pearmak pearmak - 2 months ago 15
Android Question

android drawing apps line once change colour all the previously lines drawn are painted with new colour

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);
}


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

Answer

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");        
} 

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

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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