Add FORM_ReplaceSelection() and embedder tests.

This method replaces the selected text in a user-editable form text
area with another text string (which can be empty or non-empty). If
there is no selected text, FORM_ReplaceSelection() will append the
replacement text after the current caret position.

BUG=chromium:59266

Change-Id: I76448ef757d107888c33ebd5656457ebac93b952
Reviewed-on: https://pdfium-review.googlesource.com/8812
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Diana Gage <drgage@google.com>

8 files changed, 314 insertions, 36 deletions

diff --git a/fpdfsdk/pwl/cpwl_combo_box.cpp b/fpdfsdk/pwl/cpwl_combo_box.cpp
index 9514e55646..49254b8171 100644
--- a/fpdfsdk/pwl/cpwl_combo_box.cpp
+++ b/fpdfsdk/pwl/cpwl_combo_box.cpp
@@ -184,9 +184,9 @@ CFX_WideString CPWL_ComboBox::GetSelectedText() {
   return CFX_WideString();
 }
 
-void CPWL_ComboBox::DeleteSelectedText() {
+void CPWL_ComboBox::ReplaceSelection(const CFX_WideString& text) {
   if (m_pEdit)
-    m_pEdit->DeleteSelectedText();
+    m_pEdit->ReplaceSelection(text);
 }
 
 CFX_WideString CPWL_ComboBox::GetText() const {
diff --git a/fpdfsdk/pwl/cpwl_combo_box.h b/fpdfsdk/pwl/cpwl_combo_box.h
index a50c4cee37..81e4256e18 100644
--- a/fpdfsdk/pwl/cpwl_combo_box.h
+++ b/fpdfsdk/pwl/cpwl_combo_box.h
@@ -63,7 +63,7 @@ class CPWL_ComboBox : public CPWL_Wnd {
   void SetFocus() override;
   void KillFocus() override;
   CFX_WideString GetSelectedText() override;
-  void DeleteSelectedText() override;
+  void ReplaceSelection(const CFX_WideString& text) override;
 
   void SetFillerNotify(IPWL_Filler_Notify* pNotify);
 
diff --git a/fpdfsdk/pwl/cpwl_combo_box_embeddertest.cpp b/fpdfsdk/pwl/cpwl_combo_box_embeddertest.cpp
index 30fe32bc53..308ee4ac40 100644
--- a/fpdfsdk/pwl/cpwl_combo_box_embeddertest.cpp
+++ b/fpdfsdk/pwl/cpwl_combo_box_embeddertest.cpp
@@ -211,7 +211,7 @@ TEST_F(CPWLComboBoxEditEmbeddertest, DeleteEntireTextSelection) {
   EXPECT_STREQ(L"ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqr",
                GetCPWLComboBox()->GetSelectedText().c_str());
 
-  GetCPWLComboBox()->DeleteSelectedText();
+  GetCPWLComboBox()->ReplaceSelection(CFX_WideString());
   EXPECT_TRUE(GetCPWLComboBox()->GetText().IsEmpty());
 }
 
@@ -222,7 +222,7 @@ TEST_F(CPWLComboBoxEditEmbeddertest, DeleteTextSelectionMiddle) {
   GetCPWLComboBox()->SetEditSelection(12, 23);
   EXPECT_STREQ(L"MNOPQRSTUVW", GetCPWLComboBox()->GetSelectedText().c_str());
 
-  GetCPWLComboBox()->DeleteSelectedText();
+  GetCPWLComboBox()->ReplaceSelection(CFX_WideString());
   EXPECT_STREQ(L"ABCDEFGHIJKLXYZ[\\]^_`abcdefghijklmnopqr",
                GetCPWLComboBox()->GetText().c_str());
 }
@@ -234,7 +234,7 @@ TEST_F(CPWLComboBoxEditEmbeddertest, DeleteTextSelectionLeft) {
   GetCPWLComboBox()->SetEditSelection(0, 5);
   EXPECT_STREQ(L"ABCDE", GetCPWLComboBox()->GetSelectedText().c_str());
 
