cornerRadius property
The proportion of the radius to the width of the canvas. 0.0 by default.
After you set the value, width_px, height_px, and cornerRadius_px are calculated based on width, height, cornerRadius, and the width of the canvas. If cornerRadius_px < min(width_px/2, height_px/2) is met, the value of cornerRadius is set valid; if not, cornerRadius_px is set to min(width_px/2, height_px/2), and cornerRadius is set to the proportion of cornerRadius_px to the width of the canvas.
Implementation
final double cornerRadius;