Method _getDragOffset

src/dd-draggable.ts:404–428

@internal

(event: DragEvent, el: HTMLElement, parent: HTMLElement)

  /** @internal */
  protected _getDragOffset(event: DragEvent, el: HTMLElement, parent: HTMLElement): DragOffset {

    // in case ancestor has transform/perspective css properties that change the viewpoint
    let xformOffsetX = 0;
    let xformOffsetY = 0;
    if (parent) {
      xformOffsetX = this.dragTransform.xOffset;
      xformOffsetY = this.dragTransform.yOffset;
    }

    const targetOffset = el.getBoundingClientRect();
    let x = this.option.rtl ? targetOffset.right : targetOffset.left;
    let offsetX = this.option.rtl
      ? (event.clientX - targetOffset.right + xformOffsetX)
      : (-event.clientX + targetOffset.left - xformOffsetX);

    return {
      x,
      top: targetOffset.top,
      offsetX,
      offsetTop: - event.clientY + targetOffset.top - xformOffsetY,
      width: targetOffset.width * this.dragTransform.xScale,
      height: targetOffset.height * this.dragTransform.yScale
    };
  }

  /** @internal starts or continues auto-scroll when the dragged helper is clipped by the scroll container.
   * Takes the grid's own element to find the scroll container so external/sidebar drags work too (#2074). */