Fix backspace on 1st character of a line erases the line break.

Bug: chromium:836361
Change-Id: I39a0a3f9cb59ceb81f944dd5d0d4fd38a2e18a6b
Reviewed-on: https://pdfium-review.googlesource.com/31411
Reviewed-by: Ryan Harrison <rharrison@chromium.org>
Commit-Queue: Henrique Nakashima <hnakashima@chromium.org>

4 files changed, 422 insertions, 5 deletions

diff --git a/testing/resources/xfa/xfa_multiline_textfield.in b/testing/resources/xfa/xfa_multiline_textfield.in
new file mode 100644
index 0000000000..215bc28015
--- /dev/null
+++ b/testing/resources/xfa/xfa_multiline_textfield.in
@@ -0,0 +1,73 @@
+{{header}}
+
+%% Original object ID: 24 0
+{{object 1 0}}
+<<
+  /AcroForm 2 0 R
+  /Extensions <<
+    /ADBE <<
+      /BaseVersion /1.7
+      /ExtensionLevel 8
+    >>
+  >>
+  /NeedsRendering true
+  /Type /Catalog
+>>
+endobj
+
+%% Original object ID: 32 0
+{{object 2 0}}
+<<
+  /XFA [
+    (preamble)
+    3 0 R
+    (config)
+    4 0 R
+    (template)
+    5 0 R
+    (localeSet)
+    6 0 R
+    (postamble)
+    7 0 R
+  ]
+>>
+endobj
+
+{{xfapreamble 3 0}}
+{{xfaconfig 4 0}}
+
+{{object 5 0}}
+<<
+  {{streamlen}}
+>>
+stream
+<template xmlns="http://www.xfa.org/schema/xfa-template/3.3/">
+  <subform name="form1" layout="tb" locale="en_US" restoreState="auto">
+    <pageSet>
+      <pageArea name="Page1" id="Page1">
+        <contentArea x="18pt" y="18pt" w="612pt" h="792pt"/>
+        <medium stock="default" short="612pt" long="792pt"/>
+      </pageArea>
+    </pageSet>
+    <subform w="576pt" h="756pt" name="Page1">
+      <field name="TextField1" y="0pt" x="0pt" w="425pt" h="80pt">
+        <ui>
+          <textEdit multiLine="1">
+            <font typeface="Helvetica" size="16pt"/>
+          </textEdit>
+        </ui>
+      </field>
+    </subform>
+  </subform>
+</template>
+endstream
+endobj
+
+{{xfalocale 6 0}}
+
+{{xfapostamble 7 0}}
+
+{{xref}}
+{{trailer}}
+{{startxref}}
+%%EOF
diff --git a/testing/resources/xfa/xfa_multiline_textfield.pdf b/testing/resources/xfa/xfa_multiline_textfield.pdf
new file mode 100644
index 0000000000..f88af5bf9a
--- /dev/null
+++ b/testing/resources/xfa/xfa_multiline_textfield.pdf
@@ -0,0 +1,244 @@
+%PDF-1.7
+% ò¤ô
+
+%% Original object ID: 24 0
+1 0 obj
+<<
+  /AcroForm 2 0 R
+  /Extensions <<
+    /ADBE <<
+      /BaseVersion /1.7
+      /ExtensionLevel 8
+    >>
+  >>
+  /NeedsRendering true
+  /Type /Catalog
+>>
+endobj
+
+%% Original object ID: 32 0
+2 0 obj
+<<
+  /XFA [
+    (preamble)
+    3 0 R
+    (config)
+    4 0 R
+    (template)
+    5 0 R
+    (localeSet)
+    6 0 R
+    (postamble)
+    7 0 R
+  ]
+>>
+endobj
+
+3 0 obj
+<<
+  /Length 123
+>>
+stream
+<xdp:xdp xmlns:xdp="http://ns.adobe.com/xdp/" timeStamp="2018-02-23T21:37:11Z" uuid="21482798-7bf0-40a4-bc5d-3cefdccf32b5">
+endstream
+endobj
+4 0 obj
+<<
+  /Length 697
+>>
+stream
+<config xmlns="http://www.xfa.org/schema/xci/3.0/">
+  <agent name="designer">
+    <destination>pdf</destination>
+    <pdf>
+      <fontInfo/>
+    </pdf>
+  </agent>
+  <present>
+    <pdf>
+      <version>1.7</version>
