Android的应用程序绘制线条，一旦变色所有的previously绘制的线条涂上新颜色 [英] android drawing apps line once change colour all the previously lines drawn are painted with new colour

问题描述

我想提出一个绘图应用程序，以下code工作正常，但那个时候我想改变paintline的颜色，绘制将变更为新颜色全部previous行：

I am making a drawing app and the following code works fine, except that when i would like to change the colour of the paintline, all the previous line drawn will be changed to the new color:

    private Bitmap bitmap; // drawing area for display or saving
    private Canvas bitmapCanvas; // used to draw on bitmap
    private Paint paintLine; // used to draw lines onto bitmap   
    private Path mPath; 
    private ArrayList<Path> paths = new ArrayList<Path>();
    private ArrayList<Path> undonePaths = new ArrayList<Path>();
    private float mX, mY;
    private static final float TOUCH_TOLERANCE = 4;    

    // DoodleView constructor initializes the DoodleView

    public DoodleView(Context context, AttributeSet attrs) 
    {
       super(context, attrs); // pass context to View's constructor
       this.context_new=context;
       setFocusable(true);
       setFocusableInTouchMode(true);      

       // set the initial display settings for the painted line
       paintLine = new Paint();
       paintLine.setAntiAlias(true); // smooth edges of drawn line
       paintLine.setDither(true);
       paintLine.setColor(Color.BLACK); // default color is black
       paintLine.setStyle(Paint.Style.STROKE); // solid line
       paintLine.setStrokeJoin(Paint.Join.ROUND);
       paintLine.setStrokeWidth(5); // set the default line width
       paintLine.setStrokeCap(Paint.Cap.ROUND); // rounded line ends

       bitmapCanvas = new Canvas();
       mPath = new Path();            
     } // end DoodleView constructor

     // Method onSizeChanged creates BitMap and Canvas after app displays

     @Override
     public void onSizeChanged(int w, int h, int oldW, int oldH)
     {
        super.onSizeChanged(w, h, oldW, oldH);
        DoodlzViewWidth = w;       
        DoodlzViewHeight = h;           
     } 

     @Override

     protected void onDraw(Canvas canvas) 
     {         
       for (Path p : paths){canvas.drawPath(p, paintLine);}  
       canvas.drawPath(mPath, paintLine);
       Log.i("OnDRAWING", "REACH ON DRAW");        
    } 

  // START TOUCH: handle touch event
     @Override

     public boolean onTouchEvent(MotionEvent event) 
     {            
          float x = event.getX();
          float y = event.getY();

          switch (event.getAction())
          {
              case MotionEvent.ACTION_DOWN:
                  touch_start(x, y);
                  invalidate();
                  break;
              case MotionEvent.ACTION_MOVE:
                 touch_move(x, y);
                  invalidate();
                  break;
              case MotionEvent.ACTION_UP:
                  touch_up();
                  invalidate();
                  break;
          }
          return true;
    }

     private void touch_start(float x, float y) 
     {
       undonePaths.clear();
       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);      
        bitmapCanvas.drawPath(mPath, paintLine);// commit the path to our offscreen  
        paths.add(mPath);
        mPath = new Path(); 
    }

    public void onClickUndo() 
    { 
       if (paths.size()>0) 
        { 
           undonePaths.add(paths.remove(paths.size()-1));
           invalidate();
        }      
       else Toast.makeText(getContext(), "nothing more to undo", Toast.LENGTH_SHORT).show();  
    }

setDrawingColor：

   public void setDrawingColor(int color) // set the painted line's color 
   {       
       paintLine.setColor(color);
   } 

如何才能上述code进行修改，使得previous线固定在其原来的颜色？谢谢！！

How could the above code be modified such that the previous line are fixed in their original colours??? Thanks!!

推荐答案

您需要跟踪路径的颜色和的onDraw 恢复是使用油漆的颜色路径开始。

You need to keep track of path color and in the onDraw restore the color that was use to paint the path initially.

 protected void onDraw(Canvas canvas) 
 {          
   for (Path p : paths){canvas.drawPath(p, paintLine);}  
   paintLine.setColor(restoreColorForPath(p));
   canvas.drawPath(mPath, paintLine);
   Log.i("OnDRAWING", "REACH ON DRAW");        
} 

您只需要执行 restoreColorForPath 和它的康特一部分 storeColorForPath（路径，颜色）（可能用一个简单的地图）

You just have to implement restoreColorForPath and it's conter part storeColorForPath(path,color) (probably with a simple Map)

这类似的问题可以帮助你：<一href=\"http://stackoverflow.com/questions/13705973/how-to-draw-the-multiple-lines-with-different-color-and-undo-redo-the-paths-in-a/13740234#13740234\">How绘制多行用不同的颜色和撤消，重做android系统的路径？

This similar question can help you : How to draw the multiple lines with different color and undo,redo the paths in android?

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