撤消和重做畫布

Question

我試圖在我的應用程序中實現撤消和重做。我正在閱讀其他問題和論壇，但代碼不適合我。我只在這裏發佈相關的代碼，以便於閱讀，因爲我繪製了不同的形狀。對於重做和撤消，我在另一個活動中有兩個按鈕，我在每個按鈕的onclicklistener中調用函數redo或undo。

private void setupDrawing(){ 
    drawPath=new Path(); 

    //Set up paint 

    paths.add(drawPaint); 
} 

public boolean onTouchEvent(MotionEvent event){ 
    tX=event.getX(); 
    tY=event.getY(); 
    switch(event.getAction()){ 
     case MotionEvent.ACTION_DOWN: 

      //Action move down 

     break; 
     case MotionEvent.ACTION_MOVE: 

      //Action move 

     break; 
     case MotionEvent.ACTION_UP: 
      drawCanvas.drawCircle(x, y, radius, drawPaint); //Example of drawing object 
      drawPath = new Path(); 
      paths.add(drawPath); 
     break; 
     default: 
      return false; 
    } 
    invalidate(); 
    return true; 
}  

public void undo(){ 
    if(paths.size()>0){ 
     undonePaths.add(paths.remove(paths.size()-1)); 
     invalidate(); 
    } 
    if(undo==true){ 
     undo=false; 
    }else{ 
     undo=true; 
    } 
} 

public void redo(){ 
    if(undonePaths.size()>0){ 
     paths.add(undonePaths.remove(undonePaths.size()-1)); 
     invalidate(); 
    } 
    if(redo==true){ 
     redo=false; 
    }else{ 
     redo=true; 
    } 
} 

Answer 1

我發現我的代碼有問題。我在畫布上繪畫，我需要將這些形狀添加到路徑中。如果有人需要，我在這裏留下代碼。

protected void onDraw(Canvas canvas){ 
    for(Path p : paths){ 
     canvas.drawPath(p, drawPaint); 
    } 
    canvas.drawPath(drawPath, drawPaint); 
} 

//Here all the code for the Motion Event. I will show only the Action Up. 

case MotionEvent.ACTION_UP: 
     drawPath.addCircle(x, y, radius, Path.Direction.CCW); //Example of drawing object 
     paths.add(drawPath); 
     drawPath = new Path(); 
    break;