Add PDF text selection rendering test case to illustrate gaps/unevenness

Take PDFium's bigtable_mini.pdf, with corresponding .in file, shrink its
page size, and save it as //pdf/test/data/bigtable_micro.pdf. Then add
PDFiumEngineTest.DrawTextSelectionsBigtableMicro to check how it
renders. This shows how the PDF Viewer draws the selection with gaps and
unevenness between parts of the text. Whereas other PDF viewers
generally draw one rectangle that covers this line of text.

Bug: 40448046
Change-Id: I781fb357c62fe7f2168c713011807d0ece1ebd65
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5896038
Reviewed-by: Andy Phan <andyphan@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1361434}

pdf/pdfium/pdfium_engine_unittest.cc

@@ -1064,6 +1064,23 @@ TEST_P(PDFiumEngineTest, DrawTextSelectionsHelloWorld) {
       *engine, kPageIndex, "hello_world_selection_3.png");
 }
 
+TEST_P(PDFiumEngineTest, DrawTextSelectionsBigtableMicro) {
+  NiceMock<MockTestClient> client;
+  std::unique_ptr<PDFiumEngine> engine =
+      InitializeEngine(&client, FILE_PATH_LITERAL("bigtable_micro.pdf"));
+  ASSERT_TRUE(engine);
+
+  // Update the plugin size so that all the text is visible by
+  // `SelectionChangeInvalidator`.
+  engine->PluginSizeUpdated({500, 500});
+
+  engine->SelectAll();
+  EXPECT_EQ("{fay,jeff,sanjay,wilsonh,kerr,m3b,tushar,k es,gruber}@google.com",
+            engine->GetSelectedText());
+  DrawSelectionAndCompareWithPlatformExpectations(
+      *engine, /*page_index=*/0, "bigtable_micro_selection.png");
+}
+
 TEST_P(PDFiumEngineTest, LinkNavigates) {
   NiceMock<MockTestClient> client;
   std::unique_ptr<PDFiumEngine> engine =

pdf/test/data/bigtable_micro.in

@@ -0,0 +1,113 @@
+{{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
+  /MediaBox [0 0 250 100]
+  /Resources <<
+    /ProcSet [/PDF /ImageB /Text]
+    /Font <<
+      /F1 5 0 R
+      /F2 6 0 R
+    >>
+  >>
+>>
+endobj
+{{object 4 0}} <<
+  {{streamlen}}
+>>
+stream
+q BT
+1 0 0 1 250 67 Tm
+/F2 8.96638 Tf
+-243.635 -15.84 Td
+(f)Tj
+/F1 8.96638 Tf
+4.55491 0 Td
+(f)Tj
+2.87476 0 Td
+(ay)Tj
+7.79253 0 Td
+(,jef)Tj
+11.506 0 Td
+(f,sanjay)Tj
+27.4558 0 Td
+(,wilsonh,k)Tj
+37.1801 0 Td
+(err)Tj
+9.58372 0 Td
+(,m3b,tushar)Tj
+41.8537 0 Td
+(,k)Tj
+11.6349 0 Td
+(es,gruber)Tj
+/F2 8.96638 Tf
+32.9694 0 Td
+(g)Tj
+/F1 8.96638 Tf
+4.55491 0 Td
+(@google.com)Tj
+ET Q
+endstream
+endobj
+{{object 5 0}} <<
+  /Type /Font
+  /Subtype /Type1
+  /BaseFont /Times-Roman
+>>
+endobj
+{{object 6 0}} <<
+  /Type /Font
+  /Subtype /Type1
+  /FirstChar 102
+  /BaseFont /RFSQHQ+CMSY9
+  /FontDescriptor 7 0 R
+  /LastChar 103
+  /Widths [508 508]
+>>
+endobj
+{{object 7 0}} <<
+  /Type /FontDescriptor
+  /Ascent 750
+  /CapHeight 750
+  /CharSet (/braceleft/braceright)
+  /Descent -250
+  /Flags 4
+  /FontBBox [0 -250 440 750]
+  /FontFile3 8 0 R
+  /FontName /RFSQHQ+CMSY9
+  /ItalicAngle 0
+  /StemV 65
+>>
+endobj
+{{object 8 0}} <<
+  /Subtype /Type1C
+  /Filter [/ASCII85Decode /FlateDecode]
+  {{streamlen}}
+>>
+stream
+GhQY<?t!MPA7Xa1EXNBL#h4%k%?@du#q5_5B)EgioL"p)pKs!j9@_A!X@n"A#^s/nr,0aY?!i,5R?>nA
+43BRuTX#t%4ekD2_c]pSd*g?I_(dmV-o3k<:Veup,U50*Ylr.i;$bHCc:fghe5L>1a\`<FkpTR<8hEdi
+.SEJ:>O%`N>>SLd>,:)GT9<BBa2#L+Pa9V1&Ao("^^P</!u&Ql7PhdY9T5#6IePGiOgOaNdLsRg)OHi+
+n+a.f[/4_7lnp:OXP)%6XER"WK`:C2*&F%pl[L]/LH0S#rJk:S[coEjaA0p=l`BI4BP[$LCn09862jKs
+Y)F7W^!5B(h.[kDUY*1W\e@l8mE%N?^8RN2qNUCce!bWPjLtF8=4Zg,R,1!:HR6^V/b\TIh0Z`11`hZZ
+*BO'Za1C[ph)dSm>aE#>k-A'_h4)!bqJD$jjj@/_bu*BN?.Ud@HV0Y&l1Vg$1F)e^]:6ER3IV(Tbj1;S
+BposQ0Df/MDiTcoYO4BSY\&*%<aJs1;J/:.>?>$UG7-pseF)R.T'a;@,PN5BX]sWQf<*o6H:RGZ*f^Pj
+qkd,*mVA#1lAJeH\%d!)GAm3[%_gAF5OB8mr>(pE^5_Fj[i?3Bq0X7/D)6E](`9a_gaUoK~>
+endstream
+endobj
+{{xref}}
+{{trailer}}
+{{startxref}}
+%%EOF

