Links with bounds outside the page appear in the wrong place

[nvinen]

I'm using the current beta version (pdfjs-2.6.347-dist).

I traced the bug to incorrect code for negating numbers by pasting a hyphen on the front of the string, rather than actually negating the numbers. Pasting a hyphen in front of a negative number like -3 gives you --3 instead of 3.

It's certainly possible for link (and other annotation) bounds can be negative (ie, beyond the top/left edge of the page). The current pdf.js code offsets such regions significantly from where they should be. The following patch fixes this bug and a related bug, and also adds a few lines to clip the regions so that they are within the page so they look neater.

--- pdf.js (revision 1225)
+++ pdf.js (working copy)
@@ -9374,14 +9374,18 @@
page = this.page,
viewport = this.viewport;
const container = document.createElement("section");

• let width = data.rect[2] - data.rect[0];

• let height = data.rect[3] - data.rect[1];
  container.setAttribute("data-annotation-id", data.id);

  const rect = _util.Util.normalizeRect([data.rect[0], page.view[3] - data.rect[1] + page.view[1], data.rect[2], page.view[3] - data.rect[3] + page.view[1]]);

• if( rect[0] < page.view[0] ) rect[0] = page.view[0]; else if( rect[0] > page.view[2] ) rect[0] = page.view[2];

• if( rect[1] < page.view[1] ) rect[1] = page.view[1]; else if( rect[1] > page.view[3] ) rect[1] = page.view[3];

• if( rect[2] < page.view[0] ) rect[2] = page.view[0]; else if( rect[2] > page.view[2] ) rect[2] = page.view[2];

• if( rect[3] < page.view[1] ) rect[3] = page.view[1]; else if( rect[3] > page.view[3] ) rect[3] = page.view[3];

• let width = rect[2] - rect[0];

• let height = rect[3] - rect[1];

  container.style.transform = matrix(${viewport.transform.join(",")});

• container.style.transformOrigin = -${rect[0]}px -${rect[1]}px;

• container.style.transformOrigin = ${-rect[0]}px ${-rect[1]}px;

  if (!ignoreBorder && data.borderStyle.width > 0) {
  container.style.borderWidth = ${data.borderStyle.width}px;
  @@ -9801,7 +9805,7 @@
  });
  const parentLeft = parseFloat(parentElement.style.left);
  const parentWidth = parseFloat(parentElement.style.width);

• this.container.style.transformOrigin = -${parentLeft + parentWidth}px -${parentElement.style.top};

• this.container.style.transformOrigin = ${-(parentLeft + parentWidth)}px ${-parentElement.style.top};
  this.container.style.left = ${parentLeft + parentWidth}px;
  this.container.appendChild(popup.render());
  return this.container;

[Snuffleupagus]

When opening an issue, please remember to provide all of the information requested in https://github.com/mozilla/pdf.js/blob/master/.github/ISSUE_TEMPLATE.md in order for the issue to be actionable/valid.

Please also note that any patches to this code would need to be accompanied by tests, see https://github.com/mozilla/pdf.js/wiki/Contributing and in particular https://github.com/mozilla/pdf.js/wiki/Contributing#4-run-lint-and-testing

The following patch fixes this bug and a related bug, and also adds a few lines to clip the regions so that they are within the page so they look neater.

Finally, also keep in mind that it's always best to have non-related changes in separate commits (although they can obviously be in the same PR).

[Snuffleupagus]

@nvinen Do you want to attempt to submit a PR for this?

[timvandermeij]

Fixed by the PR above.