Method _getConstrainedPointerPosition

src/cdk/drag-drop/drag-ref.ts:1301–1336

Gets the pointer position on the page, accounting for any position constraints.

(point: Point)

  /** Gets the pointer position on the page, accounting for any position constraints. */
  private _getConstrainedPointerPosition(point: Point): Point {
    const dropContainerLock = this._dropContainer ? this._dropContainer.lockAxis : null;
    let {x, y} = this.constrainPosition
      ? this.constrainPosition(point, this, this._initialDomRect!, this._pickupPositionInElement)
      : point;

    if (this.lockAxis === 'x' || dropContainerLock === 'x') {
      y =
        this._pickupPositionOnPage.y -
        (this.constrainPosition ? this._pickupPositionInElement.y : 0);
    } else if (this.lockAxis === 'y' || dropContainerLock === 'y') {
      x =
        this._pickupPositionOnPage.x -
        (this.constrainPosition ? this._pickupPositionInElement.x : 0);
    }

    if (this._boundaryRect) {
      // If not using a custom constrain we need to account for the pickup position in the element
      // otherwise we do not need to do this, as it has already been accounted for
      const {x: pickupX, y: pickupY} = !this.constrainPosition
        ? this._pickupPositionInElement
        : {x: 0, y: 0};

      const boundaryRect = this._boundaryRect;
      const {width: previewWidth, height: previewHeight} = this._getPreviewRect();
      const minY = boundaryRect.top + pickupY;
      const maxY = boundaryRect.bottom - (previewHeight - pickupY);
      const minX = boundaryRect.left + pickupX;
      const maxX = boundaryRect.right - (previewWidth - pickupX);

      x = clamp(x, minX, maxX);
      y = clamp(y, minY, maxY);
    }

    return {x, y};
  }

  /** Updates the current drag delta, based on the user's current pointer position on the page. */
  private _updatePointerDirectionDelta(pointerPositionOnPage: Point) {