Add a pixel test for masked image filtering
Adds a pixel test that covers filtering of masked images. On the Skia
backend, the SkMipmapMode::kLinear sampling option incorrectly draws a
fully transparent stencil mask.
Bug: chromium:1396266, skia:14070
Change-Id: If3b1d7cfca14a3891fe7ba4d84d6d30dc31a1f2a
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/103476
Reviewed-by: Nigi <nigi@chromium.org>
Commit-Queue: K. Moon <kmoon@chromium.org>
diff --git a/testing/SUPPRESSIONS b/testing/SUPPRESSIONS
index e9b32ac..8e02bed 100644
--- a/testing/SUPPRESSIONS
+++ b/testing/SUPPRESSIONS
@@ -422,6 +422,9 @@
# TODO(chromium:1028991): Remove after associated bug is fixed
reset_button.in * * * *
+# TODO(chromium:1396266, skia:14070): Remove after associated bug is fixed
+bug_1396266.in * * * skia
+
# xfa_specific
# TODO(pdfium:1095): Remove after associated bug is fixed
diff --git a/testing/resources/pixel/bug_1396266.in b/testing/resources/pixel/bug_1396266.in
new file mode 100644
index 0000000..fdeaf43
--- /dev/null
+++ b/testing/resources/pixel/bug_1396266.in
@@ -0,0 +1,98 @@
+{{header}}
+{{object 1 0}} <<
+ /Type /Catalog
+ /Pages 2 0 R
+>>
+endobj
+{{object 2 0}} <<
+ /Type /Pages
+ /Count 1
+ /Kids [3 0 R]
+>>
+endobj
+
+% A page with scaled copies of a masked image. Any scaled image with an area
+% less than 8 times the stencil mask's original area (64x64 * 8 = 32,768) forces
+% bilinear interpolation of the stencil mask, which triggers the bug.
+{{object 3 0}} <<
+ /Type /Page
+ /Parent 2 0 R
+ /Contents 4 0 R
+ /MediaBox [0 0 432 288]
+ /Resources <<
+ /XObject <<
+ /Masked 5 0 R
+ >>
+ >>
+>>
+endobj
+{{object 4 0}} <<
+ {{streamlen}}
+>>
+stream
+
+% 32x32 image has an area of 1,024, so it is interpolated.
+q
+ 32 0 0 32 64 240 cm
+ /Masked Do
+Q
+
+% 64x64 image has an area of 4,096, so it is interpolated.
+q
+ 64 0 0 64 48 160 cm
+ /Masked Do
+Q
+
+% 128x128 image has an area of 16,384, so it is interpolated.
+q
+ 128 0 0 128 16 16 cm
+ /Masked Do
+Q
+
+% 256x256 image has an area of 65,536, so it is not interpolated.
+q
+ 256 0 0 256 160 16 cm
+ /Masked Do
+Q
+
+endstream
+endobj
+
+% A 3x3 base image with a stencil mask.
+{{object 5 0}} <<
+ /Subtype /Image
+ /BitsPerComponent 8
+ /ColorSpace /DeviceRGB
+ /Filter /ASCIIHexDecode
+ /Height 3
+ /Mask 6 0 R
+ /Width 3
+ {{streamlen}}
+>>
+stream
+B8C3E9 7793DB C3CEEF
+8CADF2 1B74E8 BFD5FB
+C2D3FA 9FBDF8 D9E5FC
+endstream
+endobj
+
+% A 64x64 stencil mask with horizontal and vertical lines.
+{{object 6 0}} <<
+ /Subtype /Image
+ /BitsPerComponent 1
+ /Filter [/ASCIIHexDecode /FlateDecode]
+ /Height 64
+ /ImageMask true
+ /Width 64
+ {{streamlen}}
+>>
+stream
+78DA63608080FAFF10E000E5C3687FA8388CF6818A63D0500330E802A83C41BA1EAA9E105D03554F
+36CD0C35876CFA0FD41CDAD3F2FF694D03002512CA0A
+endstream
+endobj
+
+{{xref}}
+{{trailer}}
+{{startxref}}
+%%EOF
diff --git a/testing/resources/pixel/bug_1396266_expected.pdf.0.png b/testing/resources/pixel/bug_1396266_expected.pdf.0.png
new file mode 100644
index 0000000..6cacddf
--- /dev/null
+++ b/testing/resources/pixel/bug_1396266_expected.pdf.0.png
Binary files differ
