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POHow to draw line during runtime in a custom view?
 

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  1. POHow to draw line during runtime in a custom view?
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    <p>I am trying to draw a line using on touch method.</p> <p>I want that when user touches a particular point and then drags the finger, the line should be drawn.</p> <p>using <code>canvas.drawLine(_,_,_,_,_ );</code> is not drawing lines. as <code>onDraw</code> works only once.</p> <p>my main question is "how to draw a line during runtime without using <code>onDraw()</code>? "</p> <p>edit :</p> <pre><code>public class DrawView extends View { int radius=30; int initialX =0; int initialY=0; int finalX=0; int finalY=0; private Point currentPoint; private int index; static ArrayList&lt;Point&gt; pointListDrawView = new ArrayList&lt;Point&gt;(); public DrawView(Context context, ArrayList&lt;Point&gt; pointList) { super(context); // TODO Auto-generated constructor stub this.setBackgroundColor(Color.WHITE); //pointListDrawView = pointList; pointListDrawView.add(pt(600,200)); pointListDrawView.add(pt(500,200)); pointListDrawView.add(pt(400,200)); pointListDrawView.add(pt(400,300)); pointListDrawView.add(pt(400,400)); pointListDrawView.add(pt(500,400)); pointListDrawView.add(pt(400,400)); pointListDrawView.add(pt(400,500)); pointListDrawView.add(pt(400,600)); pointListDrawView.add(pt(500,600)); pointListDrawView.add(pt(600,600)); } private Point pt(int i, int j) { // TODO Auto-generated method stub Point P = new Point(i, j); return P ; } Paint paint= new Paint(); Canvas universalCanvas; @Override protected void onDraw(final Canvas canvas) { paint.setColor(Color.GREEN); paint.setStrokeWidth(10); for(int i=0; i&lt;pointListDrawView.size();i++){ canvas.drawCircle(pointListDrawView.get(i).x, pointListDrawView.get(i).y, 15, paint); } universalCanvas = canvas; // drawLines(canvas); } @Override public boolean onTouchEvent(MotionEvent event) { // TODO Auto-generated method stub int i =0; switch (event.getAction()){ case MotionEvent.ACTION_DOWN: if(((event.getX()&gt;pointListDrawView.get(i).x-radius) &amp;&amp; (event.getX()&lt;pointListDrawView.get(i).x+radius) &amp;&amp; (event.getY()&gt;pointListDrawView.get(i).y-radius) &amp;&amp; (event.getY()&lt;pointListDrawView.get(i).y+radius))) { Log.d("touch", "touched correct point"); initialX=pointListDrawView.get(i).x; initialY=pointListDrawView.get(i).y; } else{ Log.d("touch", "touch discarded"); return false; } break; case MotionEvent.ACTION_MOVE: universalCanvas.drawLine(initialX, initialY, event.getX(), event.getY(), paint); break; case MotionEvent.ACTION_UP: if(((event.getX()&gt;pointListDrawView.get(i+1).x-radius) &amp;&amp; (event.getX()&lt;pointListDrawView.get(i+1).x+radius) &amp;&amp; (event.getY()&gt;pointListDrawView.get(i+1).y-radius) &amp;&amp; (event.getY()&lt;pointListDrawView.get(i+1).y+radius))) { finalX=pointListDrawView.get(i+1).x; finalY=pointListDrawView.get(i+1).y; universalCanvas.drawLine(initialX,initialY, finalX,finalY, paint); Log.d("touch", "line drawn"); return true; } else { Log.d("touch", "correct point touched and discarded"); return false; } default: break; } invalidate(); return true; } } </code></pre>
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    1. USjeet.chanchawat
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      1. POHow to draw line during runtime in a custom view?
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    2. VO
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    1. COJust call `invalidate()` after updating the new points of line. If you call `invalidate()` then `onDraw()` will call again.
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      1. POHow to draw line during runtime in a custom view?
      1. USShaiful
    2. COplease chk source code
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      1. POHow to draw line during runtime in a custom view?
      1. USjeet.chanchawat
    3. COPost my answer. Check if it helps.
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      1. POHow to draw line during runtime in a custom view?
      1. USShaiful
 

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