pdf/test/data/bigtable_micro.pdf

@@ -0,0 +1,128 @@
+%PDF-1.7
+%<25><><EFBFBD><EFBFBD>
+1 0 obj <<
+  /Type /Catalog
+  /Pages 2 0 R
+>>
+endobj
+2 0 obj <<
+  /Type /Pages
+  /Count 1
+  /Kids [3 0 R]
+>>
+endobj
+3 0 obj <<
+  /Type /Page
+  /Parent 2 0 R
+  /Contents 4 0 R
+  /MediaBox [0 0 250 100]
+  /Resources <<
+    /ProcSet [/PDF /ImageB /Text]
+    /Font <<
+      /F1 5 0 R
+      /F2 6 0 R
+    >>
+  >>
+>>
+endobj
+4 0 obj <<
+  /Length 373
+>>
+stream
+q BT
+1 0 0 1 250 67 Tm
+/F2 8.96638 Tf
+-243.635 -15.84 Td
+(f)Tj
+/F1 8.96638 Tf
+4.55491 0 Td
+(f)Tj
+2.87476 0 Td
+(ay)Tj
+7.79253 0 Td
+(,jef)Tj
+11.506 0 Td
+(f,sanjay)Tj
+27.4558 0 Td
+(,wilsonh,k)Tj
+37.1801 0 Td
+(err)Tj
+9.58372 0 Td
+(,m3b,tushar)Tj
+41.8537 0 Td
+(,k)Tj
+11.6349 0 Td
+(es,gruber)Tj
+/F2 8.96638 Tf
+32.9694 0 Td
+(g)Tj
+/F1 8.96638 Tf
+4.55491 0 Td
+(@google.com)Tj
+ET Q
+endstream
+endobj
+5 0 obj <<
+  /Type /Font
+  /Subtype /Type1
+  /BaseFont /Times-Roman
+>>
+endobj
+6 0 obj <<
+  /Type /Font
+  /Subtype /Type1
+  /FirstChar 102
+  /BaseFont /RFSQHQ+CMSY9
+  /FontDescriptor 7 0 R
+  /LastChar 103
+  /Widths [508 508]
+>>
+endobj
+7 0 obj <<
+  /Type /FontDescriptor
+  /Ascent 750
+  /CapHeight 750
+  /CharSet (/braceleft/braceright)
+  /Descent -250
+  /Flags 4
+  /FontBBox [0 -250 440 750]
+  /FontFile3 8 0 R
+  /FontName /RFSQHQ+CMSY9
+  /ItalicAngle 0
+  /StemV 65
+>>
+endobj
+8 0 obj <<
+  /Subtype /Type1C
+  /Filter [/ASCII85Decode /FlateDecode]
+  /Length 640
+>>
+stream
+GhQY<?t!MPA7Xa1EXNBL#h4%k%?@du#q5_5B)EgioL"p)pKs!j9@_A!X@n"A#^s/nr,0aY?!i,5R?>nA
+43BRuTX#t%4ekD2_c]pSd*g?I_(dmV-o3k<:Veup,U50*Ylr.i;$bHCc:fghe5L>1a\`<FkpTR<8hEdi
+.SEJ:>O%`N>>SLd>,:)GT9<BBa2#L+Pa9V1&Ao("^^P</!u&Ql7PhdY9T5#6IePGiOgOaNdLsRg)OHi+
+n+a.f[/4_7lnp:OXP)%6XER"WK`:C2*&F%pl[L]/LH0S#rJk:S[coEjaA0p=l`BI4BP[$LCn09862jKs
+Y)F7W^!5B(h.[kDUY*1W\e@l8mE%N?^8RN2qNUCce!bWPjLtF8=4Zg,R,1!:HR6^V/b\TIh0Z`11`hZZ
+*BO'Za1C[ph)dSm>aE#>k-A'_h4)!bqJD$jjj@/_bu*BN?.Ud@HV0Y&l1Vg$1F)e^]:6ER3IV(Tbj1;S
+BposQ0Df/MDiTcoYO4BSY\&*%<aJs1;J/:.>?>$UG7-pseF)R.T'a;@,PN5BX]sWQf<*o6H:RGZ*f^Pj
+qkd,*mVA#1lAJeH\%d!)GAm3[%_gAF5OB8mr>(pE^5_Fj[i?3Bq0X7/D)6E](`9a_gaUoK~>
+endstream
+endobj
+xref
+0 9
+0000000000 65535 f 
+0000000015 00000 n 
+0000000068 00000 n 
+0000000131 00000 n 
+0000000333 00000 n 
+0000000758 00000 n 
+0000000836 00000 n 
+0000000992 00000 n 
+0000001233 00000 n 
+trailer <<
+  /Root 1 0 R
+  /Size 9
+>>
+startxref
+1984
+%%EOF