tree bb868128f943df8edf31a9cb805a27b120f72748
parent 59e45fab0feb64ae54379dabd849a5d60499253f
author Manoj Biswas <manojb@microsoft.com> 1553295754 +0000
committer Chromium commit bot <commit-bot@chromium.org> 1553295754 +0000

Serialize floats in page content to avoid exponential representation

CPDF_PageContentGenerator class uses std::ostringstream to serialize
floats to string while generating the content stream. Float values
close to 0 (e.g., 0.00000001) and large numbers (e.g., 10000000) get
converted to their exponential representation (e.g., 1e-7 and 1e+7
respectively). PDF specification does not recognize exponential format
representation for floats.

CPDF_PageContentGenerator is invoked when FPDFPage_GenerateContent API
is called. Existing code addressed a specific case in path generation
code by using SkFloatToDecimal to serialize floats. The fix in this
CL is to re-factor that code into a utility function and use it in
other places except for the color operators. Code that serializes the
color operators (rg and RG) and their operands, converts an integer in
CPDF_Color::GetRGB into float dividing by 256. Thus the floating point
serialization anomaly wasn't observed for these operators.

A new unit-test CPDF_PageContentGeneratorTest::BUG_937 was added to
test the product code changes. Existing unit-tests and embedder-tests
needed to be updated to reflect the serialization format.

R=thestig@chromium.org

Bug: pdfium:937
Change-Id: I38f066a0ad074cd0d68d6b7620fb581d04ce2c16
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/52070
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>