Snap-to lines & objects in PDFs using JavaScript

(() => {
  let snapMode;

  const getMouseLocation = e => {
    const scrollElement = instance.Core.documentViewer.getScrollViewElement();
    const scrollLeft = scrollElement.scrollLeft || 0;
    const scrollTop = scrollElement.scrollTop || 0;

    return {
      x: e.pageX + scrollLeft,
      y: e.pageY + scrollTop,
    };
  };

  const mouseToPagePoint = e => {
    const displayMode = instance.Core.documentViewer.getDisplayModeManager().getDisplayMode();
    const windowPoint = getMouseLocation(e);

    const page = displayMode.getSelectedPages(windowPoint, windowPoint);
    const pageNumber = page.first !== null ? page.first : instance.Core.documentViewer.getCurrentPage();

    return {
      point: displayMode.windowToPage(windowPoint, pageNumber),
      pageNumber,
    };
  };

  const createSnapModesPanel = () => {
    const snapModesPanel = {
      tab: {
        dataElement: 'snapModesPanelTab',
        title: 'snapModesPanelTab',
        img:
          '<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" viewBox="0 0 24 24"><defs><path id="a" d="M0 0h24v24H0V0z"/></defs><clipPath id="b"><use xlink:href="#a" overflow="visible"/></clipPath><path clip-path="url(#b)" d="M19.5 9.5c-1.03 0-1.9.62-2.29 1.5h-2.92c-.39-.88-1.26-1.5-2.29-1.5s-1.9.62-2.29 1.5H6.79c-.39-.88-1.26-1.5-2.29-1.5C3.12 9.5 2 10.62 2 12s1.12 2.5 2.5 2.5c1.03 0 1.9-.62 2.29-1.5h2.92c.39.88 1.26 1.5 2.29 1.5s1.9-.62 2.29-1.5h2.92c.39.88 1.26 1.5 2.29 1.5 1.38 0 2.5-1.12 2.5-2.5s-1.12-2.5-2.5-2.5z"/></svg>',
      },
      panel: {
        dataElement: 'snapModesPanel',
        render: () => {
          const { DEFAULT, POINT_ON_LINE, LINE_MID_POINT, LINE_INTERSECTION, PATH_ENDPOINT } = instance.Core.documentViewer.SnapMode;

          const buttonContainer = document.createElement('div');
          const map = {
            Default: DEFAULT,
            'Point On Line': POINT_ON_LINE,
            'Line Midpoint': LINE_MID_POINT,
            'Line Intersection': LINE_INTERSECTION,
            'Path Endpoint': PATH_ENDPOINT,
          };
          Object.keys(map).forEach(key => {
            const div = document.createElement('div');
            div.style.margin = '0px 0px 12px 12px';

            const radioBtn = document.createElement('input');
            radioBtn.type = 'radio';
            radioBtn.style.marginRight = '10px';
            radioBtn.name = 'snapMode';
            radioBtn.value = map[key];
            radioBtn.id = key;
            radioBtn.addEventListener('change', e => {
              snapMode = parseInt(e.target.value, 10);
            });

            const label = document.createElement('label');
            label.innerHTML = key;
            label.for = key;

            div.appendChild(radioBtn);
            div.appendChild(label);
            buttonContainer.appendChild(div);
          });

          // make the default radio button checked
          buttonContainer.querySelector('input[id="Default"]').checked = true;

          return buttonContainer;
        },
      },
    };

    instance.UI.setCustomPanel(snapModesPanel);

    instance.UI.openElements([snapModesPanel.panel.dataElement]);
  };

  createSnapModesPanel();

  instance.Core.documentViewer.addEventListener('pageComplete', () => {
    const lineAnnot = new Core.Annotations.LineAnnotation();
    lineAnnot.setStartPoint(0, 0);
    lineAnnot.setEndPoint(0, 0);
    lineAnnot.PageNumber = 1;

    const annotationManager = instance.Core.documentViewer.getAnnotationManager();
    annotationManager.addAnnotation(lineAnnot);

    let timeout;
    let shouldAddMouseMoveListener = true;
    document.onmousemove = () => {
      clearTimeout(timeout);
      timeout = setTimeout(() => {
        if (shouldAddMouseMoveListener) {
          instance.Core.documentViewer.addEventListener('mouseMove', e => {
            const result = mouseToPagePoint(e);
            const pagePoint = result.point;
            const pageNumber = result.pageNumber;
            const oldPageNumber = lineAnnot.PageNumber;

            lineAnnot.PageNumber = pageNumber;
            lineAnnot.setStartPoint(pagePoint.x, pagePoint.y);
            // refresh old page since line annotation has been removed from it
            if (pageNumber !== oldPageNumber) {
              annotationManager.drawAnnotations(oldPageNumber);
            }

            instance.Core.documentViewer.snapToNearest(pageNumber, pagePoint.x, pagePoint.y, snapMode).then(snapPoint => {
              lineAnnot.setEndPoint(snapPoint.x, snapPoint.y);
              annotationManager.redrawAnnotation(lineAnnot);
            });
          });
        }

        shouldAddMouseMoveListener = false;
      }, 100);
    };
  });
})(window);
// eslint-disable-next-line spaced-comment
//# sourceURL=config.js