drawCross method
绘制交叉线
Implementation
void drawCross(Canvas canvas) {
if (pressOffset == null) {
return;
}
double bw = _width / 2;
/// 二分法查找当前选中索引
double dx = dxToTransformX(pressOffset!.dx) - bw;
int index = transformXToIndex(dx);
dx = indexToX(index) + bw;
drawCrossLine(
canvas: canvas,
canvasWidth: canvasWidth,
canvasHeight: canvasHeight,
scrollX: scrollX,
scale: scale,
dx: dx,
dy: -10,
strokeWidth: crossLineWidth,
color: crossLineColor,
);
}