+      <adobeExtensionLevel>8</adobeExtensionLevel>
+      <renderPolicy>client</renderPolicy>
+      <scriptModel>XFA</scriptModel>
+      <interactive>1</interactive>
+    </pdf>
+    <xdp>
+      <packets>*</packets>
+    </xdp>
+    <destination>pdf</destination>
+    <script>
+      <runScripts>server</runScripts>
+    </script>
+  </present>
+  <acrobat>
+    <acrobat7>
+      <dynamicRender>required</dynamicRender>
+    </acrobat7>
+    <validate>preSubmit</validate>
+  </acrobat>
+</config>
+endstream
+endobj
+
+5 0 obj
+<<
+  /Length 651
+>>
+stream
+<template xmlns="http://www.xfa.org/schema/xfa-template/3.3/">
+  <subform name="form1" layout="tb" locale="en_US" restoreState="auto">
+    <pageSet>
+      <pageArea name="Page1" id="Page1">
+        <contentArea x="18pt" y="18pt" w="612pt" h="792pt"/>
+        <medium stock="default" short="612pt" long="792pt"/>
+      </pageArea>
+    </pageSet>
+    <subform w="576pt" h="756pt" name="Page1">
+      <field name="TextField1" y="0pt" x="0pt" w="425pt" h="80pt">
+        <ui>
+          <textEdit multiLine="1">
+            <font typeface="Helvetica" size="16pt"/>
+          </textEdit>
+        </ui>
+      </field>
+    </subform>
+  </subform>
+</template>
+endstream
+endobj
+
+6 0 obj
+<<
+  /Length 3454
+>>
+stream
+<localeSet xmlns="http://www.xfa.org/schema/xfa-locale-set/2.7/">
+  <locale name="en_US" desc="English (United States)">
+    <calendarSymbols name="gregorian">
+      <monthNames>
+        <month>January</month>
+        <month>February</month>
+        <month>March</month>
+        <month>April</month>
+        <month>May</month>
+        <month>June</month>
+        <month>July</month>
+        <month>August</month>
+        <month>September</month>
+        <month>October</month>
+        <month>November</month>
+        <month>December</month>
+      </monthNames>
+      <monthNames abbr="1">
+        <month>Jan</month>
+        <month>Feb</month>
+        <month>Mar</month>
+        <month>Apr</month>
+        <month>May</month>
+        <month>Jun</month>
+        <month>Jul</month>
+        <month>Aug</month>
+        <month>Sep</month>
+        <month>Oct</month>
+        <month>Nov</month>
+        <month>Dec</month>
+      </monthNames>
+      <dayNames>
+        <day>Sunday</day>
+        <day>Monday</day>
+        <day>Tuesday</day>
+        <day>Wednesday</day>
+        <day>Thursday</day>
+        <day>Friday</day>
+        <day>Saturday</day>
+      </dayNames>
+      <dayNames abbr="1">
+        <day>Sun</day>
+        <day>Mon</day>
+        <day>Tue</day>
+        <day>Wed</day>
+        <day>Thu</day>
+        <day>Fri</day>
+        <day>Sat</day>
+      </dayNames>
+      <meridiemNames>
+        <meridiem>AM</meridiem>
+        <meridiem>PM</meridiem>
+      </meridiemNames>
+      <eraNames>
+        <era>BC</era>
+        <era>AD</era>
+      </eraNames>
+    </calendarSymbols>
+    <datePatterns>
+      <datePattern name="full">EEEE, MMMM D, YYYY</datePattern>