-  GetCPWLComboBox()->DeleteSelectedText();
+  GetCPWLComboBox()->ReplaceSelection(CFX_WideString());
   EXPECT_STREQ(L"FGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqr",
                GetCPWLComboBox()->GetText().c_str());
 }
@@ -246,7 +246,7 @@ TEST_F(CPWLComboBoxEditEmbeddertest, DeleteTextSelectionRight) {
   GetCPWLComboBox()->SetEditSelection(45, 50);
   EXPECT_STREQ(L"nopqr", GetCPWLComboBox()->GetSelectedText().c_str());
 
-  GetCPWLComboBox()->DeleteSelectedText();
+  GetCPWLComboBox()->ReplaceSelection(CFX_WideString());
   EXPECT_STREQ(L"ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklm",
                GetCPWLComboBox()->GetText().c_str());
 }
@@ -255,7 +255,94 @@ TEST_F(CPWLComboBoxEditEmbeddertest, DeleteEmptyTextSelection) {
   FormFillerAndWindowSetup(GetCPDFSDKAnnotUserEditable());
   TypeTextIntoTextField(50);
 
-  GetCPWLComboBox()->DeleteSelectedText();
+  GetCPWLComboBox()->ReplaceSelection(CFX_WideString());
   EXPECT_STREQ(L"ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqr",
                GetCPWLComboBox()->GetText().c_str());
 }
+
+TEST_F(CPWLComboBoxEditEmbeddertest, InsertTextInEmptyEditableComboBox) {
+  FormFillerAndWindowSetup(GetCPDFSDKAnnotUserEditable());
+  GetCPWLComboBox()->ReplaceSelection(CFX_WideString(L"Hello"));
+  EXPECT_STREQ(L"Hello", GetCPWLComboBox()->GetText().c_str());
+}
+
+TEST_F(CPWLComboBoxEditEmbeddertest,
+       InsertTextInPopulatedEditableComboBoxLeft) {
+  FormFillerAndWindowSetup(GetCPDFSDKAnnotUserEditable());
+  TypeTextIntoTextField(10);
+
+  // Move cursor to beginning of user-editable combobox text field.
+  EXPECT_TRUE(GetCFFLFormFiller()->OnKeyDown(GetCPDFSDKAnnotUserEditable(),
+                                             FWL_VKEY_Home, 0));
+
+  GetCPWLComboBox()->ReplaceSelection(CFX_WideString(L"Hello"));
+  EXPECT_STREQ(L"HelloABCDEFGHIJ", GetCPWLComboBox()->GetText().c_str());
+}
+
+TEST_F(CPWLComboBoxEditEmbeddertest,
+       InsertTextInPopulatedEditableComboBoxMiddle) {
+  FormFillerAndWindowSetup(GetCPDFSDKAnnotUserEditable());
+  TypeTextIntoTextField(10);
+
+  // Move cursor to middle of user-editable combobox text field.
+  for (int i = 0; i < 5; ++i) {
+    EXPECT_TRUE(GetCFFLFormFiller()->OnKeyDown(GetCPDFSDKAnnotUserEditable(),
+                                               FWL_VKEY_Left, 0));
+  }
+
+  GetCPWLComboBox()->ReplaceSelection(CFX_WideString(L"Hello"));
+  EXPECT_STREQ(L"ABCDEHelloFGHIJ", GetCPWLComboBox()->GetText().c_str());
+}
+
+TEST_F(CPWLComboBoxEditEmbeddertest,
+       InsertTextInPopulatedEditableComboBoxRight) {
+  FormFillerAndWindowSetup(GetCPDFSDKAnnotUserEditable());
+  TypeTextIntoTextField(10);
+
+  GetCPWLComboBox()->ReplaceSelection(CFX_WideString(L"Hello"));
+  EXPECT_STREQ(L"ABCDEFGHIJHello", GetCPWLComboBox()->GetText().c_str());
+}
+
+TEST_F(CPWLComboBoxEditEmbeddertest,
+       InsertTextAndReplaceSelectionInPopulatedEditableComboBoxWhole) {
+  FormFillerAndWindowSetup(GetCPDFSDKAnnotUserEditable());
+  TypeTextIntoTextField(10);
+
+  GetCPWLComboBox()->SetEditSelection(0, -1);
+  EXPECT_STREQ(L"ABCDEFGHIJ", GetCPWLComboBox()->GetSelectedText().c_str());
+  GetCPWLComboBox()->ReplaceSelection(CFX_WideString(L"Hello"));
+  EXPECT_STREQ(L"Hello", GetCPWLComboBox()->GetText().c_str());
+}
+
+TEST_F(CPWLComboBoxEditEmbeddertest,
+       InsertTextAndReplaceSelectionInPopulatedEditableComboBoxLeft) {
+  FormFillerAndWindowSetup(GetCPDFSDKAnnotUserEditable());
+  TypeTextIntoTextField(10);
+
+  GetCPWLComboBox()->SetEditSelection(0, 5);
+  EXPECT_STREQ(L"ABCDE", GetCPWLComboBox()->GetSelectedText().c_str());
+  GetCPWLComboBox()->ReplaceSelection(CFX_WideString(L"Hello"));
+  EXPECT_STREQ(L"HelloFGHIJ", GetCPWLComboBox()->GetText().c_str());
+}
+
+TEST_F(CPWLComboBoxEditEmbeddertest,
+       InsertTextAndReplaceSelectionInPopulatedEditableComboBoxMiddle) {
+  FormFillerAndWindowSetup(GetCPDFSDKAnnotUserEditable());
+  TypeTextIntoTextField(10);
+
+  GetCPWLComboBox()->SetEditSelection(2, 7);
+  EXPECT_STREQ(L"CDEFG", GetCPWLComboBox()->GetSelectedText().c_str());
+  GetCPWLComboBox()->ReplaceSelection(CFX_WideString(L"Hello"));
+  EXPECT_STREQ(L"ABHelloHIJ", GetCPWLComboBox()->GetText().c_str());
+}
+
+TEST_F(CPWLComboBoxEditEmbeddertest,
+       InsertTextAndReplaceSelectionInPopulatedEditableComboBoxRight) {
+  FormFillerAndWindowSetup(GetCPDFSDKAnnotUserEditable());
+  TypeTextIntoTextField(10);
+
+  GetCPWLComboBox()->SetEditSelection(5, 10);
+  EXPECT_STREQ(L"FGHIJ", GetCPWLComboBox()->GetSelectedText().c_str());
+  GetCPWLComboBox()->ReplaceSelection(CFX_WideString(L"Hello"));
+  EXPECT_STREQ(L"ABCDEHello", GetCPWLComboBox()->GetText().c_str());
+}
diff --git a/fpdfsdk/pwl/cpwl_edit_ctrl.cpp b/fpdfsdk/pwl/cpwl_edit_ctrl.cpp
index a852cb6231..1a7b0e4c49 100644
--- a/fpdfsdk/pwl/cpwl_edit_ctrl.cpp
+++ b/fpdfsdk/pwl/cpwl_edit_ctrl.cpp
@@ -59,9 +59,12 @@ CFX_WideString CPWL_EditCtrl::GetSelectedText() {
   return CFX_WideString();
 }
 
