SketchWave Rounded Trapezoid Demo

What is SWRoundedTrapezoid?

SWRoundedTrapezoid extends SWTrapezoid by rounding each of the four corners using quadratic Bézier curves. The shape is otherwise identical to its parent — it supports the same parallel bases, height, regular/isosceles mode, breathing, rotation, grid drawing, and dragging. The only new property is cornerRadius.

Inheritance

SWRoundedTrapezoid extends SWTrapezoid

Because the relationship is "is a" (a rounded trapezoid IS a trapezoid), all parent capabilities are inherited for free. Only _drawAtPx(), reset(), and toString() are overridden.

Key Formulas

Area      = (a + b) / 2 × h

Left leg  = √((b/2 − a/2 + offset)² + h²)
Right leg = √((b/2 − a/2 − offset)² + h²)

Perimeter = a + b + left leg + right leg
  (note: perimeter does not include the arc adjustments at corners)

Constructor

new SWRoundedTrapezoid(cx, cy, topBase, bottomBase, height, fillColor, options)

Using the Controls

• Top Base / Bottom Base / Height / Corner Radius: Sliders above the accordion. Corner Radius is expressed as a percentage of canvas width.
• Regular checkbox: Uncheck to reveal the Offset slider.
• Breathing, Spinning, Appearance, Actions: Same as SWTrapezoid demo.
• Drag: Click and drag the shape to reposition it.

Keyboard Shortcuts

• B — toggle breathing
• S — toggle spin
• R — factory reset
• Q — quit all animations