Add a test case for Type3 glyphs with negative width.

Illustate a case where 3 glyphs should be drawn from right to left, but
only the first glyph appears.

Bug: chromium:1128284
Change-Id: I979e38155338af52b4e2cc491f5b90bb75c6b3b7
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/73750
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: Hui Yingst <nigi@chromium.org>

testing/resources/pixel/bug_1128284.in

diff --git a/testing/resources/pixel/bug_1128284.in b/testing/resources/pixel/bug_1128284.in
new file mode 100644
index 0000000..0dfda97
--- /dev/null
+++ b/testing/resources/pixel/bug_1128284.in
@@ -0,0 +1,94 @@
+{{header}}
+{{object 1 0}} <<
+  /Type /Catalog
+  /Pages 2 0 R
+>>
+endobj
+{{object 2 0}} <<
+  /Type /Pages
+  /Count 1
+  /Kids [3 0 R]
+>>
+endobj
+{{object 3 0}} <<
+  /Type /Page
+  /Parent 2 0 R
+  /Contents 4 0 R
+  /Resources <<
+    /Font <<
+      /F1 5 0 R
+    >>
+  >>
+  /MediaBox [0 0 200 200]
+>>
+endobj
+{{object 4 0}} <<
+  {{streamlen}}
+>>
+stream
+0 g
+BT
+/F1 .1 Tf 1 0 0 1 100 100 Tm
+[(a)16000(b)17000(c)]TJ
+ET
+endstream
+endobj
+{{object 5 0}} <<
+  /Type /Font
+  /Subtype /Type3
+  /CharProcs <<
+    /a97 6 0 R
+    /a98 7 0 R
+    /a99 6 0 R
+  >>
+  /Encoding 8 0 R
+  /FirstChar 97
+  /FontBBox [0 0 100 100]
+  /LastChar 99
+  /Widths [-100 -50 -75]
+>>
+endobj
+{{object 6 0}} <<
+  {{streamlen}}
+>>
+stream
+q
+6 0 0 48 6 0 cm
+BI
+/W 6
+/H 48
+/BPC 1
+/IM true
+ID
+xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
+EI
+Q
+endstream
+endobj
+{{object 7 0}} <<
+  {{streamlen}}
+>>
+stream
+q
+6 0 0 48 6 0 cm
+BI
+/W 6
+/H 48
+/BPC 1
+/IM true
+ID
+!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+EI
+Q
+endstream
+endobj
+{{object 8 0}} <<
+  /Type /Encoding
+  /BaseEncoding /WinAnsiEncoding
+  /Differences [97 /a97 /a98 /a99]
+>>
+endobj
+{{xref}}
+{{trailer}}
+{{startxref}}
+%%EOF

testing/resources/pixel/bug_1128284_expected.pdf.0.png

diff --git a/testing/resources/pixel/bug_1128284_expected.pdf.0.png b/testing/resources/pixel/bug_1128284_expected.pdf.0.png
new file mode 100644
index 0000000..5405729
--- /dev/null
+++ b/testing/resources/pixel/bug_1128284_expected.pdf.0.png
Binary files differ