SkPaint::getFillPath seems to distort geometry of small ellipses

[Igor Shturma]

Hi, 

When I apply SkPaint::getFillPath() to ellipses that are small (e.g. 1.0x1.0 circle with 0.05 stroke width), the geometry is getting distorted.

So the result of drawing an ellipse with kStroke_Style-paint and the result of getting fill path and drawing with kFill_Style-paint are different.

Here is an example:

void draw(SkCanvas* canvas) {
    canvas->drawColor(SK_ColorWHITE);


    SkPaint paint;
    paint.setStyle(SkPaint::kStroke_Style);
    paint.setStrokeWidth(.05);
    paint.setColor(0xff1f78b4);
    paint.setAntiAlias(true);
    paint.setStrokeCap(SkPaint::kRound_Cap);


    SkPaint paint2(paint);
    paint2.setStyle(SkPaint::kFill_Style);
    paint2.setColor(0xfff10600);    
   
    SkRect rect;
    rect.setXYWH(.05, .05, 1., 1.);
    SkPath path;
    path.addOval(rect, SkPath::kCW_Direction);
   
    SkPath path2;
    paint.getFillPath(path, &path2);    
   
    canvas->scale(200., 200.);


    canvas->drawPath(path, paint);
    canvas->drawPath(path2, paint2);
}

https://fiddle.skia.org/c/d9b5c49fb382e8d9321cf0b43c23fd93

Is this a known issue?

Thanks,

Igor

[Cary Clark]

Igor, thanks for the bug report. It appears that getFillPath is returning the wrong weight for the conics. I'll investigate.

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[Cary Clark]

Igor

The behavior is as expected. You are calling getFillPath without specifying the device resolution, so the stroker assumes that the path covers a single pixel.

Here's a modified fiddle that passes in the resolution: https://fiddle.skia.org/c/4493cfea9b1fab4b8e70edc6e298ce2f

Cary

[Igor Shturma]

Cary, 

Thank you for clarification.

Igor