-void CPWL_EditCtrl::DeleteSelectedText() {
-  if (m_pEdit)
-    m_pEdit->ClearSelection();
+void CPWL_EditCtrl::ReplaceSelection(const CFX_WideString& text) {
+  if (!m_pEdit)
+    return;
+
+  m_pEdit->ClearSelection();
+  m_pEdit->InsertText(text, FX_CHARSET_Default);
 }
 
 void CPWL_EditCtrl::RePosChildWnd() {
diff --git a/fpdfsdk/pwl/cpwl_edit_ctrl.h b/fpdfsdk/pwl/cpwl_edit_ctrl.h
index 4fb86fab62..03dc4be1e1 100644
--- a/fpdfsdk/pwl/cpwl_edit_ctrl.h
+++ b/fpdfsdk/pwl/cpwl_edit_ctrl.h
@@ -61,7 +61,7 @@ class CPWL_EditCtrl : public CPWL_Wnd {
   float GetFontSize() const override;
   void SetCursor() override;
   CFX_WideString GetSelectedText() override;
-  void DeleteSelectedText() override;
+  void ReplaceSelection(const CFX_WideString& text) override;
 
   void SetCaret(bool bVisible,
                 const CFX_PointF& ptHead,
diff --git a/fpdfsdk/pwl/cpwl_edit_embeddertest.cpp b/fpdfsdk/pwl/cpwl_edit_embeddertest.cpp
index 98cc44ab86..34569b2491 100644
--- a/fpdfsdk/pwl/cpwl_edit_embeddertest.cpp
+++ b/fpdfsdk/pwl/cpwl_edit_embeddertest.cpp
@@ -24,35 +24,44 @@ class CPWLEditEmbeddertest : public EmbedderTest {
   }
 
   void CreateAndInitializeFormPDF() {
-    EXPECT_TRUE(OpenDocument("text_form.pdf"));
+    EXPECT_TRUE(OpenDocument("text_form_multiple.pdf"));
     m_page = LoadPage(0);
     ASSERT_TRUE(m_page);
 
