I'm really stuck on how to go about programming this. How to draw a circle in Android Canvas with a radius and points around the edge?
What is best approach to design this?
Asked
Active
Viewed 3,577 times
9
Sam Spencer
- 8,492
- 12
- 76
- 133
user991429
- 322
- 1
- 5
- 15
-
possible duplicate of http://stackoverflow.com/questions/18073084/draw-circle-and-points-on-circle-edge – Raghunandan Aug 06 '13 at 11:40
-
1possible duplicate of [Draw a circle with a radius and points around the edge](http://stackoverflow.com/questions/2508704/draw-a-circle-with-a-radius-and-points-around-the-edge) – g00dy Aug 06 '13 at 11:45
-
Please some one help me for same. Help will be appreciated ... – user991429 Aug 06 '13 at 19:52
-
I want to use this circular image but main thing want to place multiple pins on circle edge. – user991429 Aug 07 '13 at 08:21
2 Answers
7
the point(cX,cY) you want draw
the center point(centerX,centerY) of the circle
the radius of the circle
the angle is the point(cX,cY) on the circle.
also see the image:
https://i.stack.imgur.com/2Dx2r.jpg
the code:
cX = centerX + radius*Math.cos(angle*Math.PI/180);
cY = centerY + radius*Math.sin(angle*Math.PI/180);
canvas.drawCircle(cX, cY, radius, paint);
Sea
- 71
- 1
- 3
-
While this code block may answer the question, it would be best if you could provide a little explanation for why it does so. – David Mar 20 '15 at 09:10
-
3
Well; drawing a circle is a very straightforward, inside your onDraw() method add this line
canvas.drawCircle(cX, cY, radius, paint);
Simply provide the center point's x and y values and radius and paint object as well.
And for the pins around the corner you can go like this, e.g you want a pin at 30 degrees; with a simple trigonometric calculation, your pin's x and y values can be these;
pX = mX + radius * Math.cos(Math.toRadians(30));
pY = mY + radius * Math.sin(Math.toRadians(30));
So you can draw your pin at these x and y values respectively, also the degree can be changed.
