How to draw Arc between two points on the Canvas?

Question

I have two points in the canvas, now I\'m able to draw a line between those points like this below image by using

This code canvas.drawLine(p1.x, p1.y, p2.x,

Answer 1

I may be late to answer but I got more information.

After Android Lollipop there are two ways to address this problem

public void drawArc(RectF oval, float startAngle, float sweepAngle, boolean useCenter, Paint paint)

public void drawArc(float left, float top, float right, float bottom, float startAngle, float sweepAngle, boolean useCenter, Paint paint)

Usage:

   RectF rectF = new RectF(left, top, right, bottom);

    // method 1
    canvas.drawArc (rectF, 90, 45, true,  paints[0]);

    // method 2
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
        canvas.drawArc (left, top, right, bottom, 0, 45, true, paints[1]);
    }

Sweep angle is nothing more than angle of Sector which is drawn clockwise eg. for below code

private void drawArcs(Canvas canvas) {
    RectF rectF = new RectF(left, top, right, bottom);

    // white arc
    canvas.drawArc (rectF, 90, 45, true,  paints[0]);

    // Green arc
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
        canvas.drawArc (left, top, right, bottom, 0, 45, true, paints[1]);
    }

    // Red stroked arc
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
        canvas.drawArc (left, top, right, bottom, 180, 45, true,  paints[2]);
    }
}

Result will look like this

Same can be achieved with the help of defining Paths and then iterating over them in onDraw method as illustrated in this snippet:

 public class ArcDrawable extends Drawable {

    private int left, right, top, bottom;
    private  Paint[] paints = new Paint[3];
    private HashMap<Path, Paint> pathMap = new HashMap();


    public ArcDrawable() {

        // white paint
        Paint whitePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        whitePaint.setColor(Color.WHITE);
        paints[0]= whitePaint;

        // green paint
        Paint greenPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        greenPaint.setColor(Color.GREEN);
        paints[1]= greenPaint;

        // red paint
        Paint redPaint =new Paint(Paint.ANTI_ALIAS_FLAG);
        redPaint.setColor(Color.RED);
        redPaint.setStyle(Paint.Style.STROKE);
        paints[2]= redPaint;
    }

    @Override
    public void draw(Canvas canvas) {

        //----------USE PATHS----------
        // Define and use custom  Path
        for (Map.Entry<Path, Paint> entry : pathMap.entrySet()) {
            // Draw Path on respective Paint style
            canvas.drawPath(entry.getKey(),  entry.getValue());

        }

        // -------OR use conventional Style---------
        //drawArcs(canvas);

    }


    //Same result
    private void drawArcs(Canvas canvas) {
        RectF rectF = new RectF(left, top, right, bottom);

        // method 1
        canvas.drawArc (rectF, 90, 45, true,  paints[0]);

        // method 2
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            canvas.drawArc (left, top, right, bottom, 0, 45, true, paints[1]);
        }

        // method two with stroke
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            canvas.drawArc (left, top, right, bottom, 180, 45, true,  paints[2]);
        }
    }


    @Override
    protected void onBoundsChange(Rect bounds) {
        super.onBoundsChange(bounds);

        int width = bounds.width();
        int height = bounds.height();

        left = bounds.left;
        right = bounds.right;
        top = bounds.top;
        bottom = bounds.bottom;

        final int size = Math.min(width, height);
        final int centerX = bounds.left + (width / 2);
        final int centerY = bounds.top + (height / 2);

        pathMap.clear();
        //update pathmap using new bounds
        recreatePathMap(size, centerX, centerY);
        invalidateSelf();
    }


    private Path recreatePathMap(int size, int centerX, int centerY) {

        RectF rectF = new RectF(left, top, right, bottom);

        // first arc
        Path arcPath = new Path();
        arcPath.moveTo(centerX,centerY);
        arcPath.arcTo (rectF, 90, 45);
        arcPath.close();
        // add to draw Map
        pathMap.put(arcPath, paints[0]);

        //second arc
        arcPath = new Path();
        arcPath.moveTo(centerX,centerY);
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
          arcPath.arcTo (rectF, 0, 45);
        }
        arcPath.close();
        // add to draw Map
        pathMap.put(arcPath, paints[1]);

        // third arc
        arcPath = new Path();
        arcPath.moveTo(centerX,centerY);
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            arcPath.arcTo (rectF, 180, 45);

        }
        arcPath.close();
        // add to draw Map
        pathMap.put(arcPath, paints[2]);

        return arcPath;

    }

    @Override
    public void setAlpha(int alpha) {

    }

    @Override
    public void setColorFilter(@Nullable ColorFilter colorFilter) {

    }

    @Override
    public int getOpacity() {
        return 0;
    }


}

Complete source code:

https://github.com/hiteshsahu/Arc-Drawable