-    CPDFSDK_FormFillEnvironment* pFormFillEnv =
-        static_cast<CPDFSDK_FormFillEnvironment*>(form_handle());
-
-    {
-      CBA_AnnotIterator iter(pFormFillEnv->GetPageView(0),
-                             CPDF_Annot::Subtype::WIDGET);
-      m_pAnnot = iter.GetFirstAnnot();
-      CPDFSDK_Annot* pLastAnnot = iter.GetLastAnnot();
-      ASSERT_EQ(m_pAnnot, pLastAnnot);
-      ASSERT_TRUE(m_pAnnot);
-      ASSERT_EQ(CPDF_Annot::Subtype::WIDGET, m_pAnnot->GetAnnotSubtype());
-    }
+    m_pFormFillEnv = static_cast<CPDFSDK_FormFillEnvironment*>(form_handle());
+    CBA_AnnotIterator iter(m_pFormFillEnv->GetPageView(0),
+                           CPDF_Annot::Subtype::WIDGET);
+    // Normal text field.
+    m_pAnnot = iter.GetFirstAnnot();
+    ASSERT_TRUE(m_pAnnot);
+    ASSERT_EQ(CPDF_Annot::Subtype::WIDGET, m_pAnnot->GetAnnotSubtype());
+
+    // Read-only text field.
+    CPDFSDK_Annot* pAnnotReadOnly = iter.GetNextAnnot(m_pAnnot);
+
+    // Pre-filled text field with char limit of 10.
+    m_pAnnotCharLimit = iter.GetNextAnnot(pAnnotReadOnly);
+    ASSERT_TRUE(m_pAnnotCharLimit);
+    ASSERT_EQ(CPDF_Annot::Subtype::WIDGET,
+              m_pAnnotCharLimit->GetAnnotSubtype());
+    CPDFSDK_Annot* pLastAnnot = iter.GetLastAnnot();
+    ASSERT_EQ(m_pAnnotCharLimit, pLastAnnot);
+  }
 
+  void FormFillerAndWindowSetup(CPDFSDK_Annot* pAnnotTextField) {
     CFFL_InteractiveFormFiller* pInteractiveFormFiller =
-        pFormFillEnv->GetInteractiveFormFiller();
+        m_pFormFillEnv->GetInteractiveFormFiller();
     {
-      CPDFSDK_Annot::ObservedPtr pObserved(m_pAnnot);
+      CPDFSDK_Annot::ObservedPtr pObserved(pAnnotTextField);
       EXPECT_TRUE(pInteractiveFormFiller->OnSetFocus(&pObserved, 0));
     }
 
-    m_pFormFiller = pInteractiveFormFiller->GetFormFiller(m_pAnnot, false);
+    m_pFormFiller =
+        pInteractiveFormFiller->GetFormFiller(pAnnotTextField, false);
     ASSERT_TRUE(m_pFormFiller);
 
     CPWL_Wnd* pWindow =
-        m_pFormFiller->GetPDFWindow(pFormFillEnv->GetPageView(0), false);
+        m_pFormFiller->GetPDFWindow(m_pFormFillEnv->GetPageView(0), false);
     ASSERT_TRUE(pWindow);
     ASSERT_EQ(PWL_CLASSNAME_EDIT, pWindow->GetClassName());
 
@@ -70,15 +79,19 @@ class CPWLEditEmbeddertest : public EmbedderTest {
   CPWL_Edit* GetCPWLEdit() { return m_pEdit; }
   CFFL_FormFiller* GetCFFLFormFiller() { return m_pFormFiller; }
   CPDFSDK_Annot* GetCPDFSDKAnnot() { return m_pAnnot; }
+  CPDFSDK_Annot* GetCPDFSDKAnnotCharLimit() { return m_pAnnotCharLimit; }
 
  private:
   FPDF_PAGE m_page;
   CPWL_Edit* m_pEdit;
   CFFL_FormFiller* m_pFormFiller;
   CPDFSDK_Annot* m_pAnnot;
+  CPDFSDK_Annot* m_pAnnotCharLimit;
+  CPDFSDK_FormFillEnvironment* m_pFormFillEnv;
 };
 
