tree 94b115657109d6029b7ec90395364b358a748901
parent 26ed89d18bf0e1af1a9e3a8bab41c8bad28e13cd
author Lei Zhang <thestig@chromium.org> 1589323314 +0000
committer Chromium commit bot <commit-bot@chromium.org> 1589323314 +0000

Fix image mask area calculations used by FPDF_RenderPage().

Inside FPDF_RenderPage(), when it encounters an image mask, it falls
back to rasterizing the entire PDF to ensure correctness. There is a
disabled implementation to only rasterize the areas of the page that
contains image masks. This code is disabled because it contains a bug
that causes missing content.

In particular, GetMaskBitmap() calls GetMaskDimensionsAndOffsets() to
figure out where the image mask is. The input for the image mask area
is in the user (page) coordinate space, but the output needs to be in
the device coordinate space. GetMaskDimensionsAndOffsets() does not
always do this transformation correctly, so remove it entirely. Instead,
use CPDF_Page::GetDisplayMatrix() to get the correct transformation
matrix and apply it.

Bug: chromium:674771
Change-Id: Ic827a8f82e3e896e5120f70b51be7bfd149c4ca0
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/69733
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: Rebekah Potter <rbpotter@chromium.org>