+      <datePattern name="long">MMMM D, YYYY</datePattern>
+      <datePattern name="med">MMM D, YYYY</datePattern>
+      <datePattern name="short">M/D/YY</datePattern>
+    </datePatterns>
+    <timePatterns>
+      <timePattern name="full">h:MM:SS A Z</timePattern>
+      <timePattern name="long">h:MM:SS A Z</timePattern>
+      <timePattern name="med">h:MM:SS A</timePattern>
+      <timePattern name="short">h:MM A</timePattern>
+    </timePatterns>
+    <dateTimeSymbols>GyMdkHmsSEDFwWahKzZ</dateTimeSymbols>
+    <numberPatterns>
+      <numberPattern name="numeric">z,zz9.zzz</numberPattern>
+      <numberPattern name="currency">$z,zz9.99|($z,zz9.99)</numberPattern>
+      <numberPattern name="percent">z,zz9%</numberPattern>
+    </numberPatterns>
+    <numberSymbols>
+      <numberSymbol name="decimal">.</numberSymbol>
+      <numberSymbol name="grouping">,</numberSymbol>
+      <numberSymbol name="percent">%</numberSymbol>
+      <numberSymbol name="minus">-</numberSymbol>
+      <numberSymbol name="zero">0</numberSymbol>
+    </numberSymbols>
+    <currencySymbols>
+      <currencySymbol name="symbol">$</currencySymbol>
+      <currencySymbol name="isoname">USD</currencySymbol>
+      <currencySymbol name="decimal">.</currencySymbol>
+    </currencySymbols>
+    <typefaces>
+      <typeface name="Myriad Pro"/>
+      <typeface name="Minion Pro"/>
+      <typeface name="Courier Std"/>
+      <typeface name="Adobe Pi Std"/>
+      <typeface name="Adobe Hebrew"/>
+      <typeface name="Adobe Arabic"/>
+      <typeface name="Adobe Thai"/>
+      <typeface name="Kozuka Gothic Pro-VI M"/>
+      <typeface name="Kozuka Mincho Pro-VI R"/>
+      <typeface name="Adobe Ming Std L"/>
+      <typeface name="Adobe Song Std L"/>
+      <typeface name="Adobe Myungjo Std M"/>
+    </typefaces>
+  </locale>
+</localeSet>
+endstream
+endobj
+
+7 0 obj
+<<
+  /Length 10
+>>
+stream
+</xdp:xdp>
+endstream
+endobj
+
+xref
+0 8
+0000000000 65535 f 
+0000000044 00000 n 
+0000000242 00000 n 
+0000000402 00000 n 
+0000000578 00000 n 
+0000001329 00000 n 
+0000002033 00000 n 
+0000005542 00000 n 
+trailer<< /Root 1 0 R /Size 8 >>
+startxref
+5605
+%%EOF
diff --git a/xfa/fwl/cfwl_edit.cpp b/xfa/fwl/cfwl_edit.cpp
index afa9aac87d..8ebc155a80 100644
--- a/xfa/fwl/cfwl_edit.cpp
+++ b/xfa/fwl/cfwl_edit.cpp
@@ -1252,7 +1252,7 @@ void CFWL_Edit::OnChar(CFWL_MessageKey* pMsg) {
   switch (c) {
     case L'\b':
       if (m_CursorPosition > 0) {
-        SetCursorPosition(m_EdtEngine.GetIndexBefore(m_CursorPosition));
+        SetCursorPosition(m_CursorPosition - 1);
         m_EdtEngine.Delete(m_CursorPosition, 1);
       }
       break;
diff --git a/xfa/fwl/cfwl_edit_embeddertest.cpp b/xfa/fwl/cfwl_edit_embeddertest.cpp
index 7415e05845..ecc3b5ed13 100644
--- a/xfa/fwl/cfwl_edit_embeddertest.cpp
+++ b/xfa/fwl/cfwl_edit_embeddertest.cpp
@@ -8,13 +8,13 @@
 #include "testing/embedder_test.h"
 #include "testing/embedder_test_timer_handling_delegate.h"
 #include "testing/gtest/include/gtest/gtest.h"
+#include "testing/xfa_js_embedder_test.h"
 