 TEST_F(CPWLEditEmbeddertest, TypeText) {
+  FormFillerAndWindowSetup(GetCPDFSDKAnnot());
   EXPECT_TRUE(GetCPWLEdit()->GetText().IsEmpty());
   EXPECT_TRUE(GetCFFLFormFiller()->OnChar(GetCPDFSDKAnnot(), 'a', 0));
   EXPECT_TRUE(GetCFFLFormFiller()->OnChar(GetCPDFSDKAnnot(), 'b', 0));
@@ -88,6 +101,7 @@ TEST_F(CPWLEditEmbeddertest, TypeText) {
 }
 
 TEST_F(CPWLEditEmbeddertest, GetSelectedTextEmptyAndBasic) {
+  FormFillerAndWindowSetup(GetCPDFSDKAnnot());
   // Attempt to set selection before text has been typed to test that
   // selection is identified as empty.
   //
@@ -104,6 +118,7 @@ TEST_F(CPWLEditEmbeddertest, GetSelectedTextEmptyAndBasic) {
 }
 
 TEST_F(CPWLEditEmbeddertest, GetSelectedTextFragments) {
+  FormFillerAndWindowSetup(GetCPDFSDKAnnot());
   TypeTextIntoTextField(50);
 
   GetCPWLEdit()->SetSelection(0, 0);
@@ -133,53 +148,226 @@ TEST_F(CPWLEditEmbeddertest, GetSelectedTextFragments) {
 }
 
 TEST_F(CPWLEditEmbeddertest, DeleteEntireTextSelection) {
+  FormFillerAndWindowSetup(GetCPDFSDKAnnot());
   TypeTextIntoTextField(50);
 
   GetCPWLEdit()->SetSelection(0, -1);
   EXPECT_STREQ(L"ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqr",
                GetCPWLEdit()->GetSelectedText().c_str());
 
-  GetCPWLEdit()->DeleteSelectedText();
+  GetCPWLEdit()->ReplaceSelection(CFX_WideString());
   EXPECT_TRUE(GetCPWLEdit()->GetText().IsEmpty());
 }
 
 TEST_F(CPWLEditEmbeddertest, DeleteTextSelectionMiddle) {
+  FormFillerAndWindowSetup(GetCPDFSDKAnnot());
   TypeTextIntoTextField(50);
 
   GetCPWLEdit()->SetSelection(12, 23);
   EXPECT_STREQ(L"MNOPQRSTUVW", GetCPWLEdit()->GetSelectedText().c_str());
 
-  GetCPWLEdit()->DeleteSelectedText();
+  GetCPWLEdit()->ReplaceSelection(CFX_WideString());
   EXPECT_STREQ(L"ABCDEFGHIJKLXYZ[\\]^_`abcdefghijklmnopqr",
                GetCPWLEdit()->GetText().c_str());
 }
 
 TEST_F(CPWLEditEmbeddertest, DeleteTextSelectionLeft) {
+  FormFillerAndWindowSetup(GetCPDFSDKAnnot());
   TypeTextIntoTextField(50);
 
   GetCPWLEdit()->SetSelection(0, 5);
   EXPECT_STREQ(L"ABCDE", GetCPWLEdit()->GetSelectedText().c_str());
 
-  GetCPWLEdit()->DeleteSelectedText();
+  GetCPWLEdit()->ReplaceSelection(CFX_WideString());
   EXPECT_STREQ(L"FGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqr",
                GetCPWLEdit()->GetText().c_str());
 }
 
 TEST_F(CPWLEditEmbeddertest, DeleteTextSelectionRight) {
+  FormFillerAndWindowSetup(GetCPDFSDKAnnot());
   TypeTextIntoTextField(50);
 
   GetCPWLEdit()->SetSelection(45, 50);
   EXPECT_STREQ(L"nopqr", GetCPWLEdit()->GetSelectedText().c_str());
 
