[webkit-changes] [WebKit/WebKit] 0ad581: REGRESSION: Thumbnail turns blank after choose A3/...

[Richard Robinson]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: 0ad581ba4f4a68ed4ccdad22996301ffde891b2f
      https://github.com/WebKit/WebKit/commit/0ad581ba4f4a68ed4ccdad22996301ffde891b2f
  Author: Richard Robinson <richard_robinson2 at apple.com>
  Date:   2023-04-10 (Mon, 10 Apr 2023)

  Changed paths:
    M Source/WebKit/WebProcess/WebPage/ios/WebPageIOS.mm

  Log Message:
  -----------
  REGRESSION: Thumbnail turns blank after choose A3/Tabloid paper size in Print Screen
https://bugs.webkit.org/show_bug.cgi?id=255210
rdar://107503946

Reviewed by Wenson Hsieh.

iOS print preview thumbnail generation uses `CGBitmapContextCreateImage` to create the bitmap image.
However, with some combinations of page scale size with paper size, the resulting image dimension
becomes too large, resulting in the function returning null and no thumbnail being generated.

This PR fixes this by scaling down the dimensions before the image is created to ensure the maximum
possible size of the image is constrained. This limit is the size at which the thumbnail itself is
rendered, so the scaling is safe to do.

* Source/WebKit/WebProcess/WebPage/ios/WebPageIOS.mm:
(WebKit::WebPage::drawToImage):

Canonical link: https://commits.webkit.org/262780@main