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    <p><strong>1-</strong> I guess that you only use a few points to draw graphs of signals. All graph/chart applications try to connect points with direct lines and then your chart will be shown. So if you only use three points, your graph will looks like a triangle! If you want your graph to be curved, you have to add more points. Then it comes out like a curve.</p> <p><strong>2-</strong> Or you can find any library that can draw <code>sin</code> graph, for example <a href="http://android-graphview.org/" rel="nofollow noreferrer"><code>GraphView Library</code></a>. Then try to draw this function:</p> <p><img src="https://i.stack.imgur.com/IWjyY.png" alt="Enter image description here"></p> <p>So it looks like to this:</p> <p><img src="https://i.stack.imgur.com/bdB49.png" alt="Enter image description here"></p> <p>Then translate it to <code>(a,0)</code>, so result seems like what you want.</p> <p><strong>3-</strong> And another way, you can use built in <code>Math.sin</code> in Java:</p> <p>Chose for example 1000 point in range <code>a</code> to <code>b</code> and compute value of above function for each point and finally create a <code>path</code> and show them in a canvas.</p> <p>You can use <a href="http://developer.android.com/reference/android/graphics/Path.html#quadTo%28float,%20float,%20float,%20float%29" rel="nofollow noreferrer">quadTo (float x1, float y1, float x2, float y2)</a> that simplify drawing <code>quad curves</code> for you. The documentation says:</p> <blockquote> <p>Add a quadratic bezier from the last point, approaching control point (x1,y1), and ending at (x2,y2). If no moveTo() call has been made for this contour, the first point is automatically set to (0,0).</p> <p>Parameters <br/> <br/> x1 The x-coordinate of the control point on a quadratic curve <br/> y1 The y-coordinate of the control point on a quadratic curve <br/> x2 The x-coordinate of the end point on a quadratic curve <br/> y2 The y-coordinate of the end point on a quadratic curve <br/></p> </blockquote> <p>Finally, I add a simple class that extends <code>View</code> and can draw a curve that looks like what you want:</p> <pre><code>public class SinWave extends View { private float first_X = 50; private float first_Y = 230; private float end_X = 100; private float end_Y = 230; private float Max = 50; public SinWave(Context context, AttributeSet attrs) { super(context, attrs); } @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); Paint paint = new Paint() { { setStyle(Paint.Style.STROKE); setStrokeCap(Paint.Cap.ROUND); setStrokeWidth(0.7f); setAntiAlias(true); setColor(0xFFFF00FF); } }; final Path path = new Path(); path.moveTo(first_X, first_Y); path.quadTo((first_X + end_X)/2, Max, end_X, end_Y); canvas.drawPath(path, paint); } } </code></pre> <p>The result must look like this:</p> <p><img src="https://i.stack.imgur.com/tWoO3.png" alt="Enter image description here"></p> <p>You can add more methods to the class and change it to increase performance!</p>
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    1. POHow to make line with rounded (smooth) corners with AndroidPlot
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    1. USPeter Mortensen
    1. UShasanghaforian
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    1. CO@ can you provide some code? im not good in math enough. i dont like math. thanks in advance.
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      1. USSimon Dorociak
    2. CO@Sajmon I edited answer.Please see it again.
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    3. COHi man, im here. So its nice but this is paint and i need to do it in some graph API. Could you do in in especially in AndroidPlot? thanks (sorry that im writing now, im busy in last days).
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