-  GetCPWLEdit()->DeleteSelectedText();
+  GetCPWLEdit()->ReplaceSelection(CFX_WideString());
   EXPECT_STREQ(L"ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklm",
                GetCPWLEdit()->GetText().c_str());
 }
 
 TEST_F(CPWLEditEmbeddertest, DeleteEmptyTextSelection) {
+  FormFillerAndWindowSetup(GetCPDFSDKAnnot());
   TypeTextIntoTextField(50);
 
-  GetCPWLEdit()->DeleteSelectedText();
+  GetCPWLEdit()->ReplaceSelection(CFX_WideString());
   EXPECT_STREQ(L"ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqr",
                GetCPWLEdit()->GetText().c_str());
 }
+
+TEST_F(CPWLEditEmbeddertest, InsertTextInEmptyTextField) {
+  FormFillerAndWindowSetup(GetCPDFSDKAnnot());
+  GetCPWLEdit()->ReplaceSelection(CFX_WideString(L"Hello"));
+  EXPECT_STREQ(L"Hello", GetCPWLEdit()->GetText().c_str());
+}
+
+TEST_F(CPWLEditEmbeddertest, InsertTextInPopulatedTextFieldLeft) {
+  FormFillerAndWindowSetup(GetCPDFSDKAnnot());
+  TypeTextIntoTextField(10);
+
+  // Move cursor to beginning of text field.
+  EXPECT_TRUE(
+      GetCFFLFormFiller()->OnKeyDown(GetCPDFSDKAnnot(), FWL_VKEY_Home, 0));
+
+  GetCPWLEdit()->ReplaceSelection(CFX_WideString(L"Hello"));
+  EXPECT_STREQ(L"HelloABCDEFGHIJ", GetCPWLEdit()->GetText().c_str());
+}
+
+TEST_F(CPWLEditEmbeddertest, InsertTextInPopulatedTextFieldMiddle) {
+  FormFillerAndWindowSetup(GetCPDFSDKAnnot());
+  TypeTextIntoTextField(10);
+
+  // Move cursor to middle of text field.
+  for (int i = 0; i < 5; ++i) {
+    EXPECT_TRUE(
+        GetCFFLFormFiller()->OnKeyDown(GetCPDFSDKAnnot(), FWL_VKEY_Left, 0));
+  }
+
+  GetCPWLEdit()->ReplaceSelection(CFX_WideString(L"Hello"));
+  EXPECT_STREQ(L"ABCDEHelloFGHIJ", GetCPWLEdit()->GetText().c_str());
+}
+
+TEST_F(CPWLEditEmbeddertest, InsertTextInPopulatedTextFieldRight) {
+  FormFillerAndWindowSetup(GetCPDFSDKAnnot());
+  TypeTextIntoTextField(10);
+
+  GetCPWLEdit()->ReplaceSelection(CFX_WideString(L"Hello"));
+  EXPECT_STREQ(L"ABCDEFGHIJHello", GetCPWLEdit()->GetText().c_str());
+}
+
+TEST_F(CPWLEditEmbeddertest,
+       InsertTextAndReplaceSelectionInPopulatedTextFieldWhole) {
+  FormFillerAndWindowSetup(GetCPDFSDKAnnot());
+  TypeTextIntoTextField(10);
+
+  GetCPWLEdit()->SetSelection(0, -1);
+  EXPECT_STREQ(L"ABCDEFGHIJ", GetCPWLEdit()->GetSelectedText().c_str());
+  GetCPWLEdit()->ReplaceSelection(CFX_WideString(L"Hello"));
+  EXPECT_STREQ(L"Hello", GetCPWLEdit()->GetText().c_str());
+}
+
+TEST_F(CPWLEditEmbeddertest,
+       InsertTextAndReplaceSelectionInPopulatedTextFieldLeft) {
+  FormFillerAndWindowSetup(GetCPDFSDKAnnot());
+  TypeTextIntoTextField(10);
+
+  GetCPWLEdit()->SetSelection(0, 5);
+  EXPECT_STREQ(L"ABCDE", GetCPWLEdit()->GetSelectedText().c_str());
+  GetCPWLEdit()->ReplaceSelection(CFX_WideString(L"Hello"));
