temp_point.add(new Point(X,Y)); 

       } 
       invalidate(); 
       break; 

      case MotionEvent.ACTION_UP: 

       main_Points.add(temp_point); 
       temp_point = null; 

       touch_up(); 

       invalidate(); 
       break; 
      } 

      return true; 

     } 




     public void undopath() 
     { 
       main_Points.remove(main_Points.size()-1); 
      invalidate(); 
     } 

    } 
    @Override 
    public void onClick(View v) { 


     if(v == Undo) 
     {  
      Drawview abc=new Drawview(); 
      abc.undopath(); 
     }

但是撤消撤消功能不起作用。

来源

2012-03-26 user1287756

而究竟是什么你有问题吗？ – 2012-03-26 13:01:57

我的问题是根据代码我已经使X的Arraylist，y点后，从arraylist元素删除后，我怎么得到这一行main_Points.remove（main_Points.size（） - 1）;如何得到先前的图纸线 – user1287756 2012-03-26 13:03:25

是啊，但是到目前为止您尝试过的撤销/重做逻辑在哪里？你说：“撤消不工作”，但我没有看到你说的撤消代码不起作用。 – 2012-03-26 13:04:29

我没有尝试，但我认为使用两个画布和位图是有帮助的，在绘制当前状态时，一个仍然是原来的状态，只需要恢复前一个状态。但它只能在一步恢复。

来源

2013-09-21 14:14:14 zjywill

嗨，这是一个比答案更多的评论....你能用一些代码来证明你是正确的吗？ – Ben 2013-09-21 14:31:40

这里的一些代码：创建：

private Canvas mCanvas; 
private Bitmap mBitmap; 

private Canvas mRestoreCanvas; 
private Bitmap mRestoreBitmap;

初始化：

@Override 
protected void onSizeChanged(int w, int h, int oldw, int oldh) { 
    mPictureWidth = w; 
    mPictureHeight = h; 

    Loge.i("mPictureWidth = " + mPictureWidth + " mPictureHeight = " 
      + mPictureHeight); 
    if (mCanvas == null && mBitmap == null && mPictureWidth > 0 
      && mPictureHeight > 0) { 
     mBitmap = Bitmap.createBitmap(mPictureWidth, mPictureHeight, 
       Bitmap.Config.ARGB_8888); 
     mCanvas = new Canvas(mBitmap); 
     mCanvas.save(); 

     mRestoreBitmap = Bitmap.createBitmap(mPictureWidth, mPictureHeight, 
       Bitmap.Config.ARGB_8888); 
     mRestoreCanvas = new Canvas(mRestoreBitmap); 
     mRestoreCanvas.save(); 
    } 
    super.onSizeChanged(w, h, oldw, oldh); 
}

的onDraw：

@Override 
protected void onDraw(Canvas canvas) { 
    if (mPattern == DRAW_LINE) { 
     mCanvas.restore(); 
     mCanvas.drawPath(path, paint); 
     mCanvas.save(); 
    } 
    mCanvas.save(); 
    if (mBitmap != null) 
     canvas.drawBitmap(mBitmap, 0, 0, null); 
}

的onTouchEvent：

@Override 
public boolean onTouchEvent(MotionEvent event) { 

    if(event.getAction() == MotionEvent.ACTION_DOWN){ 
     mRestoreCanvas.drawBitmap(mBitmap, 0, 0, bitmapPaint); 
    } 

    if (mPattern == DRAW_LINE) { 
     return drawLines(event); 
    } else if (mPattern == DRAW_PATTERN) { 
     return drawPattern(event); 
    } 
    return false; 
}

撤消：

public void dust() { 
    path.reset(); 
    mBitmap.recycle(); 
    mBitmap = Bitmap.createBitmap(mPictureWidth, mPictureHeight, 
      Bitmap.Config.ARGB_8888); 
    mCanvas.setBitmap(mBitmap); 

    mCanvas.drawBitmap(mRestoreBitmap, 0, 0, bitmapPaint); 

    invalidate(); 
}

测试OK;

来源

2013-09-23 02:44:21 zjywill

嘿，我已经使用了一个把戏，以消除黑line.In我的删除按钮，我已经将颜色设置为白色，而是采用XferMode ..

if(erase){ 
    paintColor = Color.parseColor(newColor); 
    drawPaint.setColor(paintColor); 
    }

来源

2013-09-23 21:12:37 Atihska

private Slate mSlate; 
private TiledBitmapCanvas mTiledCanvas; 

public void clickUndo(View unused) { 

     mSlate.undo(); 
    } 


public void undo() { 
     if (mTiledCanvas == null) { 
      Log.v(TAG, "undo before mTiledCanvas inited"); 
     } 
     mTiledCanvas.step(-1); 

     invalidate(); 
    }

来源

2014-08-04 05:22:22

如何在Android的绘画应用中实现撤消功能？

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