-class CFWLEditEmbeddertest : public EmbedderTest {
+class CFWLEditEmbeddertest : public XFAJSEmbedderTest {
  protected:
   void SetUp() override {
     EmbedderTest::SetUp();
     SetDelegate(&delegate_);
-    CreateAndInitializeFormPDF();
   }
 
   void TearDown() override {
@@ -22,8 +22,8 @@ class CFWLEditEmbeddertest : public EmbedderTest {
     EmbedderTest::TearDown();
   }
 
-  void CreateAndInitializeFormPDF() {
-    EXPECT_TRUE(OpenDocument("xfa/email_recommended.pdf"));
+  void CreateAndInitializeFormPDF(const char* filename) {
+    EXPECT_TRUE(OpenDocument(filename));
     page_ = LoadPage(0);
     ASSERT_TRUE(page_);
   }
@@ -37,10 +37,12 @@ class CFWLEditEmbeddertest : public EmbedderTest {
 };
 
 TEST_F(CFWLEditEmbeddertest, Trivial) {
+  CreateAndInitializeFormPDF("xfa/email_recommended.pdf");
   ASSERT_EQ(0u, delegate().GetAlerts().size());
 }
 
 TEST_F(CFWLEditEmbeddertest, LeftClickMouseSelection) {
+  CreateAndInitializeFormPDF("xfa/email_recommended.pdf");
   FORM_OnLButtonDown(form_handle(), page(), 0, 115, 58);
   for (size_t i = 0; i < 10; ++i)
     FORM_OnChar(form_handle(), page(), 'a' + i, 0);
@@ -58,6 +60,7 @@ TEST_F(CFWLEditEmbeddertest, LeftClickMouseSelection) {
 }
 