+  EXPECT_STREQ(L"HelloFGHIJ", GetCPWLEdit()->GetText().c_str());
+}
+
+TEST_F(CPWLEditEmbeddertest,
+       InsertTextAndReplaceSelectionInPopulatedTextFieldMiddle) {
+  FormFillerAndWindowSetup(GetCPDFSDKAnnot());
+  TypeTextIntoTextField(10);
+
+  GetCPWLEdit()->SetSelection(2, 7);
+  EXPECT_STREQ(L"CDEFG", GetCPWLEdit()->GetSelectedText().c_str());
+  GetCPWLEdit()->ReplaceSelection(CFX_WideString(L"Hello"));
+  EXPECT_STREQ(L"ABHelloHIJ", GetCPWLEdit()->GetText().c_str());
+}
+
+TEST_F(CPWLEditEmbeddertest,
+       InsertTextAndReplaceSelectionInPopulatedTextFieldRight) {
+  FormFillerAndWindowSetup(GetCPDFSDKAnnot());
+  TypeTextIntoTextField(10);
+
+  GetCPWLEdit()->SetSelection(5, 10);
+  EXPECT_STREQ(L"FGHIJ", GetCPWLEdit()->GetSelectedText().c_str());
+  GetCPWLEdit()->ReplaceSelection(CFX_WideString(L"Hello"));
+  EXPECT_STREQ(L"ABCDEHello", GetCPWLEdit()->GetText().c_str());
+}
+
+TEST_F(CPWLEditEmbeddertest, InsertTextInEmptyCharLimitTextFieldOverflow) {
+  FormFillerAndWindowSetup(GetCPDFSDKAnnotCharLimit());
+  GetCPWLEdit()->SetSelection(0, -1);
+  EXPECT_STREQ(L"Elephant", GetCPWLEdit()->GetSelectedText().c_str());
+  GetCPWLEdit()->ReplaceSelection(CFX_WideString());
+
+  GetCPWLEdit()->ReplaceSelection(CFX_WideString(L"Hippopotamus"));
+  EXPECT_STREQ(L"Hippopotam", GetCPWLEdit()->GetText().c_str());
+}
+
+TEST_F(CPWLEditEmbeddertest, InsertTextInEmptyCharLimitTextFieldFit) {
+  FormFillerAndWindowSetup(GetCPDFSDKAnnotCharLimit());
+  GetCPWLEdit()->SetSelection(0, -1);
+  EXPECT_STREQ(L"Elephant", GetCPWLEdit()->GetSelectedText().c_str());
+  GetCPWLEdit()->ReplaceSelection(CFX_WideString());
+
+  GetCPWLEdit()->ReplaceSelection(CFX_WideString(L"Zebra"));
+  EXPECT_STREQ(L"Zebra", GetCPWLEdit()->GetText().c_str());
+}
+
+TEST_F(CPWLEditEmbeddertest, InsertTextInPopulatedCharLimitTextFieldLeft) {
+  FormFillerAndWindowSetup(GetCPDFSDKAnnotCharLimit());
+  GetCPWLEdit()->ReplaceSelection(CFX_WideString(L"Hippopotamus"));
+  EXPECT_STREQ(L"HiElephant", GetCPWLEdit()->GetText().c_str());
+}
+
+TEST_F(CPWLEditEmbeddertest, InsertTextInPopulatedCharLimitTextFieldMiddle) {
+  FormFillerAndWindowSetup(GetCPDFSDKAnnotCharLimit());
+  // Move cursor to middle of text field.
+  for (int i = 0; i < 5; ++i) {
+    EXPECT_TRUE(GetCFFLFormFiller()->OnKeyDown(GetCPDFSDKAnnotCharLimit(),
+                                               FWL_VKEY_Right, 0));
+  }
+
+  GetCPWLEdit()->ReplaceSelection(CFX_WideString(L"Hippopotamus"));
+  EXPECT_STREQ(L"ElephHiant", GetCPWLEdit()->GetText().c_str());
+}
+
+TEST_F(CPWLEditEmbeddertest, InsertTextInPopulatedCharLimitTextFieldRight) {
+  FormFillerAndWindowSetup(GetCPDFSDKAnnotCharLimit());
+  // Move cursor to end of text field.
+  EXPECT_TRUE(GetCFFLFormFiller()->OnKeyDown(GetCPDFSDKAnnotCharLimit(),
+                                             FWL_VKEY_End, 0));
