[webkit-changes] [WebKit/WebKit] 808bcd: [UnifiedPDF] Implement two-up display mode

[Simon Fraser]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: 808bcd5e0a980840b1dd1fcbc6787aa654c79cb8
      https://github.com/WebKit/WebKit/commit/808bcd5e0a980840b1dd1fcbc6787aa654c79cb8
  Author: Simon Fraser <simon.fraser at apple.com>
  Date:   2023-10-02 (Mon, 02 Oct 2023)

  Changed paths:
    M Source/WebKit/WebProcess/Plugins/PDF/UnifiedPDF/PDFDocumentLayout.h
    M Source/WebKit/WebProcess/Plugins/PDF/UnifiedPDF/PDFDocumentLayout.mm

  Log Message:
  -----------
  [UnifiedPDF] Implement two-up display mode
https://bugs.webkit.org/show_bug.cgi?id=262454
rdar://116296737

Reviewed by Dan Glastonbury.

Implement two-up display mode, which displays pairs of pages side-by-side.

In this mode, the height of the pair of pages is the larger of the two heights, and pages with
unequal heights are vertically centered in the row. If there is a single page on the last row, it's
centered (which is also the case for a single page PDF).

Have `PDFDocumentLayout::updateLayout()` keep track of the width of page pairs when necessary, which
is passed to `layoutTwoUpColumn()`.

* Source/WebKit/WebProcess/Plugins/PDF/UnifiedPDF/PDFDocumentLayout.h:
* Source/WebKit/WebProcess/Plugins/PDF/UnifiedPDF/PDFDocumentLayout.mm:
(WebKit::PDFDocumentLayout::updateLayout):
(WebKit::PDFDocumentLayout::layoutPages):
(WebKit::PDFDocumentLayout::layoutSingleColumn):
(WebKit::PDFDocumentLayout::layoutTwoUpColumn):

Canonical link: https://commits.webkit.org/268733@main