 TEST_F(CFWLEditEmbeddertest, DragMouseSelection) {
+  CreateAndInitializeFormPDF("xfa/email_recommended.pdf");
   FORM_OnLButtonDown(form_handle(), page(), 0, 115, 58);
   for (size_t i = 0; i < 10; ++i)
     FORM_OnChar(form_handle(), page(), 'a' + i, 0);
@@ -72,4 +75,101 @@ TEST_F(CFWLEditEmbeddertest, DragMouseSelection) {
   unsigned short buf[128];
   unsigned long len = FORM_GetSelectedText(form_handle(), page(), &buf, 128);
   EXPECT_STREQ(L"defgh", WideString::FromUTF16LE(buf, len).c_str());
+
+  // TODO(hnakashima): This is incorrect. Visually 'abcdefgh' are selected.
+  const char kDraggedMD5[] = "69c13fe53b5fc422ebeab56d101a4658";
+  {
+    ScopedFPDFBitmap page_bitmap =
+        RenderPageWithFlags(page(), form_handle(), FPDF_ANNOT);
+    CompareBitmap(page_bitmap.get(), 612, 792, kDraggedMD5);
+  }
+}
+
+TEST_F(CFWLEditEmbeddertest, SimpleFill) {
+  CreateAndInitializeFormPDF("xfa/email_recommended.pdf");
+  const char kBlankMD5[] = "eea5c72701270ac4a7edcc4df66d812a";
+  {
+    ScopedFPDFBitmap page_bitmap =
+        RenderPageWithFlags(page(), form_handle(), FPDF_ANNOT);
+    CompareBitmap(page_bitmap.get(), 612, 792, kBlankMD5);
+  }
+
+  FORM_OnLButtonDown(form_handle(), page(), 0, 115, 58);
+  for (size_t i = 0; i < 10; ++i)
+    FORM_OnChar(form_handle(), page(), 'a' + i, 0);
+
+  const char kFilledMD5[] = "e73263fcea46c18d874b3d5a79f53805";
+  {
+    ScopedFPDFBitmap page_bitmap =
+        RenderPageWithFlags(page(), form_handle(), FPDF_ANNOT);
+    CompareBitmap(page_bitmap.get(), 612, 792, kFilledMD5);
+  }
+}
+
+TEST_F(CFWLEditEmbeddertest, FillWithNewLineWithoutMultiline) {
+  CreateAndInitializeFormPDF("xfa/email_recommended.pdf");
+  FORM_OnLButtonDown(form_handle(), page(), 0, 115, 58);
+  for (size_t i = 0; i < 5; ++i)
+    FORM_OnChar(form_handle(), page(), 'a' + i, 0);
+  FORM_OnChar(form_handle(), page(), '\r', 0);
+  for (size_t i = 5; i < 10; ++i)
+    FORM_OnChar(form_handle(), page(), 'a' + i, 0);
+
+  const char kFilledMD5[] = "e73263fcea46c18d874b3d5a79f53805";
+  {
+    ScopedFPDFBitmap page_bitmap =
+        RenderPageWithFlags(page(), form_handle(), FPDF_ANNOT);
+    CompareBitmap(page_bitmap.get(), 612, 792, kFilledMD5);
+  }
+}
+
+// Disabled due to flakiness.
+TEST_F(CFWLEditEmbeddertest, DISABLED_FillWithNewLineWithMultiline) {
+  CreateAndInitializeFormPDF("xfa/xfa_multiline_textfield.pdf");
+  FORM_OnLButtonDown(form_handle(), page(), 0, 115, 58);
+
+  for (size_t i = 0; i < 5; ++i)
+    FORM_OnChar(form_handle(), page(), 'a' + i, 0);
+  FORM_OnChar(form_handle(), page(), '\r', 0);
+  for (size_t i = 5; i < 10; ++i)
+    FORM_OnChar(form_handle(), page(), 'a' + i, 0);
+
+  // Should look like:
+  // abcde
+  // fghij|
+  {
+#if _FX_PLATFORM_ == _FX_PLATFORM_LINUX_
+    const char kFilledMultilineMD5[] = "fc1f4d5fdb2c5755005fc525b0a60ec9";
+#else
+    const char kFilledMultilineMD5[] = "a5654e027d8b1667c20f3b86d1918003";
+#endif  // _FX_PLATFORM_ == _FX_PLATFORM_LINUX_
+    ScopedFPDFBitmap page_bitmap =
+        RenderPageWithFlags(page(), form_handle(), FPDF_ANNOT);
+    CompareBitmap(page_bitmap.get(), 612, 792, kFilledMultilineMD5);
+  }
+
+  for (size_t i = 0; i < 4; ++i)
+    FORM_OnKeyDown(form_handle(), page(), FWL_VKEY_Left, 0);
+
+  // Should look like:
+  // abcde
+  // f|ghij
+
+  // Two backspaces is a workaround because left arrow does not behave well
+  // in the first character of a line. It skips back to the previous line.
+  for (size_t i = 0; i < 2; ++i)
+    FORM_OnChar(form_handle(), page(), '\b', 0);
+
+  // Should look like:
+  // abcde|ghij
+  {
+#if _FX_PLATFORM_ == _FX_PLATFORM_LINUX_
+    const char kMultilineBackspaceMD5[] = "8bb62a8100ff1e1cc113d4033e0d824e";
+#else
+    const char kMultilineBackspaceMD5[] = "a2f1dcab92bb1fb7c2f9ccc70100c989";
+#endif  // _FX_PLATFORM_ == _FX_PLATFORM_LINUX_
+    ScopedFPDFBitmap page_bitmap =
+        RenderPageWithFlags(page(), form_handle(), FPDF_ANNOT);
+    CompareBitmap(page_bitmap.get(), 612, 792, kMultilineBackspaceMD5);
+  }
 }