+
+  GetCPWLEdit()->ReplaceSelection(CFX_WideString(L"Hippopotamus"));
+  EXPECT_STREQ(L"ElephantHi", GetCPWLEdit()->GetText().c_str());
+}
+
+TEST_F(CPWLEditEmbeddertest,
+       InsertTextAndReplaceSelectionInPopulatedCharLimitTextFieldWhole) {
+  FormFillerAndWindowSetup(GetCPDFSDKAnnotCharLimit());
+  GetCPWLEdit()->SetSelection(0, -1);
+  EXPECT_STREQ(L"Elephant", GetCPWLEdit()->GetSelectedText().c_str());
+  GetCPWLEdit()->ReplaceSelection(CFX_WideString(L"Hippopotamus"));
+  EXPECT_STREQ(L"Hippopotam", GetCPWLEdit()->GetText().c_str());
+}
+
+TEST_F(CPWLEditEmbeddertest,
+       InsertTextAndReplaceSelectionInPopulatedCharLimitTextFieldLeft) {
+  FormFillerAndWindowSetup(GetCPDFSDKAnnotCharLimit());
+  GetCPWLEdit()->SetSelection(0, 4);
+  EXPECT_STREQ(L"Elep", GetCPWLEdit()->GetSelectedText().c_str());
+  GetCPWLEdit()->ReplaceSelection(CFX_WideString(L"Hippopotamus"));
+  EXPECT_STREQ(L"Hippophant", GetCPWLEdit()->GetText().c_str());
+}
+
+TEST_F(CPWLEditEmbeddertest,
+       InsertTextAndReplaceSelectionInPopulatedCharLimitTextFieldMiddle) {
+  FormFillerAndWindowSetup(GetCPDFSDKAnnotCharLimit());
+  GetCPWLEdit()->SetSelection(2, 6);
+  EXPECT_STREQ(L"epha", GetCPWLEdit()->GetSelectedText().c_str());
+  GetCPWLEdit()->ReplaceSelection(CFX_WideString(L"Hippopotamus"));
+  EXPECT_STREQ(L"ElHippopnt", GetCPWLEdit()->GetText().c_str());
+}
+
+TEST_F(CPWLEditEmbeddertest,
+       InsertTextAndReplaceSelectionInPopulatedCharLimitTextFieldRight) {
+  FormFillerAndWindowSetup(GetCPDFSDKAnnotCharLimit());
+  GetCPWLEdit()->SetSelection(4, 8);
+  EXPECT_STREQ(L"hant", GetCPWLEdit()->GetSelectedText().c_str());
+  GetCPWLEdit()->ReplaceSelection(CFX_WideString(L"Hippopotamus"));
+  EXPECT_STREQ(L"ElepHippop", GetCPWLEdit()->GetText().c_str());
+}
diff --git a/fpdfsdk/pwl/cpwl_wnd.cpp b/fpdfsdk/pwl/cpwl_wnd.cpp
index 2269162260..c7bf23ce60 100644
--- a/fpdfsdk/pwl/cpwl_wnd.cpp
+++ b/fpdfsdk/pwl/cpwl_wnd.cpp
@@ -369,7 +369,7 @@ CFX_WideString CPWL_Wnd::GetSelectedText() {
   return CFX_WideString();
 }
 
-void CPWL_Wnd::DeleteSelectedText() {}
+void CPWL_Wnd::ReplaceSelection(const CFX_WideString& text) {}
 
 bool CPWL_Wnd::OnMouseWheel(short zDelta,
                             const CFX_PointF& point,
diff --git a/fpdfsdk/pwl/cpwl_wnd.h b/fpdfsdk/pwl/cpwl_wnd.h
index 7c93216a58..15487a3c07 100644
--- a/fpdfsdk/pwl/cpwl_wnd.h
+++ b/fpdfsdk/pwl/cpwl_wnd.h
@@ -202,7 +202,7 @@ class CPWL_Wnd : public CPWL_TimerHandler, public CFX_Observable<CPWL_Wnd> {
   virtual float GetFontSize() const;
 
   virtual CFX_WideString GetSelectedText();
-  virtual void DeleteSelectedText();
+  virtual void ReplaceSelection(const CFX_WideString& text);
   virtual CFX_FloatRect GetFocusRect() const;
   virtual CFX_FloatRect GetClientRect() const;