CODEWITHSUNDEEP
javaandroidandroid-canvasandroid-view
User3
User3

Reputation: 2535

Trying to draw bitmaps on circumference of a circle, find some offset in the implementation

I have this class: 

public class MockDraw extends View {

    private Paint mPaint;
    public static float angle = 0f;
    private int width;
    private int height;
    Context ctx;
    Bitmap icon;
    PointF pf;

    public MockDraw(Context ctx) {
        super(ctx);
        this.ctx = ctx;
        setFocusable(true);
        mPaint = new Paint();
        this.mPaint.setAntiAlias(true);
        this.mPaint.setStrokeWidth(4f);
        this.mPaint.setColor(Color.WHITE);
        this.mPaint.setStyle(Paint.Style.STROKE);
        this.mPaint.setStrokeJoin(Paint.Join.ROUND);

        icon = BitmapFactory.decodeResource(ctx.getResources(), R.drawable.ic_action_send_now);
    }


    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        this.width = w;
        this.height = h;

        float centerX = (float) width / 2;
        float centerY = (float) height / 2;

        pf = new PointF(centerX, centerY);
        super.onSizeChanged(w, h, oldw, oldh);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        canvas.drawColor(Color.BLACK);


        for (int i = 0; i <= 360; i += 45) {
            PointF px = getPosition(pf, 400, i);

            //   canvas.drawPoint(centerX, centerY, mPaint);
            canvas.drawPoint(px.x, px.y, mPaint);
            canvas.drawBitmap(icon, px.x, px.y, mPaint);

        }

    }

    private PointF getPosition(PointF center, float radius, float angle) {

        return new PointF((float) (center.x + radius * Math.cos(Math.toRadians(angle))),
                (float) (center.y + radius * Math.sin(Math.toRadians(angle))));
    }

    //  canvas.drawText("TEST", centerX, centerY, mPaint);


}

This is hurried up code, which I intend to clean up later for memory optimization and logical standards.

My aim from the above class is to find the center of the screen, calculate the points at 45 degree angles on the circumference with a certain radius.

This is working properly for Points however when I draw a bitmap on these points I get a little offset. I have attached an example:

enter image description here

Upvotes: 2

Views: 303

Answers (1)

Dinesh Kannan
Dinesh Kannan

Reputation: 1255

i think if you aligned the bitmap center to the points drawn , then it will give the correct results.

canvas.drawBitmap(icon, px.x, px.y, mPaint);

change to 

if(px.x-icon.getWidth()/2>0&&px.y-icon.getHeight()/2>0)
canvas.drawBitmap(icon, px.x-icon.getWidth()/2, px.y-icon.getHeight()/2, mPaint);

Upvotes: 2

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