draw method
Implementation
void draw(Canvas canvas, double space, double size, double radius) {
double progress = page - index;
double distance = size + space;
double start = index * (size + space);
if (progress > 0.5) {
double right = start + size + distance;
//progress=>0.5-1.0
//left:0.0=>distance
double left = index * distance + distance * (progress - 0.5) * 2;
canvas.drawRRect(RRect.fromLTRBR(left, 0.0, right, size, Radius.circular(radius)), getPaint());
} else {
double right = start + size + distance * progress * 2;
canvas.drawRRect(RRect.fromLTRBR(start, 0.0, right, size, Radius.circular(radius)), getPaint());
}
}